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linux/io_uring/io_uring.c
Pavel Begunkov c98c81a4ac io_uring: merge conditional unlock flush helpers 
There is no reason not to use __io_cq_unlock_post_flush for intermediate
aux CQE flushing, all ->task_complete should apply there, i.e. if set it
should be the submitter task. Combine them, get rid of of
__io_cq_unlock_post() and rename the left function.

This place was also taking a couple percents of CPU according to
profiles for max throughput net benchmarks due to multishot recv
flooding it with completions.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/bbed60734cbec2e833d9c7bdcf9741aada5d8aab.1687518903.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-06-23 08:19:40 -06:00

4583 lines
119 KiB
C
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// SPDX-License-Identifier: GPL-2.0
/*
* Shared application/kernel submission and completion ring pairs, for
* supporting fast/efficient IO.
*
* A note on the read/write ordering memory barriers that are matched between
* the application and kernel side.
*
* After the application reads the CQ ring tail, it must use an
* appropriate smp_rmb() to pair with the smp_wmb() the kernel uses
* before writing the tail (using smp_load_acquire to read the tail will
* do). It also needs a smp_mb() before updating CQ head (ordering the
* entry load(s) with the head store), pairing with an implicit barrier
* through a control-dependency in io_get_cqe (smp_store_release to
* store head will do). Failure to do so could lead to reading invalid
* CQ entries.
*
* Likewise, the application must use an appropriate smp_wmb() before
* writing the SQ tail (ordering SQ entry stores with the tail store),
* which pairs with smp_load_acquire in io_get_sqring (smp_store_release
* to store the tail will do). And it needs a barrier ordering the SQ
* head load before writing new SQ entries (smp_load_acquire to read
* head will do).
*
* When using the SQ poll thread (IORING_SETUP_SQPOLL), the application
* needs to check the SQ flags for IORING_SQ_NEED_WAKEUP *after*
* updating the SQ tail; a full memory barrier smp_mb() is needed
* between.
*
* Also see the examples in the liburing library:
*
* git://git.kernel.dk/liburing
*
* io_uring also uses READ/WRITE_ONCE() for _any_ store or load that happens
* from data shared between the kernel and application. This is done both
* for ordering purposes, but also to ensure that once a value is loaded from
* data that the application could potentially modify, it remains stable.
*
* Copyright (C) 2018-2019 Jens Axboe
* Copyright (c) 2018-2019 Christoph Hellwig
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/syscalls.h>
#include <net/compat.h>
#include <linux/refcount.h>
#include <linux/uio.h>
#include <linux/bits.h>
#include <linux/sched/signal.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/fdtable.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/percpu.h>
#include <linux/slab.h>
#include <linux/bvec.h>
#include <linux/net.h>
#include <net/sock.h>
#include <net/af_unix.h>
#include <net/scm.h>
#include <linux/anon_inodes.h>
#include <linux/sched/mm.h>
#include <linux/uaccess.h>
#include <linux/nospec.h>
#include <linux/highmem.h>
#include <linux/fsnotify.h>
#include <linux/fadvise.h>
#include <linux/task_work.h>
#include <linux/io_uring.h>
#include <linux/audit.h>
#include <linux/security.h>
#include <asm/shmparam.h>
#define CREATE_TRACE_POINTS
#include <trace/events/io_uring.h>
#include <uapi/linux/io_uring.h>
#include "io-wq.h"
#include "io_uring.h"
#include "opdef.h"
#include "refs.h"
#include "tctx.h"
#include "sqpoll.h"
#include "fdinfo.h"
#include "kbuf.h"
#include "rsrc.h"
#include "cancel.h"
#include "net.h"
#include "notif.h"
#include "timeout.h"
#include "poll.h"
#include "rw.h"
#include "alloc_cache.h"
#define IORING_MAX_ENTRIES 32768
#define IORING_MAX_CQ_ENTRIES (2 * IORING_MAX_ENTRIES)
#define IORING_MAX_RESTRICTIONS (IORING_RESTRICTION_LAST + \
IORING_REGISTER_LAST + IORING_OP_LAST)
#define SQE_COMMON_FLAGS (IOSQE_FIXED_FILE | IOSQE_IO_LINK | \
IOSQE_IO_HARDLINK | IOSQE_ASYNC)
#define SQE_VALID_FLAGS (SQE_COMMON_FLAGS | IOSQE_BUFFER_SELECT | \
IOSQE_IO_DRAIN | IOSQE_CQE_SKIP_SUCCESS)
#define IO_REQ_CLEAN_FLAGS (REQ_F_BUFFER_SELECTED | REQ_F_NEED_CLEANUP | \
REQ_F_POLLED | REQ_F_INFLIGHT | REQ_F_CREDS | \
REQ_F_ASYNC_DATA)
#define IO_REQ_CLEAN_SLOW_FLAGS (REQ_F_REFCOUNT | REQ_F_LINK | REQ_F_HARDLINK |\
IO_REQ_CLEAN_FLAGS)
#define IO_TCTX_REFS_CACHE_NR (1U << 10)
#define IO_COMPL_BATCH 32
#define IO_REQ_ALLOC_BATCH 8
enum {
IO_CHECK_CQ_OVERFLOW_BIT,
IO_CHECK_CQ_DROPPED_BIT,
};
enum {
IO_EVENTFD_OP_SIGNAL_BIT,
IO_EVENTFD_OP_FREE_BIT,
};
struct io_defer_entry {
struct list_head list;
struct io_kiocb *req;
u32 seq;
};
/* requests with any of those set should undergo io_disarm_next() */
#define IO_DISARM_MASK (REQ_F_ARM_LTIMEOUT | REQ_F_LINK_TIMEOUT | REQ_F_FAIL)
#define IO_REQ_LINK_FLAGS (REQ_F_LINK | REQ_F_HARDLINK)
static bool io_uring_try_cancel_requests(struct io_ring_ctx *ctx,
struct task_struct *task,
bool cancel_all);
static void io_queue_sqe(struct io_kiocb *req);
static void io_move_task_work_from_local(struct io_ring_ctx *ctx);
static void __io_submit_flush_completions(struct io_ring_ctx *ctx);
static __cold void io_fallback_tw(struct io_uring_task *tctx);
struct kmem_cache *req_cachep;
struct sock *io_uring_get_socket(struct file *file)
{
#if defined(CONFIG_UNIX)
if (io_is_uring_fops(file)) {
struct io_ring_ctx *ctx = file->private_data;
return ctx->ring_sock->sk;
}
#endif
return NULL;
}
EXPORT_SYMBOL(io_uring_get_socket);
static inline void io_submit_flush_completions(struct io_ring_ctx *ctx)
{
if (!wq_list_empty(&ctx->submit_state.compl_reqs) ||
ctx->submit_state.cqes_count)
__io_submit_flush_completions(ctx);
}
static inline unsigned int __io_cqring_events(struct io_ring_ctx *ctx)
{
return ctx->cached_cq_tail - READ_ONCE(ctx->rings->cq.head);
}
static inline unsigned int __io_cqring_events_user(struct io_ring_ctx *ctx)
{
return READ_ONCE(ctx->rings->cq.tail) - READ_ONCE(ctx->rings->cq.head);
}
static bool io_match_linked(struct io_kiocb *head)
{
struct io_kiocb *req;
io_for_each_link(req, head) {
if (req->flags & REQ_F_INFLIGHT)
return true;
}
return false;
}
/*
* As io_match_task() but protected against racing with linked timeouts.
* User must not hold timeout_lock.
*/
bool io_match_task_safe(struct io_kiocb *head, struct task_struct *task,
bool cancel_all)
{
bool matched;
if (task && head->task != task)
return false;
if (cancel_all)
return true;
if (head->flags & REQ_F_LINK_TIMEOUT) {
struct io_ring_ctx *ctx = head->ctx;
/* protect against races with linked timeouts */
spin_lock_irq(&ctx->timeout_lock);
matched = io_match_linked(head);
spin_unlock_irq(&ctx->timeout_lock);
} else {
matched = io_match_linked(head);
}
return matched;
}
static inline void req_fail_link_node(struct io_kiocb *req, int res)
{
req_set_fail(req);
io_req_set_res(req, res, 0);
}
static inline void io_req_add_to_cache(struct io_kiocb *req, struct io_ring_ctx *ctx)
{
wq_stack_add_head(&req->comp_list, &ctx->submit_state.free_list);
kasan_poison_object_data(req_cachep, req);
}
static __cold void io_ring_ctx_ref_free(struct percpu_ref *ref)
{
struct io_ring_ctx *ctx = container_of(ref, struct io_ring_ctx, refs);
complete(&ctx->ref_comp);
}
static __cold void io_fallback_req_func(struct work_struct *work)
{
struct io_ring_ctx *ctx = container_of(work, struct io_ring_ctx,
fallback_work.work);
struct llist_node *node = llist_del_all(&ctx->fallback_llist);
struct io_kiocb *req, *tmp;
struct io_tw_state ts = { .locked = true, };
mutex_lock(&ctx->uring_lock);
llist_for_each_entry_safe(req, tmp, node, io_task_work.node)
req->io_task_work.func(req, &ts);
if (WARN_ON_ONCE(!ts.locked))
return;
io_submit_flush_completions(ctx);
mutex_unlock(&ctx->uring_lock);
}
static int io_alloc_hash_table(struct io_hash_table *table, unsigned bits)
{
unsigned hash_buckets = 1U << bits;
size_t hash_size = hash_buckets * sizeof(table->hbs[0]);
table->hbs = kmalloc(hash_size, GFP_KERNEL);
if (!table->hbs)
return -ENOMEM;
table->hash_bits = bits;
init_hash_table(table, hash_buckets);
return 0;
}
static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
{
struct io_ring_ctx *ctx;
int hash_bits;
ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
if (!ctx)
return NULL;
xa_init(&ctx->io_bl_xa);
/*
* Use 5 bits less than the max cq entries, that should give us around
* 32 entries per hash list if totally full and uniformly spread, but
* don't keep too many buckets to not overconsume memory.
*/
hash_bits = ilog2(p->cq_entries) - 5;
hash_bits = clamp(hash_bits, 1, 8);
if (io_alloc_hash_table(&ctx->cancel_table, hash_bits))
goto err;
if (io_alloc_hash_table(&ctx->cancel_table_locked, hash_bits))
goto err;
ctx->dummy_ubuf = kzalloc(sizeof(*ctx->dummy_ubuf), GFP_KERNEL);
if (!ctx->dummy_ubuf)
goto err;
/* set invalid range, so io_import_fixed() fails meeting it */
ctx->dummy_ubuf->ubuf = -1UL;
if (percpu_ref_init(&ctx->refs, io_ring_ctx_ref_free,
0, GFP_KERNEL))
goto err;
ctx->flags = p->flags;
init_waitqueue_head(&ctx->sqo_sq_wait);
INIT_LIST_HEAD(&ctx->sqd_list);
INIT_LIST_HEAD(&ctx->cq_overflow_list);
INIT_LIST_HEAD(&ctx->io_buffers_cache);
io_alloc_cache_init(&ctx->rsrc_node_cache, IO_NODE_ALLOC_CACHE_MAX,
sizeof(struct io_rsrc_node));
io_alloc_cache_init(&ctx->apoll_cache, IO_ALLOC_CACHE_MAX,
sizeof(struct async_poll));
io_alloc_cache_init(&ctx->netmsg_cache, IO_ALLOC_CACHE_MAX,
sizeof(struct io_async_msghdr));
init_completion(&ctx->ref_comp);
xa_init_flags(&ctx->personalities, XA_FLAGS_ALLOC1);
mutex_init(&ctx->uring_lock);
init_waitqueue_head(&ctx->cq_wait);
init_waitqueue_head(&ctx->poll_wq);
init_waitqueue_head(&ctx->rsrc_quiesce_wq);
spin_lock_init(&ctx->completion_lock);
spin_lock_init(&ctx->timeout_lock);
INIT_WQ_LIST(&ctx->iopoll_list);
INIT_LIST_HEAD(&ctx->io_buffers_pages);
INIT_LIST_HEAD(&ctx->io_buffers_comp);
INIT_LIST_HEAD(&ctx->defer_list);
INIT_LIST_HEAD(&ctx->timeout_list);
INIT_LIST_HEAD(&ctx->ltimeout_list);
INIT_LIST_HEAD(&ctx->rsrc_ref_list);
init_llist_head(&ctx->work_llist);
INIT_LIST_HEAD(&ctx->tctx_list);
ctx->submit_state.free_list.next = NULL;
INIT_WQ_LIST(&ctx->locked_free_list);
INIT_DELAYED_WORK(&ctx->fallback_work, io_fallback_req_func);
INIT_WQ_LIST(&ctx->submit_state.compl_reqs);
return ctx;
err:
kfree(ctx->dummy_ubuf);
kfree(ctx->cancel_table.hbs);
kfree(ctx->cancel_table_locked.hbs);
kfree(ctx->io_bl);
xa_destroy(&ctx->io_bl_xa);
kfree(ctx);
return NULL;
}
static void io_account_cq_overflow(struct io_ring_ctx *ctx)
{
struct io_rings *r = ctx->rings;
WRITE_ONCE(r->cq_overflow, READ_ONCE(r->cq_overflow) + 1);
ctx->cq_extra--;
}
static bool req_need_defer(struct io_kiocb *req, u32 seq)
{
if (unlikely(req->flags & REQ_F_IO_DRAIN)) {
struct io_ring_ctx *ctx = req->ctx;
return seq + READ_ONCE(ctx->cq_extra) != ctx->cached_cq_tail;
}
return false;
}
static void io_clean_op(struct io_kiocb *req)
{
if (req->flags & REQ_F_BUFFER_SELECTED) {
spin_lock(&req->ctx->completion_lock);
io_put_kbuf_comp(req);
spin_unlock(&req->ctx->completion_lock);
}
if (req->flags & REQ_F_NEED_CLEANUP) {
const struct io_cold_def *def = &io_cold_defs[req->opcode];
if (def->cleanup)
def->cleanup(req);
}
if ((req->flags & REQ_F_POLLED) && req->apoll) {
kfree(req->apoll->double_poll);
kfree(req->apoll);
req->apoll = NULL;
}
if (req->flags & REQ_F_INFLIGHT) {
struct io_uring_task *tctx = req->task->io_uring;
atomic_dec(&tctx->inflight_tracked);
}
if (req->flags & REQ_F_CREDS)
put_cred(req->creds);
if (req->flags & REQ_F_ASYNC_DATA) {
kfree(req->async_data);
req->async_data = NULL;
}
req->flags &= ~IO_REQ_CLEAN_FLAGS;
}
static inline void io_req_track_inflight(struct io_kiocb *req)
{
if (!(req->flags & REQ_F_INFLIGHT)) {
req->flags |= REQ_F_INFLIGHT;
atomic_inc(&req->task->io_uring->inflight_tracked);
}
}
static struct io_kiocb *__io_prep_linked_timeout(struct io_kiocb *req)
{
if (WARN_ON_ONCE(!req->link))
return NULL;
req->flags &= ~REQ_F_ARM_LTIMEOUT;
req->flags |= REQ_F_LINK_TIMEOUT;
/* linked timeouts should have two refs once prep'ed */
io_req_set_refcount(req);
__io_req_set_refcount(req->link, 2);
return req->link;
}
static inline struct io_kiocb *io_prep_linked_timeout(struct io_kiocb *req)
{
if (likely(!(req->flags & REQ_F_ARM_LTIMEOUT)))
return NULL;
return __io_prep_linked_timeout(req);
}
static noinline void __io_arm_ltimeout(struct io_kiocb *req)
{
io_queue_linked_timeout(__io_prep_linked_timeout(req));
}
static inline void io_arm_ltimeout(struct io_kiocb *req)
{
if (unlikely(req->flags & REQ_F_ARM_LTIMEOUT))
__io_arm_ltimeout(req);
}
static void io_prep_async_work(struct io_kiocb *req)
{
const struct io_issue_def *def = &io_issue_defs[req->opcode];
struct io_ring_ctx *ctx = req->ctx;
if (!(req->flags & REQ_F_CREDS)) {
req->flags |= REQ_F_CREDS;
req->creds = get_current_cred();
}
req->work.list.next = NULL;
req->work.flags = 0;
req->work.cancel_seq = atomic_read(&ctx->cancel_seq);
if (req->flags & REQ_F_FORCE_ASYNC)
req->work.flags |= IO_WQ_WORK_CONCURRENT;
if (req->file && !(req->flags & REQ_F_FIXED_FILE))
req->flags |= io_file_get_flags(req->file);
if (req->file && (req->flags & REQ_F_ISREG)) {
bool should_hash = def->hash_reg_file;
/* don't serialize this request if the fs doesn't need it */
if (should_hash && (req->file->f_flags & O_DIRECT) &&
(req->file->f_mode & FMODE_DIO_PARALLEL_WRITE))
should_hash = false;
if (should_hash || (ctx->flags & IORING_SETUP_IOPOLL))
io_wq_hash_work(&req->work, file_inode(req->file));
} else if (!req->file || !S_ISBLK(file_inode(req->file)->i_mode)) {
if (def->unbound_nonreg_file)
req->work.flags |= IO_WQ_WORK_UNBOUND;
}
}
static void io_prep_async_link(struct io_kiocb *req)
{
struct io_kiocb *cur;
if (req->flags & REQ_F_LINK_TIMEOUT) {
struct io_ring_ctx *ctx = req->ctx;
spin_lock_irq(&ctx->timeout_lock);
io_for_each_link(cur, req)
io_prep_async_work(cur);
spin_unlock_irq(&ctx->timeout_lock);
} else {
io_for_each_link(cur, req)
io_prep_async_work(cur);
}
}
void io_queue_iowq(struct io_kiocb *req, struct io_tw_state *ts_dont_use)
{
struct io_kiocb *link = io_prep_linked_timeout(req);
struct io_uring_task *tctx = req->task->io_uring;
BUG_ON(!tctx);
BUG_ON(!tctx->io_wq);
/* init ->work of the whole link before punting */
io_prep_async_link(req);
/*
* Not expected to happen, but if we do have a bug where this _can_
* happen, catch it here and ensure the request is marked as
* canceled. That will make io-wq go through the usual work cancel
* procedure rather than attempt to run this request (or create a new
* worker for it).
