Hello, Lai. On Fri, Apr 18, 2014 at 12:04:29AM +0800, Lai Jiangshan wrote: > > I don't think this is reliable. What if mayday requests take place > > between wq_mayday_lock and kthread_should_stop() check? We'll > > probably need to run through mayday list after checking should_stop. > > It is destroy_workqueue()'s responsibility to avoid this. > destroy_workqueue() should drain all works and refuse any new work queued > on the wq before destroy the wq. > > So since there is no works, there is no new mayday request, > and there is no mayday request take place between wq_mayday_lock > and kthread_should_stop() check.
Hmmm? Isn't this the same race condition that you tried to remove by relocating the test? It doesn't matter what destroy_workqueue() does, the rescuer may get preempted inbetween and anything can happen inbetween including someone maydaying and initiation of destroy_workqueue(). Your patch doesn't change the situation at all. It can still return with non-empty mayday list. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/