path: root/net/sched/sch_generic.c
diff options
authorCong Wang <>2017-12-20 23:26:24 -0800
committerDavid S. Miller <>2017-12-26 12:28:40 -0500
commitb2fb01f426883a794ed80be9110675a2d8356347 (patch)
tree27c6f9bc0269903fe480f9a69530fd3ea0e08d22 /net/sched/sch_generic.c
parentc1a8d0a3accf64a014d605e6806ce05d1c17adf1 (diff)
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 <> Tested-by: Jakub Kicinski <> Cc: Jiri Pirko <> Cc: John Fastabend <> Signed-off-by: Cong Wang <> Acked-by: Jiri Pirko <> Signed-off-by: David S. Miller <>
Diffstat (limited to 'net/sched/sch_generic.c')
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();
@@ -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.