*/
if (WARN_ON_ONCE(!same_thread_group(req->task, current)))
req->work.flags |= IO_WQ_WORK_CANCEL;
trace_io_uring_queue_async_work(req, io_wq_is_hashed(&req->work));
io_wq_enqueue(tctx->io_wq, &req->work);
if (link)
io_queue_linked_timeout(link);
}
static __cold void io_queue_deferred(struct io_ring_ctx *ctx)
{
while (!list_empty(&ctx->defer_list)) {
struct io_defer_entry *de = list_first_entry(&ctx->defer_list,
struct io_defer_entry, list);
if (req_need_defer(de->req, de->seq))
break;
list_del_init(&de->list);
io_req_task_queue(de->req);
kfree(de);
}
}
static void io_eventfd_ops(struct rcu_head *rcu)
{
struct io_ev_fd *ev_fd = container_of(rcu, struct io_ev_fd, rcu);
int ops = atomic_xchg(&ev_fd->ops, 0);
if (ops & BIT(IO_EVENTFD_OP_SIGNAL_BIT))
eventfd_signal_mask(ev_fd->cq_ev_fd, 1, EPOLL_URING_WAKE);
/* IO_EVENTFD_OP_FREE_BIT may not be set here depending on callback
* ordering in a race but if references are 0 we know we have to free
* it regardless.
*/
if (atomic_dec_and_test(&ev_fd->refs)) {
eventfd_ctx_put(ev_fd->cq_ev_fd);
kfree(ev_fd);
}
}
static void io_eventfd_signal(struct io_ring_ctx *ctx)
{
struct io_ev_fd *ev_fd = NULL;
rcu_read_lock();
/*
* rcu_dereference ctx->io_ev_fd once and use it for both for checking
* and eventfd_signal
*/
ev_fd = rcu_dereference(ctx->io_ev_fd);
/*
* Check again if ev_fd exists incase an io_eventfd_unregister call
* completed between the NULL check of ctx->io_ev_fd at the start of
* the function and rcu_read_lock.
*/
if (unlikely(!ev_fd))
goto out;
if (READ_ONCE(ctx->rings->cq_flags) & IORING_CQ_EVENTFD_DISABLED)
goto out;
if (ev_fd->eventfd_async && !io_wq_current_is_worker())
goto out;
if (likely(eventfd_signal_allowed())) {
eventfd_signal_mask(ev_fd->cq_ev_fd, 1, EPOLL_URING_WAKE);
} else {
atomic_inc(&ev_fd->refs);
if (!atomic_fetch_or(BIT(IO_EVENTFD_OP_SIGNAL_BIT), &ev_fd->ops))
call_rcu_hurry(&ev_fd->rcu, io_eventfd_ops);
else
atomic_dec(&ev_fd->refs);
}
out:
rcu_read_unlock();
}
static void io_eventfd_flush_signal(struct io_ring_ctx *ctx)
{
bool skip;
spin_lock(&ctx->completion_lock);
/*
* Eventfd should only get triggered when at least one event has been
* posted. Some applications rely on the eventfd notification count
* only changing IFF a new CQE has been added to the CQ ring. There's
* no depedency on 1:1 relationship between how many times this
* function is called (and hence the eventfd count) and number of CQEs
* posted to the CQ ring.
*/
skip = ctx->cached_cq_tail == ctx->evfd_last_cq_tail;
ctx->evfd_last_cq_tail = ctx->cached_cq_tail;
spin_unlock(&ctx->completion_lock);
if (skip)
return;
io_eventfd_signal(ctx);
}
void __io_commit_cqring_flush(struct io_ring_ctx *ctx)
{
if (ctx->poll_activated)
io_poll_wq_wake(ctx);
if (ctx->off_timeout_used)
io_flush_timeouts(ctx);
if (ctx->drain_active) {
spin_lock(&ctx->completion_lock);
io_queue_deferred(ctx);
spin_unlock(&ctx->completion_lock);
}
if (ctx->has_evfd)
io_eventfd_flush_signal(ctx);
}
static inline void __io_cq_lock(struct io_ring_ctx *ctx)
{
if (!ctx->task_complete)
spin_lock(&ctx->completion_lock);
}
static inline void io_cq_lock(struct io_ring_ctx *ctx)
__acquires(ctx->completion_lock)
{
spin_lock(&ctx->completion_lock);
}
static inline void __io_cq_unlock_post(struct io_ring_ctx *ctx)
{
io_commit_cqring(ctx);
if (ctx->task_complete) {
/*
* ->task_complete implies that only current might be waiting
* for CQEs, and obviously, we currently don't. No one is
* waiting, wakeups are futile, skip them.
*/
io_commit_cqring_flush(ctx);
} else {
spin_unlock(&ctx->completion_lock);
io_commit_cqring_flush(ctx);
io_cqring_wake(ctx);
}
}
static void io_cq_unlock_post(struct io_ring_ctx *ctx)
__releases(ctx->completion_lock)
{
io_commit_cqring(ctx);
spin_unlock(&ctx->completion_lock);
io_commit_cqring_flush(ctx);
io_cqring_wake(ctx);
}
/* Returns true if there are no backlogged entries after the flush */
static void io_cqring_overflow_kill(struct io_ring_ctx *ctx)
{
struct io_overflow_cqe *ocqe;
LIST_HEAD(list);
spin_lock(&ctx->completion_lock);
list_splice_init(&ctx->cq_overflow_list, &list);
clear_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq);
spin_unlock(&ctx->completion_lock);
while (!list_empty(&list)) {
ocqe = list_first_entry(&list, struct io_overflow_cqe, list);
list_del(&ocqe->list);
kfree(ocqe);
}
}
static void __io_cqring_overflow_flush(struct io_ring_ctx *ctx)
{
size_t cqe_size = sizeof(struct io_uring_cqe);
if (__io_cqring_events(ctx) == ctx->cq_entries)
return;
if (ctx->flags & IORING_SETUP_CQE32)
cqe_size <<= 1;
io_cq_lock(ctx);
while (!list_empty(&ctx->cq_overflow_list)) {
struct io_uring_cqe *cqe = io_get_cqe_overflow(ctx, true);
struct io_overflow_cqe *ocqe;
if (!cqe)
break;
ocqe = list_first_entry(&ctx->cq_overflow_list,
struct io_overflow_cqe, list);
memcpy(cqe, &ocqe->cqe, cqe_size);
list_del(&ocqe->list);
kfree(ocqe);
}
if (list_empty(&ctx->cq_overflow_list)) {
clear_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq);
atomic_andnot(IORING_SQ_CQ_OVERFLOW, &ctx->rings->sq_flags);
}
io_cq_unlock_post(ctx);
}
static void io_cqring_do_overflow_flush(struct io_ring_ctx *ctx)
{
/* iopoll syncs against uring_lock, not completion_lock */
if (ctx->flags & IORING_SETUP_IOPOLL)
mutex_lock(&ctx->uring_lock);
__io_cqring_overflow_flush(ctx);
if (ctx->flags & IORING_SETUP_IOPOLL)
mutex_unlock(&ctx->uring_lock);
}
static void io_cqring_overflow_flush(struct io_ring_ctx *ctx)
{
if (test_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq))
io_cqring_do_overflow_flush(ctx);
}
/* can be called by any task */
static void io_put_task_remote(struct task_struct *task)
{
struct io_uring_task *tctx = task->io_uring;
percpu_counter_sub(&tctx->inflight, 1);
if (unlikely(atomic_read(&tctx->in_cancel)))
wake_up(&tctx->wait);
put_task_struct(task);
}
/* used by a task to put its own references */
static void io_put_task_local(struct task_struct *task)
{
task->io_uring->cached_refs++;
}
/* must to be called somewhat shortly after putting a request */
static inline void io_put_task(struct task_struct *task)
{
if (likely(task == current))
io_put_task_local(task);
else
io_put_task_remote(task);
}
void io_task_refs_refill(struct io_uring_task *tctx)
{
unsigned int refill = -tctx->cached_refs + IO_TCTX_REFS_CACHE_NR;
percpu_counter_add(&tctx->inflight, refill);
refcount_add(refill, &current->usage);
tctx->cached_refs += refill;
}
static __cold void io_uring_drop_tctx_refs(struct task_struct *task)
{
struct io_uring_task *tctx = task->io_uring;
unsigned int refs = tctx->cached_refs;
if (refs) {
tctx->cached_refs = 0;
percpu_counter_sub(&tctx->inflight, refs);
put_task_struct_many(task, refs);
}
}
static bool io_cqring_event_overflow(struct io_ring_ctx *ctx, u64 user_data,
s32 res, u32 cflags, u64 extra1, u64 extra2)
{
struct io_overflow_cqe *ocqe;
size_t ocq_size = sizeof(struct io_overflow_cqe);
bool is_cqe32 = (ctx->flags & IORING_SETUP_CQE32);
lockdep_assert_held(&ctx->completion_lock);
if (is_cqe32)
ocq_size += sizeof(struct io_uring_cqe);
ocqe = kmalloc(ocq_size, GFP_ATOMIC | __GFP_ACCOUNT);
trace_io_uring_cqe_overflow(ctx, user_data, res, cflags, ocqe);
if (!ocqe) {
/*
* If we're in ring overflow flush mode, or in task cancel mode,
* or cannot allocate an overflow entry, then we need to drop it
* on the floor.
*/
io_account_cq_overflow(ctx);
set_bit(IO_CHECK_CQ_DROPPED_BIT, &ctx->check_cq);
return false;
}
if (list_empty(&ctx->cq_overflow_list)) {
set_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq);
atomic_or(IORING_SQ_CQ_OVERFLOW, &ctx->rings->sq_flags);
}
ocqe->cqe.user_data = user_data;
ocqe->cqe.res = res;
ocqe->cqe.flags = cflags;
if (is_cqe32) {
ocqe->cqe.big_cqe[0] = extra1;
ocqe->cqe.big_cqe[1] = extra2;
}
list_add_tail(&ocqe->list, &ctx->cq_overflow_list);
return true;
}
bool io_req_cqe_overflow(struct io_kiocb *req)
{
if (!(req->flags & REQ_F_CQE32_INIT)) {
req->extra1 = 0;
req->extra2 = 0;
}
return io_cqring_event_overflow(req->ctx, req->cqe.user_data,
req->cqe.res, req->cqe.flags,
req->extra1, req->extra2);
}
/*
* writes to the cq entry need to come after reading head; the
* control dependency is enough as we're using WRITE_ONCE to
* fill the cq entry
*/
struct io_uring_cqe *__io_get_cqe(struct io_ring_ctx *ctx, bool overflow)
{
struct io_rings *rings = ctx->rings;
unsigned int off = ctx->cached_cq_tail & (ctx->cq_entries - 1);
unsigned int free, queued, len;
/*
* Posting into the CQ when there are pending overflowed CQEs may break
* ordering guarantees, which will affect links, F_MORE users and more.
* Force overflow the completion.
*/
if (!overflow && (ctx->check_cq & BIT(IO_CHECK_CQ_OVERFLOW_BIT)))
return NULL;
/* userspace may cheat modifying the tail, be safe and do min */
queued = min(__io_cqring_events(ctx), ctx->cq_entries);
free = ctx->cq_entries - queued;
/* we need a contiguous range, limit based on the current array offset */
len = min(free, ctx->cq_entries - off);
if (!len)
return NULL;
if (ctx->flags & IORING_SETUP_CQE32) {
off <<= 1;
len <<= 1;
}
ctx->cqe_cached = &rings->cqes[off];
ctx->cqe_sentinel = ctx->cqe_cached + len;
ctx->cached_cq_tail++;
ctx->cqe_cached++;
if (ctx->flags & IORING_SETUP_CQE32)
ctx->cqe_cached++;
return &rings->cqes[off];
}
static bool io_fill_cqe_aux(struct io_ring_ctx *ctx, u64 user_data, s32 res,
u32 cflags)
{
struct io_uring_cqe *cqe;
ctx->cq_extra++;
/*
* If we can't get a cq entry, userspace overflowed the
* submission (by quite a lot). Increment the overflow count in
* the ring.
*/
cqe = io_get_cqe(ctx);
if (likely(cqe)) {
trace_io_uring_complete(ctx, NULL, user_data, res, cflags, 0, 0);
WRITE_ONCE(cqe->user_data, user_data);
WRITE_ONCE(cqe->res, res);
WRITE_ONCE(cqe->flags, cflags);
if (ctx->flags & IORING_SETUP_CQE32) {
WRITE_ONCE(cqe->big_cqe[0], 0);
WRITE_ONCE(cqe->big_cqe[1], 0);
}
return true;
}
return false;
}
static void __io_flush_post_cqes(struct io_ring_ctx *ctx)
__must_hold(&ctx->uring_lock)
{
struct io_submit_state *state = &ctx->submit_state;
unsigned int i;
lockdep_assert_held(&ctx->uring_lock);
for (i = 0; i < state->cqes_count; i++) {
struct io_uring_cqe *cqe = &state->cqes[i];
if (!io_fill_cqe_aux(ctx, cqe->user_data, cqe->res, cqe->flags)) {
if (ctx->task_complete) {
spin_lock(&ctx->completion_lock);
io_cqring_event_overflow(ctx, cqe->user_data,
cqe->res, cqe->flags, 0, 0);
spin_unlock(&ctx->completion_lock);
} else {
io_cqring_event_overflow(ctx, cqe->user_data,
cqe->res, cqe->flags, 0, 0);
}
}
}
state->cqes_count = 0;
}
static bool __io_post_aux_cqe(struct io_ring_ctx *ctx, u64 user_data, s32 res, u32 cflags,
bool allow_overflow)
{
bool filled;
io_cq_lock(ctx);
filled = io_fill_cqe_aux(ctx, user_data, res, cflags);
if (!filled && allow_overflow)
filled = io_cqring_event_overflow(ctx, user_data, res, cflags, 0, 0);
io_cq_unlock_post(ctx);
return filled;
}
bool io_post_aux_cqe(struct io_ring_ctx *ctx, u64 user_data, s32 res, u32 cflags)
{
return __io_post_aux_cqe(ctx, user_data, res, cflags, true);
}
bool io_aux_cqe(const struct io_kiocb *req, bool defer, s32 res, u32 cflags,
bool allow_overflow)
{
struct io_ring_ctx *ctx = req->ctx;
u64 user_data = req->cqe.user_data;
struct io_uring_cqe *cqe;
if (!defer)
return __io_post_aux_cqe(ctx, user_data, res, cflags, allow_overflow);
lockdep_assert_held(&ctx->uring_lock);
if (ctx->submit_state.cqes_count == ARRAY_SIZE(ctx->submit_state.cqes)) {
__io_cq_lock(ctx);
__io_flush_post_cqes(ctx);
/* no need to flush - flush is deferred */
__io_cq_unlock_post(ctx);
}
/* For defered completions this is not as strict as it is otherwise,
* however it's main job is to prevent unbounded posted completions,
* and in that it works just as well.
*/
if (!allow_overflow && test_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq))
return false;
cqe = &ctx->submit_state.cqes[ctx->submit_state.cqes_count++];
cqe->user_data = user_data;
cqe->res = res;
cqe->flags = cflags;
return true;
}
static void __io_req_complete_post(struct io_kiocb *req, unsigned issue_flags)
{
struct io_ring_ctx *ctx = req->ctx;
struct io_rsrc_node *rsrc_node = NULL;
io_cq_lock(ctx);
if (!(req->flags & REQ_F_CQE_SKIP))
io_fill_cqe_req(ctx, req);
/*
* If we're the last reference to this request, add to our locked
* free_list cache.
*/
if (req_ref_put_and_test(req)) {
if (req->flags & IO_REQ_LINK_FLAGS) {
if (req->flags & IO_DISARM_MASK)
io_disarm_next(req);
if (req->link) {
io_req_task_queue(req->link);
req->link = NULL;
}
}
io_put_kbuf_comp(req);
if (unlikely(req->flags & IO_REQ_CLEAN_FLAGS))
io_clean_op(req);
if (!(req->flags & REQ_F_FIXED_FILE))
io_put_file(req->file);
rsrc_node = req->rsrc_node;
/*
* Selected buffer deallocation in io_clean_op() assumes that
* we don't hold ->completion_lock. Clean them here to avoid
* deadlocks.
*/
io_put_task_remote(req->task);
wq_list_add_head(&req->comp_list, &ctx->locked_free_list);
ctx->locked_free_nr++;
}
io_cq_unlock_post(ctx);
if (rsrc_node) {
io_ring_submit_lock(ctx, issue_flags);
io_put_rsrc_node(ctx, rsrc_node);
io_ring_submit_unlock(ctx, issue_flags);
}
}
void io_req_complete_post(struct io_kiocb *req, unsigned issue_flags)
{
if (req->ctx->task_complete && req->ctx->submitter_task != current) {
req->io_task_work.func = io_req_task_complete;
io_req_task_work_add(req);
} else if (!(issue_flags & IO_URING_F_UNLOCKED) ||
!(req->ctx->flags & IORING_SETUP_IOPOLL)) {
__io_req_complete_post(req, issue_flags);
} else {
struct io_ring_ctx *ctx = req->ctx;
mutex_lock(&ctx->uring_lock);
__io_req_complete_post(req, issue_flags & ~IO_URING_F_UNLOCKED);
mutex_unlock(&ctx->uring_lock);
}
}
void io_req_defer_failed(struct io_kiocb *req, s32 res)
__must_hold(&ctx->uring_lock)
{
const struct io_cold_def *def = &io_cold_defs[req->opcode];
lockdep_assert_held(&req->ctx->uring_lock);
req_set_fail(req);
io_req_set_res(req, res, io_put_kbuf(req, IO_URING_F_UNLOCKED));
if (def->fail)
def->fail(req);
io_req_complete_defer(req);
}
/*
* Don't initialise the fields below on every allocation, but do that in
* advance and keep them valid across allocations.
*/
static void io_preinit_req(struct io_kiocb *req, struct io_ring_ctx *ctx)
{
req->ctx = ctx;
req->link = NULL;
req->async_data = NULL;
/* not necessary, but safer to zero */
req->cqe.res = 0;
}
static void io_flush_cached_locked_reqs(struct io_ring_ctx *ctx,
struct io_submit_state *state)
{
spin_lock(&ctx->completion_lock);
wq_list_splice(&ctx->locked_free_list, &state->free_list);
ctx->locked_free_nr = 0;
spin_unlock(&ctx->completion_lock);
}
/*
* A request might get retired back into the request caches even before opcode
* handlers and io_issue_sqe() are done with it, e.g. inline completion path.
* Because of that, io_alloc_req() should be called only under ->uring_lock
* and with extra caution to not get a request that is still worked on.
