Hi!
> Currently try_to_freeze_tasks() has to wait until all of the vforked processes
> exit and for this reason every user can make it fail. To fix this problem
> we can introduce the additional process flag PF_FREEZER_SKIP to be used by tasks
> that do not want to be counted as freezable by the freezer and want to have
> TIF_FREEZE set nevertheless. Then, this flag can be set by tasks using
> sys_vfork() before they call wait_for_completion() and cleared after they have
> woken up and called try_to_freeze(). In case such a task freezes with
> PF_FREEZER_SKIP set, refrigerator() clears this flag for the current task before
> calling frozen_process(current) to avoid having both PF_FREEZER_SKIP and
> PF_FROZEN set at the same time.
>
> Signed-off-by: Rafael J. Wysocki <[email protected]>
> @@ -1393,7 +1394,9 @@ long do_fork(unsigned long clone_flags,
> tracehook_report_clone_complete(clone_flags, nr, p);
>
> if (clone_flags & CLONE_VFORK) {
> + freezer_do_not_count();
> wait_for_completion(&vfork);
> + freezer_count();
> tracehook_report_vfork_done(p, nr);
> }
> } else {
All the infrastructure for this...Would it be easier to introduce
void fastcall __sched wait_for_completion_freezeable(struct completion *x)
{
might_sleep();
spin_lock_irq(&x->wait.lock);
if (!x->done) {
DECLARE_WAITQUEUE(wait, current);
wait.flags |= WQ_FLAG_EXCLUSIVE;
__add_wait_queue_tail(&x->wait, &wait);
do {
__set_current_state(TASK_UNINTERRUPTIBLE);
spin_unlock_irq(&x->wait.lock);
schedule();
try_to_freeze(); /* HERE */
spin_lock_irq(&x->wait.lock);
} while (!x->done);
__remove_wait_queue(&x->wait, &wait);
}
x->done--;
spin_unlock_irq(&x->wait.lock);
}
...and be done with that, in a very obvious way? (Ok, you probably do
not want to duplicate the function, but you get the idea).
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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