On 05/20/2014 04:08 PM, Srivatsa S. Bhat wrote: > On 05/20/2014 04:01 PM, Srivatsa S. Bhat wrote: >> On 05/20/2014 03:55 PM, Peter Zijlstra wrote: >>> On Tue, May 20, 2014 at 03:39:59PM +0530, Srivatsa S. Bhat wrote: >>>>> The multi_cpu_stop() path isn't exclusive to hotplug, so your changelog >>>>> is wrong or the patch is. >>>>> >>>> >>>> Yes, I know that multi_cpu_stop() isn't exclusive to hotplug. That's why >>>> I have explicitly referred to CPU hotplug in the comment as well as the >>>> changelog. >>>> >>>> But I totally agree that code-wise this is not the best way to do it since >>>> this affects (although harmlessly) usecases other than hotplug as well. >>>> >>>> Do you have any other suggestions? >>> >>> How about making a kernel/smp.c hotplug notifier and stuffing it in the >>> CPU_DYING list? That's typically after we've already torn down the >>> interrupts for that cpu, so no chance of any new ones coming in. >>> >>> Or is that too late? >>> >> >> No, that should work just fine. Thank you for the suggestion! I'll give >> it a shot. >> > > The only problem will be that CPU_DYING notifiers are run after marking > the CPU offline, and hence the warning will trigger. We can avoid that by > defining a __generic_smp_call_function_single_interrupt() that doesn't > check for cpu_online(smp_processor_id) and call this function from the > hotplug notifier. > >
(And that's probably something to fix while cleaning up hotplug later: Why should we mark the CPU offline _before_ running CPU_DYING? It makes more sense to mark it offline _after_ running CPU_DYING notifiers. I'll audit that path as well and see what I can find). Regards, Srivatsa S. Bhat -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
