On Fri, Mar 11, 2016 at 11:52:38AM +0100, Anna-Maria Gleixner wrote: > The cpumf_pmu_notfier() hotplug callback lacks handling of the > CPU_DOWN_FAILED case. That means, if CPU_DOWN_PREPARE failes, the PMC > of the CPU is not setup again. Furthermore the CPU_ONLINE_FROZEN case > will never be processed because of masking the switch expression with > CPU_TASKS_FROZEN. > > Add handling for CPU_DOWN_FAILED transition to setup the PMC of the > CPU. Remove CPU_ONLINE_FROZEN case. > > Cc: Martin Schwidefsky <[email protected]> > Cc: Heiko Carstens <[email protected]> > Cc: [email protected] > Signed-off-by: Anna-Maria Gleixner <[email protected]> > --- > arch/s390/kernel/perf_cpum_sf.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > --- a/arch/s390/kernel/perf_cpum_sf.c > +++ b/arch/s390/kernel/perf_cpum_sf.c > @@ -1518,7 +1518,7 @@ static int cpumf_pmu_notifier(struct not > > switch (action & ~CPU_TASKS_FROZEN) { > case CPU_ONLINE: > - case CPU_ONLINE_FROZEN: > + case CPU_DOWN_FAILED: > flags = PMC_INIT; > smp_call_function_single(cpu, setup_pmc_cpu, &flags, 1); > break;
This is a bit odd, but independent from your patch: setup_pmc_cpu() will only deallocate buffers but not allocate them. Looking at the code a bit further this seems to imply that sampling will not work on cpus that were added later. Hendrik, could you please have a look?
