On Wed, 2015-10-21 at 14:03 +0100, Alan Burlison wrote:

On 21/10/2015 12:28, Eric Dumazet wrote:

quoted

This works for me. Please double check your programs

I have just done so, it works as you say for AF_INET sockets but if you 
switch to AF_UNIX sockets it does the wrong thing in the way I described.

Oh well. Please try the following :

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 94f658235fb4..24dec8bb571d 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c

@@ -328,7 +328,8 @@ found:
 
 static inline int unix_writable(struct sock *sk)
 {
-	return (atomic_read(&sk->sk_wmem_alloc) << 2) <= sk->sk_sndbuf;
+	return sk->sk_state != TCP_LISTEN &&
+	       (atomic_read(&sk->sk_wmem_alloc) << 2) <= sk->sk_sndbuf;
 }
 
 static void unix_write_space(struct sock *sk)