mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-12 21:44:06 +08:00
29f1c1ae6d
originally, stack closures were only used synchronously, and with the original implementation of closure_sync() the ref never hit 0; thus, closure_put_after_sub() assumes that if the ref hits 0 it's on the debug list, in debug mode. that's no longer true with the current implementation of closure_sync, so we need a new magic so closure_debug_destroy() doesn't pop an assert. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
298 lines
6.8 KiB
C
298 lines
6.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* Asynchronous refcounty things
|
|
*
|
|
* Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
|
|
* Copyright 2012 Google, Inc.
|
|
*/
|
|
|
|
#include <linux/closure.h>
|
|
#include <linux/debugfs.h>
|
|
#include <linux/export.h>
|
|
#include <linux/rcupdate.h>
|
|
#include <linux/seq_file.h>
|
|
#include <linux/sched/debug.h>
|
|
|
|
static inline void closure_put_after_sub_checks(int flags)
|
|
{
|
|
int r = flags & CLOSURE_REMAINING_MASK;
|
|
|
|
if (WARN(flags & CLOSURE_GUARD_MASK,
|
|
"closure has guard bits set: %x (%u)",
|
|
flags & CLOSURE_GUARD_MASK, (unsigned) __fls(r)))
|
|
r &= ~CLOSURE_GUARD_MASK;
|
|
|
|
WARN(!r && (flags & ~CLOSURE_DESTRUCTOR),
|
|
"closure ref hit 0 with incorrect flags set: %x (%u)",
|
|
flags & ~CLOSURE_DESTRUCTOR, (unsigned) __fls(flags));
|
|
}
|
|
|
|
static inline void closure_put_after_sub(struct closure *cl, int flags)
|
|
{
|
|
closure_put_after_sub_checks(flags);
|
|
|
|
if (!(flags & CLOSURE_REMAINING_MASK)) {
|
|
smp_acquire__after_ctrl_dep();
|
|
|
|
cl->closure_get_happened = false;
|
|
|
|
if (cl->fn && !(flags & CLOSURE_DESTRUCTOR)) {
|
|
atomic_set(&cl->remaining,
|
|
CLOSURE_REMAINING_INITIALIZER);
|
|
closure_queue(cl);
|
|
} else {
|
|
struct closure *parent = cl->parent;
|
|
closure_fn *destructor = cl->fn;
|
|
|
|
closure_debug_destroy(cl);
|
|
|
|
if (destructor)
|
|
destructor(&cl->work);
|
|
|
|
if (parent)
|
|
closure_put(parent);
|
|
}
|
|
}
|
|
}
|
|
|
|
/* For clearing flags with the same atomic op as a put */
|
|
void closure_sub(struct closure *cl, int v)
|
|
{
|
|
closure_put_after_sub(cl, atomic_sub_return_release(v, &cl->remaining));
|
|
}
|
|
EXPORT_SYMBOL(closure_sub);
|
|
|
|
/*
|
|
* closure_put - decrement a closure's refcount
|
|
*/
|
|
void closure_put(struct closure *cl)
|
|
{
|
|
closure_put_after_sub(cl, atomic_dec_return_release(&cl->remaining));
|
|
}
|
|
EXPORT_SYMBOL(closure_put);
|
|
|
|
/*
|
|
* closure_wake_up - wake up all closures on a wait list, without memory barrier
|
|
*/
|
|
void __closure_wake_up(struct closure_waitlist *wait_list)
|
|
{
|
|
struct llist_node *list;
|
|
struct closure *cl, *t;
|
|
struct llist_node *reverse = NULL;
|
|
|
|
list = llist_del_all(&wait_list->list);
|
|
|
|
/* We first reverse the list to preserve FIFO ordering and fairness */
|
|
reverse = llist_reverse_order(list);
|
|
|
|
/* Then do the wakeups */
|
|
llist_for_each_entry_safe(cl, t, reverse, list) {
|
|
closure_set_waiting(cl, 0);
|
|
closure_sub(cl, CLOSURE_WAITING + 1);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(__closure_wake_up);
|
|
|
|
/**
|
|
* closure_wait - add a closure to a waitlist
|
|
* @waitlist: will own a ref on @cl, which will be released when
|
|
* closure_wake_up() is called on @waitlist.
