perf: Fix context leak in put_event()

clyu · Ingo Molnar · commit d415a7f1c1a8 · 2015-03-13T10:02:18.000+01:00
Commit: a83fe28 ("perf: Fix put_event() ctx lock") changed the locking logic in put_event() by replacing mutex_lock_nested() with perf_event_ctx_lock_nested(), but didn't fix the subsequent mutex_unlock() with a correct counterpart, perf_event_ctx_unlock(). Contexts are thus leaked as a result of incremented refcount in perf_event_ctx_lock_nested(). Signed-off-by: Leon Yu <chianglungyu@gmail.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Fixes: a83fe28 ("perf: Fix put_event() ctx lock") Link: http://lkml.kernel.org/r/1424954613-5034-1-git-send-email-chianglungyu@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/kernel/events/core.c b/kernel/events/core.c
@@ -3591,7 +3591,7 @@ static void put_event(struct perf_event *event)
 	ctx = perf_event_ctx_lock_nested(event, SINGLE_DEPTH_NESTING);
 	WARN_ON_ONCE(ctx->parent_ctx);
 	perf_remove_from_context(event, true);
-	mutex_unlock(&ctx->mutex);
+	perf_event_ctx_unlock(event, ctx);
 
 	_free_event(event);
 }

Original file line number	Diff line number	Diff line change
`@@ -3591,7 +3591,7 @@ static void put_event(struct perf_event *event)`
`3591`	`3591`	`ctx = perf_event_ctx_lock_nested(event, SINGLE_DEPTH_NESTING);`
`3592`	`3592`	`WARN_ON_ONCE(ctx->parent_ctx);`
`3593`	`3593`	`perf_remove_from_context(event, true);`
`3594`		`- mutex_unlock(&ctx->mutex);`
	`3594`	`+ perf_event_ctx_unlock(event, ctx);`
`3595`	`3595`
`3596`	`3596`	`_free_event(event);`
`3597`	`3597`	`}`