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>

1 files changed, 29 insertions, 6 deletions

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index eac7e3364335..7b870174c56d 100644
--- 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)