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 <[email protected]> --- 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); for_each_cpu(i, &cqm_cpumask) { if (phys_id == topology_physical_package_id(i)) - return; /* already got reader for this socket */ + goto out; /* already got reader for this socket */ } cpumask_set_cpu(cpu, &cqm_cpumask); +out: + mutex_unlock(&cache_mutex); } static void intel_cqm_cpu_prepare(unsigned int cpu) -- 2.1.0 -- 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/
