Messages in this thread | | | Date | Tue, 23 Jun 2015 13:32:42 -0700 (PDT) | From | Vikas Shivappa <> | Subject | Re: [PATCH v1 2/2] x86, perf,cqm: handle CPU hotplug |
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On Thu, 18 Jun 2015, Thomas Gleixner wrote:
> On Thu, 18 Jun 2015, Kanaka Juvva wrote: > >> Added lock in event reader function. The cqm_pick_event_reader() function >> accesses cqm_cpumask and it is critical section between this and >> cqm_stable(). >> >> This situation is true when a CPU is hotplugged. Mutex is used to protect >> the critical section. >> >> Signed-off-by: Kanaka Juvva <kanaka.d.juvva@linux.intel.com> >> --- >> arch/x86/kernel/cpu/perf_event_intel_cqm.c | 5 ++++- >> 1 file changed, 4 insertions(+), 1 deletion(-) >> >> diff --git a/arch/x86/kernel/cpu/perf_event_intel_cqm.c b/arch/x86/kernel/cpu/perf_event_intel_cqm.c >> index 1880761..e17e37f 100644 >> --- a/arch/x86/kernel/cpu/perf_event_intel_cqm.c >> +++ b/arch/x86/kernel/cpu/perf_event_intel_cqm.c >> @@ -1239,12 +1239,15 @@ static inline void cqm_pick_event_reader(int cpu) >> int phys_id = topology_physical_package_id(cpu); >> int i; >> >> + mutex_lock(&cache_mutex); > > I already explained it to Vikas. You CANNOT take a mutex in that code > path as it runs with interrupts disabled on a CPU which cannot > schedule.
This patch also needs to be merged with the new package mask changes that was added. Will merge and send the fix.
Thanks, Vikas
> > Sigh. > > tglx >
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