[TCP]: Fix a bug in strategy_allowed_congestion_control

In strategy_allowed_congestion_control of the 2.6.24 kernel, when
sysctl_string return 1 on success,it should call
tcp_set_allowed_congestion_control to set the allowed congestion
control.But, it don't.  the sysctl_string return 1 on success,
otherwise return negative, never return 0.The patch fix the problem.
Signed-off-by: NShan Wei <shanwei@cn.fujitsu.com>
Acked-by: NStephen Hemminger <shemminger@vyatta.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/sysctl_net_ipv4.c

@@ -185,7 +185,7 @@ static int strategy_allowed_congestion_control(ctl_table *table, int __user *nam
 
 	tcp_get_available_congestion_control(tbl.data, tbl.maxlen);
 	ret = sysctl_string(&tbl, name, nlen, oldval, oldlenp, newval, newlen);
-	if (ret == 0 && newval && newlen)
+	if (ret == 1 && newval && newlen)
 		ret = tcp_set_allowed_congestion_control(tbl.data);
 	kfree(tbl.data);