On Wednesday, August 06, 2014 11:02:05 AM Lan Tianyu wrote: > On 2014年08月06日 09:30, Rafael J. Wysocki wrote: > > On Friday, August 01, 2014 10:51:46 AM Lan Tianyu wrote: > >> On 2014年08月01日 05:20, Rafael J. Wysocki wrote: > >>> On Thursday, July 31, 2014 05:20:26 PM Lan Tianyu wrote: > >>>> The callback of CPU_STARTING event can't sleep and so acpi_cpu_soft_notify() > >>>> return directly when CPU_STARTING event is triggered. But cpu hotplug also > >>>> happens during S2RAM. The action will become CPU_STARTING_FROZEN. This > >>>> patch is to fix missing check the frozen event. > > > > OK > > > > What's the impact of the bug you're fixing? Do we sleep when we shouldn't? > > > > In particular, are there any bugs reported that are related to it? > > So far, there is such bug report. I found the issue when test my patch > of parallel non-boot cpu up with resuming device for S2RAM. Because > original code will wait all cpu up and then do other resume task, the > semaphore of ACPICA can always be get in the cpu notify callback and it > will not fall in the sleep. It's different situation for paralleling > non-boot cpu. The lock will be held by other threads and fall into > sleep. Further thinking, this may not cause bug in the old kernel and it > isn't needed by stable tree but the code should consider cpu frozen event. OK, so we don't need to propagate this to -stable I'd say. I'll queue it up for the second 3.17 pull request. Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
