[PATCH 6/8] perf sched: Fix thread reference leak in idle hist processing

[Arnaldo Carvalho de Melo <acme@kernel.org>]

From: Arnaldo Carvalho de Melo <acme@redhat.com>

timehist_sched_change_event() sets itr->last_thread to NULL at the end
of idle hist processing without calling thread__put() first.  The
thread reference was acquired via thread__get() in timehist_get_thread()
(line 2581), so every idle context switch leaks a thread reference when
--idle-hist is active.

Use thread__zput() to properly release the reference before clearing
the pointer.

Fixes: 5d8f17fb5822 ("perf sched timehist: Add -I/--idle-hist option")
Reported-by: sashiko-bot <sashiko-bot@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Assisted-by: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/builtin-sched.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index e4378cc9ab3ed48b..af6322ffaaa6eb1d 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -2934,7 +2934,7 @@ static int timehist_sched_change_event(const struct perf_tool *tool,
 			if (itr->cursor.nr)
 				callchain_append(&itr->callchain, &itr->cursor, t - tprev);
 
-			itr->last_thread = NULL;
+			thread__zput(itr->last_thread);
 		}
 
 		if (!sched->summary_only)
-- 
2.54.0