From ab6e3feba1f1bc3b9418b854da6f481408d243de Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 10 May 2010 11:31:49 +0000 Subject: [PATCH] net: No dst refcounting in ip_queue_xmit() TCP outgoing packets can avoid two atomic ops, and dirtying of previously higly contended cache line using new refdst infrastructure. Note 1: loopback device excluded because of !IFF_XMIT_DST_RELEASE Note 2: UDP packets dsts are built before ip_queue_xmit(). Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/ip_output.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index 252897443ef9..9a4a6c96cb0d 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -318,10 +318,12 @@ int ip_queue_xmit(struct sk_buff *skb) struct ip_options *opt = inet->opt; struct rtable *rt; struct iphdr *iph; + int res; /* Skip all of this if the packet is already routed, * f.e. by something like SCTP. */ + rcu_read_lock(); rt = skb_rtable(skb); if (rt != NULL) goto packet_routed; @@ -359,7 +361,7 @@ int ip_queue_xmit(struct sk_buff *skb) } sk_setup_caps(sk, &rt->u.dst); } - skb_dst_set(skb, dst_clone(&rt->u.dst)); + skb_dst_set_noref(skb, &rt->u.dst); packet_routed: if (opt && opt->is_strictroute && rt->rt_dst != rt->rt_gateway) @@ -391,9 +393,12 @@ packet_routed: skb->priority = sk->sk_priority; skb->mark = sk->sk_mark; - return ip_local_out(skb); + res = ip_local_out(skb); + rcu_read_unlock(); + return res; no_route: + rcu_read_unlock(); IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES); kfree_skb(skb); return -EHOSTUNREACH; -- 2.39.5