[PATCH] perf/core: Fix reversed NULL check in perf_event_groups_less()

[Dan Carpenter <dan.carpenter@xxxxxxxxxx>]

This NULL check is reversed so it leads to a Smatch warning and
presumably a NULL dereference.

    kernel/events/core.c:1598 perf_event_groups_less()
    error: we previously assumed 'right->cgrp->css.cgroup' could be null
	(see line 1590)

Fixes: 95ed6c707f26 ("perf/cgroup: Order events in RB tree by cgroup id")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
---
 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 6a47c3e54fe9..607c04ec7cfa 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1587,7 +1587,7 @@ perf_event_groups_less(struct perf_event *left, struct perf_event *right)
 			 */
 			return true;
 		}
-		if (!right->cgrp || right->cgrp->css.cgroup) {
+		if (!right->cgrp || !right->cgrp->css.cgroup) {
 			/*
 			 * Right has no cgroup but left does, no cgroups come
 			 * first.
-- 
2.20.1