Patch "perf: Fix running time accounting" has been added to the 4.1-stable tree

Patch "perf: Fix running time accounting" has been added to the 4.1-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    perf: Fix running time accounting

to the 4.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     perf-fix-running-time-accounting.patch
and it can be found in the queue-4.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 00a2916f7f82c348a2a94dbb572874173bc308a3 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Mon, 27 Jul 2015 10:35:07 +0200
Subject: perf: Fix running time accounting

From: Peter Zijlstra <peterz@infradead.org>

commit 00a2916f7f82c348a2a94dbb572874173bc308a3 upstream.

A recent fix to the shadow timestamp inadvertly broke the running time
accounting.

We must not update the running timestamp if we fail to schedule the
event, the event will not have ran. This can (and did) result in
negative total runtime because the stopped timestamp was before the
running timestamp (we 'started' but never stopped the event -- because
it never really started we didn't have to stop it either).

Reported-and-Tested-by: Vince Weaver <vincent.weaver@maine.edu>
Fixes: 72f669c0086f ("perf: Update shadow timestamp before add event")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Shaohua Li <shli@fb.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 kernel/events/core.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1886,8 +1886,6 @@ event_sched_in(struct perf_event *event,
 
 	perf_pmu_disable(event->pmu);
 
-	event->tstamp_running += tstamp - event->tstamp_stopped;
-
 	perf_set_shadow_time(event, ctx, tstamp);
 
 	perf_log_itrace_start(event);
@@ -1899,6 +1897,8 @@ event_sched_in(struct perf_event *event,
 		goto out;
 	}
 
+	event->tstamp_running += tstamp - event->tstamp_stopped;
+
 	if (!is_software_event(event))
 		cpuctx->active_oncpu++;
 	if (!ctx->nr_active++)


Patches currently in stable-queue which might be from peterz@infradead.org are

queue-4.1/perf-fix-perf_event_ioc_period-migration-race.patch
queue-4.1/ipc-sem.c-update-correct-memory-barriers.patch
queue-4.1/perf-fix-fasync-handling-on-inherited-events.patch
queue-4.1/perf-fix-double-free-of-the-aux-buffer.patch
queue-4.1/perf-fix-running-time-accounting.patch