*/
__cold bool __io_alloc_req_refill(struct io_ring_ctx *ctx)
__must_hold(&ctx->uring_lock)
{
gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;
void *reqs[IO_REQ_ALLOC_BATCH];
int ret, i;
/*
* If we have more than a batch's worth of requests in our IRQ side
* locked cache, grab the lock and move them over to our submission
* side cache.
*/
if (data_race(ctx->locked_free_nr) > IO_COMPL_BATCH) {
io_flush_cached_locked_reqs(ctx, &ctx->submit_state);
if (!io_req_cache_empty(ctx))
return true;
}
ret = kmem_cache_alloc_bulk(req_cachep, gfp, ARRAY_SIZE(reqs), reqs);
/*
* Bulk alloc is all-or-nothing. If we fail to get a batch,
* retry single alloc to be on the safe side.
*/
if (unlikely(ret <= 0)) {
reqs[0] = kmem_cache_alloc(req_cachep, gfp);
if (!reqs[0])
return false;
ret = 1;
}
percpu_ref_get_many(&ctx->refs, ret);
for (i = 0; i < ret; i++) {
struct io_kiocb *req = reqs[i];
io_preinit_req(req, ctx);
io_req_add_to_cache(req, ctx);
}
return true;
}
__cold void io_free_req(struct io_kiocb *req)
{
/* refs were already put, restore them for io_req_task_complete() */
req->flags &= ~REQ_F_REFCOUNT;
/* we only want to free it, don't post CQEs */
req->flags |= REQ_F_CQE_SKIP;
req->io_task_work.func = io_req_task_complete;
io_req_task_work_add(req);
}
static void __io_req_find_next_prep(struct io_kiocb *req)
{
struct io_ring_ctx *ctx = req->ctx;
spin_lock(&ctx->completion_lock);
io_disarm_next(req);
spin_unlock(&ctx->completion_lock);
}
static inline struct io_kiocb *io_req_find_next(struct io_kiocb *req)
{
struct io_kiocb *nxt;
/*
* If LINK is set, we have dependent requests in this chain. If we
* didn't fail this request, queue the first one up, moving any other
* dependencies to the next request. In case of failure, fail the rest
* of the chain.
*/
if (unlikely(req->flags & IO_DISARM_MASK))
__io_req_find_next_prep(req);
nxt = req->link;
req->link = NULL;
return nxt;
}
static void ctx_flush_and_put(struct io_ring_ctx *ctx, struct io_tw_state *ts)
{
if (!ctx)
return;
if (ctx->flags & IORING_SETUP_TASKRUN_FLAG)
atomic_andnot(IORING_SQ_TASKRUN, &ctx->rings->sq_flags);
if (ts->locked) {
io_submit_flush_completions(ctx);
mutex_unlock(&ctx->uring_lock);
ts->locked = false;
}
percpu_ref_put(&ctx->refs);
}
static unsigned int handle_tw_list(struct llist_node *node,
struct io_ring_ctx **ctx,
struct io_tw_state *ts,
struct llist_node *last)
{
unsigned int count = 0;
while (node && node != last) {
struct llist_node *next = node->next;
struct io_kiocb *req = container_of(node, struct io_kiocb,
io_task_work.node);
prefetch(container_of(next, struct io_kiocb, io_task_work.node));
if (req->ctx != *ctx) {
ctx_flush_and_put(*ctx, ts);
*ctx = req->ctx;
/* if not contended, grab and improve batching */
ts->locked = mutex_trylock(&(*ctx)->uring_lock);
percpu_ref_get(&(*ctx)->refs);
}
INDIRECT_CALL_2(req->io_task_work.func,
io_poll_task_func, io_req_rw_complete,
req, ts);
node = next;
count++;
if (unlikely(need_resched())) {
ctx_flush_and_put(*ctx, ts);
*ctx = NULL;
cond_resched();
}
}
return count;
}
/**
* io_llist_xchg - swap all entries in a lock-less list
* @head: the head of lock-less list to delete all entries
* @new: new entry as the head of the list
*
* If list is empty, return NULL, otherwise, return the pointer to the first entry.
* The order of entries returned is from the newest to the oldest added one.
*/
static inline struct llist_node *io_llist_xchg(struct llist_head *head,
struct llist_node *new)
{
return xchg(&head->first, new);
}
/**
* io_llist_cmpxchg - possibly swap all entries in a lock-less list
* @head: the head of lock-less list to delete all entries
* @old: expected old value of the first entry of the list
* @new: new entry as the head of the list
*
* perform a cmpxchg on the first entry of the list.
*/
static inline struct llist_node *io_llist_cmpxchg(struct llist_head *head,
struct llist_node *old,
struct llist_node *new)
{
return cmpxchg(&head->first, old, new);
}
void tctx_task_work(struct callback_head *cb)
{
struct io_tw_state ts = {};
struct io_ring_ctx *ctx = NULL;
struct io_uring_task *tctx = container_of(cb, struct io_uring_task,
task_work);
struct llist_node fake = {};
struct llist_node *node;
unsigned int loops = 0;
unsigned int count = 0;
if (unlikely(current->flags & PF_EXITING)) {
io_fallback_tw(tctx);
return;
}
do {
loops++;
node = io_llist_xchg(&tctx->task_list, &fake);
count += handle_tw_list(node, &ctx, &ts, &fake);
/* skip expensive cmpxchg if there are items in the list */
if (READ_ONCE(tctx->task_list.first) != &fake)
continue;
if (ts.locked && !wq_list_empty(&ctx->submit_state.compl_reqs)) {
io_submit_flush_completions(ctx);
if (READ_ONCE(tctx->task_list.first) != &fake)
continue;
}
node = io_llist_cmpxchg(&tctx->task_list, &fake, NULL);
} while (node != &fake);
ctx_flush_and_put(ctx, &ts);
/* relaxed read is enough as only the task itself sets ->in_cancel */
if (unlikely(atomic_read(&tctx->in_cancel)))
io_uring_drop_tctx_refs(current);
trace_io_uring_task_work_run(tctx, count, loops);
}
static __cold void io_fallback_tw(struct io_uring_task *tctx)
{
struct llist_node *node = llist_del_all(&tctx->task_list);
struct io_kiocb *req;
while (node) {
req = container_of(node, struct io_kiocb, io_task_work.node);
node = node->next;
if (llist_add(&req->io_task_work.node,
&req->ctx->fallback_llist))
schedule_delayed_work(&req->ctx->fallback_work, 1);
}
}
static inline void io_req_local_work_add(struct io_kiocb *req, unsigned flags)
{
struct io_ring_ctx *ctx = req->ctx;
unsigned nr_wait, nr_tw, nr_tw_prev;
struct llist_node *first;
if (req->flags & (REQ_F_LINK | REQ_F_HARDLINK))
flags &= ~IOU_F_TWQ_LAZY_WAKE;
first = READ_ONCE(ctx->work_llist.first);
do {
nr_tw_prev = 0;
if (first) {
struct io_kiocb *first_req = container_of(first,
struct io_kiocb,
io_task_work.node);
/*
* Might be executed at any moment, rely on
* SLAB_TYPESAFE_BY_RCU to keep it alive.
*/
nr_tw_prev = READ_ONCE(first_req->nr_tw);
}
nr_tw = nr_tw_prev + 1;
/* Large enough to fail the nr_wait comparison below */
if (!(flags & IOU_F_TWQ_LAZY_WAKE))
nr_tw = -1U;
req->nr_tw = nr_tw;
req->io_task_work.node.next = first;
} while (!try_cmpxchg(&ctx->work_llist.first, &first,
&req->io_task_work.node));
if (!first) {
if (ctx->flags & IORING_SETUP_TASKRUN_FLAG)
atomic_or(IORING_SQ_TASKRUN, &ctx->rings->sq_flags);
if (ctx->has_evfd)
io_eventfd_signal(ctx);
}
nr_wait = atomic_read(&ctx->cq_wait_nr);
/* no one is waiting */
if (!nr_wait)
return;
/* either not enough or the previous add has already woken it up */
if (nr_wait > nr_tw || nr_tw_prev >= nr_wait)
return;
/* pairs with set_current_state() in io_cqring_wait() */
smp_mb__after_atomic();
wake_up_state(ctx->submitter_task, TASK_INTERRUPTIBLE);
}
static void io_req_normal_work_add(struct io_kiocb *req)
{
struct io_uring_task *tctx = req->task->io_uring;
struct io_ring_ctx *ctx = req->ctx;
/* task_work already pending, we're done */
if (!llist_add(&req->io_task_work.node, &tctx->task_list))
return;
if (ctx->flags & IORING_SETUP_TASKRUN_FLAG)
atomic_or(IORING_SQ_TASKRUN, &ctx->rings->sq_flags);
if (likely(!task_work_add(req->task, &tctx->task_work, ctx->notify_method)))
return;
io_fallback_tw(tctx);
}
void __io_req_task_work_add(struct io_kiocb *req, unsigned flags)
{
if (req->ctx->flags & IORING_SETUP_DEFER_TASKRUN) {
rcu_read_lock();
io_req_local_work_add(req, flags);
rcu_read_unlock();
} else {
io_req_normal_work_add(req);
}
}
static void __cold io_move_task_work_from_local(struct io_ring_ctx *ctx)
{
struct llist_node *node;
node = llist_del_all(&ctx->work_llist);
while (node) {
struct io_kiocb *req = container_of(node, struct io_kiocb,
io_task_work.node);
node = node->next;
io_req_normal_work_add(req);
}
}
static int __io_run_local_work(struct io_ring_ctx *ctx, struct io_tw_state *ts)
{
struct llist_node *node;
unsigned int loops = 0;
int ret = 0;
if (WARN_ON_ONCE(ctx->submitter_task != current))
return -EEXIST;
if (ctx->flags & IORING_SETUP_TASKRUN_FLAG)
atomic_andnot(IORING_SQ_TASKRUN, &ctx->rings->sq_flags);
again:
/*
* llists are in reverse order, flip it back the right way before
* running the pending items.
*/
node = llist_reverse_order(io_llist_xchg(&ctx->work_llist, NULL));
while (node) {
struct llist_node *next = node->next;
struct io_kiocb *req = container_of(node, struct io_kiocb,
io_task_work.node);
prefetch(container_of(next, struct io_kiocb, io_task_work.node));
INDIRECT_CALL_2(req->io_task_work.func,
io_poll_task_func, io_req_rw_complete,
req, ts);
ret++;
node = next;
}
loops++;
if (!llist_empty(&ctx->work_llist))
goto again;
if (ts->locked) {
io_submit_flush_completions(ctx);
if (!llist_empty(&ctx->work_llist))
goto again;
}
trace_io_uring_local_work_run(ctx, ret, loops);
return ret;
}
static inline int io_run_local_work_locked(struct io_ring_ctx *ctx)
{
struct io_tw_state ts = { .locked = true, };
int ret;
if (llist_empty(&ctx->work_llist))
return 0;
ret = __io_run_local_work(ctx, &ts);
/* shouldn't happen! */
if (WARN_ON_ONCE(!ts.locked))
mutex_lock(&ctx->uring_lock);
return ret;
}
static int io_run_local_work(struct io_ring_ctx *ctx)
{
struct io_tw_state ts = {};
int ret;
ts.locked = mutex_trylock(&ctx->uring_lock);
ret = __io_run_local_work(ctx, &ts);
if (ts.locked)
mutex_unlock(&ctx->uring_lock);
return ret;
}
static void io_req_task_cancel(struct io_kiocb *req, struct io_tw_state *ts)
{
io_tw_lock(req->ctx, ts);
io_req_defer_failed(req, req->cqe.res);
}
void io_req_task_submit(struct io_kiocb *req, struct io_tw_state *ts)
{
io_tw_lock(req->ctx, ts);
/* req->task == current here, checking PF_EXITING is safe */
if (unlikely(req->task->flags & PF_EXITING))
io_req_defer_failed(req, -EFAULT);
else if (req->flags & REQ_F_FORCE_ASYNC)
io_queue_iowq(req, ts);
else
io_queue_sqe(req);
}
void io_req_task_queue_fail(struct io_kiocb *req, int ret)
{
io_req_set_res(req, ret, 0);
req->io_task_work.func = io_req_task_cancel;
io_req_task_work_add(req);
}
void io_req_task_queue(struct io_kiocb *req)
{
req->io_task_work.func = io_req_task_submit;
io_req_task_work_add(req);
}
void io_queue_next(struct io_kiocb *req)
{
struct io_kiocb *nxt = io_req_find_next(req);
if (nxt)
io_req_task_queue(nxt);
}
void io_free_batch_list(struct io_ring_ctx *ctx, struct io_wq_work_node *node)
__must_hold(&ctx->uring_lock)
{
do {
struct io_kiocb *req = container_of(node, struct io_kiocb,
comp_list);
if (unlikely(req->flags & IO_REQ_CLEAN_SLOW_FLAGS)) {
if (req->flags & REQ_F_REFCOUNT) {
node = req->comp_list.next;
if (!req_ref_put_and_test(req))
continue;
}
if ((req->flags & REQ_F_POLLED) && req->apoll) {
struct async_poll *apoll = req->apoll;
if (apoll->double_poll)
kfree(apoll->double_poll);
if (!io_alloc_cache_put(&ctx->apoll_cache, &apoll->cache))
kfree(apoll);
req->flags &= ~REQ_F_POLLED;
}
if (req->flags & IO_REQ_LINK_FLAGS)
io_queue_next(req);
if (unlikely(req->flags & IO_REQ_CLEAN_FLAGS))
io_clean_op(req);
}
if (!(req->flags & REQ_F_FIXED_FILE))
io_put_file(req->file);
io_req_put_rsrc_locked(req, ctx);
io_put_task(req->task);
node = req->comp_list.next;
io_req_add_to_cache(req, ctx);
} while (node);
}
static void __io_submit_flush_completions(struct io_ring_ctx *ctx)
__must_hold(&ctx->uring_lock)
{
struct io_submit_state *state = &ctx->submit_state;
struct io_wq_work_node *node;
__io_cq_lock(ctx);
/* must come first to preserve CQE ordering in failure cases */
if (state->cqes_count)
__io_flush_post_cqes(ctx);
__wq_list_for_each(node, &state->compl_reqs) {
struct io_kiocb *req = container_of(node, struct io_kiocb,
comp_list);
if (!(req->flags & REQ_F_CQE_SKIP) &&
unlikely(!__io_fill_cqe_req(ctx, req))) {
if (ctx->task_complete) {
spin_lock(&ctx->completion_lock);
io_req_cqe_overflow(req);
spin_unlock(&ctx->completion_lock);
} else {
io_req_cqe_overflow(req);
}
}
}
__io_cq_unlock_post(ctx);
if (!wq_list_empty(&ctx->submit_state.compl_reqs)) {
io_free_batch_list(ctx, state->compl_reqs.first);
INIT_WQ_LIST(&state->compl_reqs);
}
}
static unsigned io_cqring_events(struct io_ring_ctx *ctx)
{
/* See comment at the top of this file */
smp_rmb();
return __io_cqring_events(ctx);
}
/*
* We can't just wait for polled events to come to us, we have to actively
* find and complete them.
*/
static __cold void io_iopoll_try_reap_events(struct io_ring_ctx *ctx)
{
if (!(ctx->flags & IORING_SETUP_IOPOLL))
return;
mutex_lock(&ctx->uring_lock);
while (!wq_list_empty(&ctx->iopoll_list)) {
/* let it sleep and repeat later if can't complete a request */
if (io_do_iopoll(ctx, true) == 0)
break;
/*
* Ensure we allow local-to-the-cpu processing to take place,
* in this case we need to ensure that we reap all events.
* Also let task_work, etc. to progress by releasing the mutex
*/
if (need_resched()) {
mutex_unlock(&ctx->uring_lock);
cond_resched();
mutex_lock(&ctx->uring_lock);
}
}
mutex_unlock(&ctx->uring_lock);
}
static int io_iopoll_check(struct io_ring_ctx *ctx, long min)
{
unsigned int nr_events = 0;
int ret = 0;
unsigned long check_cq;
if (!io_allowed_run_tw(ctx))
return -EEXIST;
check_cq = READ_ONCE(ctx->check_cq);
if (unlikely(check_cq)) {
if (check_cq & BIT(IO_CHECK_CQ_OVERFLOW_BIT))
__io_cqring_overflow_flush(ctx);
/*
* Similarly do not spin if we have not informed the user of any
* dropped CQE.
*/
if (check_cq & BIT(IO_CHECK_CQ_DROPPED_BIT))
return -EBADR;
}
/*
* Don't enter poll loop if we already have events pending.
* If we do, we can potentially be spinning for commands that
* already triggered a CQE (eg in error).
*/
if (io_cqring_events(ctx))
return 0;
do {
/*
* If a submit got punted to a workqueue, we can have the
* application entering polling for a command before it gets
* issued. That app will hold the uring_lock for the duration
* of the poll right here, so we need to take a breather every
* now and then to ensure that the issue has a chance to add
* the poll to the issued list. Otherwise we can spin here
* forever, while the workqueue is stuck trying to acquire the
* very same mutex.
*/
if (wq_list_empty(&ctx->iopoll_list) ||
io_task_work_pending(ctx)) {
u32 tail = ctx->cached_cq_tail;
(void) io_run_local_work_locked(ctx);
if (task_work_pending(current) ||
wq_list_empty(&ctx->iopoll_list)) {
mutex_unlock(&ctx->uring_lock);
io_run_task_work();
mutex_lock(&ctx->uring_lock);
}
/* some requests don't go through iopoll_list */
if (tail != ctx->cached_cq_tail ||
wq_list_empty(&ctx->iopoll_list))
break;
}
ret = io_do_iopoll(ctx, !min);
if (ret < 0)
break;
nr_events += ret;
ret = 0;
} while (nr_events < min && !need_resched());
return ret;
}
void io_req_task_complete(struct io_kiocb *req, struct io_tw_state *ts)
{
if (ts->locked)
io_req_complete_defer(req);
else
io_req_complete_post(req, IO_URING_F_UNLOCKED);
}
/*
* After the iocb has been issued, it's safe to be found on the poll list.
* Adding the kiocb to the list AFTER submission ensures that we don't
* find it from a io_do_iopoll() thread before the issuer is done
* accessing the kiocb cookie.
*/
static void io_iopoll_req_issued(struct io_kiocb *req, unsigned int issue_flags)
{
struct io_ring_ctx *ctx = req->ctx;
const bool needs_lock = issue_flags & IO_URING_F_UNLOCKED;
/* workqueue context doesn't hold uring_lock, grab it now */
if (unlikely(needs_lock))
mutex_lock(&ctx->uring_lock);
/*
* Track whether we have multiple files in our lists. This will impact
* how we do polling eventually, not spinning if we're on potentially
* different devices.
*/
if (wq_list_empty(&ctx->iopoll_list)) {
ctx->poll_multi_queue = false;
} else if (!ctx->poll_multi_queue) {
struct io_kiocb *list_req;
list_req = container_of(ctx->iopoll_list.first, struct io_kiocb,
comp_list);
if (list_req->file != req->file)
ctx->poll_multi_queue = true;
}
/*
* For fast devices, IO may have already completed. If it has, add
* it to the front so we find it first.
*/
if (READ_ONCE(req->iopoll_completed))
wq_list_add_head(&req->comp_list, &ctx->iopoll_list);
else
wq_list_add_tail(&req->comp_list, &ctx->iopoll_list);
if (unlikely(needs_lock)) {
/*
* If IORING_SETUP_SQPOLL is enabled, sqes are either handle
* in sq thread task context or in io worker task context. If
* current task context is sq thread, we don't need to check
* whether should wake up sq thread.
*/
if ((ctx->flags & IORING_SETUP_SQPOLL) &&
wq_has_sleeper(&ctx->sq_data->wait))
wake_up(&ctx->sq_data->wait);
mutex_unlock(&ctx->uring_lock);
}
}
unsigned int io_file_get_flags(struct file *file)
{
unsigned int res = 0;
if (S_ISREG(file_inode(file)->i_mode))
res |= REQ_F_ISREG;
if ((file->f_flags & O_NONBLOCK) || (file->f_mode & FMODE_NOWAIT))
res |= REQ_F_SUPPORT_NOWAIT;
return res;
}
bool io_alloc_async_data(struct io_kiocb *req)
{
WARN_ON_ONCE(!io_cold_defs[req->opcode].async_size);
req->async_data = kmalloc(io_cold_defs[req->opcode].async_size, GFP_KERNEL);
if (req->async_data) {
req->flags |= REQ_F_ASYNC_DATA;
return false;
}
return true;
}
int io_req_prep_async(struct io_kiocb *req)
{
const struct io_cold_def *cdef = &io_cold_defs[req->opcode];
const struct io_issue_def *def = &io_issue_defs[req->opcode];
/* assign early for deferred execution for non-fixed file */
if (def->needs_file && !(req->flags & REQ_F_FIXED_FILE) && !req->file)
req->file = io_file_get_normal(req, req->cqe.fd);
if (!cdef->prep_async)
return 0;
if (WARN_ON_ONCE(req_has_async_data(req)))
return -EFAULT;
if (!def->manual_alloc) {
if (io_alloc_async_data(req))
return -EAGAIN;
}
return cdef->prep_async(req);
}
static u32 io_get_sequence(struct io_kiocb *req)
{
u32 seq = req->ctx->cached_sq_head;
struct io_kiocb *cur;
/* need original cached_sq_head, but it was increased for each req */
io_for_each_link(cur, req)
seq--;
return seq;
}
static __cold void io_drain_req(struct io_kiocb *req)
__must_hold(&ctx->uring_lock)
{
struct io_ring_ctx *ctx = req->ctx;
struct io_defer_entry *de;
int ret;
u32 seq = io_get_sequence(req);
/* Still need defer if there is pending req in defer list. */
spin_lock(&ctx->completion_lock);
if (!req_need_defer(req, seq) && list_empty_careful(&ctx->defer_list)) {
spin_unlock(&ctx->completion_lock);
queue:
ctx->drain_active = false;
io_req_task_queue(req);
return;
}
spin_unlock(&ctx->completion_lock);
io_prep_async_link(req);
de = kmalloc(sizeof(*de), GFP_KERNEL);
if (!de) {
ret = -ENOMEM;
io_req_defer_failed(req, ret);
return;
}
spin_lock(&ctx->completion_lock);
if (!req_need_defer(req, seq) && list_empty(&ctx->defer_list)) {
spin_unlock(&ctx->completion_lock);
kfree(de);
goto queue;
}
trace_io_uring_defer(req);
de->req = req;
de->seq = seq;
list_add_tail(&de->list, &ctx->defer_list);
spin_unlock(&ctx->completion_lock);
}
static bool io_assign_file(struct io_kiocb *req, const struct io_issue_def *def,
unsigned int issue_flags)
{
if (req->file || !def->needs_file)
return true;
if (req->flags & REQ_F_FIXED_FILE)
req->file = io_file_get_fixed(req, req->cqe.fd, issue_flags);
else
req->file = io_file_get_normal(req, req->cqe.fd);
return !!req->file;
}
static int io_issue_sqe(struct io_kiocb *req, unsigned int issue_flags)
{
const struct io_issue_def *def = &io_issue_defs[req->opcode];
const struct cred *creds = NULL;
int ret;
if (unlikely(!io_assign_file(req, def, issue_flags)))
return -EBADF;
if (unlikely((req->flags & REQ_F_CREDS) && req->creds != current_cred()))
creds = override_creds(req->creds);
if (!def->audit_skip)
audit_uring_entry(req->opcode);
ret = def->issue(req, issue_flags);
if (!def->audit_skip)
audit_uring_exit(!ret, ret);
if (creds)
revert_creds(creds);
if (ret == IOU_OK) {
if (issue_flags & IO_URING_F_COMPLETE_DEFER)
io_req_complete_defer(req);
else
io_req_complete_post(req, issue_flags);
} else if (ret != IOU_ISSUE_SKIP_COMPLETE)
return ret;
/* If the op doesn't have a file, we're not polling for it */
if ((req->ctx->flags & IORING_SETUP_IOPOLL) && def->iopoll_queue)
io_iopoll_req_issued(req, issue_flags);
return 0;
}
int io_poll_issue(struct io_kiocb *req, struct io_tw_state *ts)
{
io_tw_lock(req->ctx, ts);
return io_issue_sqe(req, IO_URING_F_NONBLOCK|IO_URING_F_MULTISHOT|
IO_URING_F_COMPLETE_DEFER);
}
struct io_wq_work *io_wq_free_work(struct io_wq_work *work)
{
struct io_kiocb *req = container_of(work, struct io_kiocb, work);
struct io_kiocb *nxt = NULL;
if (req_ref_put_and_test(req)) {
if (req->flags & IO_REQ_LINK_FLAGS)
nxt = io_req_find_next(req);
io_free_req(req);
}
return nxt ? &nxt->work : NULL;
}
void io_wq_submit_work(struct io_wq_work *work)
{
struct io_kiocb *req = container_of(work, struct io_kiocb, work);
const struct io_issue_def *def = &io_issue_defs[req->opcode];
unsigned int issue_flags = IO_URING_F_UNLOCKED | IO_URING_F_IOWQ;
bool needs_poll = false;
int ret = 0, err = -ECANCELED;
/* one will be dropped by ->io_wq_free_work() after returning to io-wq */
if (!(req->flags & REQ_F_REFCOUNT))
__io_req_set_refcount(req, 2);
else
req_ref_get(req);
io_arm_ltimeout(req);
/* either cancelled or io-wq is dying, so don't touch tctx->iowq */
if (work->flags & IO_WQ_WORK_CANCEL) {
fail:
io_req_task_queue_fail(req, err);
return;
}
if (!io_assign_file(req, def, issue_flags)) {
err = -EBADF;
work->flags |= IO_WQ_WORK_CANCEL;
goto fail;
}
if (req->flags & REQ_F_FORCE_ASYNC) {
bool opcode_poll = def->pollin || def->pollout;
if (opcode_poll && file_can_poll(req->file)) {
needs_poll = true;
issue_flags |= IO_URING_F_NONBLOCK;
}
}
do {
ret = io_issue_sqe(req, issue_flags);
if (ret != -EAGAIN)
break;
/*
* We can get EAGAIN for iopolled IO even though we're
* forcing a sync submission from here, since we can't
* wait for request slots on the block side.
*/
if (!needs_poll) {
if (!(req->ctx->flags & IORING_SETUP_IOPOLL))
break;
cond_resched();
continue;
}
if (io_arm_poll_handler(req, issue_flags) == IO_APOLL_OK)
return;
/* aborted or ready, in either case retry blocking */
needs_poll = false;
issue_flags &= ~IO_URING_F_NONBLOCK;
} while (1);
/* avoid locking problems by failing it from a clean context */
if (ret < 0)
io_req_task_queue_fail(req, ret);
}
inline struct file *io_file_get_fixed(struct io_kiocb *req, int fd,
unsigned int issue_flags)
{
struct io_ring_ctx *ctx = req->ctx;
struct io_fixed_file *slot;
struct file *file = NULL;
io_ring_submit_lock(ctx, issue_flags);
if (unlikely((unsigned int)fd >= ctx->nr_user_files))
goto out;
fd = array_index_nospec(fd, ctx->nr_user_files);
slot = io_fixed_file_slot(&ctx->file_table, fd);
file = io_slot_file(slot);
req->flags |= io_slot_flags(slot);
io_req_set_rsrc_node(req, ctx, 0);
out:
io_ring_submit_unlock(ctx, issue_flags);
return file;
}
struct file *io_file_get_normal(struct io_kiocb *req, int fd)
{
struct file *file = fget(fd);
trace_io_uring_file_get(req, fd);
/* we don't allow fixed io_uring files */
if (file && io_is_uring_fops(file))
io_req_track_inflight(req);
return file;
}
static void io_queue_async(struct io_kiocb *req, int ret)
__must_hold(&req->ctx->uring_lock)
{
struct io_kiocb *linked_timeout;
if (ret != -EAGAIN || (req->flags & REQ_F_NOWAIT)) {
io_req_defer_failed(req, ret);
return;
}
linked_timeout = io_prep_linked_timeout(req);
switch (io_arm_poll_handler(req, 0)) {
case IO_APOLL_READY:
io_kbuf_recycle(req, 0);
io_req_task_queue(req);
break;
case IO_APOLL_ABORTED:
io_kbuf_recycle(req, 0);
io_queue_iowq(req, NULL);
break;
case IO_APOLL_OK:
break;
}
if (linked_timeout)
io_queue_linked_timeout(linked_timeout);
}
static inline void io_queue_sqe(struct io_kiocb *req)
__must_hold(&req->ctx->uring_lock)
{
int ret;
ret = io_issue_sqe(req, IO_URING_F_NONBLOCK|IO_URING_F_COMPLETE_DEFER);
/*
* We async punt it if the file wasn't marked NOWAIT, or if the file
* doesn't support non-blocking read/write attempts
*/
if (likely(!ret))
io_arm_ltimeout(req);
else
io_queue_async(req, ret);
}
static void io_queue_sqe_fallback(struct io_kiocb *req)
__must_hold(&req->ctx->uring_lock)
{
if (unlikely(req->flags & REQ_F_FAIL)) {
/*
* We don't submit, fail them all, for that replace hardlinks
* with normal links. Extra REQ_F_LINK is tolerated.
*/
req->flags &= ~REQ_F_HARDLINK;
req->flags |= REQ_F_LINK;
io_req_defer_failed(req, req->cqe.res);
} else {
int ret = io_req_prep_async(req);
if (unlikely(ret)) {
io_req_defer_failed(req, ret);
return;
}
if (unlikely(req->ctx->drain_active))
io_drain_req(req);
else
io_queue_iowq(req, NULL);
}
}
/*
* Check SQE restrictions (opcode and flags).
*
* Returns 'true' if SQE is allowed, 'false' otherwise.
*/
static inline bool io_check_restriction(struct io_ring_ctx *ctx,
struct io_kiocb *req,
unsigned int sqe_flags)
{
if (!test_bit(req->opcode, ctx->restrictions.sqe_op))
return false;
if ((sqe_flags & ctx->restrictions.sqe_flags_required) !=
ctx->restrictions.sqe_flags_required)
return false;
if (sqe_flags & ~(ctx->restrictions.sqe_flags_allowed |
ctx->restrictions.sqe_flags_required))
return false;
return true;
}
static void io_init_req_drain(struct io_kiocb *req)
{
struct io_ring_ctx *ctx = req->ctx;
struct io_kiocb *head = ctx->submit_state.link.head;
ctx->drain_active = true;
if (head) {
/*
* If we need to drain a request in the middle of a link, drain
* the head request and the next request/link after the current
* link. Considering sequential execution of links,
* REQ_F_IO_DRAIN will be maintained for every request of our
* link.
*/
head->flags |= REQ_F_IO_DRAIN | REQ_F_FORCE_ASYNC;
ctx->drain_next = true;
}
}
static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
const struct io_uring_sqe *sqe)
__must_hold(&ctx->uring_lock)
{
const struct io_issue_def *def;
unsigned int sqe_flags;
int personality;
u8 opcode;
/* req is partially pre-initialised, see io_preinit_req() */
req->opcode = opcode = READ_ONCE(sqe->opcode);
/* same numerical values with corresponding REQ_F_*, safe to copy */
req->flags = sqe_flags = READ_ONCE(sqe->flags);
req->cqe.user_data = READ_ONCE(sqe->user_data);
req->file = NULL;
req->rsrc_node = NULL;
req->task = current;
if (unlikely(opcode >= IORING_OP_LAST)) {
req->opcode = 0;
return -EINVAL;
}
def = &io_issue_defs[opcode];
if (unlikely(sqe_flags & ~SQE_COMMON_FLAGS)) {
/* enforce forwards compatibility on users */
if (sqe_flags & ~SQE_VALID_FLAGS)
return -EINVAL;
if (sqe_flags & IOSQE_BUFFER_SELECT) {
if (!def->buffer_select)
return -EOPNOTSUPP;
req->buf_index = READ_ONCE(sqe->buf_group);
}
if (sqe_flags & IOSQE_CQE_SKIP_SUCCESS)
ctx->drain_disabled = true;
if (sqe_flags & IOSQE_IO_DRAIN) {
if (ctx->drain_disabled)
return -EOPNOTSUPP;
io_init_req_drain(req);
}
}
if (unlikely(ctx->restricted || ctx->drain_active || ctx->drain_next)) {
if (ctx->restricted && !io_check_restriction(ctx, req, sqe_flags))
return -EACCES;
/* knock it to the slow queue path, will be drained there */
if (ctx->drain_active)
req->flags |= REQ_F_FORCE_ASYNC;
/* if there is no link, we're at "next" request and need to drain */
if (unlikely(ctx->drain_next) && !ctx->submit_state.link.head) {
ctx->drain_next = false;
ctx->drain_active = true;
req->flags |= REQ_F_IO_DRAIN | REQ_F_FORCE_ASYNC;
}
}
if (!def->ioprio && sqe->ioprio)
return -EINVAL;
if (!def->iopoll && (ctx->flags & IORING_SETUP_IOPOLL))
return -EINVAL;
if (def->needs_file) {
struct io_submit_state *state = &ctx->submit_state;
req->cqe.fd = READ_ONCE(sqe->fd);
/*
* Plug now if we have more than 2 IO left after this, and the
* target is potentially a read/write to block based storage.
*/
if (state->need_plug && def->plug) {
state->plug_started = true;
state->need_plug = false;
blk_start_plug_nr_ios(&state->plug, state->submit_nr);
}
}
personality = READ_ONCE(sqe->personality);
if (personality) {
int ret;
req->creds = xa_load(&ctx->personalities, personality);
if (!req->creds)
return -EINVAL;
get_cred(req->creds);
ret = security_uring_override_creds(req->creds);
if (ret) {
put_cred(req->creds);
return ret;
}
req->flags |= REQ_F_CREDS;
}
return def->prep(req, sqe);
}
static __cold int io_submit_fail_init(const struct io_uring_sqe *sqe,
struct io_kiocb *req, int ret)
{
struct io_ring_ctx *ctx = req->ctx;
struct io_submit_link *link = &ctx->submit_state.link;
struct io_kiocb *head = link->head;
trace_io_uring_req_failed(sqe, req, ret);
/*
* Avoid breaking links in the middle as it renders links with SQPOLL
* unusable. Instead of failing eagerly, continue assembling the link if
* applicable and mark the head with REQ_F_FAIL. The link flushing code
* should find the flag and handle the rest.
*/
req_fail_link_node(req, ret);
if (head && !(head->flags & REQ_F_FAIL))
req_fail_link_node(head, -ECANCELED);
if (!(req->flags & IO_REQ_LINK_FLAGS)) {
if (head) {
link->last->link = req;
link->head = NULL;
req = head;
}
io_queue_sqe_fallback(req);
return ret;
}
if (head)
link->last->link = req;
else
link->head = req;
link->last = req;
return 0;
}
static inline int io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
const struct io_uring_sqe *sqe)
__must_hold(&ctx->uring_lock)
{
struct io_submit_link *link = &ctx->submit_state.link;
int ret;
ret = io_init_req(ctx, req, sqe);
if (unlikely(ret))
return io_submit_fail_init(sqe, req, ret);
trace_io_uring_submit_req(req);
/*
* If we already have a head request, queue this one for async
* submittal once the head completes. If we don't have a head but
* IOSQE_IO_LINK is set in the sqe, start a new head. This one will be
* submitted sync once the chain is complete. If none of those
* conditions are true (normal request), then just queue it.
*/
if (unlikely(link->head)) {
ret = io_req_prep_async(req);
if (unlikely(ret))
return io_submit_fail_init(sqe, req, ret);
trace_io_uring_link(req, link->head);
link->last->link = req;
link->last = req;
if (req->flags & IO_REQ_LINK_FLAGS)
return 0;
/* last request of the link, flush it */
req = link->head;
link->head = NULL;
if (req->flags & (REQ_F_FORCE_ASYNC | REQ_F_FAIL))
goto fallback;
} else if (unlikely(req->flags & (IO_REQ_LINK_FLAGS |
REQ_F_FORCE_ASYNC | REQ_F_FAIL))) {
if (req->flags & IO_REQ_LINK_FLAGS) {
link->head = req;
link->last = req;
} else {
fallback:
io_queue_sqe_fallback(req);
}
return 0;
}
io_queue_sqe(req);
return 0;
}
/*
* Batched submission is done, ensure local IO is flushed out.
*/
static void io_submit_state_end(struct io_ring_ctx *ctx)
{
struct io_submit_state *state = &ctx->submit_state;
if (unlikely(state->link.head))
io_queue_sqe_fallback(state->link.head);
/* flush only after queuing links as they can generate completions */
io_submit_flush_completions(ctx);
if (state->plug_started)
blk_finish_plug(&state->plug);
}
/*
* Start submission side cache.
*/
static void io_submit_state_start(struct io_submit_state *state,
unsigned int max_ios)
{
state->plug_started = false;
state->need_plug = max_ios > 2;
state->submit_nr = max_ios;
/* set only head, no need to init link_last in advance */
state->link.head = NULL;
}
static void io_commit_sqring(struct io_ring_ctx *ctx)
{
struct io_rings *rings = ctx->rings;
/*
* Ensure any loads from the SQEs are done at this point,
* since once we write the new head, the application could
* write new data to them.
*/
smp_store_release(&rings->sq.head, ctx->cached_sq_head);
}
/*
* Fetch an sqe, if one is available. Note this returns a pointer to memory
* that is mapped by userspace. This means that care needs to be taken to
* ensure that reads are stable, as we cannot rely on userspace always
* being a good citizen. If members of the sqe are validated and then later
* used, it's important that those reads are done through READ_ONCE() to
* prevent a re-load down the line.
*/
static bool io_get_sqe(struct io_ring_ctx *ctx, const struct io_uring_sqe **sqe)
{
unsigned head, mask = ctx->sq_entries - 1;
unsigned sq_idx = ctx->cached_sq_head++ & mask;
/*
* The cached sq head (or cq tail) serves two purposes:
*
* 1) allows us to batch the cost of updating the user visible
* head updates.
* 2) allows the kernel side to track the head on its own, even
* though the application is the one updating it.
*/
head = READ_ONCE(ctx->sq_array[sq_idx]);
if (likely(head < ctx->sq_entries)) {
/* double index for 128-byte SQEs, twice as long */
if (ctx->flags & IORING_SETUP_SQE128)
head <<= 1;
*sqe = &ctx->sq_sqes[head];
return true;
}
/* drop invalid entries */
ctx->cq_extra--;
WRITE_ONCE(ctx->rings->sq_dropped,
READ_ONCE(ctx->rings->sq_dropped) + 1);
return false;
}
int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr)
__must_hold(&ctx->uring_lock)
{
unsigned int entries = io_sqring_entries(ctx);
unsigned int left;
int ret;
if (unlikely(!entries))
return 0;
/* make sure SQ entry isn't read before tail */
ret = left = min(nr, entries);
io_get_task_refs(left);
io_submit_state_start(&ctx->submit_state, left);
do {
const struct io_uring_sqe *sqe;
struct io_kiocb *req;
if (unlikely(!io_alloc_req(ctx, &req)))
break;
if (unlikely(!io_get_sqe(ctx, &sqe))) {
io_req_add_to_cache(req, ctx);
break;
}
/*
* Continue submitting even for sqe failure if the
* ring was setup with IORING_SETUP_SUBMIT_ALL
*/
if (unlikely(io_submit_sqe(ctx, req, sqe)) &&
!(ctx->flags & IORING_SETUP_SUBMIT_ALL)) {
left--;
break;
}
} while (--left);
if (unlikely(left)) {
ret -= left;
/* try again if it submitted nothing and can't allocate a req */
if (!ret && io_req_cache_empty(ctx))
ret = -EAGAIN;
current->io_uring->cached_refs += left;
}
io_submit_state_end(ctx);
/* Commit SQ ring head once we've consumed and submitted all SQEs */
io_commit_sqring(ctx);
return ret;
}
struct io_wait_queue {
struct wait_queue_entry wq;
struct io_ring_ctx *ctx;
unsigned cq_tail;
unsigned nr_timeouts;
ktime_t timeout;
};
static inline bool io_has_work(struct io_ring_ctx *ctx)
{
return test_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq) ||
!llist_empty(&ctx->work_llist);
}
static inline bool io_should_wake(struct io_wait_queue *iowq)
{
struct io_ring_ctx *ctx = iowq->ctx;
int dist = READ_ONCE(ctx->rings->cq.tail) - (int) iowq->cq_tail;
/*
* Wake up if we have enough events, or if a timeout occurred since we
* started waiting. For timeouts, we always want to return to userspace,
* regardless of event count.
*/
return dist >= 0 || atomic_read(&ctx->cq_timeouts) != iowq->nr_timeouts;
}
static int io_wake_function(struct wait_queue_entry *curr, unsigned int mode,
int wake_flags, void *key)
{
struct io_wait_queue *iowq = container_of(curr, struct io_wait_queue, wq);
/*
* Cannot safely flush overflowed CQEs from here, ensure we wake up
* the task, and the next invocation will do it.
*/
if (io_should_wake(iowq) || io_has_work(iowq->ctx))
return autoremove_wake_function(curr, mode, wake_flags, key);
return -1;
}
int io_run_task_work_sig(struct io_ring_ctx *ctx)
{
if (!llist_empty(&ctx->work_llist)) {
__set_current_state(TASK_RUNNING);
if (io_run_local_work(ctx) > 0)
return 1;
}
if (io_run_task_work() > 0)
return 1;
if (task_sigpending(current))
return -EINTR;
return 0;
}
/* when returns >0, the caller should retry */
static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx,
struct io_wait_queue *iowq)
{
if (unlikely(READ_ONCE(ctx->check_cq)))
return 1;
if (unlikely(!llist_empty(&ctx->work_llist)))
return 1;
if (unlikely(test_thread_flag(TIF_NOTIFY_SIGNAL)))
return 1;
if (unlikely(task_sigpending(current)))
return -EINTR;
if (unlikely(io_should_wake(iowq)))
return 0;
if (iowq->timeout == KTIME_MAX)
schedule();
else if (!schedule_hrtimeout(&iowq->timeout, HRTIMER_MODE_ABS))
return -ETIME;
return 0;
}
/*
* Wait until events become available, if we don't already have some. The
* application must reap them itself, as they reside on the shared cq ring.
*/
static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
const sigset_t __user *sig, size_t sigsz,
struct __kernel_timespec __user *uts)
{
struct io_wait_queue iowq;
struct io_rings *rings = ctx->rings;
int ret;
if (!io_allowed_run_tw(ctx))
return -EEXIST;
if (!llist_empty(&ctx->work_llist))
io_run_local_work(ctx);
io_run_task_work();
io_cqring_overflow_flush(ctx);
/* if user messes with these they will just get an early return */
if (__io_cqring_events_user(ctx) >= min_events)
return 0;
if (sig) {
#ifdef CONFIG_COMPAT
if (in_compat_syscall())
ret = set_compat_user_sigmask((const compat_sigset_t __user *)sig,
sigsz);
else
#endif
ret = set_user_sigmask(sig, sigsz);
if (ret)
return ret;
}
init_waitqueue_func_entry(&iowq.wq, io_wake_function);
iowq.wq.private = current;
INIT_LIST_HEAD(&iowq.wq.entry);
iowq.ctx = ctx;
iowq.nr_timeouts = atomic_read(&ctx->cq_timeouts);
iowq.cq_tail = READ_ONCE(ctx->rings->cq.head) + min_events;
iowq.timeout = KTIME_MAX;
if (uts) {
struct timespec64 ts;
if (get_timespec64(&ts, uts))
return -EFAULT;
iowq.timeout = ktime_add_ns(timespec64_to_ktime(ts), ktime_get_ns());
}
trace_io_uring_cqring_wait(ctx, min_events);
do {
unsigned long check_cq;
if (ctx->flags & IORING_SETUP_DEFER_TASKRUN) {
int nr_wait = (int) iowq.cq_tail - READ_ONCE(ctx->rings->cq.tail);
atomic_set(&ctx->cq_wait_nr, nr_wait);
set_current_state(TASK_INTERRUPTIBLE);
} else {
prepare_to_wait_exclusive(&ctx->cq_wait, &iowq.wq,
TASK_INTERRUPTIBLE);
}
ret = io_cqring_wait_schedule(ctx, &iowq);
__set_current_state(TASK_RUNNING);
atomic_set(&ctx->cq_wait_nr, 0);
if (ret < 0)
break;
/*
* Run task_work after scheduling and before io_should_wake().
* If we got woken because of task_work being processed, run it
* now rather than let the caller do another wait loop.
*/
io_run_task_work();
if (!llist_empty(&ctx->work_llist))
io_run_local_work(ctx);
check_cq = READ_ONCE(ctx->check_cq);
if (unlikely(check_cq)) {
/* let the caller flush overflows, retry */
if (check_cq & BIT(IO_CHECK_CQ_OVERFLOW_BIT))
io_cqring_do_overflow_flush(ctx);
if (check_cq & BIT(IO_CHECK_CQ_DROPPED_BIT)) {
ret = -EBADR;
break;
}
}
if (io_should_wake(&iowq)) {
ret = 0;
break;
}
cond_resched();
} while (1);
if (!(ctx->flags & IORING_SETUP_DEFER_TASKRUN))
finish_wait(&ctx->cq_wait, &iowq.wq);
restore_saved_sigmask_unless(ret == -EINTR);
return READ_ONCE(rings->cq.head) == READ_ONCE(rings->cq.tail) ? ret : 0;
}
static void io_mem_free(void *ptr)
{
struct page *page;
if (!ptr)
return;
page = virt_to_head_page(ptr);
if (put_page_testzero(page))
free_compound_page(page);
}
static void io_pages_free(struct page ***pages, int npages)
{
struct page **page_array;
int i;
if (!pages)
return;
page_array = *pages;
for (i = 0; i < npages; i++)
unpin_user_page(page_array[i]);
kvfree(page_array);
*pages = NULL;
}
static void *__io_uaddr_map(struct page ***pages, unsigned short *npages,
unsigned long uaddr, size_t size)
{
struct page **page_array;
unsigned int nr_pages;
int ret;
*npages = 0;
if (uaddr & (PAGE_SIZE - 1) || !size)
return ERR_PTR(-EINVAL);
nr_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
if (nr_pages > USHRT_MAX)
return ERR_PTR(-EINVAL);
page_array = kvmalloc_array(nr_pages, sizeof(struct page *), GFP_KERNEL);
if (!page_array)
return ERR_PTR(-ENOMEM);
ret = pin_user_pages_fast(uaddr, nr_pages, FOLL_WRITE | FOLL_LONGTERM,
page_array);
if (ret != nr_pages) {
err:
io_pages_free(&page_array, ret > 0 ? ret : 0);
return ret < 0 ? ERR_PTR(ret) : ERR_PTR(-EFAULT);
}
/*
* Should be a single page. If the ring is small enough that we can
* use a normal page, that is fine. If we need multiple pages, then
* userspace should use a huge page. That's the only way to guarantee
* that we get contigious memory, outside of just being lucky or
* (currently) having low memory fragmentation.
*/
if (page_array[0] != page_array[ret - 1])
goto err;
*pages = page_array;
*npages = nr_pages;
return page_to_virt(page_array[0]);
}
static void *io_rings_map(struct io_ring_ctx *ctx, unsigned long uaddr,
size_t size)
{
return __io_uaddr_map(&ctx->ring_pages, &ctx->n_ring_pages, uaddr,
size);
}
static void *io_sqes_map(struct io_ring_ctx *ctx, unsigned long uaddr,
size_t size)
{
return __io_uaddr_map(&ctx->sqe_pages, &ctx->n_sqe_pages, uaddr,
size);
}
static void io_rings_free(struct io_ring_ctx *ctx)
{
if (!(ctx->flags & IORING_SETUP_NO_MMAP)) {
io_mem_free(ctx->rings);
io_mem_free(ctx->sq_sqes);
ctx->rings = NULL;
ctx->sq_sqes = NULL;
} else {
io_pages_free(&ctx->ring_pages, ctx->n_ring_pages);
io_pages_free(&ctx->sqe_pages, ctx->n_sqe_pages);
}
}
static void *io_mem_alloc(size_t size)
{
gfp_t gfp = GFP_KERNEL_ACCOUNT | __GFP_ZERO | __GFP_NOWARN | __GFP_COMP;
void *ret;
ret = (void *) __get_free_pages(gfp, get_order(size));
if (ret)
return ret;
return ERR_PTR(-ENOMEM);
}
static unsigned long rings_size(struct io_ring_ctx *ctx, unsigned int sq_entries,
unsigned int cq_entries, size_t *sq_offset)
{
struct io_rings *rings;
size_t off, sq_array_size;
off = struct_size(rings, cqes, cq_entries);
if (off == SIZE_MAX)
return SIZE_MAX;
if (ctx->flags & IORING_SETUP_CQE32) {
if (check_shl_overflow(off, 1, &off))
return SIZE_MAX;
}
#ifdef CONFIG_SMP
off = ALIGN(off, SMP_CACHE_BYTES);
if (off == 0)
return SIZE_MAX;
#endif
if (sq_offset)
*sq_offset = off;
sq_array_size = array_size(sizeof(u32), sq_entries);
if (sq_array_size == SIZE_MAX)
return SIZE_MAX;
if (check_add_overflow(off, sq_array_size, &off))
return SIZE_MAX;
return off;
}
static int io_eventfd_register(struct io_ring_ctx *ctx, void __user *arg,
unsigned int eventfd_async)
{
struct io_ev_fd *ev_fd;
__s32 __user *fds = arg;
int fd;
ev_fd = rcu_dereference_protected(ctx->io_ev_fd,
lockdep_is_held(&ctx->uring_lock));
if (ev_fd)
return -EBUSY;
if (copy_from_user(&fd, fds, sizeof(*fds)))
return -EFAULT;
ev_fd = kmalloc(sizeof(*ev_fd), GFP_KERNEL);
if (!ev_fd)
return -ENOMEM;
ev_fd->cq_ev_fd = eventfd_ctx_fdget(fd);
if (IS_ERR(ev_fd->cq_ev_fd)) {
int ret = PTR_ERR(ev_fd->cq_ev_fd);
kfree(ev_fd);
return ret;
}
spin_lock(&ctx->completion_lock);
ctx->evfd_last_cq_tail = ctx->cached_cq_tail;
spin_unlock(&ctx->completion_lock);
ev_fd->eventfd_async = eventfd_async;
ctx->has_evfd = true;
rcu_assign_pointer(ctx->io_ev_fd, ev_fd);
atomic_set(&ev_fd->refs, 1);
atomic_set(&ev_fd->ops, 0);
return 0;
}
static int io_eventfd_unregister(struct io_ring_ctx *ctx)
{
struct io_ev_fd *ev_fd;
ev_fd = rcu_dereference_protected(ctx->io_ev_fd,
lockdep_is_held(&ctx->uring_lock));
if (ev_fd) {
ctx->has_evfd = false;
rcu_assign_pointer(ctx->io_ev_fd, NULL);
if (!atomic_fetch_or(BIT(IO_EVENTFD_OP_FREE_BIT), &ev_fd->ops))
call_rcu(&ev_fd->rcu, io_eventfd_ops);
return 0;
}
return -ENXIO;
}
static void io_req_caches_free(struct io_ring_ctx *ctx)
{
struct io_kiocb *req;
int nr = 0;
mutex_lock(&ctx->uring_lock);
io_flush_cached_locked_reqs(ctx, &ctx->submit_state);
while (!io_req_cache_empty(ctx)) {
req = io_extract_req(ctx);
kmem_cache_free(req_cachep, req);
nr++;
}
if (nr)
percpu_ref_put_many(&ctx->refs, nr);
mutex_unlock(&ctx->uring_lock);
}
static void io_rsrc_node_cache_free(struct io_cache_entry *entry)
{
kfree(container_of(entry, struct io_rsrc_node, cache));
}
static __cold void io_ring_ctx_free(struct io_ring_ctx *ctx)
{
io_sq_thread_finish(ctx);
/* __io_rsrc_put_work() may need uring_lock to progress, wait w/o it */
if (WARN_ON_ONCE(!list_empty(&ctx->rsrc_ref_list)))
return;
mutex_lock(&ctx->uring_lock);
if (ctx->buf_data)
__io_sqe_buffers_unregister(ctx);
if (ctx->file_data)
__io_sqe_files_unregister(ctx);
io_cqring_overflow_kill(ctx);
io_eventfd_unregister(ctx);
io_alloc_cache_free(&ctx->apoll_cache, io_apoll_cache_free);
io_alloc_cache_free(&ctx->netmsg_cache, io_netmsg_cache_free);
io_destroy_buffers(ctx);
mutex_unlock(&ctx->uring_lock);
if (ctx->sq_creds)
put_cred(ctx->sq_creds);
if (ctx->submitter_task)
put_task_struct(ctx->submitter_task);
/* there are no registered resources left, nobody uses it */
if (ctx->rsrc_node)
io_rsrc_node_destroy(ctx, ctx->rsrc_node);
WARN_ON_ONCE(!list_empty(&ctx->rsrc_ref_list));
#if defined(CONFIG_UNIX)
if (ctx->ring_sock) {
ctx->ring_sock->file = NULL; /* so that iput() is called */
sock_release(ctx->ring_sock);
}
#endif
WARN_ON_ONCE(!list_empty(&ctx->ltimeout_list));
io_alloc_cache_free(&ctx->rsrc_node_cache, io_rsrc_node_cache_free);
if (ctx->mm_account) {
mmdrop(ctx->mm_account);
ctx->mm_account = NULL;
}
io_rings_free(ctx);
percpu_ref_exit(&ctx->refs);
free_uid(ctx->user);
io_req_caches_free(ctx);
if (ctx->hash_map)
io_wq_put_hash(ctx->hash_map);
kfree(ctx->cancel_table.hbs);
kfree(ctx->cancel_table_locked.hbs);
kfree(ctx->dummy_ubuf);
kfree(ctx->io_bl);
xa_destroy(&ctx->io_bl_xa);
kfree(ctx);
}
static __cold void io_activate_pollwq_cb(struct callback_head *cb)
{
struct io_ring_ctx *ctx = container_of(cb, struct io_ring_ctx,
poll_wq_task_work);
mutex_lock(&ctx->uring_lock);
ctx->poll_activated = true;
mutex_unlock(&ctx->uring_lock);
/*
* Wake ups for some events between start of polling and activation
* might've been lost due to loose synchronisation.
*/
wake_up_all(&ctx->poll_wq);
percpu_ref_put(&ctx->refs);
}
static __cold void io_activate_pollwq(struct io_ring_ctx *ctx)
{
spin_lock(&ctx->completion_lock);
/* already activated or in progress */
if (ctx->poll_activated || ctx->poll_wq_task_work.func)
goto out;
if (WARN_ON_ONCE(!ctx->task_complete))
goto out;
if (!ctx->submitter_task)
goto out;
/*
* with ->submitter_task only the submitter task completes requests, we
* only need to sync with it, which is done by injecting a tw
*/
init_task_work(&ctx->poll_wq_task_work, io_activate_pollwq_cb);
percpu_ref_get(&ctx->refs);
if (task_work_add(ctx->submitter_task, &ctx->poll_wq_task_work, TWA_SIGNAL))
percpu_ref_put(&ctx->refs);
out:
spin_unlock(&ctx->completion_lock);
}
static __poll_t io_uring_poll(struct file *file, poll_table *wait)
{
struct io_ring_ctx *ctx = file->private_data;
__poll_t mask = 0;
if (unlikely(!ctx->poll_activated))
io_activate_pollwq(ctx);
poll_wait(file, &ctx->poll_wq, wait);
/*
* synchronizes with barrier from wq_has_sleeper call in
* io_commit_cqring
*/
smp_rmb();
if (!io_sqring_full(ctx))
mask |= EPOLLOUT | EPOLLWRNORM;
/*
* Don't flush cqring overflow list here, just do a simple check.
* Otherwise there could possible be ABBA deadlock:
* CPU0 CPU1
* ---- ----
* lock(&ctx->uring_lock);
* lock(&ep->mtx);
* lock(&ctx->uring_lock);
* lock(&ep->mtx);
*
* Users may get EPOLLIN meanwhile seeing nothing in cqring, this
* pushes them to do the flush.
*/
if (__io_cqring_events_user(ctx) || io_has_work(ctx))
mask |= EPOLLIN | EPOLLRDNORM;
return mask;
}
static int io_unregister_personality(struct io_ring_ctx *ctx, unsigned id)
{
const struct cred *creds;
creds = xa_erase(&ctx->personalities, id);
if (creds) {
put_cred(creds);
return 0;
}
return -EINVAL;
}
struct io_tctx_exit {
struct callback_head task_work;
struct completion completion;
struct io_ring_ctx *ctx;
};
static __cold void io_tctx_exit_cb(struct callback_head *cb)
{
struct io_uring_task *tctx = current->io_uring;
struct io_tctx_exit *work;
work = container_of(cb, struct io_tctx_exit, task_work);
/*
* When @in_cancel, we're in cancellation and it's racy to remove the
* node. It'll be removed by the end of cancellation, just ignore it.
* tctx can be NULL if the queueing of this task_work raced with
* work cancelation off the exec path.
*/
if (tctx && !atomic_read(&tctx->in_cancel))
io_uring_del_tctx_node((unsigned long)work->ctx);
complete(&work->completion);
}
static __cold bool io_cancel_ctx_cb(struct io_wq_work *work, void *data)
{
struct io_kiocb *req = container_of(work, struct io_kiocb, work);
return req->ctx == data;
}
static __cold void io_ring_exit_work(struct work_struct *work)
{
struct io_ring_ctx *ctx = container_of(work, struct io_ring_ctx, exit_work);
unsigned long timeout = jiffies + HZ * 60 * 5;
unsigned long interval = HZ / 20;
struct io_tctx_exit exit;
struct io_tctx_node *node;
int ret;
/*
* If we're doing polled IO and end up having requests being
* submitted async (out-of-line), then completions can come in while
* we're waiting for refs to drop. We need to reap these manually,
* as nobody else will be looking for them.
*/
do {
if (test_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq)) {
mutex_lock(&ctx->uring_lock);
io_cqring_overflow_kill(ctx);
mutex_unlock(&ctx->uring_lock);
}
if (ctx->flags & IORING_SETUP_DEFER_TASKRUN)
io_move_task_work_from_local(ctx);
while (io_uring_try_cancel_requests(ctx, NULL, true))
cond_resched();
if (ctx->sq_data) {
struct io_sq_data *sqd = ctx->sq_data;
struct task_struct *tsk;
io_sq_thread_park(sqd);
tsk = sqd->thread;
if (tsk && tsk->io_uring && tsk->io_uring->io_wq)
io_wq_cancel_cb(tsk->io_uring->io_wq,
io_cancel_ctx_cb, ctx, true);
io_sq_thread_unpark(sqd);
}
io_req_caches_free(ctx);
if (WARN_ON_ONCE(time_after(jiffies, timeout))) {
/* there is little hope left, don't run it too often */
interval = HZ * 60;
}
/*
* This is really an uninterruptible wait, as it has to be
* complete. But it's also run from a kworker, which doesn't
* take signals, so it's fine to make it interruptible. This
* avoids scenarios where we knowingly can wait much longer
* on completions, for example if someone does a SIGSTOP on
* a task that needs to finish task_work to make this loop
* complete. That's a synthetic situation that should not
* cause a stuck task backtrace, and hence a potential panic
* on stuck tasks if that is enabled.
*/
} while (!wait_for_completion_interruptible_timeout(&ctx->ref_comp, interval));
init_completion(&exit.completion);
init_task_work(&exit.task_work, io_tctx_exit_cb);
exit.ctx = ctx;
/*
* Some may use context even when all refs and requests have been put,
* and they are free to do so while still holding uring_lock or
* completion_lock, see io_req_task_submit(). Apart from other work,
* this lock/unlock section also waits them to finish.
*/
mutex_lock(&ctx->uring_lock);
while (!list_empty(&ctx->tctx_list)) {
WARN_ON_ONCE(time_after(jiffies, timeout));
node = list_first_entry(&ctx->tctx_list, struct io_tctx_node,
ctx_node);
/* don't spin on a single task if cancellation failed */
list_rotate_left(&ctx->tctx_list);
ret = task_work_add(node->task, &exit.task_work, TWA_SIGNAL);
if (WARN_ON_ONCE(ret))
continue;
mutex_unlock(&ctx->uring_lock);
/*
* See comment above for
* wait_for_completion_interruptible_timeout() on why this
* wait is marked as interruptible.
*/
wait_for_completion_interruptible(&exit.completion);
mutex_lock(&ctx->uring_lock);
}
mutex_unlock(&ctx->uring_lock);
spin_lock(&ctx->completion_lock);
spin_unlock(&ctx->completion_lock);
/* pairs with RCU read section in io_req_local_work_add() */
if (ctx->flags & IORING_SETUP_DEFER_TASKRUN)
synchronize_rcu();
io_ring_ctx_free(ctx);
}
static __cold void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx)
{
unsigned long index;
struct creds *creds;
mutex_lock(&ctx->uring_lock);
percpu_ref_kill(&ctx->refs);
xa_for_each(&ctx->personalities, index, creds)
io_unregister_personality(ctx, index);
if (ctx->rings)
io_poll_remove_all(ctx, NULL, true);
mutex_unlock(&ctx->uring_lock);
/*
* If we failed setting up the ctx, we might not have any rings
* and therefore did not submit any requests
*/
if (ctx->rings)
io_kill_timeouts(ctx, NULL, true);
INIT_WORK(&ctx->exit_work, io_ring_exit_work);
/*
* Use system_unbound_wq to avoid spawning tons of event kworkers
* if we're exiting a ton of rings at the same time. It just adds
* noise and overhead, there's no discernable change in runtime
* over using system_wq.
*/
queue_work(system_unbound_wq, &ctx->exit_work);
}
static int io_uring_release(struct inode *inode, struct file *file)
{
struct io_ring_ctx *ctx = file->private_data;
file->private_data = NULL;
io_ring_ctx_wait_and_kill(ctx);
return 0;
}
struct io_task_cancel {
struct task_struct *task;
bool all;
};
static bool io_cancel_task_cb(struct io_wq_work *work, void *data)
{
struct io_kiocb *req = container_of(work, struct io_kiocb, work);
struct io_task_cancel *cancel = data;
return io_match_task_safe(req, cancel->task, cancel->all);
}
static __cold bool io_cancel_defer_files(struct io_ring_ctx *ctx,
struct task_struct *task,
bool cancel_all)
{
struct io_defer_entry *de;
LIST_HEAD(list);
spin_lock(&ctx->completion_lock);
list_for_each_entry_reverse(de, &ctx->defer_list, list) {
if (io_match_task_safe(de->req, task, cancel_all)) {
list_cut_position(&list, &ctx->defer_list, &de->list);
break;
}
}
spin_unlock(&ctx->completion_lock);
if (list_empty(&list))
return false;
while (!list_empty(&list)) {
de = list_first_entry(&list, struct io_defer_entry, list);
list_del_init(&de->list);
io_req_task_queue_fail(de->req, -ECANCELED);
kfree(de);
}
return true;
}
static __cold bool io_uring_try_cancel_iowq(struct io_ring_ctx *ctx)
{
struct io_tctx_node *node;
enum io_wq_cancel cret;
bool ret = false;
mutex_lock(&ctx->uring_lock);
list_for_each_entry(node, &ctx->tctx_list, ctx_node) {
struct io_uring_task *tctx = node->task->io_uring;
/*
* io_wq will stay alive while we hold uring_lock, because it's
* killed after ctx nodes, which requires to take the lock.
*/
if (!tctx || !tctx->io_wq)
continue;
cret = io_wq_cancel_cb(tctx->io_wq, io_cancel_ctx_cb, ctx, true);
ret |= (cret != IO_WQ_CANCEL_NOTFOUND);
}
mutex_unlock(&ctx->uring_lock);
return ret;
}
static __cold bool io_uring_try_cancel_requests(struct io_ring_ctx *ctx,
struct task_struct *task,
bool cancel_all)
{
struct io_task_cancel cancel = { .task = task, .all = cancel_all, };
struct io_uring_task *tctx = task ? task->io_uring : NULL;
enum io_wq_cancel cret;
bool ret = false;
/* set it so io_req_local_work_add() would wake us up */
if (ctx->flags & IORING_SETUP_DEFER_TASKRUN) {
atomic_set(&ctx->cq_wait_nr, 1);
smp_mb();
}
/* failed during ring init, it couldn't have issued any requests */
if (!ctx->rings)
return false;
if (!task) {
ret |= io_uring_try_cancel_iowq(ctx);
} else if (tctx && tctx->io_wq) {
/*
* Cancels requests of all rings, not only @ctx, but
* it's fine as the task is in exit/exec.
*/
cret = io_wq_cancel_cb(tctx->io_wq, io_cancel_task_cb,
&cancel, true);
ret |= (cret != IO_WQ_CANCEL_NOTFOUND);
}
/* SQPOLL thread does its own polling */
if ((!(ctx->flags & IORING_SETUP_SQPOLL) && cancel_all) ||
(ctx->sq_data && ctx->sq_data->thread == current)) {
while (!wq_list_empty(&ctx->iopoll_list)) {
io_iopoll_try_reap_events(ctx);
ret = true;
cond_resched();
}
}
if ((ctx->flags & IORING_SETUP_DEFER_TASKRUN) &&
io_allowed_defer_tw_run(ctx))
ret |= io_run_local_work(ctx) > 0;
ret |= io_cancel_defer_files(ctx, task, cancel_all);
mutex_lock(&ctx->uring_lock);
ret |= io_poll_remove_all(ctx, task, cancel_all);
mutex_unlock(&ctx->uring_lock);
ret |= io_kill_timeouts(ctx, task, cancel_all);
if (task)
ret |= io_run_task_work() > 0;
return ret;
}
static s64 tctx_inflight(struct io_uring_task *tctx, bool tracked)
{
if (tracked)
return atomic_read(&tctx->inflight_tracked);
return percpu_counter_sum(&tctx->inflight);
}
/*
* Find any io_uring ctx that this task has registered or done IO on, and cancel
* requests. @sqd should be not-null IFF it's an SQPOLL thread cancellation.
*/
__cold void io_uring_cancel_generic(bool cancel_all, struct io_sq_data *sqd)
{
struct io_uring_task *tctx = current->io_uring;
struct io_ring_ctx *ctx;
struct io_tctx_node *node;
unsigned long index;
s64 inflight;
DEFINE_WAIT(wait);
WARN_ON_ONCE(sqd && sqd->thread != current);
if (!current->io_uring)
return;
if (tctx->io_wq)
io_wq_exit_start(tctx->io_wq);
atomic_inc(&tctx->in_cancel);
do {
bool loop = false;
io_uring_drop_tctx_refs(current);
/* read completions before cancelations */
inflight = tctx_inflight(tctx, !cancel_all);
if (!inflight)
break;
if (!sqd) {
xa_for_each(&tctx->xa, index, node) {
/* sqpoll task will cancel all its requests */
if (node->ctx->sq_data)
continue;
loop |= io_uring_try_cancel_requests(node->ctx,
current, cancel_all);
}
} else {
list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)
loop |= io_uring_try_cancel_requests(ctx,
current,
cancel_all);
}
if (loop) {
cond_resched();
continue;
}
prepare_to_wait(&tctx->wait, &wait, TASK_INTERRUPTIBLE);
io_run_task_work();
io_uring_drop_tctx_refs(current);
xa_for_each(&tctx->xa, index, node) {
if (!llist_empty(&node->ctx->work_llist)) {
WARN_ON_ONCE(node->ctx->submitter_task &&
node->ctx->submitter_task != current);
goto end_wait;
}
}
/*
* If we've seen completions, retry without waiting. This
* avoids a race where a completion comes in before we did
* prepare_to_wait().
*/
if (inflight == tctx_inflight(tctx, !cancel_all))
schedule();
end_wait:
finish_wait(&tctx->wait, &wait);
} while (1);
io_uring_clean_tctx(tctx);
if (cancel_all) {
/*
* We shouldn't run task_works after cancel, so just leave
* ->in_cancel set for normal exit.
*/
atomic_dec(&tctx->in_cancel);
/* for exec all current's requests should be gone, kill tctx */
__io_uring_free(current);
}
}
void __io_uring_cancel(bool cancel_all)
{
io_uring_cancel_generic(cancel_all, NULL);
}
static void *io_uring_validate_mmap_request(struct file *file,
loff_t pgoff, size_t sz)
{
struct io_ring_ctx *ctx = file->private_data;
loff_t offset = pgoff << PAGE_SHIFT;
struct page *page;
void *ptr;
/* Don't allow mmap if the ring was setup without it */
if (ctx->flags & IORING_SETUP_NO_MMAP)
return ERR_PTR(-EINVAL);
switch (offset & IORING_OFF_MMAP_MASK) {
case IORING_OFF_SQ_RING:
case IORING_OFF_CQ_RING:
ptr = ctx->rings;
break;
case IORING_OFF_SQES:
ptr = ctx->sq_sqes;
break;
case IORING_OFF_PBUF_RING: {
unsigned int bgid;
bgid = (offset & ~IORING_OFF_MMAP_MASK) >> IORING_OFF_PBUF_SHIFT;
mutex_lock(&ctx->uring_lock);
ptr = io_pbuf_get_address(ctx, bgid);
mutex_unlock(&ctx->uring_lock);
if (!ptr)
return ERR_PTR(-EINVAL);
break;
}
default:
return ERR_PTR(-EINVAL);
}
page = virt_to_head_page(ptr);
if (sz > page_size(page))
return ERR_PTR(-EINVAL);
return ptr;
}
#ifdef CONFIG_MMU
static __cold int io_uring_mmap(struct file *file, struct vm_area_struct *vma)
{
size_t sz = vma->vm_end - vma->vm_start;
unsigned long pfn;
void *ptr;
ptr = io_uring_validate_mmap_request(file, vma->vm_pgoff, sz);
if (IS_ERR(ptr))
return PTR_ERR(ptr);
pfn = virt_to_phys(ptr) >> PAGE_SHIFT;
return remap_pfn_range(vma, vma->vm_start, pfn, sz, vma->vm_page_prot);
}
static unsigned long io_uring_mmu_get_unmapped_area(struct file *filp,
unsigned long addr, unsigned long len,
unsigned long pgoff, unsigned long flags)
{
const unsigned long mmap_end = arch_get_mmap_end(addr, len, flags);
struct vm_unmapped_area_info info;
void *ptr;
/*
* Do not allow to map to user-provided address to avoid breaking the
* aliasing rules. Userspace is not able to guess the offset address of
* kernel kmalloc()ed memory area.
*/
if (addr)
return -EINVAL;
ptr = io_uring_validate_mmap_request(filp, pgoff, len);
if (IS_ERR(ptr))
return -ENOMEM;
info.flags = VM_UNMAPPED_AREA_TOPDOWN;
info.length = len;
info.low_limit = max(PAGE_SIZE, mmap_min_addr);
info.high_limit = arch_get_mmap_base(addr, current->mm->mmap_base);
#ifdef SHM_COLOUR
info.align_mask = PAGE_MASK & (SHM_COLOUR - 1UL);
#else
info.align_mask = PAGE_MASK & (SHMLBA - 1UL);
#endif
info.align_offset = (unsigned long) ptr;
/*
* A failed mmap() very likely causes application failure,
* so fall back to the bottom-up function here. This scenario
* can happen with large stack limits and large mmap()
* allocations.
*/
addr = vm_unmapped_area(&info);
if (offset_in_page(addr)) {
info.flags = 0;
info.low_limit = TASK_UNMAPPED_BASE;
info.high_limit = mmap_end;
addr = vm_unmapped_area(&info);
}
return addr;
}
#else /* !CONFIG_MMU */
static int io_uring_mmap(struct file *file, struct vm_area_struct *vma)
{
return is_nommu_shared_mapping(vma->vm_flags) ? 0 : -EINVAL;
}
static unsigned int io_uring_nommu_mmap_capabilities(struct file *file)
{
return NOMMU_MAP_DIRECT | NOMMU_MAP_READ | NOMMU_MAP_WRITE;
}
static unsigned long io_uring_nommu_get_unmapped_area(struct file *file,
unsigned long addr, unsigned long len,
unsigned long pgoff, unsigned long flags)
{
void *ptr;
ptr = io_uring_validate_mmap_request(file, pgoff, len);
if (IS_ERR(ptr))
return PTR_ERR(ptr);
return (unsigned long) ptr;
}
#endif /* !CONFIG_MMU */
static int io_validate_ext_arg(unsigned flags, const void __user *argp, size_t argsz)
{
if (flags & IORING_ENTER_EXT_ARG) {
struct io_uring_getevents_arg arg;
if (argsz != sizeof(arg))
return -EINVAL;
if (copy_from_user(&arg, argp, sizeof(arg)))
return -EFAULT;
}
return 0;
}
static int io_get_ext_arg(unsigned flags, const void __user *argp, size_t *argsz,
struct __kernel_timespec __user **ts,
const sigset_t __user **sig)
{
struct io_uring_getevents_arg arg;
/*
* If EXT_ARG isn't set, then we have no timespec and the argp pointer
* is just a pointer to the sigset_t.
*/
if (!(flags & IORING_ENTER_EXT_ARG)) {
*sig = (const sigset_t __user *) argp;
*ts = NULL;
return 0;
}
/*
* EXT_ARG is set - ensure we agree on the size of it and copy in our
* timespec and sigset_t pointers if good.
