Hi,
On Sunday, 25 February 2007 11:46, Pavel Machek wrote:
> 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).
Yes, I though about that too, but I was thinking of sticking try_to_freeze()
in wait wait_for_completion() itself, which was obviously wrong.
Still, the above might work. I'll try to prepare a patch.
Greetings,
Rafael
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