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#include <linux/spinlock.h>
#include <linux/task_work.h>
#include <linux/tracehook.h>
int
task_work_add(struct task_struct *task, struct callback_head *twork, bool notify)
{
unsigned long flags;
int err = -ESRCH;
#ifndef TIF_NOTIFY_RESUME
if (notify)
return -ENOTSUPP;
#endif
/*
* We must not insert the new work if the task has already passed
* exit_task_work(). We rely on do_exit()->raw_spin_unlock_wait()
* and check PF_EXITING under pi_lock.
*/
raw_spin_lock_irqsave(&task->pi_lock, flags);
if (likely(!(task->flags & PF_EXITING))) {
struct callback_head *last = task->task_works;
struct callback_head *first = last ? last->next : twork;
twork->next = first;
if (last)
last->next = twork;
task->task_works = twork;
err = 0;
}
raw_spin_unlock_irqrestore(&task->pi_lock, flags);
/* test_and_set_bit() implies mb(), see tracehook_notify_resume(). */
if (likely(!err) && notify)
set_notify_resume(task);
return err;
}
struct callback_head *
task_work_cancel(struct task_struct *task, task_work_func_t func)
{
unsigned long flags;
struct callback_head *last, *res = NULL;
raw_spin_lock_irqsave(&task->pi_lock, flags);
last = task->task_works;
if (last) {
struct callback_head *q = last, *p = q->next;
while (1) {
if (p->func == func) {
q->next = p->next;
if (p == last)
task->task_works = q == p ? NULL : q;
res = p;
break;
}
if (p == last)
break;
q = p;
p = q->next;
}
}
raw_spin_unlock_irqrestore(&task->pi_lock, flags);
return res;
}
void task_work_run(void)
{
struct task_struct *task = current;
struct callback_head *p, *q;
raw_spin_lock_irq(&task->pi_lock);
p = task->task_works;
task->task_works = NULL;
raw_spin_unlock_irq(&task->pi_lock);
if (unlikely(!p))
return;
q = p->next; /* head */
p->next = NULL; /* cut it */
while (q) {
p = q->next;
q->func(q);
q = p;
}
}
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