Hi Boaz,
I'll read this series tomorrow, but
On 03/26, Boaz Harrosh wrote:
>
> int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
> {
> DECLARE_COMPLETION_ONSTACK(done);
> + int wait_state;
> int retval = 0;
>
> helper_lock();
> @@ -540,19 +541,15 @@ int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
> if (wait == UMH_NO_WAIT) /* task has freed sub_info */
> goto unlock;
>
> - if (wait & UMH_KILLABLE) {
> - retval = wait_for_completion_killable(&done);
> - if (!retval)
> - goto wait_done;
> -
> + wait_state = (wait & UMH_KILLABLE) ? TASK_KILLABLE : 0;
> + retval = wait_for_completion_timeout_state(&done, sub_info->timeout,
> + wait_state);
> + if (unlikely(retval)) {
> /* umh_complete() will see NULL and free sub_info */
> if (xchg(&sub_info->complete, NULL))
> goto unlock;
> - /* fallthrough, umh_complete() was already called */
> }
>
> - wait_for_completion(&done);
at first glance this looks certainly wrong, or I misread the patch.
We can't remove the "fallback to wait_for_completion" logic until
you move the completion into subprocess_info (the next patch seems
to do this).
xchg() can race with umh_complete(). If it returns NULL, umh_complete()
was already called and got ->complete != NULL, we must not return until
umh_complete() finishes complete().
Oleg.
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