Commit 1f9a7268 authored Jun 24, 2014 by Jiri Olsa Committed by Ingo Molnar Jul 02, 2014

perf: Do not allow optimized switch for non-cloned events



The context check in perf_event_context_sched_out allows
non-cloned context to be part of the optimized schedule
out switch.

This could move non-cloned context into another workload
child. Once this child exits, the context is closed and
leaves all original (parent) events in closed state.

Any other new cloned event will have closed state and not
measure anything. And probably causing other odd bugs.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1403598026-2310-2-git-send-email-jolsa@kernel.org


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent b292d7a1

kernel/events/core.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -2320,7 +2320,7 @@ static void perf_event_context_sched_out(struct task_struct *task, int ctxn,
		next_parent = rcu_dereference(next_ctx->parent_ctx);

		/* If neither context have a parent context; they cannot be clones. */
		if (!parent && !next_parent)
		if (!parent \|\| !next_parent)
		goto unlock;

		if (next_parent == ctx \|\| next_ctx == parent \|\| next_parent == parent) {

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