perf_events: Revert: Fix transaction recovery in group_sched_in()

This patch reverts commit 8e5fc1a (perf_events: Fix transaction
recovery in group_sched_in()) because it had one flaw in case the
group could never be scheduled. It would cause time_enabled to get
negative.

Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <4cbeeeb7.0aefd80a.6e40.0e2f@mx.google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 13 insertions, 63 deletions

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index f309e8014c78..39afdb07d758 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -417,8 +417,8 @@ event_filter_match(struct perf_event *event)
         return event->cpu == -1 || event->cpu == smp_processor_id();
 }
 
-static int
-__event_sched_out(struct perf_event *event,
+static void
+event_sched_out(struct perf_event *event,
                   struct perf_cpu_context *cpuctx,
                   struct perf_event_context *ctx)
 {
@@ -437,13 +437,14 @@ __event_sched_out(struct perf_event *event,
         }
 
         if (event->state != PERF_EVENT_STATE_ACTIVE)
-                return 0;
+                return;
 
         event->state = PERF_EVENT_STATE_INACTIVE;
         if (event->pending_disable) {
                 event->pending_disable = 0;
                 event->state = PERF_EVENT_STATE_OFF;
         }
+        event->tstamp_stopped = ctx->time;
         event->pmu->del(event, 0);
         event->oncpu = -1;
 
@@ -452,19 +453,6 @@ __event_sched_out(struct perf_event *event,
         ctx->nr_active--;
         if (event->attr.exclusive || !cpuctx->active_oncpu)
                 cpuctx->exclusive = 0;
-        return 1;
-}
-
-static void
-event_sched_out(struct perf_event *event,
-                  struct perf_cpu_context *cpuctx,
-                  struct perf_event_context *ctx)
-{
-        int ret;
-
-        ret = __event_sched_out(event, cpuctx, ctx);
-        if (ret)
-                event->tstamp_stopped = ctx->time;
 }
 
 static void
@@ -664,7 +652,7 @@ retry:
 }
 
 static int
-__event_sched_in(struct perf_event *event,
+event_sched_in(struct perf_event *event,
                  struct perf_cpu_context *cpuctx,
                  struct perf_event_context *ctx)
 {
@@ -684,6 +672,8 @@ __event_sched_in(struct perf_event *event,
                 return -EAGAIN;
         }
 
+        event->tstamp_running += ctx->time - event->tstamp_stopped;
+
         if (!is_software_event(event))
                 cpuctx->active_oncpu++;
         ctx->nr_active++;
@@ -694,35 +684,6 @@ __event_sched_in(struct perf_event *event,
         return 0;
 }
 
-static inline int
-event_sched_in(struct perf_event *event,
-                 struct perf_cpu_context *cpuctx,
-                 struct perf_event_context *ctx)
-{
-        int ret = __event_sched_in(event, cpuctx, ctx);
-        if (ret)
-                return ret;
-        event->tstamp_running += ctx->time - event->tstamp_stopped;
-        return 0;
-}
-
-static void
-group_commit_event_sched_in(struct perf_event *group_event,
-               struct perf_cpu_context *cpuctx,
-               struct perf_event_context *ctx)
-{
-        struct perf_event *event;
-        u64 now = ctx->time;
-
-        group_event->tstamp_running += now - group_event->tstamp_stopped;
-        /*
-         * Schedule in siblings as one group (if any):
-         */
-        list_for_each_entry(event, &group_event->sibling_list, group_entry) {
-                event->tstamp_running += now - event->tstamp_stopped;
-        }
-}
-
 static int
 group_sched_in(struct perf_event *group_event,
                struct perf_cpu_context *cpuctx,
@@ -736,13 +697,7 @@ group_sched_in(struct perf_event *group_event,
 
         pmu->start_txn(pmu);
 
-        /*
-         * use __event_sched_in() to delay updating tstamp_running
-         * until the transaction is committed. In case of failure
-         * we will keep an unmodified tstamp_running which is a
-         * requirement to get correct timing information
-         */
-        if (__event_sched_in(group_event, cpuctx, ctx)) {
+        if (event_sched_in(group_event, cpuctx, ctx)) {
                 pmu->cancel_txn(pmu);
                 return -EAGAIN;
         }
@@ -751,31 +706,26 @@ group_sched_in(struct perf_event *group_event,
          * Schedule in siblings as one group (if any):
          */
         list_for_each_entry(event, &group_event->sibling_list, group_entry) {
-                if (__event_sched_in(event, cpuctx, ctx)) {
+                if (event_sched_in(event, cpuctx, ctx)) {
                         partial_group = event;
                         goto group_error;
                 }
         }
 
-        if (!pmu->commit_txn(pmu)) {
-                /* commit tstamp_running */
-                group_commit_event_sched_in(group_event, cpuctx, ctx);
+        if (!pmu->commit_txn(pmu))
                 return 0;
-        }
+
 group_error:
         /*
          * Groups can be scheduled in as one unit only, so undo any
          * partial group before returning:
-         *
-         * use __event_sched_out() to avoid updating tstamp_stopped
-         * because the event never actually ran
          */
         list_for_each_entry(event, &group_event->sibling_list, group_entry) {
                 if (event == partial_group)
                         break;
-                __event_sched_out(event, cpuctx, ctx);
+                event_sched_out(event, cpuctx, ctx);
         }
-        __event_sched_out(group_event, cpuctx, ctx);
+        event_sched_out(group_event, cpuctx, ctx);
 
         pmu->cancel_txn(pmu);