perf: Fix scaling vs. perf_event_enable()

Similar to the perf_enable_on_exec(), ensure that event timings are
consistent across perf_event_enable().

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dvyukov@google.com
Cc: eranian@google.com
Cc: oleg@redhat.com
Cc: panand@redhat.com
Cc: sasha.levin@oracle.com
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160224174948.218288698@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 23 insertions, 19 deletions

diff --git a/kernel/events/core.c b/kernel/events/core.c
index d0030886c402..57c25faecfa5 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -2069,14 +2069,27 @@ static void add_event_to_ctx(struct perf_event *event,
         event->tstamp_stopped = tstamp;
 }
 
-static void task_ctx_sched_out(struct perf_cpu_context *cpuctx,
-                               struct perf_event_context *ctx);
+static void ctx_sched_out(struct perf_event_context *ctx,
+                          struct perf_cpu_context *cpuctx,
+                          enum event_type_t event_type);
 static void
 ctx_sched_in(struct perf_event_context *ctx,
              struct perf_cpu_context *cpuctx,
              enum event_type_t event_type,
              struct task_struct *task);
 
+static void task_ctx_sched_out(struct perf_cpu_context *cpuctx,
+                               struct perf_event_context *ctx)
+{
+        if (!cpuctx->task_ctx)
+                return;
+
+        if (WARN_ON_ONCE(ctx != cpuctx->task_ctx))
+                return;
+
+        ctx_sched_out(ctx, cpuctx, EVENT_ALL);
+}
+
 static void perf_event_sched_in(struct perf_cpu_context *cpuctx,
                                 struct perf_event_context *ctx,
                                 struct task_struct *task)
@@ -2227,17 +2240,18 @@ static void __perf_event_enable(struct perf_event *event,
             event->state <= PERF_EVENT_STATE_ERROR)
                 return;
 
-        update_context_time(ctx);
+        if (ctx->is_active)
+                ctx_sched_out(ctx, cpuctx, EVENT_TIME);
+
         __perf_event_mark_enabled(event);
 
         if (!ctx->is_active)
                 return;
 
         if (!event_filter_match(event)) {
-                if (is_cgroup_event(event)) {
-                        perf_cgroup_set_timestamp(current, ctx); // XXX ?
+                if (is_cgroup_event(event))
                         perf_cgroup_defer_enabled(event);
-                }
+                ctx_sched_in(ctx, cpuctx, EVENT_TIME, current);
                 return;
         }
 
@@ -2245,8 +2259,10 @@ static void __perf_event_enable(struct perf_event *event,
          * If the event is in a group and isn't the group leader,
          * then don't put it on unless the group is on.
          */
-        if (leader != event && leader->state != PERF_EVENT_STATE_ACTIVE)
+        if (leader != event && leader->state != PERF_EVENT_STATE_ACTIVE) {
+                ctx_sched_in(ctx, cpuctx, EVENT_TIME, current);
                 return;
+        }
 
         task_ctx = cpuctx->task_ctx;
         if (ctx->task)
@@ -2658,18 +2674,6 @@ void __perf_event_task_sched_out(struct task_struct *task,
                 perf_cgroup_sched_out(task, next);
 }
 
-static void task_ctx_sched_out(struct perf_cpu_context *cpuctx,
-                               struct perf_event_context *ctx)
-{
-        if (!cpuctx->task_ctx)
-                return;
-
-        if (WARN_ON_ONCE(ctx != cpuctx->task_ctx))
-                return;
-
-        ctx_sched_out(ctx, cpuctx, EVENT_ALL);
-}
-
 /*
  * Called with IRQs disabled
  */