[tip: perf/urgent] perf: Fix check before add_event_to_groups() in perf_group_detach()

[tip-bot2 for Budimir Markovic]

The following commit has been merged into the perf/urgent branch of tip:

Commit-ID:     fd0815f632c24878e325821943edccc7fde947a2
Gitweb:        https://git.kernel.org/tip/fd0815f632c24878e325821943edccc7fde947a2
Author:        Budimir Markovic <markovicbudimir@xxxxxxxxx>
AuthorDate:    Wed, 15 Mar 2023 00:29:01 -07:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Wed, 15 Mar 2023 21:49:47 +01:00

perf: Fix check before add_event_to_groups() in perf_group_detach()

Events should only be added to a groups rb tree if they have not been
removed from their context by list_del_event(). Since remove_on_exec
made it possible to call list_del_event() on individual events before
they are detached from their group, perf_group_detach() should check each
sibling's attach_state before calling add_event_to_groups() on it.

Fixes: 2e498d0a74e5 ("perf: Add support for event removal on exec")
Signed-off-by: Budimir Markovic <markovicbudimir@xxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/ZBFzvQV9tEqoHEtH@gentoo
---
 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 52b4aa0..fb3e436 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -2163,7 +2163,7 @@ static void perf_group_detach(struct perf_event *event)
 		/* Inherit group flags from the previous leader */
 		sibling->group_caps = event->group_caps;
 
-		if (!RB_EMPTY_NODE(&event->group_node)) {
+		if (sibling->attach_state & PERF_ATTACH_CONTEXT) {
 			add_event_to_groups(sibling, event->ctx);
 
 			if (sibling->state == PERF_EVENT_STATE_ACTIVE)