From baf1b12a67f5b24f395baca03e442ce27cab0c18 Mon Sep 17 00:00:00 2001 From: Song Liu Date: Mon, 13 Mar 2023 10:16:08 -0700 Subject: [PATCH] perf: fix perf_event_context->time 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 Signed-off-by: Peter Zijlstra (Intel) Acked-by: Namhyung Kim Link: https://lkml.kernel.org/r/20230313171608.298734-1-song@kernel.org --- kernel/events/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 296617e..52b4aa0 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3872,7 +3872,7 @@ ctx_sched_in(struct perf_event_context *ctx, enum event_type_t event_type) 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); -- 2.7.4