Re: lockdep trace from posix timers

[Oleg Nesterov]

On 08/21, Oleg Nesterov wrote:
>
> static inline bool cmp_xchg(struct callback_head **ptr, void *old, void *new)
> {
> 	return cmpxchg(ptr, old, new) == old;
> }
>
> int
> task_work_add(struct task_struct *task, struct callback_head *twork, bool notify)
> {
> 	do {
> 		twork->next = ACCESS_ONCE(task->task_works);
> 		if (unlikely(twork->next == TWORK_EXITED))
> 			return -ESRCH;
> 	} while (cmp_xchg(&task->task_works, twork->next, twork));
          ^^^^^^^^^^^^^^^

while (!cmp_xchg(...))

Oleg.

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