Re: [PATCH RFC v2 1/4] cgroup: implement eventfd-based generic API for notifications

[KAMEZAWA Hiroyuki]

On Tue, 15 Dec 2009 17:03:37 +0200
"Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx> wrote:
> >> > + Â Â Â /*
> >> > + Â Â Â Â* Unregister events and notify userspace.
> >> > + Â Â Â Â* FIXME: How to avoid race with cgroup_event_remove_work()
> >> > + Â Â Â Â* Â Â Â Âwhich runs from workqueue?
> >> > + Â Â Â Â*/
> >> > + Â Â Â mutex_lock(&cgrp->event_list_mutex);
> >> > + Â Â Â list_for_each_entry_safe(event, tmp, &cgrp->event_list, list) {
> >> > + Â Â Â Â Â Â Â cgroup_event_remove(event);
> >> > + Â Â Â Â Â Â Â eventfd_signal(event->eventfd, 1);
> >> > + Â Â Â }
> >> > + Â Â Â mutex_unlock(&cgrp->event_list_mutex);
> >> > +
> >> > +out:
> >> > Â Â Â Âreturn ret;
> >> > Â}
> >
> > How ciritical is this FIXME ?
> > But Hmm..can't we use RCU ?
> 
> It's not reasonable to have RCU here, since event_list isn't mostly-read.
> 
ok.

Thanks,
-Kame

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