From 7aa0045dadb6ef37485ea9f2a7d28278ca588b51 Mon Sep 17 00:00:00 2001 From: Cong Wang Date: Thu, 26 Oct 2017 18:24:28 -0700 Subject: net_sched: introduce a workqueue for RCU callbacks of tc filter This patch introduces a dedicated workqueue for tc filters so that each tc filter's RCU callback could defer their action destroy work to this workqueue. The helper tcf_queue_work() is introduced for them to use. Because we hold RTNL lock when calling tcf_block_put(), we can not simply flush works inside it, therefore we have to defer it again to this workqueue and make sure all flying RCU callbacks have already queued their work before this one, in other words, to ensure this is the last one to execute to prevent any use-after-free. On the other hand, this makes tcf_block_put() ugly and harder to understand. Since David and Eric strongly dislike adding synchronize_rcu(), this is probably the only solution that could make everyone happy. Please also see the code comments below. Reported-by: Chris Mi Cc: Daniel Borkmann Cc: Jiri Pirko Cc: John Fastabend Cc: Jamal Hadi Salim Cc: "Paul E. McKenney" Signed-off-by: Cong Wang Signed-off-by: David S. Miller --- include/net/pkt_cls.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/net/pkt_cls.h') diff --git a/include/net/pkt_cls.h b/include/net/pkt_cls.h index e80edd8879ef..3009547f3c66 100644 --- a/include/net/pkt_cls.h +++ b/include/net/pkt_cls.h @@ -2,6 +2,7 @@ #define __NET_PKT_CLS_H #include +#include #include #include @@ -17,6 +18,8 @@ struct tcf_walker { int register_tcf_proto_ops(struct tcf_proto_ops *ops); int unregister_tcf_proto_ops(struct tcf_proto_ops *ops); +bool tcf_queue_work(struct work_struct *work); + #ifdef CONFIG_NET_CLS struct tcf_chain *tcf_chain_get(struct tcf_block *block, u32 chain_index, bool create); -- cgit v1.2.3