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authorEric Dumazet <edumazet@google.com>2012-07-30 03:20:37 +0400
committerDavid S. Miller <davem@davemloft.net>2012-07-31 01:53:22 +0400
commit404e0a8b6a55d5e1cd138c6deb1bca9abdf75d8c (patch)
tree38e9748d38c415cc97b973fecb9279cd43f76393 /include/net/inet_sock.h
parentcca32e4bf999a34ac08d959f351f2b30bcd02460 (diff)
downloadlinux-404e0a8b6a55d5e1cd138c6deb1bca9abdf75d8c.tar.xz
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.h13
1 files changed, 13 insertions, 0 deletions
diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
index 613cfa401672..e3fd34c83ac9 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)
return flags;
}
+static inline void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb)
+{
+ struct dst_entry *dst = skb_dst(skb);
+
+ if (atomic_inc_not_zero(&dst->__refcnt)) {
+ if (!(dst->flags & DST_RCU_FREE))
+ dst->flags |= DST_RCU_FREE;
+
+ sk->sk_rx_dst = dst;
+ inet_sk(sk)->rx_dst_ifindex = skb->skb_iif;
+ }
+}
+
#endif /* _INET_SOCK_H */