perf/x86/intel: Handle exclusive threadid correctly on CPU hotplug

The CPU hotplug function intel_pmu_cpu_starting() sets
cpu_hw_events.excl_thread_id unconditionally to 1 when the shared exclusive
counters data structure is already availabe for the sibling thread.

This works during the boot process because the first sibling gets threadid
0 assigned and the second sibling which shares the data structure gets 1.

But when the first thread of the core is offlined and onlined again it
shares the data structure with the second thread and gets exclusive thread
id 1 assigned as well.

Prevent this by checking the threadid of the already online thread.

[ tglx: Rewrote changelog ]

Signed-off-by: Zhou Chengming <zhouchengming1@huawei.com>
Cc: NuoHan Qiao <qiaonuohan@huawei.com>
Cc: ak@linux.intel.com
Cc: peterz@infradead.org
Cc: kan.liang@intel.com
Cc: dave.hansen@linux.intel.com
Cc: eranian@google.com
Cc: qiaonuohan@huawei.com
Cc: davidcc@google.com
Cc: guohanjun@huawei.com
Link: http://lkml.kernel.org/r/1484536871-3131-1-git-send-email-zhouchengming1@huawei.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---					---
 arch/x86/events/intel/core.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index d611cab214a6050555eb4c5f6f5638ca46b4659e..eb1484c86bb4b4611450c49df01aab1a18d8fa5f 100644 (file)
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -3176,13 +3176,16 @@ static void intel_pmu_cpu_starting(int cpu)
 
        if (x86_pmu.flags & PMU_FL_EXCL_CNTRS) {
                for_each_cpu(i, topology_sibling_cpumask(cpu)) {
+                       struct cpu_hw_events *sibling;
                        struct intel_excl_cntrs *c;
 
-                       c = per_cpu(cpu_hw_events, i).excl_cntrs;
+                       sibling = &per_cpu(cpu_hw_events, i);
+                       c = sibling->excl_cntrs;
                        if (c && c->core_id == core_id) {
                                cpuc->kfree_on_online[1] = cpuc->excl_cntrs;
                                cpuc->excl_cntrs = c;
-                               cpuc->excl_thread_id = 1;
+                               if (!sibling->excl_thread_id)
+                                       cpuc->excl_thread_id = 1;
                                break;
                        }
                }