diff options
author | Eric Dumazet <edumazet@google.com> | 2012-07-29 19:20:37 -0400 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2012-07-30 17:53:22 -0400 |
commit | 404e0a8b6a55d5e1cd138c6deb1bca9abdf75d8c (patch) | |
tree | 38e9748d38c415cc97b973fecb9279cd43f76393 /include/net/inet_sock.h | |
parent | cca32e4bf999a34ac08d959f351f2b30bcd02460 (diff) |
net: ipv4: fix RCU races on dst refcounts
commit c6cffba4ffa2 (ipv4: Fix input route performance regression.)
added various fatal races with dst refcounts.
crashes happen on tcp workloads if routes are added/deleted at the same
time.
The dst_free() calls from free_fib_info_rcu() are clearly racy.
We need instead regular dst refcounting (dst_release()) and make
sure dst_release() is aware of RCU grace periods :
Add DST_RCU_FREE flag so that dst_release() respects an RCU grace period
before dst destruction for cached dst
Introduce a new inet_sk_rx_dst_set() helper, using atomic_inc_not_zero()
to make sure we dont increase a zero refcount (On a dst currently
waiting an rcu grace period before destruction)
rt_cache_route() must take a reference on the new cached route, and
release it if was not able to install it.
With this patch, my machines survive various benchmarks.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net/inet_sock.h')
-rw-r--r-- | include/net/inet_sock.h | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h index 613cfa40167..e3fd34c83ac 100644 --- a/include/net/inet_sock.h +++ b/include/net/inet_sock.h | |||
@@ -249,4 +249,17 @@ static inline __u8 inet_sk_flowi_flags(const struct sock *sk) | |||
249 | return flags; | 249 | return flags; |
250 | } | 250 | } |
251 | 251 | ||
252 | static inline void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb) | ||
253 | { | ||
254 | struct dst_entry *dst = skb_dst(skb); | ||
255 | |||
256 | if (atomic_inc_not_zero(&dst->__refcnt)) { | ||
257 | if (!(dst->flags & DST_RCU_FREE)) | ||
258 | dst->flags |= DST_RCU_FREE; | ||
259 | |||
260 | sk->sk_rx_dst = dst; | ||
261 | inet_sk(sk)->rx_dst_ifindex = skb->skb_iif; | ||
262 | } | ||
263 | } | ||
264 | |||
252 | #endif /* _INET_SOCK_H */ | 265 | #endif /* _INET_SOCK_H */ |