On 10/10/2011 07:56 PM, Peter Zijlstra wrote: > 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. > Sure. I'll put together whatever I have understood, in the form of a patch to Documentation/power directory and post it tomorrow, for the benefit of all. > 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). > > > -- Regards, Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx> Linux Technology Center, IBM India Systems and Technology Lab -- 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
