[PATCH AUTOSEL 6.6 020/139] net: sched: consistently use rcu_replace_pointer() in taprio_change()
From: Sasha Levin <sashal@kernel.org>
Date: 2024-09-25 12:12:26
Also in:
lkml, stable
Subsystem:
cbs/etf/taprio qdiscs, networking [general], tc subsystem, the rest · Maintainers:
Vinicius Costa Gomes, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Jamal Hadi Salim, Jiri Pirko, Linus Torvalds
From: Dmitry Antipov <redacted> [ 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 <vinicius.gomes@intel.com> Signed-off-by: Dmitry Antipov <redacted> Acked-by: Vinicius Costa Gomes <vinicius.gomes@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org> --- 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 418d4a846d04a..87090d6790362 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 {
--
2.43.0