tcp: Namespace-ify sysctl_tcp_fack

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index f6e1c00..c7c983f 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2517,7 +2517,7 @@ static int tcp_repair_options_est(struct sock *sk,
 				return -EINVAL;
 
 			tp->rx_opt.sack_ok |= TCP_SACK_SEEN;
-			if (sysctl_tcp_fack)
+			if (sock_net(sk)->ipv4.sysctl_tcp_fack)
 				tcp_enable_fack(tp);
 			break;
 		case TCPOPT_TIMESTAMP: