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linux/io_uring/futex.c
Jens Axboe 30dab608c3 io_uring/futex: always remove futex entry for cancel all
We know the request is either being removed, or already in the process of
being removed through task_work, so we can delete it from our futex list
upfront. This is important for remove all conditions, as we otherwise
will find it multiple times and prevent cancelation progress.

Cc: stable@vger.kernel.org
Fixes: 194bb58c60 ("io_uring: add support for futex wake and wait")
Fixes: 8f350194d5 ("io_uring: add support for vectored futex waits")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-03-15 15:37:15 -06:00

388 lines
9.5 KiB
C

// SPDX-License-Identifier: GPL-2.0
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/io_uring.h>
#include <uapi/linux/io_uring.h>
#include "../kernel/futex/futex.h"
#include "io_uring.h"
#include "rsrc.h"
#include "futex.h"
struct io_futex {
struct file *file;
union {
u32 __user *uaddr;
struct futex_waitv __user *uwaitv;
};
unsigned long futex_val;
unsigned long futex_mask;
unsigned long futexv_owned;
u32 futex_flags;
unsigned int futex_nr;
bool futexv_unqueued;
};
struct io_futex_data {
union {
struct futex_q q;
struct io_cache_entry cache;
};
struct io_kiocb *req;
};
void io_futex_cache_init(struct io_ring_ctx *ctx)
{
io_alloc_cache_init(&ctx->futex_cache, IO_NODE_ALLOC_CACHE_MAX,
sizeof(struct io_futex_data));
}
static void io_futex_cache_entry_free(struct io_cache_entry *entry)
{
kfree(container_of(entry, struct io_futex_data, cache));
}
void io_futex_cache_free(struct io_ring_ctx *ctx)
{
io_alloc_cache_free(&ctx->futex_cache, io_futex_cache_entry_free);
}
static void __io_futex_complete(struct io_kiocb *req, struct io_tw_state *ts)
{
req->async_data = NULL;
hlist_del_init(&req->hash_node);
io_req_task_complete(req, ts);
}
static void io_futex_complete(struct io_kiocb *req, struct io_tw_state *ts)
{
struct io_futex_data *ifd = req->async_data;
struct io_ring_ctx *ctx = req->ctx;
io_tw_lock(ctx, ts);
if (!io_alloc_cache_put(&ctx->futex_cache, &ifd->cache))
kfree(ifd);
__io_futex_complete(req, ts);
}
static void io_futexv_complete(struct io_kiocb *req, struct io_tw_state *ts)
{
struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex);
struct futex_vector *futexv = req->async_data;
io_tw_lock(req->ctx, ts);
if (!iof->futexv_unqueued) {
int res;
res = futex_unqueue_multiple(futexv, iof->futex_nr);
if (res != -1)
io_req_set_res(req, res, 0);
}
kfree(req->async_data);
req->flags &= ~REQ_F_ASYNC_DATA;
__io_futex_complete(req, ts);
}
static bool io_futexv_claim(struct io_futex *iof)
{
if (test_bit(0, &iof->futexv_owned) ||
test_and_set_bit_lock(0, &iof->futexv_owned))
return false;
return true;
}
static bool __io_futex_cancel(struct io_ring_ctx *ctx, struct io_kiocb *req)
{
/* futex wake already done or in progress */
if (req->opcode == IORING_OP_FUTEX_WAIT) {
struct io_futex_data *ifd = req->async_data;
if (!futex_unqueue(&ifd->q))
return false;
req->io_task_work.func = io_futex_complete;
} else {
struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex);
if (!io_futexv_claim(iof))
return false;
req->io_task_work.func = io_futexv_complete;
}
hlist_del_init(&req->hash_node);
io_req_set_res(req, -ECANCELED, 0);
io_req_task_work_add(req);
return true;
}
int io_futex_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd,
unsigned int issue_flags)
{
struct hlist_node *tmp;
struct io_kiocb *req;
int nr = 0;
if (cd->flags & (IORING_ASYNC_CANCEL_FD|IORING_ASYNC_CANCEL_FD_FIXED))
return -ENOENT;
io_ring_submit_lock(ctx, issue_flags);
hlist_for_each_entry_safe(req, tmp, &ctx->futex_list, hash_node) {
if (req->cqe.user_data != cd->data &&
!(cd->flags & IORING_ASYNC_CANCEL_ANY))
continue;
if (__io_futex_cancel(ctx, req))
nr++;
if (!(cd->flags & IORING_ASYNC_CANCEL_ALL))
break;
}
io_ring_submit_unlock(ctx, issue_flags);
if (nr)
return nr;
return -ENOENT;
}
bool io_futex_remove_all(struct io_ring_ctx *ctx, struct task_struct *task,
bool cancel_all)
{
struct hlist_node *tmp;
struct io_kiocb *req;
bool found = false;
lockdep_assert_held(&ctx->uring_lock);
hlist_for_each_entry_safe(req, tmp, &ctx->futex_list, hash_node) {
if (!io_match_task_safe(req, task, cancel_all))
continue;
hlist_del_init(&req->hash_node);
__io_futex_cancel(ctx, req);
found = true;
}
return found;
}
int io_futex_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex);
u32 flags;
if (unlikely(sqe->len || sqe->futex_flags || sqe->buf_index ||
sqe->file_index))
return -EINVAL;
iof->uaddr = u64_to_user_ptr(READ_ONCE(sqe->addr));
iof->futex_val = READ_ONCE(sqe->addr2);
iof->futex_mask = READ_ONCE(sqe->addr3);
flags = READ_ONCE(sqe->fd);
if (flags & ~FUTEX2_VALID_MASK)
return -EINVAL;
iof->futex_flags = futex2_to_flags(flags);
if (!futex_flags_valid(iof->futex_flags))
return -EINVAL;
if (!futex_validate_input(iof->futex_flags, iof->futex_val) ||
!futex_validate_input(iof->futex_flags, iof->futex_mask))
return -EINVAL;
return 0;
}
static void io_futex_wakev_fn(struct wake_q_head *wake_q, struct futex_q *q)
{
struct io_kiocb *req = q->wake_data;
struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex);
if (!io_futexv_claim(iof))
return;
if (unlikely(!__futex_wake_mark(q)))
return;
io_req_set_res(req, 0, 0);
req->io_task_work.func = io_futexv_complete;
io_req_task_work_add(req);
}
int io_futexv_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex);
struct futex_vector *futexv;
int ret;
/* No flags or mask supported for waitv */
if (unlikely(sqe->fd || sqe->buf_index || sqe->file_index ||
sqe->addr2 || sqe->futex_flags || sqe->addr3))
return -EINVAL;
iof->uaddr = u64_to_user_ptr(READ_ONCE(sqe->addr));
iof->futex_nr = READ_ONCE(sqe->len);
if (!iof->futex_nr || iof->futex_nr > FUTEX_WAITV_MAX)
return -EINVAL;
futexv = kcalloc(iof->futex_nr, sizeof(*futexv), GFP_KERNEL);
if (!futexv)
return -ENOMEM;
ret = futex_parse_waitv(futexv, iof->uwaitv, iof->futex_nr,
io_futex_wakev_fn, req);
if (ret) {
kfree(futexv);
return ret;
}
iof->futexv_owned = 0;
iof->futexv_unqueued = 0;
req->flags |= REQ_F_ASYNC_DATA;
req->async_data = futexv;
return 0;
}
static void io_futex_wake_fn(struct wake_q_head *wake_q, struct futex_q *q)
{
struct io_futex_data *ifd = container_of(q, struct io_futex_data, q);
struct io_kiocb *req = ifd->req;
if (unlikely(!__futex_wake_mark(q)))
return;
io_req_set_res(req, 0, 0);
req->io_task_work.func = io_futex_complete;
io_req_task_work_add(req);
}
static struct io_futex_data *io_alloc_ifd(struct io_ring_ctx *ctx)
{
struct io_cache_entry *entry;
entry = io_alloc_cache_get(&ctx->futex_cache);
if (entry)
return container_of(entry, struct io_futex_data, cache);
return kmalloc(sizeof(struct io_futex_data), GFP_NOWAIT);
}
int io_futexv_wait(struct io_kiocb *req, unsigned int issue_flags)
{
struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex);
struct futex_vector *futexv = req->async_data;
struct io_ring_ctx *ctx = req->ctx;
int ret, woken = -1;
io_ring_submit_lock(ctx, issue_flags);
ret = futex_wait_multiple_setup(futexv, iof->futex_nr, &woken);
/*
* Error case, ret is < 0. Mark the request as failed.
