perf/core: Fix perf_event_enable_on_exec() timekeeping (again)

Where commit:

  7fce250915ef ("perf: Fix scaling vs.  perf_event_enable_on_exec()")

disabled the ctx-time a-priory, such that all events get enabled and
scheduled at the time point in time, there is one hole in that patch,
when no events do get enabled nothing re-enables the ctx-time.

Reported-by: Ravi Bangoria <[email protected]>
Reported-by: Anton Blanchard <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Vince Weaver <[email protected]>
Fixes: 7fce250915ef ("perf: Fix scaling vs.  perf_event_enable_on_exec()")
Signed-off-by: Ingo Molnar <[email protected]>

1 files changed, 2 insertions, 0 deletions

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 94d7b9aae925..d4e3f8d8238b 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3522,6 +3522,8 @@ static void perf_event_enable_on_exec(int ctxn)
 	if (enabled) {
 		clone_ctx = unclone_ctx(ctx);
 		ctx_resched(cpuctx, ctx, event_type);
+	} else {
+		ctx_sched_in(ctx, cpuctx, EVENT_TIME, current);
 	}
 	perf_ctx_unlock(cpuctx, ctx);