Subject: [PATCH 1/4] sctp: add sctp_sock_set_nodelay

From: Christoph Hellwig <[email-masked]>
Date: Fri, 29 May 2020 14:09:40 +0200

Add a helper to directly set the SCTP_NODELAY sockopt from kernel space
without going through a fake uaccess.

Signed-off-by: Christoph Hellwig <[email-masked]>
---
 fs/dlm/lowcomms.c       | 10 ++--------
 include/net/sctp/sctp.h |  7 +++++++
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index 69333728d871b..9f1c3cdc9d653 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -914,7 +914,6 @@ static int sctp_bind_addrs(struct connection *con, uint16_t port)
 static void sctp_connect_to_sock(struct connection *con)
 {
 	struct sockaddr_storage daddr;
-	int one = 1;
 	int result;
 	int addr_len;
 	struct socket *sock;
@@ -961,8 +960,7 @@ static void sctp_connect_to_sock(struct connection *con)
 	log_print("connecting to %d", con->nodeid);
 
 	/* Turn off Nagle's algorithm */
-	kernel_setsockopt(sock, SOL_SCTP, SCTP_NODELAY, (char *)&one,
-			  sizeof(one));
+	sctp_sock_set_nodelay(sock->sk);
 
 	/*
 	 * Make sock->ops->connect() function return in specified time,
@@ -1176,7 +1174,6 @@ static int sctp_listen_for_all(void)
 	struct socket *sock = NULL;
 	int result = -EINVAL;
 	struct connection *con = nodeid2con(0, GFP_NOFS);
-	int one = 1;
 
 	if (!con)
 		return -ENOMEM;
@@ -1191,10 +1188,7 @@ static int sctp_listen_for_all(void)
 	}
 
 	sock_set_rcvbuf(sock->sk, NEEDED_RMEM);
-	result = kernel_setsockopt(sock, SOL_SCTP, SCTP_NODELAY, (char *)&one,
-				   sizeof(one));
-	if (result < 0)
-		log_print("Could not set SCTP NODELAY error %d\n", result);
+	sctp_sock_set_nodelay(sock->sk);
 
 	write_lock_bh(&sock->sk->sk_callback_lock);
 	/* Init con struct */
diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h
index 3ab5c6bbb90bd..f8bcb75bb0448 100644
--- a/include/net/sctp/sctp.h
+++ b/include/net/sctp/sctp.h
@@ -615,4 +615,11 @@ static inline bool sctp_newsk_ready(const struct sock *sk)
 	return sock_flag(sk, SOCK_DEAD) || sk->sk_socket;
 }
 
+static inline void sctp_sock_set_nodelay(struct sock *sk)
+{
+	lock_sock(sk);
+	sctp_sk(sk)->nodelay = true;
+	release_sock(sk);
+}
+
 #endif /* __net_sctp_h__ */
-- 
2.26.2