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net/sched: make psched_mtu() RTNL-less safe

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[ Upstream commit 150e33e62c1fa4af5aaab02776b6c3812711d478 ]

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: d4b36210c2 ("net: pkt_sched: PIE AQM scheme")
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Pedro Tammela <pctammela@mojatatu.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20230711021634.561598-1-pctammela@mojatatu.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Pedro Tammela 2023-07-10 23:16:34 -03:00 committed by Greg Kroah-Hartman
parent 96391959a9
commit cf57a0853b
1 changed files with 1 additions and 1 deletions
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2
include/net/pkt_sched.h
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@ -131,7 +131,7 @@ 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)