*/
if (*argsz != sizeof(arg))
return -EINVAL;
if (copy_from_user(&arg, argp, sizeof(arg)))
return -EFAULT;
if (arg.pad)
return -EINVAL;
*sig = u64_to_user_ptr(arg.sigmask);
*argsz = arg.sigmask_sz;
*ts = u64_to_user_ptr(arg.ts);
return 0;
}
SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
u32, min_complete, u32, flags, const void __user *, argp,
size_t, argsz)
{
struct io_ring_ctx *ctx;
struct fd f;
long ret;
if (unlikely(flags & ~(IORING_ENTER_GETEVENTS | IORING_ENTER_SQ_WAKEUP |
IORING_ENTER_SQ_WAIT | IORING_ENTER_EXT_ARG |
IORING_ENTER_REGISTERED_RING)))
return -EINVAL;
/*
* Ring fd has been registered via IORING_REGISTER_RING_FDS, we
* need only dereference our task private array to find it.
*/
if (flags & IORING_ENTER_REGISTERED_RING) {
struct io_uring_task *tctx = current->io_uring;
if (unlikely(!tctx || fd >= IO_RINGFD_REG_MAX))
return -EINVAL;
fd = array_index_nospec(fd, IO_RINGFD_REG_MAX);
f.file = tctx->registered_rings[fd];
f.flags = 0;
if (unlikely(!f.file))
return -EBADF;
} else {
f = fdget(fd);
if (unlikely(!f.file))
return -EBADF;
ret = -EOPNOTSUPP;
if (unlikely(!io_is_uring_fops(f.file)))
goto out;
}
ctx = f.file->private_data;
ret = -EBADFD;
if (unlikely(ctx->flags & IORING_SETUP_R_DISABLED))
goto out;
/*
* For SQ polling, the thread will do all submissions and completions.
* Just return the requested submit count, and wake the thread if
* we were asked to.
*/
ret = 0;
if (ctx->flags & IORING_SETUP_SQPOLL) {
io_cqring_overflow_flush(ctx);
if (unlikely(ctx->sq_data->thread == NULL)) {
ret = -EOWNERDEAD;
goto out;
}
if (flags & IORING_ENTER_SQ_WAKEUP)
wake_up(&ctx->sq_data->wait);
if (flags & IORING_ENTER_SQ_WAIT)
io_sqpoll_wait_sq(ctx);
ret = to_submit;
} else if (to_submit) {
ret = io_uring_add_tctx_node(ctx);
if (unlikely(ret))
goto out;
mutex_lock(&ctx->uring_lock);
ret = io_submit_sqes(ctx, to_submit);
if (ret != to_submit) {
mutex_unlock(&ctx->uring_lock);
goto out;
}
if (flags & IORING_ENTER_GETEVENTS) {
if (ctx->syscall_iopoll)
goto iopoll_locked;
/*
* Ignore errors, we'll soon call io_cqring_wait() and
* it should handle ownership problems if any.
*/
if (ctx->flags & IORING_SETUP_DEFER_TASKRUN)
(void)io_run_local_work_locked(ctx);
}
mutex_unlock(&ctx->uring_lock);
}
if (flags & IORING_ENTER_GETEVENTS) {
int ret2;
if (ctx->syscall_iopoll) {
/*
* We disallow the app entering submit/complete with
* polling, but we still need to lock the ring to
* prevent racing with polled issue that got punted to
* a workqueue.
*/
mutex_lock(&ctx->uring_lock);
iopoll_locked:
ret2 = io_validate_ext_arg(flags, argp, argsz);
if (likely(!ret2)) {
min_complete = min(min_complete,
ctx->cq_entries);
ret2 = io_iopoll_check(ctx, min_complete);
}
mutex_unlock(&ctx->uring_lock);
} else {
const sigset_t __user *sig;
struct __kernel_timespec __user *ts;
ret2 = io_get_ext_arg(flags, argp, &argsz, &ts, &sig);
if (likely(!ret2)) {
min_complete = min(min_complete,
ctx->cq_entries);
ret2 = io_cqring_wait(ctx, min_complete, sig,
argsz, ts);
}
}
if (!ret) {
ret = ret2;
/*
* EBADR indicates that one or more CQE were dropped.
* Once the user has been informed we can clear the bit
* as they are obviously ok with those drops.
*/
if (unlikely(ret2 == -EBADR))
clear_bit(IO_CHECK_CQ_DROPPED_BIT,
&ctx->check_cq);
}
}
out:
fdput(f);
return ret;
}
static const struct file_operations io_uring_fops = {
.release = io_uring_release,
.mmap = io_uring_mmap,
#ifndef CONFIG_MMU
.get_unmapped_area = io_uring_nommu_get_unmapped_area,
.mmap_capabilities = io_uring_nommu_mmap_capabilities,
#else
.get_unmapped_area = io_uring_mmu_get_unmapped_area,
#endif
.poll = io_uring_poll,
#ifdef CONFIG_PROC_FS
.show_fdinfo = io_uring_show_fdinfo,
#endif
};
bool io_is_uring_fops(struct file *file)
{
return file->f_op == &io_uring_fops;
}
static __cold int io_allocate_scq_urings(struct io_ring_ctx *ctx,
struct io_uring_params *p)
{
struct io_rings *rings;
size_t size, sq_array_offset;
void *ptr;
/* make sure these are sane, as we already accounted them */
ctx->sq_entries = p->sq_entries;
ctx->cq_entries = p->cq_entries;
size = rings_size(ctx, p->sq_entries, p->cq_entries, &sq_array_offset);
if (size == SIZE_MAX)
return -EOVERFLOW;
if (!(ctx->flags & IORING_SETUP_NO_MMAP))
rings = io_mem_alloc(size);
else
rings = io_rings_map(ctx, p->cq_off.user_addr, size);
if (IS_ERR(rings))
return PTR_ERR(rings);
ctx->rings = rings;
ctx->sq_array = (u32 *)((char *)rings + sq_array_offset);
rings->sq_ring_mask = p->sq_entries - 1;
rings->cq_ring_mask = p->cq_entries - 1;
rings->sq_ring_entries = p->sq_entries;
rings->cq_ring_entries = p->cq_entries;
if (p->flags & IORING_SETUP_SQE128)
size = array_size(2 * sizeof(struct io_uring_sqe), p->sq_entries);
else
size = array_size(sizeof(struct io_uring_sqe), p->sq_entries);
if (size == SIZE_MAX) {
io_rings_free(ctx);
return -EOVERFLOW;
}
if (!(ctx->flags & IORING_SETUP_NO_MMAP))
ptr = io_mem_alloc(size);
else
ptr = io_sqes_map(ctx, p->sq_off.user_addr, size);
if (IS_ERR(ptr)) {
io_rings_free(ctx);
return PTR_ERR(ptr);
}
ctx->sq_sqes = ptr;
return 0;
}
static int io_uring_install_fd(struct file *file)
{
int fd;
fd = get_unused_fd_flags(O_RDWR | O_CLOEXEC);
if (fd < 0)
return fd;
fd_install(fd, file);
return fd;
}
/*
* Allocate an anonymous fd, this is what constitutes the application
* visible backing of an io_uring instance. The application mmaps this
* fd to gain access to the SQ/CQ ring details. If UNIX sockets are enabled,
* we have to tie this fd to a socket for file garbage collection purposes.
*/
static struct file *io_uring_get_file(struct io_ring_ctx *ctx)
{
struct file *file;
#if defined(CONFIG_UNIX)
int ret;
ret = sock_create_kern(&init_net, PF_UNIX, SOCK_RAW, IPPROTO_IP,
&ctx->ring_sock);
if (ret)
return ERR_PTR(ret);
#endif
file = anon_inode_getfile_secure("[io_uring]", &io_uring_fops, ctx,
O_RDWR | O_CLOEXEC, NULL);
#if defined(CONFIG_UNIX)
if (IS_ERR(file)) {
sock_release(ctx->ring_sock);
ctx->ring_sock = NULL;
} else {
ctx->ring_sock->file = file;
}
#endif
return file;
}
static __cold int io_uring_create(unsigned entries, struct io_uring_params *p,
struct io_uring_params __user *params)
{
struct io_ring_ctx *ctx;
struct io_uring_task *tctx;
struct file *file;
int ret;
if (!entries)
return -EINVAL;
if (entries > IORING_MAX_ENTRIES) {
if (!(p->flags & IORING_SETUP_CLAMP))
return -EINVAL;
entries = IORING_MAX_ENTRIES;
}
if ((p->flags & IORING_SETUP_REGISTERED_FD_ONLY)
&& !(p->flags & IORING_SETUP_NO_MMAP))
return -EINVAL;
/*
* Use twice as many entries for the CQ ring. It's possible for the
* application to drive a higher depth than the size of the SQ ring,
* since the sqes are only used at submission time. This allows for
* some flexibility in overcommitting a bit. If the application has
* set IORING_SETUP_CQSIZE, it will have passed in the desired number
* of CQ ring entries manually.
*/
p->sq_entries = roundup_pow_of_two(entries);
if (p->flags & IORING_SETUP_CQSIZE) {
/*
* If IORING_SETUP_CQSIZE is set, we do the same roundup
* to a power-of-two, if it isn't already. We do NOT impose
* any cq vs sq ring sizing.
*/
if (!p->cq_entries)
return -EINVAL;
if (p->cq_entries > IORING_MAX_CQ_ENTRIES) {
if (!(p->flags & IORING_SETUP_CLAMP))
return -EINVAL;
p->cq_entries = IORING_MAX_CQ_ENTRIES;
}
p->cq_entries = roundup_pow_of_two(p->cq_entries);
if (p->cq_entries < p->sq_entries)
return -EINVAL;
} else {
p->cq_entries = 2 * p->sq_entries;
}
ctx = io_ring_ctx_alloc(p);
if (!ctx)
return -ENOMEM;
if ((ctx->flags & IORING_SETUP_DEFER_TASKRUN) &&
!(ctx->flags & IORING_SETUP_IOPOLL) &&
!(ctx->flags & IORING_SETUP_SQPOLL))
ctx->task_complete = true;
/*
* lazy poll_wq activation relies on ->task_complete for synchronisation
* purposes, see io_activate_pollwq()
*/
if (!ctx->task_complete)
ctx->poll_activated = true;
/*
* When SETUP_IOPOLL and SETUP_SQPOLL are both enabled, user
* space applications don't need to do io completion events
* polling again, they can rely on io_sq_thread to do polling
* work, which can reduce cpu usage and uring_lock contention.
*/
if (ctx->flags & IORING_SETUP_IOPOLL &&
!(ctx->flags & IORING_SETUP_SQPOLL))
ctx->syscall_iopoll = 1;
ctx->compat = in_compat_syscall();
if (!capable(CAP_IPC_LOCK))
ctx->user = get_uid(current_user());
/*
* For SQPOLL, we just need a wakeup, always. For !SQPOLL, if
* COOP_TASKRUN is set, then IPIs are never needed by the app.
*/
ret = -EINVAL;
if (ctx->flags & IORING_SETUP_SQPOLL) {
/* IPI related flags don't make sense with SQPOLL */
if (ctx->flags & (IORING_SETUP_COOP_TASKRUN |
IORING_SETUP_TASKRUN_FLAG |
IORING_SETUP_DEFER_TASKRUN))
goto err;
ctx->notify_method = TWA_SIGNAL_NO_IPI;
} else if (ctx->flags & IORING_SETUP_COOP_TASKRUN) {
ctx->notify_method = TWA_SIGNAL_NO_IPI;
} else {
if (ctx->flags & IORING_SETUP_TASKRUN_FLAG &&
!(ctx->flags & IORING_SETUP_DEFER_TASKRUN))
goto err;
ctx->notify_method = TWA_SIGNAL;
}
/*
* For DEFER_TASKRUN we require the completion task to be the same as the
* submission task. This implies that there is only one submitter, so enforce
* that.
*/
if (ctx->flags & IORING_SETUP_DEFER_TASKRUN &&
!(ctx->flags & IORING_SETUP_SINGLE_ISSUER)) {
goto err;
}
/*
* This is just grabbed for accounting purposes. When a process exits,
* the mm is exited and dropped before the files, hence we need to hang
* on to this mm purely for the purposes of being able to unaccount
* memory (locked/pinned vm). It's not used for anything else.
*/
mmgrab(current->mm);
ctx->mm_account = current->mm;
ret = io_allocate_scq_urings(ctx, p);
if (ret)
goto err;
ret = io_sq_offload_create(ctx, p);
if (ret)
goto err;
ret = io_rsrc_init(ctx);
if (ret)
goto err;
p->sq_off.head = offsetof(struct io_rings, sq.head);
p->sq_off.tail = offsetof(struct io_rings, sq.tail);
p->sq_off.ring_mask = offsetof(struct io_rings, sq_ring_mask);
p->sq_off.ring_entries = offsetof(struct io_rings, sq_ring_entries);
p->sq_off.flags = offsetof(struct io_rings, sq_flags);
p->sq_off.dropped = offsetof(struct io_rings, sq_dropped);
p->sq_off.array = (char *)ctx->sq_array - (char *)ctx->rings;
p->sq_off.resv1 = 0;
if (!(ctx->flags & IORING_SETUP_NO_MMAP))
p->sq_off.user_addr = 0;
p->cq_off.head = offsetof(struct io_rings, cq.head);
p->cq_off.tail = offsetof(struct io_rings, cq.tail);
p->cq_off.ring_mask = offsetof(struct io_rings, cq_ring_mask);
p->cq_off.ring_entries = offsetof(struct io_rings, cq_ring_entries);
p->cq_off.overflow = offsetof(struct io_rings, cq_overflow);
p->cq_off.cqes = offsetof(struct io_rings, cqes);
p->cq_off.flags = offsetof(struct io_rings, cq_flags);
p->cq_off.resv1 = 0;
if (!(ctx->flags & IORING_SETUP_NO_MMAP))
p->cq_off.user_addr = 0;
p->features = IORING_FEAT_SINGLE_MMAP | IORING_FEAT_NODROP |
IORING_FEAT_SUBMIT_STABLE | IORING_FEAT_RW_CUR_POS |
IORING_FEAT_CUR_PERSONALITY | IORING_FEAT_FAST_POLL |
IORING_FEAT_POLL_32BITS | IORING_FEAT_SQPOLL_NONFIXED |
IORING_FEAT_EXT_ARG | IORING_FEAT_NATIVE_WORKERS |
IORING_FEAT_RSRC_TAGS | IORING_FEAT_CQE_SKIP |
IORING_FEAT_LINKED_FILE | IORING_FEAT_REG_REG_RING;
if (copy_to_user(params, p, sizeof(*p))) {
ret = -EFAULT;
goto err;
}
if (ctx->flags & IORING_SETUP_SINGLE_ISSUER
&& !(ctx->flags & IORING_SETUP_R_DISABLED))
WRITE_ONCE(ctx->submitter_task, get_task_struct(current));
file = io_uring_get_file(ctx);
if (IS_ERR(file)) {
ret = PTR_ERR(file);
goto err;
}
ret = __io_uring_add_tctx_node(ctx);
if (ret)
goto err_fput;
tctx = current->io_uring;
/*
* Install ring fd as the very last thing, so we don't risk someone
* having closed it before we finish setup
*/
if (p->flags & IORING_SETUP_REGISTERED_FD_ONLY)
ret = io_ring_add_registered_file(tctx, file, 0, IO_RINGFD_REG_MAX);
else
ret = io_uring_install_fd(file);
if (ret < 0)
goto err_fput;
trace_io_uring_create(ret, ctx, p->sq_entries, p->cq_entries, p->flags);
return ret;
err:
io_ring_ctx_wait_and_kill(ctx);
return ret;
err_fput:
fput(file);
return ret;
}
/*
* Sets up an aio uring context, and returns the fd. Applications asks for a
* ring size, we return the actual sq/cq ring sizes (among other things) in the
* params structure passed in.
*/
static long io_uring_setup(u32 entries, struct io_uring_params __user *params)
{
struct io_uring_params p;
int i;
if (copy_from_user(&p, params, sizeof(p)))
return -EFAULT;
for (i = 0; i < ARRAY_SIZE(p.resv); i++) {
if (p.resv[i])
return -EINVAL;
}
if (p.flags & ~(IORING_SETUP_IOPOLL | IORING_SETUP_SQPOLL |
IORING_SETUP_SQ_AFF | IORING_SETUP_CQSIZE |
IORING_SETUP_CLAMP | IORING_SETUP_ATTACH_WQ |
IORING_SETUP_R_DISABLED | IORING_SETUP_SUBMIT_ALL |
IORING_SETUP_COOP_TASKRUN | IORING_SETUP_TASKRUN_FLAG |
IORING_SETUP_SQE128 | IORING_SETUP_CQE32 |
IORING_SETUP_SINGLE_ISSUER | IORING_SETUP_DEFER_TASKRUN |
IORING_SETUP_NO_MMAP | IORING_SETUP_REGISTERED_FD_ONLY))
return -EINVAL;
return io_uring_create(entries, &p, params);
}
SYSCALL_DEFINE2(io_uring_setup, u32, entries,
struct io_uring_params __user *, params)
{
return io_uring_setup(entries, params);
}
static __cold int io_probe(struct io_ring_ctx *ctx, void __user *arg,
unsigned nr_args)
{
struct io_uring_probe *p;
size_t size;
int i, ret;
size = struct_size(p, ops, nr_args);
if (size == SIZE_MAX)
return -EOVERFLOW;
p = kzalloc(size, GFP_KERNEL);
if (!p)
return -ENOMEM;
ret = -EFAULT;
if (copy_from_user(p, arg, size))
goto out;
ret = -EINVAL;
if (memchr_inv(p, 0, size))
goto out;
p->last_op = IORING_OP_LAST - 1;
if (nr_args > IORING_OP_LAST)
nr_args = IORING_OP_LAST;
for (i = 0; i < nr_args; i++) {
p->ops[i].op = i;
if (!io_issue_defs[i].not_supported)
p->ops[i].flags = IO_URING_OP_SUPPORTED;
}
p->ops_len = i;
ret = 0;
if (copy_to_user(arg, p, size))
ret = -EFAULT;
out:
kfree(p);
return ret;
}
static int io_register_personality(struct io_ring_ctx *ctx)
{
const struct cred *creds;
u32 id;
int ret;
creds = get_current_cred();
ret = xa_alloc_cyclic(&ctx->personalities, &id, (void *)creds,
XA_LIMIT(0, USHRT_MAX), &ctx->pers_next, GFP_KERNEL);
if (ret < 0) {
put_cred(creds);
return ret;
}
return id;
}
static __cold int io_register_restrictions(struct io_ring_ctx *ctx,
void __user *arg, unsigned int nr_args)
{
struct io_uring_restriction *res;
size_t size;
int i, ret;
/* Restrictions allowed only if rings started disabled */
if (!(ctx->flags & IORING_SETUP_R_DISABLED))
return -EBADFD;
/* We allow only a single restrictions registration */
if (ctx->restrictions.registered)
return -EBUSY;
if (!arg || nr_args > IORING_MAX_RESTRICTIONS)
return -EINVAL;
size = array_size(nr_args, sizeof(*res));
if (size == SIZE_MAX)
return -EOVERFLOW;
res = memdup_user(arg, size);
if (IS_ERR(res))
return PTR_ERR(res);
ret = 0;
for (i = 0; i < nr_args; i++) {
switch (res[i].opcode) {
case IORING_RESTRICTION_REGISTER_OP:
if (res[i].register_op >= IORING_REGISTER_LAST) {
ret = -EINVAL;
goto out;
}
__set_bit(res[i].register_op,
ctx->restrictions.register_op);
break;
case IORING_RESTRICTION_SQE_OP:
if (res[i].sqe_op >= IORING_OP_LAST) {
ret = -EINVAL;
goto out;
}
__set_bit(res[i].sqe_op, ctx->restrictions.sqe_op);
break;
case IORING_RESTRICTION_SQE_FLAGS_ALLOWED:
ctx->restrictions.sqe_flags_allowed = res[i].sqe_flags;
break;
case IORING_RESTRICTION_SQE_FLAGS_REQUIRED:
ctx->restrictions.sqe_flags_required = res[i].sqe_flags;
break;
default:
ret = -EINVAL;
goto out;
}
}
out:
/* Reset all restrictions if an error happened */
if (ret != 0)
memset(&ctx->restrictions, 0, sizeof(ctx->restrictions));
else
ctx->restrictions.registered = true;
kfree(res);
return ret;
}
static int io_register_enable_rings(struct io_ring_ctx *ctx)
{
if (!(ctx->flags & IORING_SETUP_R_DISABLED))
return -EBADFD;
if (ctx->flags & IORING_SETUP_SINGLE_ISSUER && !ctx->submitter_task) {
WRITE_ONCE(ctx->submitter_task, get_task_struct(current));
/*
* Lazy activation attempts would fail if it was polled before
* submitter_task is set.
*/
if (wq_has_sleeper(&ctx->poll_wq))
io_activate_pollwq(ctx);
}
if (ctx->restrictions.registered)
ctx->restricted = 1;
ctx->flags &= ~IORING_SETUP_R_DISABLED;
if (ctx->sq_data && wq_has_sleeper(&ctx->sq_data->wait))
wake_up(&ctx->sq_data->wait);
return 0;
}
static __cold int io_register_iowq_aff(struct io_ring_ctx *ctx,
void __user *arg, unsigned len)
{
struct io_uring_task *tctx = current->io_uring;
cpumask_var_t new_mask;
int ret;
if (!tctx || !tctx->io_wq)
return -EINVAL;
if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
return -ENOMEM;
cpumask_clear(new_mask);
if (len > cpumask_size())
len = cpumask_size();
if (in_compat_syscall()) {
ret = compat_get_bitmap(cpumask_bits(new_mask),
(const compat_ulong_t __user *)arg,
len * 8 /* CHAR_BIT */);
} else {
ret = copy_from_user(new_mask, arg, len);
}
if (ret) {
free_cpumask_var(new_mask);
return -EFAULT;
}
ret = io_wq_cpu_affinity(tctx->io_wq, new_mask);
free_cpumask_var(new_mask);
return ret;
}
static __cold int io_unregister_iowq_aff(struct io_ring_ctx *ctx)
{
struct io_uring_task *tctx = current->io_uring;
if (!tctx || !tctx->io_wq)
return -EINVAL;
return io_wq_cpu_affinity(tctx->io_wq, NULL);
}
static __cold int io_register_iowq_max_workers(struct io_ring_ctx *ctx,
void __user *arg)
__must_hold(&ctx->uring_lock)
{
struct io_tctx_node *node;
struct io_uring_task *tctx = NULL;
struct io_sq_data *sqd = NULL;
__u32 new_count[2];
int i, ret;
if (copy_from_user(new_count, arg, sizeof(new_count)))
return -EFAULT;
for (i = 0; i < ARRAY_SIZE(new_count); i++)
if (new_count[i] > INT_MAX)
return -EINVAL;
if (ctx->flags & IORING_SETUP_SQPOLL) {
sqd = ctx->sq_data;
if (sqd) {
/*
* Observe the correct sqd->lock -> ctx->uring_lock
* ordering. Fine to drop uring_lock here, we hold
* a ref to the ctx.
*/
refcount_inc(&sqd->refs);
mutex_unlock(&ctx->uring_lock);
mutex_lock(&sqd->lock);
mutex_lock(&ctx->uring_lock);
if (sqd->thread)
tctx = sqd->thread->io_uring;
}
} else {
tctx = current->io_uring;
}
BUILD_BUG_ON(sizeof(new_count) != sizeof(ctx->iowq_limits));
for (i = 0; i < ARRAY_SIZE(new_count); i++)
if (new_count[i])
ctx->iowq_limits[i] = new_count[i];
ctx->iowq_limits_set = true;
if (tctx && tctx->io_wq) {
ret = io_wq_max_workers(tctx->io_wq, new_count);
if (ret)
goto err;
} else {
memset(new_count, 0, sizeof(new_count));
}
if (sqd) {
mutex_unlock(&sqd->lock);
io_put_sq_data(sqd);
}
if (copy_to_user(arg, new_count, sizeof(new_count)))
return -EFAULT;
/* that's it for SQPOLL, only the SQPOLL task creates requests */
if (sqd)
return 0;
/* now propagate the restriction to all registered users */
list_for_each_entry(node, &ctx->tctx_list, ctx_node) {
struct io_uring_task *tctx = node->task->io_uring;
if (WARN_ON_ONCE(!tctx->io_wq))
continue;
for (i = 0; i < ARRAY_SIZE(new_count); i++)
new_count[i] = ctx->iowq_limits[i];
/* ignore errors, it always returns zero anyway */
(void)io_wq_max_workers(tctx->io_wq, new_count);
}
return 0;
err:
if (sqd) {
mutex_unlock(&sqd->lock);
io_put_sq_data(sqd);
}
return ret;
}
static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
void __user *arg, unsigned nr_args)
__releases(ctx->uring_lock)
__acquires(ctx->uring_lock)
{
int ret;
/*
* We don't quiesce the refs for register anymore and so it can't be
* dying as we're holding a file ref here.
*/
if (WARN_ON_ONCE(percpu_ref_is_dying(&ctx->refs)))
return -ENXIO;
if (ctx->submitter_task && ctx->submitter_task != current)
return -EEXIST;
if (ctx->restricted) {
opcode = array_index_nospec(opcode, IORING_REGISTER_LAST);
if (!test_bit(opcode, ctx->restrictions.register_op))
return -EACCES;
}
switch (opcode) {
case IORING_REGISTER_BUFFERS:
ret = -EFAULT;
if (!arg)
break;
ret = io_sqe_buffers_register(ctx, arg, nr_args, NULL);
break;
case IORING_UNREGISTER_BUFFERS:
ret = -EINVAL;
if (arg || nr_args)
break;
ret = io_sqe_buffers_unregister(ctx);
break;
case IORING_REGISTER_FILES:
ret = -EFAULT;
if (!arg)
break;
ret = io_sqe_files_register(ctx, arg, nr_args, NULL);
break;
case IORING_UNREGISTER_FILES:
ret = -EINVAL;
if (arg || nr_args)
break;
ret = io_sqe_files_unregister(ctx);
break;
case IORING_REGISTER_FILES_UPDATE:
ret = io_register_files_update(ctx, arg, nr_args);
break;
case IORING_REGISTER_EVENTFD:
ret = -EINVAL;
if (nr_args != 1)
break;
ret = io_eventfd_register(ctx, arg, 0);
break;
case IORING_REGISTER_EVENTFD_ASYNC:
ret = -EINVAL;
if (nr_args != 1)
break;
ret = io_eventfd_register(ctx, arg, 1);
break;
case IORING_UNREGISTER_EVENTFD:
ret = -EINVAL;
if (arg || nr_args)
break;
ret = io_eventfd_unregister(ctx);
break;
case IORING_REGISTER_PROBE:
ret = -EINVAL;
if (!arg || nr_args > 256)
break;
ret = io_probe(ctx, arg, nr_args);
break;
case IORING_REGISTER_PERSONALITY:
ret = -EINVAL;
if (arg || nr_args)
break;
ret = io_register_personality(ctx);
break;
case IORING_UNREGISTER_PERSONALITY:
ret = -EINVAL;
if (arg)
break;
ret = io_unregister_personality(ctx, nr_args);
break;
case IORING_REGISTER_ENABLE_RINGS:
ret = -EINVAL;
if (arg || nr_args)
break;
ret = io_register_enable_rings(ctx);
break;
case IORING_REGISTER_RESTRICTIONS:
ret = io_register_restrictions(ctx, arg, nr_args);
break;
case IORING_REGISTER_FILES2:
ret = io_register_rsrc(ctx, arg, nr_args, IORING_RSRC_FILE);
break;
case IORING_REGISTER_FILES_UPDATE2:
ret = io_register_rsrc_update(ctx, arg, nr_args,
IORING_RSRC_FILE);
break;
case IORING_REGISTER_BUFFERS2:
ret = io_register_rsrc(ctx, arg, nr_args, IORING_RSRC_BUFFER);
break;
case IORING_REGISTER_BUFFERS_UPDATE:
ret = io_register_rsrc_update(ctx, arg, nr_args,
IORING_RSRC_BUFFER);
break;
case IORING_REGISTER_IOWQ_AFF:
ret = -EINVAL;
if (!arg || !nr_args)
break;
ret = io_register_iowq_aff(ctx, arg, nr_args);
break;
case IORING_UNREGISTER_IOWQ_AFF:
ret = -EINVAL;
if (arg || nr_args)
break;
ret = io_unregister_iowq_aff(ctx);
break;
case IORING_REGISTER_IOWQ_MAX_WORKERS:
ret = -EINVAL;
if (!arg || nr_args != 2)
break;
ret = io_register_iowq_max_workers(ctx, arg);
break;
case IORING_REGISTER_RING_FDS:
ret = io_ringfd_register(ctx, arg, nr_args);
break;
case IORING_UNREGISTER_RING_FDS:
ret = io_ringfd_unregister(ctx, arg, nr_args);
break;
case IORING_REGISTER_PBUF_RING:
ret = -EINVAL;
if (!arg || nr_args != 1)
break;
ret = io_register_pbuf_ring(ctx, arg);
break;
case IORING_UNREGISTER_PBUF_RING:
ret = -EINVAL;
if (!arg || nr_args != 1)
break;
ret = io_unregister_pbuf_ring(ctx, arg);
break;
case IORING_REGISTER_SYNC_CANCEL:
ret = -EINVAL;
if (!arg || nr_args != 1)
break;
ret = io_sync_cancel(ctx, arg);
break;
case IORING_REGISTER_FILE_ALLOC_RANGE:
ret = -EINVAL;
if (!arg || nr_args)
break;
ret = io_register_file_alloc_range(ctx, arg);
break;
default:
ret = -EINVAL;
break;
}
return ret;
}
SYSCALL_DEFINE4(io_uring_register, unsigned int, fd, unsigned int, opcode,
void __user *, arg, unsigned int, nr_args)
{
struct io_ring_ctx *ctx;
long ret = -EBADF;
struct fd f;
bool use_registered_ring;
use_registered_ring = !!(opcode & IORING_REGISTER_USE_REGISTERED_RING);
opcode &= ~IORING_REGISTER_USE_REGISTERED_RING;
if (opcode >= IORING_REGISTER_LAST)
return -EINVAL;
if (use_registered_ring) {
/*
* Ring fd has been registered via IORING_REGISTER_RING_FDS, we
* need only dereference our task private array to find it.
*/
struct io_uring_task *tctx = current->io_uring;
if (unlikely(!tctx || fd >= IO_RINGFD_REG_MAX))
return -EINVAL;
fd = array_index_nospec(fd, IO_RINGFD_REG_MAX);
f.file = tctx->registered_rings[fd];
f.flags = 0;
if (unlikely(!f.file))
return -EBADF;
} else {
f = fdget(fd);
if (unlikely(!f.file))
return -EBADF;
ret = -EOPNOTSUPP;
if (!io_is_uring_fops(f.file))
goto out_fput;
}
ctx = f.file->private_data;
mutex_lock(&ctx->uring_lock);
ret = __io_uring_register(ctx, opcode, arg, nr_args);
mutex_unlock(&ctx->uring_lock);
trace_io_uring_register(ctx, opcode, ctx->nr_user_files, ctx->nr_user_bufs, ret);
out_fput:
fdput(f);
return ret;
}
static int __init io_uring_init(void)
{
#define __BUILD_BUG_VERIFY_OFFSET_SIZE(stype, eoffset, esize, ename) do { \
BUILD_BUG_ON(offsetof(stype, ename) != eoffset); \
BUILD_BUG_ON(sizeof_field(stype, ename) != esize); \
} while (0)
#define BUILD_BUG_SQE_ELEM(eoffset, etype, ename) \
__BUILD_BUG_VERIFY_OFFSET_SIZE(struct io_uring_sqe, eoffset, sizeof(etype), ename)
#define BUILD_BUG_SQE_ELEM_SIZE(eoffset, esize, ename) \
__BUILD_BUG_VERIFY_OFFSET_SIZE(struct io_uring_sqe, eoffset, esize, ename)
BUILD_BUG_ON(sizeof(struct io_uring_sqe) != 64);
BUILD_BUG_SQE_ELEM(0, __u8, opcode);
BUILD_BUG_SQE_ELEM(1, __u8, flags);
BUILD_BUG_SQE_ELEM(2, __u16, ioprio);
BUILD_BUG_SQE_ELEM(4, __s32, fd);
BUILD_BUG_SQE_ELEM(8, __u64, off);
BUILD_BUG_SQE_ELEM(8, __u64, addr2);
BUILD_BUG_SQE_ELEM(8, __u32, cmd_op);
BUILD_BUG_SQE_ELEM(12, __u32, __pad1);
BUILD_BUG_SQE_ELEM(16, __u64, addr);
BUILD_BUG_SQE_ELEM(16, __u64, splice_off_in);
BUILD_BUG_SQE_ELEM(24, __u32, len);
BUILD_BUG_SQE_ELEM(28, __kernel_rwf_t, rw_flags);
BUILD_BUG_SQE_ELEM(28, /* compat */ int, rw_flags);
BUILD_BUG_SQE_ELEM(28, /* compat */ __u32, rw_flags);
BUILD_BUG_SQE_ELEM(28, __u32, fsync_flags);
BUILD_BUG_SQE_ELEM(28, /* compat */ __u16, poll_events);
BUILD_BUG_SQE_ELEM(28, __u32, poll32_events);
BUILD_BUG_SQE_ELEM(28, __u32, sync_range_flags);
BUILD_BUG_SQE_ELEM(28, __u32, msg_flags);
BUILD_BUG_SQE_ELEM(28, __u32, timeout_flags);
BUILD_BUG_SQE_ELEM(28, __u32, accept_flags);
BUILD_BUG_SQE_ELEM(28, __u32, cancel_flags);
BUILD_BUG_SQE_ELEM(28, __u32, open_flags);
BUILD_BUG_SQE_ELEM(28, __u32, statx_flags);
BUILD_BUG_SQE_ELEM(28, __u32, fadvise_advice);
BUILD_BUG_SQE_ELEM(28, __u32, splice_flags);
BUILD_BUG_SQE_ELEM(28, __u32, rename_flags);
BUILD_BUG_SQE_ELEM(28, __u32, unlink_flags);
BUILD_BUG_SQE_ELEM(28, __u32, hardlink_flags);
BUILD_BUG_SQE_ELEM(28, __u32, xattr_flags);
BUILD_BUG_SQE_ELEM(28, __u32, msg_ring_flags);
BUILD_BUG_SQE_ELEM(32, __u64, user_data);
BUILD_BUG_SQE_ELEM(40, __u16, buf_index);
BUILD_BUG_SQE_ELEM(40, __u16, buf_group);
BUILD_BUG_SQE_ELEM(42, __u16, personality);
BUILD_BUG_SQE_ELEM(44, __s32, splice_fd_in);
BUILD_BUG_SQE_ELEM(44, __u32, file_index);
BUILD_BUG_SQE_ELEM(44, __u16, addr_len);
BUILD_BUG_SQE_ELEM(46, __u16, __pad3[0]);
BUILD_BUG_SQE_ELEM(48, __u64, addr3);
BUILD_BUG_SQE_ELEM_SIZE(48, 0, cmd);
BUILD_BUG_SQE_ELEM(56, __u64, __pad2);
BUILD_BUG_ON(sizeof(struct io_uring_files_update) !=
sizeof(struct io_uring_rsrc_update));
BUILD_BUG_ON(sizeof(struct io_uring_rsrc_update) >
sizeof(struct io_uring_rsrc_update2));
/* ->buf_index is u16 */
BUILD_BUG_ON(offsetof(struct io_uring_buf_ring, bufs) != 0);
BUILD_BUG_ON(offsetof(struct io_uring_buf, resv) !=
offsetof(struct io_uring_buf_ring, tail));
/* should fit into one byte */
BUILD_BUG_ON(SQE_VALID_FLAGS >= (1 << 8));
BUILD_BUG_ON(SQE_COMMON_FLAGS >= (1 << 8));
BUILD_BUG_ON((SQE_VALID_FLAGS | SQE_COMMON_FLAGS) != SQE_VALID_FLAGS);
BUILD_BUG_ON(__REQ_F_LAST_BIT > 8 * sizeof(int));
BUILD_BUG_ON(sizeof(atomic_t) != sizeof(u32));
io_uring_optable_init();
req_cachep = KMEM_CACHE(io_kiocb, SLAB_HWCACHE_ALIGN | SLAB_PANIC |
SLAB_ACCOUNT | SLAB_TYPESAFE_BY_RCU);
return 0;
};
__initcall(io_uring_init);
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