Messages in this thread | | | Date | Sun, 24 Jun 2007 19:05:14 +0200 | From | Pavel Machek <> | Subject | Re: [RC][PATCH -mm] PM: Prevent frozen user mode helpers from failing the freezing of tasks |
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Hi!
> > > Special thanks to Uli Luckas <u.luckas@road.de> for reviewing the previous > > > versions of this patch and for very useful comments. > > ... > > > Reviewed-by: Pavel Machek <pavel@ucw.cz> > > > > Eh, not sure this header is worth anything. Sometimes I'm lazy and > > stop when I see first problem. > > > > > switch (action) { > > > case PM_HIBERNATION_PREPARE: > > > case PM_SUSPEND_PREPARE: > > > usermodehelper_disabled = 1; > > > - return NOTIFY_OK; > > > + retval = wait_event_timeout(running_helpers_waitq, > > > + atomic_read(&running_helpers) == 0, > > > > Are you sure here? What happens when atomic variable changes between > > the atomic_read and the function call? > > Er, this is a macro. :-) > > In fact we rely only on atomic_read(&running_helpers) being still zero after > helper_finished() has woken us up, but I think that's acceptable. > > IOW, if the wait_event_timeout() returns with retval different from zero, this > means that atomic_read(&running_helpers) returned zero at one point after > we'd set usermodehelper_disabled, which is enough. OTOH, if it doesn't
Ok, can you write short comment explaining that? /* We have set usermodehelper_disabled, so any new usermode helpers are not a problem */.
Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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