perf: Fix duplicate events with multiple-pmu vs software events

Because the multi-pmu bits can share contexts between struct pmu
instances we could get duplicate events by iterating the pmu list.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index de2c417..4f1279e 100644 (file)
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -887,6 +887,7 @@ struct perf_cpu_context {
        int                             exclusive;
        struct list_head                rotation_list;
        int                             jiffies_interval;
+       struct pmu                      *active_pmu;
 };
 
 struct perf_output_handle {

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index eac7e33..7b87017 100644 (file)
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -3824,6 +3824,8 @@ static void perf_event_task_event(struct perf_task_event *task_event)
        rcu_read_lock();
        list_for_each_entry_rcu(pmu, &pmus, entry) {
                cpuctx = get_cpu_ptr(pmu->pmu_cpu_context);
+               if (cpuctx->active_pmu != pmu)
+                       goto next;
                perf_event_task_ctx(&cpuctx->ctx, task_event);
 
                ctx = task_event->task_ctx;
@@ -3959,6 +3961,8 @@ static void perf_event_comm_event(struct perf_comm_event *comm_event)
        rcu_read_lock();
        list_for_each_entry_rcu(pmu, &pmus, entry) {
                cpuctx = get_cpu_ptr(pmu->pmu_cpu_context);
+               if (cpuctx->active_pmu != pmu)
+                       goto next;
                perf_event_comm_ctx(&cpuctx->ctx, comm_event);
 
                ctxn = pmu->task_ctx_nr;
@@ -4144,6 +4148,8 @@ got_name:
        rcu_read_lock();
        list_for_each_entry_rcu(pmu, &pmus, entry) {
                cpuctx = get_cpu_ptr(pmu->pmu_cpu_context);
+               if (cpuctx->active_pmu != pmu)
+                       goto next;
                perf_event_mmap_ctx(&cpuctx->ctx, mmap_event,
                                        vma->vm_flags & VM_EXEC);
 
@@ -5145,20 +5151,36 @@ static void *find_pmu_context(int ctxn)
        return NULL;
 }
 
-static void free_pmu_context(void * __percpu cpu_context)
+static void update_pmu_context(struct pmu *pmu, struct pmu *old_pmu)
 {
-       struct pmu *pmu;
+       int cpu;
+
+       for_each_possible_cpu(cpu) {
+               struct perf_cpu_context *cpuctx;
+
+               cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
+
+               if (cpuctx->active_pmu == old_pmu)
+                       cpuctx->active_pmu = pmu;
+       }
+}
+
+static void free_pmu_context(struct pmu *pmu)
+{
+       struct pmu *i;
 
        mutex_lock(&pmus_lock);
        /*
         * Like a real lame refcount.
         */
-       list_for_each_entry(pmu, &pmus, entry) {
-               if (pmu->pmu_cpu_context == cpu_context)
+       list_for_each_entry(i, &pmus, entry) {
+               if (i->pmu_cpu_context == pmu->pmu_cpu_context) {
+                       update_pmu_context(i, pmu);
                        goto out;
+               }
        }
 
-       free_percpu(cpu_context);
+       free_percpu(pmu->pmu_cpu_context);
 out:
        mutex_unlock(&pmus_lock);
 }
@@ -5190,6 +5212,7 @@ int perf_pmu_register(struct pmu *pmu)
                cpuctx->ctx.pmu = pmu;
                cpuctx->jiffies_interval = 1;
                INIT_LIST_HEAD(&cpuctx->rotation_list);
+               cpuctx->active_pmu = pmu;
        }
 
 got_cpu_context:
@@ -5241,7 +5264,7 @@ void perf_pmu_unregister(struct pmu *pmu)
        synchronize_rcu();
 
        free_percpu(pmu->pmu_disable_count);
-       free_pmu_context(pmu->pmu_cpu_context);
+       free_pmu_context(pmu);
 }
 
 struct pmu *perf_init_event(struct perf_event *event)