Commit 75ea27d0 authored by Antoine Tenart's avatar Antoine Tenart Committed by David S. Miller
Browse files

net: introduce a function to check if a netdev name is in use 



__dev_get_by_name is currently used to either retrieve a net device
reference using its name or to check if a name is already used by a
registered net device (per ns). In the later case there is no need to
return a reference to a net device.

Introduce a new helper, netdev_name_in_use, to check if a name is
currently used by a registered net device without leaking a reference
the corresponding net device. This helper uses netdev_name_node_lookup
instead of __dev_get_by_name as we don't need the extra logic retrieving
a reference to the corresponding net device.

Signed-off-by: default avatarAntoine Tenart <atenart@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 12e6d7e6

include/linux/netdevice.h

+1 −0
Original line number Diff line number Diff line
@@ -2955,6 +2955,7 @@ struct net_device *__dev_get_by_flags(struct net *net, unsigned short flags, 
struct net_device *dev_get_by_name(struct net *net, const char *name);

struct net_device *dev_get_by_name_rcu(struct net *net, const char *name);

struct net_device *__dev_get_by_name(struct net *net, const char *name);

bool netdev_name_in_use(struct net *net, const char *name);

int dev_alloc_name(struct net_device *dev, const char *name);

int dev_open(struct net_device *dev, struct netlink_ext_ack *extack);

void dev_close(struct net_device *dev);

net/core/dev.c

+10 −4
Original line number Diff line number Diff line
@@ -303,6 +303,12 @@ static struct netdev_name_node *netdev_name_node_lookup_rcu(struct net *net, 
	return NULL;

}



bool netdev_name_in_use(struct net *net, const char *name)

{

	return netdev_name_node_lookup(net, name);

}

EXPORT_SYMBOL(netdev_name_in_use);



int netdev_name_node_alt_create(struct net_device *dev, const char *name)

{

	struct netdev_name_node *name_node;
@@ -1133,7 +1139,7 @@ static int __dev_alloc_name(struct net *net, const char *name, char *buf) 
	}



	snprintf(buf, IFNAMSIZ, name, i);

	if (!__dev_get_by_name(net, buf))

	if (!netdev_name_in_use(net, buf))

		return i;



	/* It is possible to run out of possible slots
@@ -1187,7 +1193,7 @@ static int dev_get_valid_name(struct net *net, struct net_device *dev, 


	if (strchr(name, '%'))

		return dev_alloc_name_ns(net, dev, name);

	else if (__dev_get_by_name(net, name))

	else if (netdev_name_in_use(net, name))

		return -EEXIST;

	else if (dev->name != name)

		strlcpy(dev->name, name, IFNAMSIZ);
@@ -11153,7 +11159,7 @@ int __dev_change_net_namespace(struct net_device *dev, struct net *net, 
	 * we can use it in the destination network namespace.

	 */

	err = -EEXIST;

	if (__dev_get_by_name(net, dev->name)) {

	if (netdev_name_in_use(net, dev->name)) {

		/* We get here if we can't use the current device name */

		if (!pat)

			goto out;
@@ -11506,7 +11512,7 @@ static void __net_exit default_device_exit(struct net *net) 


		/* Push remaining network devices to init_net */

		snprintf(fb_name, IFNAMSIZ, "dev%d", dev->ifindex);

		if (__dev_get_by_name(&init_net, fb_name))

		if (netdev_name_in_use(&init_net, fb_name))

			snprintf(fb_name, IFNAMSIZ, "dev%%d");

		err = dev_change_net_namespace(dev, &init_net, fb_name);

		if (err) {