On 07/03, Benjamin Herrenschmidt wrote: > > On Tue, 2007-06-26 at 00:27 +0200, Rafael J. Wysocki wrote: > > > > case PM_HIBERNATION_PREPARE: > > > > case PM_SUSPEND_PREPARE: > > > > usermodehelper_disabled = 1; > > > > - return NOTIFY_OK; > > > > + smp_mb(); > > > > > > usermodehelper_disabled should be atomic variable, too, so we don't > > > have to play these ugly tricks by hand? This should not be > > > performance-critical, right? > > > > Well, I think we'd need to add the barriers anyway. > > > > The problem, as far as I understand it, is that the instructions can > > get > > reordered if there are no barriers in there. > > That seems dodgy either way to me :-) > > Just use a spinlock.
Actually, spinlock_t is not suitable. Because spin_unlcok() does NOT imply mb(). The subsequent wait_event_timeout()->atomic_read() may leak into the critical section. We can use set_mb(), if we don't want to play with smp_mb() by hand :) Oleg. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
