[PATCH 6.1.y 2/2] tracing/osnoise: Call synchronize_rcu() when unregistering

[Sasha Levin <sashal@kernel.org>]

From: Crystal Wood <crwood@redhat.com>

[ Upstream commit fe58f457ad8d0a2bef4e053cfecca4b5cd266b1a ]

This ensures that any RCU readers traversing the instance list
have finished, before releasing the reference on the tracer that
the instance points to.

Cc: stable@vger.kernel.org
Fixes: a6ed2aee54644 ("tracing: Switch to kvfree_rcu() API")
Link: https://patch.msgid.link/20260609045430.1589786-1-crwood@redhat.com
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Crystal Wood <crwood@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 kernel/trace/trace_osnoise.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c
index 417b62f7550978..3b3f31ca45831b 100644
--- a/kernel/trace/trace_osnoise.c
+++ b/kernel/trace/trace_osnoise.c
@@ -137,7 +137,9 @@ static void osnoise_unregister_instance(struct trace_array *tr)
 	if (!found)
 		return;
 
-	kvfree_rcu_mightsleep(inst);
+	/* Do a full sync to ensure that tr remains valid, not just inst */
+	synchronize_rcu();
+	kvfree(inst);
 }
 
 /*
-- 
2.53.0