Hey, Steven. On Mon, Mar 18, 2013 at 12:23:19PM -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)". Because, in -rt, interrupts > (except for the timer interrupt) are run as threads, and anything that > isn't marked as raw_spin_lock() turns into a mutex. I don't believe it's > safe to turn the gcwq->lock into a raw_spin_lock either, or at least not > short enough to hold it. Anything that holds a spin_lock() for more than > a microsecond is too much for a raw lock. Does that mean that a task holding gcwq->lock may be preempted? If so, that sure could lead to weird problems. Maybe gcwq->lock should be marked non-preemptible somehow? Thanks. -- tejun -- 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
