Messages in this thread | | | Date | Fri, 5 Jul 2013 15:51:57 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [tip:timers/core] hrtimers: Support resuming with two or more CPUs online (but stopped) |
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On Fri, 5 Jul 2013, David Vrabel wrote: > On 05/07/13 11:25, Thomas Gleixner wrote: > > On Fri, 5 Jul 2013, David Vrabel wrote: > > > > You failed to CC Artem :( > > > >> On 05/07/13 10:30, Artem Savkov wrote: > >>> This commit brings up a warning about a potential deadlock in > >>> smp_call_function_many() discussed previously: > >>> https://lkml.org/lkml/2013/4/18/546 > >> > >> Can we just avoid the wait in clock_was_set()? Something like this? > >> > >> 8<------------------------------------------------------ > >> hrtimers: do not wait for other CPUs in clock_was_set() > >> > >> Calling on_each_cpu() and waiting in a softirq causes a WARNing about > >> a potential deadlock. > >> > >> Because hrtimers are per-CPU, it is sufficient to ensure that all > >> other CPUs' timers are reprogrammed as soon as possible and before the > >> next softirq on that CPU. There is no need to wait for this to be > >> complete on all CPUs. > > Unfortunately this doesn't look sufficient. on_each_cpu(..., 0) may > still wait for other calls to complete before queuing the calls due to > the use of a single set of per-CPU csd data.
Hrmpf. I'll fix it in the non elegant way :(
Thanks,
tglx
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