From cff82457c5584f6a96d2b85d1a88b81ba304a330 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Tue, 25 Aug 2015 20:06:35 -0700 Subject: net_sched: act_bpf: remove spinlock in fast path Similar to act_gact/act_mirred, act_bpf can be lockless in packet processing with extra care taken to free bpf programs after rcu grace period. Replacement of existing act_bpf (very rare) is done with synchronize_rcu() and final destruction is done from tc_action_ops->cleanup() callback that is called from tcf_exts_destroy()->tcf_action_destroy()->__tcf_hash_release() when bind and refcnt reach zero which is only possible when classifier is destroyed. Previous two patches fixed the last two classifiers (tcindex and rsvp) to call tcf_exts_destroy() from rcu callback. Similar to gact/mirred there is a race between prog->filter and prog->tcf_action. Meaning that the program being replaced may use previous default action if it happened to return TC_ACT_UNSPEC. act_mirred race betwen tcf_action and tcfm_dev is similar. In all cases the race is harmless. Long term we may want to improve the situation by replacing the whole tc_action->priv as single pointer instead of updating inner fields one by one. Signed-off-by: Alexei Starovoitov Acked-by: Daniel Borkmann Signed-off-by: David S. Miller --- include/net/tc_act/tc_bpf.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include') diff --git a/include/net/tc_act/tc_bpf.h b/include/net/tc_act/tc_bpf.h index a152e9858b2c..958d69cfb19c 100644 --- a/include/net/tc_act/tc_bpf.h +++ b/include/net/tc_act/tc_bpf.h @@ -15,7 +15,7 @@ struct tcf_bpf { struct tcf_common common; - struct bpf_prog *filter; + struct bpf_prog __rcu *filter; union { u32 bpf_fd; u16 bpf_num_ops; -- cgit v1.2.3-59-g8ed1b