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authorEric Dumazet <eric.dumazet@gmail.com>2010-04-08 23:03:29 +0000
committerDavid S. Miller <davem@davemloft.net>2010-04-13 01:41:33 -0700
commitb6c6712a42ca3f9fa7f4a3d7c40e3a9dd1fd9e03 (patch)
tree42032b4978874e8ffcf6c851d13324b8c8c7c113 /net/decnet
parent7a161ea92471087a1579239d7a58dd06eaa5601c (diff)
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net: sk_dst_cache RCUification
With latest CONFIG_PROVE_RCU stuff, I felt more comfortable to make this work. sk->sk_dst_cache is currently protected by a rwlock (sk_dst_lock) This rwlock is readlocked for a very small amount of time, and dst entries are already freed after RCU grace period. This calls for RCU again :) This patch converts sk_dst_lock to a spinlock, and use RCU for readers. __sk_dst_get() is supposed to be called with rcu_read_lock() or if socket locked by user, so use appropriate rcu_dereference_check() condition (rcu_read_lock_held() || sock_owned_by_user(sk)) This patch avoids two atomic ops per tx packet on UDP connected sockets, for example, and permits sk_dst_lock to be much less dirtied. Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/decnet')
-rw-r--r--net/decnet/af_decnet.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/net/decnet/af_decnet.c b/net/decnet/af_decnet.c
index 2b494fac946..55e3b6b0061 100644
--- a/net/decnet/af_decnet.c
+++ b/net/decnet/af_decnet.c
@@ -446,7 +446,7 @@ static void dn_destruct(struct sock *sk)
skb_queue_purge(&scp->other_xmit_queue);
skb_queue_purge(&scp->other_receive_queue);
- dst_release(xchg(&sk->sk_dst_cache, NULL));
+ dst_release(rcu_dereference_check(sk->sk_dst_cache, 1));
}
static int dn_memory_pressure;
@@ -1105,7 +1105,7 @@ static int dn_accept(struct socket *sock, struct socket *newsock, int flags)
release_sock(sk);
dst = skb_dst(skb);
- dst_release(xchg(&newsk->sk_dst_cache, dst));
+ sk_dst_set(newsk, dst);
skb_dst_set(skb, NULL);
DN_SK(newsk)->state = DN_CR;
@@ -1956,7 +1956,7 @@ static int dn_sendmsg(struct kiocb *iocb, struct socket *sock,
}
if ((flags & MSG_TRYHARD) && sk->sk_dst_cache)
- dst_negative_advice(&sk->sk_dst_cache, sk);
+ dst_negative_advice(sk);
mss = scp->segsize_rem;
fctype = scp->services_rem & NSP_FC_MASK;