[PATCH 13/28] tcp: add tcp_sock_set_syncnt

[Christoph Hellwig <hch@lst.de>]

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

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Sagi Grimberg <sagi@grimberg.me>
---
 drivers/nvme/host/tcp.c |  9 +--------
 include/linux/tcp.h     |  1 +
 net/ipv4/tcp.c          | 12 ++++++++++++
 3 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 4e4a750ecdb97..2872584f52f63 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -1336,14 +1336,7 @@ static int nvme_tcp_alloc_queue(struct nvme_ctrl *nctrl,
 	}
 
 	/* Single syn retry */
-	opt = 1;
-	ret = kernel_setsockopt(queue->sock, IPPROTO_TCP, TCP_SYNCNT,
-			(char *)&opt, sizeof(opt));
-	if (ret) {
-		dev_err(nctrl->device,
-			"failed to set TCP_SYNCNT sock opt %d\n", ret);
-		goto err_sock;
-	}
+	tcp_sock_set_syncnt(queue->sock->sk, 1);
 
 	/* Set TCP no delay */
 	tcp_sock_set_nodelay(queue->sock->sk);
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 2eaf8320b9db0..6aa4ae5ebf3d5 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -500,5 +500,6 @@ 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);
+int tcp_sock_set_syncnt(struct sock *sk, int val);
 
 #endif	/* _LINUX_TCP_H */
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 27b5e7a4e2ef9..d2c67ae1da07a 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2881,6 +2881,18 @@ void tcp_sock_set_quickack(struct sock *sk, int val)
 }
 EXPORT_SYMBOL(tcp_sock_set_quickack);
 
+int tcp_sock_set_syncnt(struct sock *sk, int val)
+{
+	if (val < 1 || val > MAX_TCP_SYNCNT)
+		return -EINVAL;
+
+	lock_sock(sk);
+	inet_csk(sk)->icsk_syn_retries = val;
+	release_sock(sk);
+	return 0;
+}
+EXPORT_SYMBOL(tcp_sock_set_syncnt);
+
 /*
  *	Socket option code for TCP.
  */
-- 
2.26.2