This is a note to let you know that I've just added the patch titled
perf: fix perf_event_context->time
to the 6.1-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-perf_event_context-time.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit c953a2c5ed43f37c2de6b1a6ff9b8f56ff2d3b8d
Author: Song Liu <song@xxxxxxxxxx>
Date: Mon Mar 13 10:16:08 2023 -0700
perf: fix perf_event_context->time
[ Upstream commit baf1b12a67f5b24f395baca03e442ce27cab0c18 ]
Time readers rely on perf_event_context->[time|timestamp|timeoffset] to get
accurate time_enabled and time_running for an event. The difference between
ctx->timestamp and ctx->time is the among of time when the context is not
enabled. __update_context_time(ctx, false) is used to increase timestamp,
but not time. Therefore, it should only be called in ctx_sched_in() when
EVENT_TIME was not enabled.
Fixes: 09f5e7dc7ad7 ("perf: Fix perf_event_read_local() time")
Signed-off-by: Song Liu <song@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: Namhyung Kim <namhyung@xxxxxxxxxx>
Link: https://lkml.kernel.org/r/20230313171608.298734-1-song@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 6c4e78cd7a8b5..2aa286b4151b3 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3830,7 +3830,7 @@ ctx_sched_in(struct perf_event_context *ctx,
if (likely(!ctx->nr_events))
return;
- if (is_active ^ EVENT_TIME) {
+ if (!(is_active & EVENT_TIME)) {
/* start ctx time */
__update_context_time(ctx, false);
perf_cgroup_set_timestamp(cpuctx);
