From: Pedro Tammela Date: Tue, 11 Jul 2023 02:16:34 +0000 (-0300) Subject: net/sched: make psched_mtu() RTNL-less safe X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=150e33e62c1fa4af5aaab02776b6c3812711d478;p=linux.git net/sched: make psched_mtu() RTNL-less safe Eric Dumazet says[1]: ------- Speaking of psched_mtu(), I see that net/sched/sch_pie.c is using it without holding RTNL, so dev->mtu can be changed underneath. KCSAN could issue a warning. ------- Annotate dev->mtu with READ_ONCE() so KCSAN don't issue a warning. [1] https://lore.kernel.org/all/CANn89iJoJO5VtaJ-2=_d2aOQhb0Xw8iBT_Cxqp2HyuS-zj6azw@mail.gmail.com/ v1 -> v2: Fix commit message Fixes: d4b36210c2e6 ("net: pkt_sched: PIE AQM scheme") Suggested-by: Eric Dumazet Signed-off-by: Pedro Tammela Reviewed-by: Simon Horman Link: https://lore.kernel.org/r/20230711021634.561598-1-pctammela@mojatatu.com Signed-off-by: Jakub Kicinski --- diff --git a/include/net/pkt_sched.h b/include/net/pkt_sched.h index e98aac9d5ad57..15960564e0c36 100644 --- a/include/net/pkt_sched.h +++ b/include/net/pkt_sched.h @@ -134,7 +134,7 @@ extern const struct nla_policy rtm_tca_policy[TCA_MAX + 1]; */ static inline unsigned int psched_mtu(const struct net_device *dev) { - return dev->mtu + dev->hard_header_len; + return READ_ONCE(dev->mtu) + dev->hard_header_len; } static inline struct net *qdisc_net(struct Qdisc *q)