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| author | Eric Dumazet <eric.dumazet@gmail.com> | 2010-04-08 23:03:29 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2010-04-13 01:41:33 -0700 |
| commit | b6c6712a42ca3f9fa7f4a3d7c40e3a9dd1fd9e03 (patch) | |
| tree | 42032b4978874e8ffcf6c851d13324b8c8c7c113 /net/decnet | |
| parent | 7a161ea92471087a1579239d7a58dd06eaa5601c (diff) | |
| download | linux-stable-b6c6712a42ca3f9fa7f4a3d7c40e3a9dd1fd9e03.tar.gz linux-stable-b6c6712a42ca3f9fa7f4a3d7c40e3a9dd1fd9e03.tar.bz2 linux-stable-b6c6712a42ca3f9fa7f4a3d7c40e3a9dd1fd9e03.zip | |
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.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/net/decnet/af_decnet.c b/net/decnet/af_decnet.c index 2b494fac9468..55e3b6b0061a 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; |