On Mon, 2011-10-10 at 18:15 +0530, Srivatsa S. Bhat wrote: > > + /* > > + * Prevent cpu online and suspend/hibernate (including freezer) > > + * operations from running in parallel. Fail cpu online if suspend or > > + * hibernate has already started. > > + */ > > + if (!trylock_pm_sleep()) > > Would it be better to hook into the suspend/hibernate notifiers and > use them to exclude cpu hotplug from suspend/hibernate, instead of > trying to take pm_mutex lock like this? > Peter, I remember you pointing out in another patch's review > (http://thread.gmane.org/gmane.linux.kernel/1198312/focus=1199087) > that introducing more locks in cpu hotplug would be a bad idea. Does that > comment hold here as well, or is this fine? Arguably pm_mutex is already involved in the whole hotplug dance due to suspend using it, that said, I'm not at all familiar with the whole suspend/hibernate side of things. I tried having a quick look this morning but failed to find the actual code. I think it would be good to have an overview of the various locks and a small description of how they interact/nest. I just remember being very surprised about finding out the hotplug usage of suspend/hibernate wasn't at all serialized against the regular hotplug thingies.. (see 144060fee07e9c22e179d00819c83c86fbcbf82c). -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
