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authorCong Wang <xiyou.wangcong@gmail.com>2017-12-20 23:26:24 -0800
committerDavid S. Miller <davem@davemloft.net>2017-12-26 12:28:40 -0500
commitb2fb01f426883a794ed80be9110675a2d8356347 (patch)
tree27c6f9bc0269903fe480f9a69530fd3ea0e08d22
parentc1a8d0a3accf64a014d605e6806ce05d1c17adf1 (diff)
downloadlinux-sh-b2fb01f426883a794ed80be9110675a2d8356347.tar.gz
net_sched: fix a missing rcu barrier in mini_qdisc_pair_swap()
The rcu_barrier_bh() in mini_qdisc_pair_swap() is to wait for flying RCU callback installed by a previous mini_qdisc_pair_swap(), however we miss it on the tp_head==NULL path, which leads to that the RCU callback still uses miniq_old->rcu after it is freed together with qdisc in qdisc_graft(). So just add it on that path too. Fixes: 46209401f8f6 ("net: core: introduce mini_Qdisc and eliminate usage of tp->q for clsact fastpath ") Reported-by: Jakub Kicinski <jakub.kicinski@netronome.com> Tested-by: Jakub Kicinski <jakub.kicinski@netronome.com> Cc: Jiri Pirko <jiri@mellanox.com> Cc: John Fastabend <john.fastabend@gmail.com> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Acked-by: Jiri Pirko <jiri@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/sched/sch_generic.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index cd1b200acae7..661c7144b53a 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -1040,6 +1040,8 @@ void mini_qdisc_pair_swap(struct mini_Qdisc_pair *miniqp,
if (!tp_head) {
RCU_INIT_POINTER(*miniqp->p_miniq, NULL);
+ /* Wait for flying RCU callback before it is freed. */
+ rcu_barrier_bh();
return;
}
@@ -1055,7 +1057,7 @@ void mini_qdisc_pair_swap(struct mini_Qdisc_pair *miniqp,
rcu_assign_pointer(*miniqp->p_miniq, miniq);
if (miniq_old)
- /* This is counterpart of the rcu barrier above. We need to
+ /* This is counterpart of the rcu barriers above. We need to
* block potential new user of miniq_old until all readers
* are not seeing it.
*/