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authorAlexei Starovoitov <ast@plumgrid.com>2015-08-25 20:06:35 -0700
committerDavid S. Miller <davem@davemloft.net>2015-08-26 11:01:45 -0700
commitcff82457c5584f6a96d2b85d1a88b81ba304a330 (patch)
treeee2e2eb473e84ba5c052dddd05ef09db5b7faeb3 /include/net/tc_act
parent9e528d89154b602209fda2fb92e89927bbffc976 (diff)
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 <ast@plumgrid.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net/tc_act')
-rw-r--r--include/net/tc_act/tc_bpf.h2
1 files changed, 1 insertions, 1 deletions
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;