|
|
* @cl: closure pointer.
|
|
*
|
|
*/
|
|
bool closure_wait(struct closure_waitlist *waitlist, struct closure *cl)
|
|
{
|
|
if (atomic_read(&cl->remaining) & CLOSURE_WAITING)
|
|
return false;
|
|
|
|
cl->closure_get_happened = true;
|
|
closure_set_waiting(cl, _RET_IP_);
|
|
atomic_add(CLOSURE_WAITING + 1, &cl->remaining);
|
|
llist_add(&cl->list, &waitlist->list);
|
|
|
|
return true;
|
|
}
|
|
EXPORT_SYMBOL(closure_wait);
|
|
|
|
struct closure_syncer {
|
|
struct task_struct *task;
|
|
int done;
|
|
};
|
|
|
|
static CLOSURE_CALLBACK(closure_sync_fn)
|
|
{
|
|
struct closure *cl = container_of(ws, struct closure, work);
|
|
struct closure_syncer *s = cl->s;
|
|
struct task_struct *p;
|
|
|
|
rcu_read_lock();
|
|
p = READ_ONCE(s->task);
|
|
s->done = 1;
|
|
wake_up_process(p);
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
void __sched __closure_sync(struct closure *cl)
|
|
{
|
|
struct closure_syncer s = { .task = current };
|
|
|
|
cl->s = &s;
|
|
continue_at(cl, closure_sync_fn, NULL);
|
|
|
|
while (1) {
|
|
set_current_state(TASK_UNINTERRUPTIBLE);
|
|
if (s.done)
|
|
break;
|
|
schedule();
|
|
}
|
|
|
|
__set_current_state(TASK_RUNNING);
|
|
}
|
|
EXPORT_SYMBOL(__closure_sync);
|
|
|
|
/*
|
|
* closure_return_sync - finish running a closure, synchronously (i.e. waiting
|
|
* for outstanding get()s to finish) and returning once closure refcount is 0.
|
|
*
|
|
* Unlike closure_sync() this doesn't reinit the ref to 1; subsequent
|
|
* closure_get_not_zero() calls waill fail.
|
|
*/
|
|
void __sched closure_return_sync(struct closure *cl)
|
|
{
|
|
struct closure_syncer s = { .task = current };
|
|
|
|
cl->s = &s;
|
|
set_closure_fn(cl, closure_sync_fn, NULL);
|
|
|
|
unsigned flags = atomic_sub_return_release(1 + CLOSURE_RUNNING - CLOSURE_DESTRUCTOR,
|
|
&cl->remaining);
|
|
|
|
closure_put_after_sub_checks(flags);
|
|
|
|
if (unlikely(flags & CLOSURE_REMAINING_MASK)) {
|
|
while (1) {
|
|
set_current_state(TASK_UNINTERRUPTIBLE);
|
|
if (s.done)
|
|
break;
|
|
schedule();
|
|
}
|
|
|
|
__set_current_state(TASK_RUNNING);
|
|
}
|
|
|
|
if (cl->parent)
|
|
closure_put(cl->parent);
|
|
}
|
|
EXPORT_SYMBOL(closure_return_sync);
|
|
|
|
int __sched __closure_sync_timeout(struct closure *cl, unsigned long timeout)
|
|
{
|
|
struct closure_syncer s = { .task = current };
|
|
int ret = 0;
|
|
|
|
cl->s = &s;
|
|
continue_at(cl, closure_sync_fn, NULL);
|
|
|
|
while (1) {
|
|
set_current_state(TASK_UNINTERRUPTIBLE);
|
|
if (s.done)
