Merge branch 'automatically-manage-dsa-master-interface-state'

Vladimir Oltean says:

====================
Automatically manage DSA master interface state

This patch series adds code that makes DSA open the master interface
automatically whenever one user interface gets opened, either by the
user, or by various networking subsystems: netconsole, nfsroot.
With that in place, we can remove some of the places in the network
stack where DSA-specific code was sprinkled.
====================

Link: https://lore.kernel.org/r/20210205133713.4172846-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

4 files changed, 50 insertions, 28 deletions

diff --git a/Documentation/networking/dsa/dsa.rst b/Documentation/networking/dsa/dsa.rst
index a8d15dd2b42b..e9517af5fe02 100644
--- a/Documentation/networking/dsa/dsa.rst
+++ b/Documentation/networking/dsa/dsa.rst
@@ -273,10 +273,6 @@ will not make us go through the switch tagging protocol transmit function, so
 the Ethernet switch on the other end, expecting a tag will typically drop this
 frame.
 
-Slave network devices check that the master network device is UP before allowing
-you to administratively bring UP these slave network devices. A common
-configuration mistake is forgetting to bring UP the master network device first.
-
 Interactions with other subsystems
 ==================================
 
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 960948290001..c310c7c1cef7 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -29,7 +29,6 @@
 #include <linux/slab.h>
 #include <linux/export.h>
 #include <linux/if_vlan.h>
-#include <net/dsa.h>
 #include <net/tcp.h>
 #include <net/udp.h>
 #include <net/addrconf.h>
@@ -658,15 +657,15 @@ EXPORT_SYMBOL_GPL(__netpoll_setup);
 
 int netpoll_setup(struct netpoll *np)
 {
-	struct net_device *ndev = NULL, *dev = NULL;
-	struct net *net = current->nsproxy->net_ns;
+	struct net_device *ndev = NULL;
 	struct in_device *in_dev;
 	int err;
 
 	rtnl_lock();
-	if (np->dev_name[0])
+	if (np->dev_name[0]) {
+		struct net *net = current->nsproxy->net_ns;
 		ndev = __dev_get_by_name(net, np->dev_name);
-
+	}
 	if (!ndev) {
 		np_err(np, "%s doesn't exist, aborting\n", np->dev_name);
 		err = -ENODEV;
@@ -674,19 +673,6 @@ int netpoll_setup(struct netpoll *np)
 	}
 	dev_hold(ndev);
 
-	/* bring up DSA management network devices up first */
-	for_each_netdev(net, dev) {
-		if (!netdev_uses_dsa(dev))
-			continue;
-
-		err = dev_change_flags(dev, dev->flags | IFF_UP, NULL);
-		if (err < 0) {
-			np_err(np, "%s failed to open %s\n",
-			       np->dev_name, dev->name);
-			goto put;
-		}
-	}
-
 	if (netdev_master_upper_dev_get(ndev)) {
 		np_err(np, "%s is a slave device, aborting\n", np->dev_name);
 		err = -EBUSY;
diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index b0571ab4e5a7..f77e9eeb1a62 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -68,8 +68,11 @@ static int dsa_slave_open(struct net_device *dev)
 	struct dsa_port *dp = dsa_slave_to_port(dev);
 	int err;
 
-	if (!(master->flags & IFF_UP))
-		return -ENETDOWN;
+	err = dev_open(master, NULL);
+	if (err < 0) {
+		netdev_err(dev, "failed to open master %s\n", master->name);
+		goto out;
+	}
 
 	if (!ether_addr_equal(dev->dev_addr, master->dev_addr)) {
 		err = dev_uc_add(master, dev->dev_addr);
@@ -2078,6 +2081,30 @@ static int dsa_slave_netdevice_event(struct notifier_block *nb,
 		err = dsa_port_lag_change(dp, info->lower_state_info);
 		return notifier_from_errno(err);
 	}
+	case NETDEV_GOING_DOWN: {
+		struct dsa_port *dp, *cpu_dp;
+		struct dsa_switch_tree *dst;
+		LIST_HEAD(close_list);
+
+		if (!netdev_uses_dsa(dev))
+			return NOTIFY_DONE;
+
+		cpu_dp = dev->dsa_ptr;
+		dst = cpu_dp->ds->dst;
+
+		list_for_each_entry(dp, &dst->ports, list) {
+			if (!dsa_is_user_port(dp->ds, dp->index))
+				continue;
+
+			list_add(&dp->slave->close_list, &close_list);
+		}
+
+		dev_close_many(&close_list, true);
+
+		return NOTIFY_OK;
+	}
+	default:
+		break;
 	}
 
 	return NOTIFY_DONE;
diff --git a/net/ipv4/ipconfig.c b/net/ipv4/ipconfig.c
index 3cd13e1bc6a7..f9ab1fb219ec 100644
--- a/net/ipv4/ipconfig.c
+++ b/net/ipv4/ipconfig.c
@@ -61,7 +61,6 @@
 #include <linux/export.h>
 #include <net/net_namespace.h>
 #include <net/arp.h>
-#include <net/dsa.h>
 #include <net/ip.h>
 #include <net/ipconfig.h>
 #include <net/route.h>
@@ -218,9 +217,9 @@ static int __init ic_open_devs(void)
 	last = &ic_first_dev;
 	rtnl_lock();
 
-	/* bring loopback and DSA master network devices up first */
+	/* bring loopback device up first */
 	for_each_netdev(&init_net, dev) {
-		if (!(dev->flags & IFF_LOOPBACK) && !netdev_uses_dsa(dev))
+		if (!(dev->flags & IFF_LOOPBACK))
 			continue;
 		if (dev_change_flags(dev, dev->flags | IFF_UP, NULL) < 0)
 			pr_err("IP-Config: Failed to open %s\n", dev->name);
@@ -305,6 +304,9 @@ have_carrier:
 	return 0;
 }
 
+/* Close all network interfaces except the one we've autoconfigured, and its
+ * lowers, in case it's a stacked virtual interface.
+ */
 static void __init ic_close_devs(void)
 {
 	struct ic_device *d, *next;
@@ -313,9 +315,20 @@ static void __init ic_close_devs(void)
 	rtnl_lock();
 	next = ic_first_dev;
 	while ((d = next)) {
+		bool bring_down = (d != ic_dev);
+		struct net_device *lower_dev;
+		struct list_head *iter;
+
 		next = d->next;
 		dev = d->dev;
-		if (d != ic_dev && !netdev_uses_dsa(dev)) {
+
+		netdev_for_each_lower_dev(ic_dev->dev, lower_dev, iter) {
+			if (dev == lower_dev) {
+				bring_down = false;
+				break;
+			}
+		}
+		if (bring_down) {
 			pr_debug("IP-Config: Downing %s\n", dev->name);
 			dev_change_flags(dev, d->flags, NULL);
 		}