On Mon, 2013-03-18 at 12:23 -0400, Steven Rostedt wrote: > > Maybe I'm confused but I can't really see how the above would be a > > problem to workqueue in itself. Both rq->lock and gcwq->lock are > > irq-safe, so spin_lock() not disabling preemption shouldn't be a > > problem. Are CPU hotplug operations involved? > > No CPU hotplug is involved here. But I will note that gcwq->lock in -rt > is not irq -safe. That is, in rt the spin_lock_irq(&gcwq->lock) really > becomes a special "mutex_lock(&gcwq->lock)". IOW, what can happen in -rt here is: spin_lock_irq(&gcwq->lock); [...] <interrupt> -> preempt_schedule(); schedule(); try_to_wake_up_local(); [...] spin_unlock_irq(&gcwq->lock); Again, with -rt, spin_lock_irq() does not prevent interrupts nor preemption. -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
