linux-kernel - Re: Honoring SO_RCVLOWAT in proto

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Date:	Wed, 05 Nov 2008 03:36:47 -0800 (PST)
From:	David Miller <davem@...emloft.net>
To:	swivel@...lls.gnugeneration.com
Cc:	alan@...rguk.ukuu.org.uk, linux-kernel@...r.kernel.org
Subject: Re: Honoring SO_RCVLOWAT in proto_ops.poll methods

From: swivel@...lls.gnugeneration.com
Date: Sun, 19 Oct 2008 22:58:19 -0500

> From what I can see the recv() MSG_PEEK fix is trivial anyways, why not
> fix it?

Does this patch work for you?

tcp: Fix recvmsg MSG_PEEK influence of blocking behavior.

Vito Caputo noticed that tcp_recvmsg() returns immediately from
partial reads when MSG_PEEK is used.  In particular, this means that
SO_RCVLOWAT is not respected.

Simply remove the test.  And this matches the behavior of several
other systems, including BSD.

Signed-off-by: David S. Miller <davem@...emloft.net>
---
 net/ipv4/tcp.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index eccb716..c5aca0b 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1374,8 +1374,7 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 			    sk->sk_state == TCP_CLOSE ||
 			    (sk->sk_shutdown & RCV_SHUTDOWN) ||
 			    !timeo ||
-			    signal_pending(current) ||
-			    (flags & MSG_PEEK))
+			    signal_pending(current))
 				break;
 		} else {
 			if (sock_flag(sk, SOCK_DONE))
-- 
1.5.6.5

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