From: Gao Feng <fgao@ikuai8.com>
Date: Tue, 21 Mar 2017 01:28:03 +0000 (+0800)
Subject: net: tcp: Permit user set TCP_MAXSEG to default value
X-Git-Tag: v4.12-rc1~108^2~368
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=cfc62d878f8d436e6a2a99cef5559a7a98c43b3c;p=users%2Fwilly%2Flinux.git

net: tcp: Permit user set TCP_MAXSEG to default value

When user_mss is zero, it means use the default value. But the current
codes don't permit user set TCP_MAXSEG to the default value.
It would return the -EINVAL when val is zero.

Signed-off-by: Gao Feng <fgao@ikuai8.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index cf4555581282..eccec53ef100 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2470,7 +2470,7 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
 		/* Values greater than interface MTU won't take effect. However
 		 * at the point when this call is done we typically don't yet
 		 * know which interface is going to be used */
-		if (val < TCP_MIN_MSS || val > MAX_TCP_WINDOW) {
+		if (val && (val < TCP_MIN_MSS || val > MAX_TCP_WINDOW)) {
 			err = -EINVAL;
 			break;
 		}