93 строки
2.2 KiB
C
93 строки
2.2 KiB
C
#include <linux/spinlock.h>
|
|
#include <linux/task_work.h>
|
|
#include <linux/tracehook.h>
|
|
|
|
static struct callback_head work_exited; /* all we need is ->next == NULL */
|
|
|
|
int
|
|
task_work_add(struct task_struct *task, struct callback_head *work, bool notify)
|
|
{
|
|
struct callback_head *head;
|
|
|
|
do {
|
|
head = ACCESS_ONCE(task->task_works);
|
|
if (unlikely(head == &work_exited))
|
|
return -ESRCH;
|
|
work->next = head;
|
|
} while (cmpxchg(&task->task_works, head, work) != head);
|
|
|
|
if (notify)
|
|
set_notify_resume(task);
|
|
return 0;
|
|
}
|
|
|
|
struct callback_head *
|
|
task_work_cancel(struct task_struct *task, task_work_func_t func)
|
|
{
|
|
struct callback_head **pprev = &task->task_works;
|
|
struct callback_head *work = NULL;
|
|
unsigned long flags;
|
|
/*
|
|
* If cmpxchg() fails we continue without updating pprev.
|
|
* Either we raced with task_work_add() which added the
|
|
* new entry before this work, we will find it again. Or
|
|
* we raced with task_work_run(), *pprev == NULL/exited.
|
|
*/
|
|
raw_spin_lock_irqsave(&task->pi_lock, flags);
|
|
while ((work = ACCESS_ONCE(*pprev))) {
|
|
read_barrier_depends();
|
|
if (work->func != func)
|
|
pprev = &work->next;
|
|
else if (cmpxchg(pprev, work, work->next) == work)
|
|
break;
|
|
}
|
|
raw_spin_unlock_irqrestore(&task->pi_lock, flags);
|
|
|
|
return work;
|
|
}
|
|
|
|
void task_work_run(void)
|
|
{
|
|
struct task_struct *task = current;
|
|
struct callback_head *work, *head, *next;
|
|
|
|
for (;;) {
|
|
/*
|
|
* work->func() can do task_work_add(), do not set
|
|
* work_exited unless the list is empty.
|
|
*/
|
|
do {
|
|
work = ACCESS_ONCE(task->task_works);
|
|
head = !work && (task->flags & PF_EXITING) ?
|
|
&work_exited : NULL;
|
|
} while (cmpxchg(&task->task_works, work, head) != work);
|
|
|
|
if (!work)
|
|
break;
|
|
/*
|
|
* Synchronize with task_work_cancel(). It can't remove
|
|
* the first entry == work, cmpxchg(task_works) should
|
|
* fail, but it can play with *work and other entries.
|
|
*/
|
|
raw_spin_unlock_wait(&task->pi_lock);
|
|
smp_mb();
|
|
|
|
/* Reverse the list to run the works in fifo order */
|
|
head = NULL;
|
|
do {
|
|
next = work->next;
|
|
work->next = head;
|
|
head = work;
|
|
work = next;
|
|
} while (work);
|
|
|
|
work = head;
|
|
do {
|
|
next = work->next;
|
|
work->func(work);
|
|
work = next;
|
|
cond_resched();
|
|
} while (work);
|
|
}
|
|
}
|