linux-kernel - [PATCH] tracing/user_events: Hold event_mutex during dyn_event

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Message-Id: <20220328223225.1992-1-beaub@linux.microsoft.com>
Date:   Mon, 28 Mar 2022 15:32:25 -0700
From:   Beau Belgrave <beaub@...ux.microsoft.com>
To:     rostedt@...dmis.org, mhiramat@...nel.org
Cc:     mathieu.desnoyers@...icios.com, linux-trace-devel@...r.kernel.org,
        linux-kernel@...r.kernel.org, beaub@...ux.microsoft.com
Subject: [PATCH] tracing/user_events: Hold event_mutex during dyn_event_add

Make sure the event_mutex is properly held during dyn_event_add call.
This is required when adding dynamic events.

Reported-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Signed-off-by: Beau Belgrave <beaub@...ux.microsoft.com>
---
 kernel/trace/trace_events_user.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c
index 8b3d241a31c2..61d78d64bdf0 100644
--- a/kernel/trace/trace_events_user.c
+++ b/kernel/trace/trace_events_user.c
@@ -1165,11 +1165,11 @@ static int user_event_parse(char *name, char *args, char *flags,
 #endif
 
 	mutex_lock(&event_mutex);
+
 	ret = user_event_trace_register(user);
-	mutex_unlock(&event_mutex);
 
 	if (ret)
-		goto put_user;
+		goto put_user_lock;
 
 	user->index = index;
 
@@ -1181,8 +1181,12 @@ static int user_event_parse(char *name, char *args, char *flags,
 	set_bit(user->index, page_bitmap);
 	hash_add(register_table, &user->node, key);
 
+	mutex_unlock(&event_mutex);
+
 	*newuser = user;
 	return 0;
+put_user_lock:
+	mutex_unlock(&event_mutex);
 put_user:
 	user_event_destroy_fields(user);
 	user_event_destroy_validators(user);

base-commit: c87857e214862a125208a4b1a510839d0c5a1bd4
-- 
2.25.1