From 37a6fc0d8fca8fd2e34835a6faabc7955fcd1419 Mon Sep 17 00:00:00 2001 From: Dmitry Antipov Date: Wed, 4 Sep 2024 14:54:01 +0300 Subject: [PATCH] net: sched: consistently use rcu_replace_pointer() in taprio_change() [ Upstream commit d5c4546062fd6f5dbce575c7ea52ad66d1968678 ] According to Vinicius (and carefully looking through the whole https://syzkaller.appspot.com/bug?extid=b65e0af58423fc8a73aa once again), txtime branch of 'taprio_change()' is not going to race against 'advance_sched()'. But using 'rcu_replace_pointer()' in the former may be a good idea as well. Suggested-by: Vinicius Costa Gomes Signed-off-by: Dmitry Antipov Acked-by: Vinicius Costa Gomes Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/sched/sch_taprio.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c index 418d4a846d04..87090d679036 100644 --- a/net/sched/sch_taprio.c +++ b/net/sched/sch_taprio.c @@ -1975,7 +1975,9 @@ static int taprio_change(struct Qdisc *sch, struct nlattr *opt, goto unlock; } - rcu_assign_pointer(q->admin_sched, new_admin); + /* Not going to race against advance_sched(), but still */ + admin = rcu_replace_pointer(q->admin_sched, new_admin, + lockdep_rtnl_is_held()); if (admin) call_rcu(&admin->rcu, taprio_free_sched_cb); } else {