tcp: add tcp_sock_set_quickack

Add a helper to directly set the TCP_QUICKACK sockopt from kernel space
without going through a fake uaccess.  Cleanup the callers to avoid
pointless wrappers now that this is a simple function call.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/block/drbd/drbd_int.h

@@ -1570,13 +1570,6 @@ extern void drbd_set_recv_tcq(struct drbd_device *device, int tcq_enabled);
 extern void _drbd_clear_done_ee(struct drbd_device *device, struct list_head *to_be_freed);
 extern int drbd_connected(struct drbd_peer_device *);
 
-static inline void drbd_tcp_quickack(struct socket *sock)
-{
-	int val = 2;
-	(void) kernel_setsockopt(sock, SOL_TCP, TCP_QUICKACK,
-			(char*)&val, sizeof(val));
-}
-
 /* sets the number of 512 byte sectors of our virtual device */
 void drbd_set_my_capacity(struct drbd_device *device, sector_t size);
 

drivers/block/drbd/drbd_receiver.c

@@ -1223,7 +1223,7 @@ static int drbd_recv_header_maybe_unplug(struct drbd_connection *connection, str
 		 * quickly as possible, and let remote TCP know what we have
 		 * received so far. */
 		if (err == -EAGAIN) {
-			drbd_tcp_quickack(connection->data.socket);
+			tcp_sock_set_quickack(connection->data.socket->sk, 2);
 			drbd_unplug_all_devices(connection);
 		}
 		if (err > 0) {
@@ -4959,8 +4959,7 @@ static int receive_UnplugRemote(struct drbd_connection *connection, struct packe
 {
 	/* Make sure we've acked all the TCP data associated
 	 * with the data requests being unplugged */
-	drbd_tcp_quickack(connection->data.socket);
-
+	tcp_sock_set_quickack(connection->data.socket->sk, 2);
 	return 0;
 }
 

include/linux/tcp.h

@@ -499,5 +499,6 @@ int tcp_skb_shift(struct sk_buff *to, struct sk_buff *from, int pcount,
 
 void tcp_sock_set_cork(struct sock *sk, bool on);
 void tcp_sock_set_nodelay(struct sock *sk);
+void tcp_sock_set_quickack(struct sock *sk, int val);
 
 #endif	/* _LINUX_TCP_H */

net/ipv4/tcp.c

@@ -2856,6 +2856,31 @@ void tcp_sock_set_nodelay(struct sock *sk)
 }
 EXPORT_SYMBOL(tcp_sock_set_nodelay);
 
+static void __tcp_sock_set_quickack(struct sock *sk, int val)
+{
+	if (!val) {
+		inet_csk_enter_pingpong_mode(sk);
+		return;
+	}
+
+	inet_csk_exit_pingpong_mode(sk);
+	if ((1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT) &&
+	    inet_csk_ack_scheduled(sk)) {
+		inet_csk(sk)->icsk_ack.pending |= ICSK_ACK_PUSHED;
+		tcp_cleanup_rbuf(sk, 1);
+		if (!(val & 1))
+			inet_csk_enter_pingpong_mode(sk);
+	}
+}
+
+void tcp_sock_set_quickack(struct sock *sk, int val)
+{
+	lock_sock(sk);
+	__tcp_sock_set_quickack(sk, val);
+	release_sock(sk);
+}
+EXPORT_SYMBOL(tcp_sock_set_quickack);
+
 /*
  *	Socket option code for TCP.
  */
@@ -3096,19 +3121,7 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
 		break;
 
 	case TCP_QUICKACK:
-		if (!val) {
-			inet_csk_enter_pingpong_mode(sk);
-		} else {
-			inet_csk_exit_pingpong_mode(sk);
-			if ((1 << sk->sk_state) &
-			    (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT) &&
-			    inet_csk_ack_scheduled(sk)) {
-				icsk->icsk_ack.pending |= ICSK_ACK_PUSHED;
-				tcp_cleanup_rbuf(sk, 1);
-				if (!(val & 1))
-					inet_csk_enter_pingpong_mode(sk);
-			}
-		}
+		__tcp_sock_set_quickack(sk, val);
 		break;
 
 #ifdef CONFIG_TCP_MD5SIG