tcp: add tcp_sock_set_keepintvl

Add a helper to directly set the TCP_KEEPINTVL sockopt from kernel space
without going through a fake uaccess.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/tcp.h

@@ -499,6 +499,7 @@ int tcp_skb_shift(struct sk_buff *to, struct sk_buff *from, int pcount,
 
 void tcp_sock_set_cork(struct sock *sk, bool on);
 int tcp_sock_set_keepidle(struct sock *sk, int val);
+int tcp_sock_set_keepintvl(struct sock *sk, int val);
 void tcp_sock_set_nodelay(struct sock *sk);
 void tcp_sock_set_quickack(struct sock *sk, int val);
 int tcp_sock_set_syncnt(struct sock *sk, int val);

net/ipv4/tcp.c

@@ -2934,6 +2934,18 @@ int tcp_sock_set_keepidle(struct sock *sk, int val)
 }
 EXPORT_SYMBOL(tcp_sock_set_keepidle);
 
+int tcp_sock_set_keepintvl(struct sock *sk, int val)
+{
+	if (val < 1 || val > MAX_TCP_KEEPINTVL)
+		return -EINVAL;
+
+	lock_sock(sk);
+	tcp_sk(sk)->keepalive_intvl = val * HZ;
+	release_sock(sk);
+	return 0;
+}
+EXPORT_SYMBOL(tcp_sock_set_keepintvl);
+
 /*
  *	Socket option code for TCP.
  */

net/rds/tcp_listen.c

@@ -53,12 +53,10 @@ int rds_tcp_keepalive(struct socket *sock)
 		goto bail;
 
 	tcp_sock_set_keepidle(sock->sk, keepidle);
-
 	/* KEEPINTVL is the interval between successive probes. We follow
 	 * the model in xs_tcp_finish_connecting() and re-use keepidle.
 	 */
-	ret = kernel_setsockopt(sock, IPPROTO_TCP, TCP_KEEPINTVL,
-				(char *)&keepidle, sizeof(keepidle));
+	tcp_sock_set_keepintvl(sock->sk, keepidle);
 bail:
 	return ret;
 }

net/sunrpc/xprtsock.c

@@ -2108,8 +2108,7 @@ static void xs_tcp_set_socket_timeouts(struct rpc_xprt *xprt,
 	/* TCP Keepalive options */
 	sock_set_keepalive(sock->sk);
 	tcp_sock_set_keepidle(sock->sk, keepidle);
-	kernel_setsockopt(sock, SOL_TCP, TCP_KEEPINTVL,
-			(char *)&keepidle, sizeof(keepidle));
+	tcp_sock_set_keepintvl(sock->sk, keepidle);
 	kernel_setsockopt(sock, SOL_TCP, TCP_KEEPCNT,
 			(char *)&keepcnt, sizeof(keepcnt));