*/
if (unlikely(ret < 0)) {
io_ring_submit_unlock(ctx, issue_flags);
req_set_fail(req);
io_req_set_res(req, ret, 0);
kfree(futexv);
req->async_data = NULL;
req->flags &= ~REQ_F_ASYNC_DATA;
return IOU_OK;
}
/*
* 0 return means that we successfully setup the waiters, and that
* nobody triggered a wakeup while we were doing so. If the wakeup
* happened post setup, the task_work will be run post this issue and
* under the submission lock. 1 means We got woken while setting up,
* let that side do the completion. Note that
* futex_wait_multiple_setup() will have unqueued all the futexes in
* this case. Mark us as having done that already, since this is
* different from normal wakeup.
*/
if (!ret) {
/*
* If futex_wait_multiple_setup() returns 0 for a
* successful setup, then the task state will not be
* runnable. This is fine for the sync syscall, as
* it'll be blocking unless we already got one of the
* futexes woken, but it obviously won't work for an
* async invocation. Mark us runnable again.
*/
__set_current_state(TASK_RUNNING);
hlist_add_head(&req->hash_node, &ctx->futex_list);
} else {
iof->futexv_unqueued = 1;
if (woken != -1)
io_req_set_res(req, woken, 0);
}
io_ring_submit_unlock(ctx, issue_flags);
return IOU_ISSUE_SKIP_COMPLETE;
}
int io_futex_wait(struct io_kiocb *req, unsigned int issue_flags)
{
struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex);
struct io_ring_ctx *ctx = req->ctx;
struct io_futex_data *ifd = NULL;
struct futex_hash_bucket *hb;
int ret;
if (!iof->futex_mask) {
ret = -EINVAL;
goto done;
}
io_ring_submit_lock(ctx, issue_flags);
ifd = io_alloc_ifd(ctx);
if (!ifd) {
ret = -ENOMEM;
goto done_unlock;
}
req->async_data = ifd;
ifd->q = futex_q_init;
ifd->q.bitset = iof->futex_mask;
ifd->q.wake = io_futex_wake_fn;
ifd->req = req;
ret = futex_wait_setup(iof->uaddr, iof->futex_val, iof->futex_flags,
&ifd->q, &hb);
if (!ret) {
hlist_add_head(&req->hash_node, &ctx->futex_list);
io_ring_submit_unlock(ctx, issue_flags);
futex_queue(&ifd->q, hb);
return IOU_ISSUE_SKIP_COMPLETE;
}
done_unlock:
io_ring_submit_unlock(ctx, issue_flags);
done:
if (ret < 0)
req_set_fail(req);
io_req_set_res(req, ret, 0);
kfree(ifd);
return IOU_OK;
}
int io_futex_wake(struct io_kiocb *req, unsigned int issue_flags)
{
struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex);
int ret;
/*
* Strict flags - ensure that waking 0 futexes yields a 0 result.
* See commit 43adf8449510 ("futex: FLAGS_STRICT") for details.
*/
ret = futex_wake(iof->uaddr, FLAGS_STRICT | iof->futex_flags,
iof->futex_val, iof->futex_mask);
if (ret < 0)
req_set_fail(req);
io_req_set_res(req, ret, 0);
return IOU_OK;
}