2 files changed, 29 insertions, 4 deletions

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index c77586061bcb..5db5b7d65a18 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -106,6 +106,7 @@ struct cpu_hw_events {
 
         int                     n_events;
         int                     n_added;
+        int                     n_txn;
         int                     assign[X86_PMC_IDX_MAX]; /* event to counter assignment */
         u64                     tags[X86_PMC_IDX_MAX];
         struct perf_event       *event_list[X86_PMC_IDX_MAX]; /* in enabled order */
@@ -983,6 +984,7 @@ static int x86_pmu_enable(struct perf_event *event)
 out:
         cpuc->n_events = n;
         cpuc->n_added += n - n0;
+        cpuc->n_txn += n - n0;
 
         return 0;
 }
@@ -1089,6 +1091,14 @@ static void x86_pmu_disable(struct perf_event *event)
         struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
         int i;
 
+        /*
+         * If we're called during a txn, we don't need to do anything.
+         * The events never got scheduled and ->cancel_txn will truncate
+         * the event_list.
+         */
+        if (cpuc->group_flag & PERF_EVENT_TXN_STARTED)
+                return;
+
         x86_pmu_stop(event);
 
         for (i = 0; i < cpuc->n_events; i++) {
@@ -1379,6 +1389,7 @@ static void x86_pmu_start_txn(const struct pmu *pmu)
         struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
 
         cpuc->group_flag |= PERF_EVENT_TXN_STARTED;
+        cpuc->n_txn = 0;
 }
 
 /*
@@ -1391,6 +1402,11 @@ static void x86_pmu_cancel_txn(const struct pmu *pmu)
         struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
 
         cpuc->group_flag &= ~PERF_EVENT_TXN_STARTED;
+        /*
+         * Truncate the collected events.
+         */
+        cpuc->n_added -= cpuc->n_txn;
+        cpuc->n_events -= cpuc->n_txn;
 }
 
 /*
@@ -1419,6 +1435,12 @@ static int x86_pmu_commit_txn(const struct pmu *pmu)
          */
         memcpy(cpuc->assign, assign, n*sizeof(int));
 
+        /*
+         * Clear out the txn count so that ->cancel_txn() which gets
+         * run after ->commit_txn() doesn't undo things.
+         */
+        cpuc->n_txn = 0;
+
         return 0;
 }
 
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 10a1aee2309e..42a0e9191af5 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -687,8 +687,11 @@ group_sched_in(struct perf_event *group_event,
         if (txn)
                 pmu->start_txn(pmu);
 
-        if (event_sched_in(group_event, cpuctx, ctx))
+        if (event_sched_in(group_event, cpuctx, ctx)) {
+                if (txn)
+                        pmu->cancel_txn(pmu);
                 return -EAGAIN;
+        }
 
         /*
          * Schedule in siblings as one group (if any):
@@ -710,9 +713,6 @@ group_sched_in(struct perf_event *group_event,
         }
 
 group_error:
-        if (txn)
-                pmu->cancel_txn(pmu);
-
         /*
          * Groups can be scheduled in as one unit only, so undo any
          * partial group before returning:
@@ -724,6 +724,9 @@ group_error:
         }
         event_sched_out(group_event, cpuctx, ctx);
 
+        if (txn)
+                pmu->cancel_txn(pmu);
+
         return -EAGAIN;
 }