From: Andrew Morton <[EMAIL PROTECTED]>
Date: Sun, 11 Dec 2005 00:19:58 -0800
> Ah, sorry. -mm's git-net is from
> git+ssh://master.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6.16.git
>
> I tend to prefer the latest and greatest of everything.
Ok. Ben, you're not off the hook sorry :-)
Maybe that stream sendmsg() AF_UNIX peer socket
reference bump is really needed.
Andrew, does reverting the following make the problem go
away?
diff-tree 918374e04126ac04f42c58905cd3e88d785a8eef (from
1e0fe0b7e1b017d47930351ec50a3f49d7c7257b)
Author: Benjamin LaHaise <[EMAIL PROTECTED]>
Date: Sat Dec 10 11:52:17 2005 -0800
[AF_UNIX]: Remove superfluous reference counting in unix_stream_sendmsg
AF_UNIX stream socket performance on P4 CPUs tends to suffer due to a
lot of pipeline flushes from atomic operations. The patch below
removes the sock_hold() and sock_put() in unix_stream_sendmsg(). This
should be safe as the socket still holds a reference to its peer which
is only released after the file descriptor's final user invokes
unix_release_sock(). The only consideration is that we must add a
memory barrier before setting the peer initially.
Signed-off-by: Benjamin LaHaise <[EMAIL PROTECTED]>
Signed-off-by: David S. Miller <[EMAIL PROTECTED]>
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index acc73ba..3593b90 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1063,10 +1063,12 @@ restart:
/* Set credentials */
sk->sk_peercred = other->sk_peercred;
- sock_hold(newsk);
- unix_peer(sk) = newsk;
sock->state = SS_CONNECTED;
sk->sk_state = TCP_ESTABLISHED;
+ sock_hold(newsk);
+
+ smp_mb__after_atomic_inc(); /* sock_hold() does an atomic_inc() */
+ unix_peer(sk) = newsk;
unix_state_wunlock(sk);
@@ -1414,7 +1416,7 @@ static int unix_stream_sendmsg(struct ki
} else {
sunaddr = NULL;
err = -ENOTCONN;
- other = unix_peer_get(sk);
+ other = unix_peer(sk);
if (!other)
goto out_err;
}
@@ -1476,7 +1478,6 @@ static int unix_stream_sendmsg(struct ki
other->sk_data_ready(other, size);
sent+=size;
}
- sock_put(other);
scm_destroy(siocb->scm);
siocb->scm = NULL;
-
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