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 cf45555..eccec53 100644 (file)
--- 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;
                }