Subject: Re: [PATCH] tcp: tcp_prequeue() can use keyed wakeups

From: John Dykstra <[email-masked]>
Date: Tue, 12 May 2009 20:34:50 -0500

On Thu, 2009-05-07 at 19:20 +0200, Eric Dumazet wrote:
> We can avoid waking up tasks not interested in receive notifications,
> using wake_up_interruptible_poll() instead of wake_up_interruptible()

Is there any reason why we shouldn't do the same thing on the write
side?

Compile-tested only.

  --  John

---
[PATCH net-next-2.6] tcp: Don't wake up reading threads on write space 

When TCP frees up write buffer space, avoid waking up tasks that have
done a poll() or select() on the same socket specifying read-side
events.

This is an extension of a read-side patch by Eric Dumazet.

Signed-off-by: John Dykstra <[email-masked]>
---
 net/core/stream.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/net/core/stream.c b/net/core/stream.c
index 8727cea..a37debf 100644
--- a/net/core/stream.c
+++ b/net/core/stream.c
@@ -33,7 +33,8 @@ void sk_stream_write_space(struct sock *sk)
 		clear_bit(SOCK_NOSPACE, &sock->flags);
 
 		if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
-			wake_up_interruptible(sk->sk_sleep);
+			wake_up_interruptible_poll(sk->sk_sleep, POLLOUT |
+						POLLWRNORM | POLLWRBAND);
 		if (sock->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN))
 			sock_wake_async(sock, SOCK_WAKE_SPACE, POLL_OUT);
 	}
-- 
1.5.4.3