[PATCH 3/5] net/rds/tcp.c: introduce rds_tcp_{init,exit}_net_sysctl() helpers

[Oleg Nesterov <oleg@redhat.com>]

Preparation to simplify the next change.

Extract the net namespace sysctl registration and unregistration logic
from rds_tcp_init_net() and rds_tcp_exit_net() into new helpers.

This also simplifies the error paths in rds_tcp_init_net(); it can use
rds_tcp_exit_net_sysctl() too.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
 net/rds/tcp.c | 93 ++++++++++++++++++++++++++++-----------------------
 1 file changed, 52 insertions(+), 41 deletions(-)

diff --git a/net/rds/tcp.c b/net/rds/tcp.c
index c1ad37505417..d6c542371611 100644
--- a/net/rds/tcp.c
+++ b/net/rds/tcp.c
@@ -82,6 +82,52 @@ static struct ctl_table rds_tcp_sysctl_table[] = {
 	},
 };
 
+static __net_init int rds_tcp_init_net_sysctl(struct net *net)
+{
+	struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
+	struct ctl_table *tbl;
+
+	/* {snd, rcv}buf_size default to 0, which implies we let the
+	 * stack pick the value, and permit auto-tuning of buffer size.
+	 */
+	if (net == &init_net) {
+		tbl = rds_tcp_sysctl_table;
+	} else {
+		tbl = kmemdup(rds_tcp_sysctl_table,
+			      sizeof(rds_tcp_sysctl_table), GFP_KERNEL);
+		if (!tbl) {
+			pr_warn("could not allocate sysctl table\n");
+			return -ENOMEM;
+		}
+		rtn->ctl_table = tbl;
+	}
+	tbl[RDS_TCP_SNDBUF].data = &rtn->sndbuf_size;
+	tbl[RDS_TCP_RCVBUF].data = &rtn->rcvbuf_size;
+	rtn->rds_tcp_sysctl = register_net_sysctl_sz(net, "net/rds/tcp", tbl,
+						     ARRAY_SIZE(rds_tcp_sysctl_table));
+	if (!rtn->rds_tcp_sysctl && IS_ENABLED(CONFIG_SYSCTL)) {
+		pr_warn("could not register sysctl\n");
+		if (net != &init_net)
+			kfree(tbl);
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static void __net_exit rds_tcp_exit_net_sysctl(struct net *net)
+{
+	struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
+
+	if (rtn->rds_tcp_sysctl) {
+		unregister_net_sysctl_table(rtn->rds_tcp_sysctl);
+		rtn->rds_tcp_sysctl = NULL;
+	}
+
+	if (net != &init_net)
+		kfree(rtn->ctl_table);
+}
+
 u32 rds_tcp_write_seq(struct rds_tcp_connection *tc)
 {
 	/* seq# of the last byte of data in tcp send buffer */
@@ -612,36 +658,15 @@ void rds_tcp_accept_work(struct rds_tcp_net *rtn)
 static __net_init int rds_tcp_init_net(struct net *net)
 {
 	struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
-	struct ctl_table *tbl;
 	int err = 0;
 
 	memset(rtn, 0, sizeof(*rtn));
 
 	mutex_init(&rtn->rds_tcp_accept_lock);
 
-	/* {snd, rcv}buf_size default to 0, which implies we let the
-	 * stack pick the value, and permit auto-tuning of buffer size.
-	 */
-	if (net == &init_net) {
-		tbl = rds_tcp_sysctl_table;
-	} else {
-		tbl = kmemdup(rds_tcp_sysctl_table,
-			      sizeof(rds_tcp_sysctl_table), GFP_KERNEL);
-		if (!tbl) {
-			pr_warn("could not set allocate sysctl table\n");
-			return -ENOMEM;
-		}
-		rtn->ctl_table = tbl;
-	}
-	tbl[RDS_TCP_SNDBUF].data = &rtn->sndbuf_size;
-	tbl[RDS_TCP_RCVBUF].data = &rtn->rcvbuf_size;
-	rtn->rds_tcp_sysctl = register_net_sysctl_sz(net, "net/rds/tcp", tbl,
-						     ARRAY_SIZE(rds_tcp_sysctl_table));
-	if (!rtn->rds_tcp_sysctl && IS_ENABLED(CONFIG_SYSCTL)) {
-		pr_warn("could not register sysctl\n");
-		err = -ENOMEM;
-		goto fail;
-	}
+	err = rds_tcp_init_net_sysctl(net);
+	if (err)
+		return err;
 
 #if IS_ENABLED(CONFIG_IPV6)
 	rtn->rds_tcp_listen_sock = rds_tcp_listen_init(net, true);
@@ -656,21 +681,14 @@ static __net_init int rds_tcp_init_net(struct net *net)
 		rtn->rds_tcp_listen_sock = rds_tcp_listen_init(net, false);
 		if (!rtn->rds_tcp_listen_sock) {
 #endif
-			unregister_net_sysctl_table(rtn->rds_tcp_sysctl);
-			rtn->rds_tcp_sysctl = NULL;
-			err = -EAFNOSUPPORT;
-			goto fail;
+			rds_tcp_exit_net_sysctl(net);
+			return -EAFNOSUPPORT;
 #if IS_ENABLED(CONFIG_IPV6)
 		}
 #endif
 	}
 	INIT_WORK(&rtn->rds_tcp_accept_w, rds_tcp_accept_worker);
 	return 0;
-
-fail:
-	if (net != &init_net)
-		kfree(tbl);
-	return err;
 }
 
 static void rds_tcp_kill_sock(struct net *net)
@@ -704,14 +722,7 @@ static void rds_tcp_kill_sock(struct net *net)
 
 static void __net_exit rds_tcp_exit_net(struct net *net)
 {
-	struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
-
-	if (rtn->rds_tcp_sysctl)
-		unregister_net_sysctl_table(rtn->rds_tcp_sysctl);
-
-	if (net != &init_net)
-		kfree(rtn->ctl_table);
-
+	rds_tcp_exit_net_sysctl(net);
 	rds_tcp_kill_sock(net);
 }
 
-- 
2.55.0