|
|
break;
|
|
if (!timeout) {
|
|
/*
|
|
* Carefully undo the continue_at() - but only if it
|
|
* hasn't completed, i.e. the final closure_put() hasn't
|
|
* happened yet:
|
|
*/
|
|
unsigned old, new, v = atomic_read(&cl->remaining);
|
|
do {
|
|
old = v;
|
|
if (!old || (old & CLOSURE_RUNNING))
|
|
goto success;
|
|
|
|
new = old + CLOSURE_REMAINING_INITIALIZER;
|
|
} while ((v = atomic_cmpxchg(&cl->remaining, old, new)) != old);
|
|
ret = -ETIME;
|
|
}
|
|
|
|
timeout = schedule_timeout(timeout);
|
|
}
|
|
success:
|
|
__set_current_state(TASK_RUNNING);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(__closure_sync_timeout);
|
|
|
|
#ifdef CONFIG_DEBUG_CLOSURES
|
|
|
|
static LIST_HEAD(closure_list);
|
|
static DEFINE_SPINLOCK(closure_list_lock);
|
|
|
|
void closure_debug_create(struct closure *cl)
|
|
{
|
|
unsigned long flags;
|
|
|
|
BUG_ON(cl->magic == CLOSURE_MAGIC_ALIVE);
|
|
cl->magic = CLOSURE_MAGIC_ALIVE;
|
|
|
|
spin_lock_irqsave(&closure_list_lock, flags);
|
|
list_add(&cl->all, &closure_list);
|
|
spin_unlock_irqrestore(&closure_list_lock, flags);
|
|
}
|
|
EXPORT_SYMBOL(closure_debug_create);
|
|
|
|
void closure_debug_destroy(struct closure *cl)
|
|
{
|
|
unsigned long flags;
|
|
|
|
if (cl->magic == CLOSURE_MAGIC_STACK)
|
|
return;
|
|
|
|
BUG_ON(cl->magic != CLOSURE_MAGIC_ALIVE);
|
|
cl->magic = CLOSURE_MAGIC_DEAD;
|
|
|
|
spin_lock_irqsave(&closure_list_lock, flags);
|
|
list_del(&cl->all);
|
|
spin_unlock_irqrestore(&closure_list_lock, flags);
|
|
}
|
|
EXPORT_SYMBOL(closure_debug_destroy);
|
|
|
|
static int debug_show(struct seq_file *f, void *data)
|
|
{
|
|
struct closure *cl;
|
|
|
|
spin_lock_irq(&closure_list_lock);
|
|
|
|
list_for_each_entry(cl, &closure_list, all) {
|
|
int r = atomic_read(&cl->remaining);
|
|
|
|
seq_printf(f, "%p: %pS -> %pS p %p r %i ",
|
|
cl, (void *) cl->ip, cl->fn, cl->parent,
|
|
r & CLOSURE_REMAINING_MASK);
|
|
|
|
seq_printf(f, "%s%s\n",
|
|
test_bit(WORK_STRUCT_PENDING_BIT,
|
|
work_data_bits(&cl->work)) ? "Q" : "",
|
|
r & CLOSURE_RUNNING ? "R" : "");
|
|
|
|
if (r & CLOSURE_WAITING)
|
|
seq_printf(f, " W %pS\n",
|
|
(void *) cl->waiting_on);
|
|
|
|
seq_puts(f, "\n");
|
|
}
|
|
|
|
spin_unlock_irq(&closure_list_lock);
|
|
return 0;
|
|
}
|
|
|
|
DEFINE_SHOW_ATTRIBUTE(debug);
|
|
|
|
static int __init closure_debug_init(void)
|
|
{
|
|
debugfs_create_file("closures", 0400, NULL, NULL, &debug_fops);
|
|
return 0;
|
|
}
|
|
late_initcall(closure_debug_init)
|
|
|
|
#endif
|