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Commit b267b179 authored by Eric W. Biederman's avatar Eric W. Biederman Committed by David S. Miller
Browse files

[NET]: Factor out __dev_alloc_name from dev_alloc_name 



When forcibly changing the network namespace of a device
I need something that can generate a name for the device
in the new namespace without overwriting the old name.

__dev_alloc_name provides me that functionality.

Signed-off-by: default avatarEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 881d966b

net/core/dev.c

+35 −13
Original line number Diff line number Diff line
@@ -739,9 +739,10 @@ int dev_valid_name(const char *name) 
}



/**

 *	dev_alloc_name - allocate a name for a device

 *	@dev: device

 *	__dev_alloc_name - allocate a name for a device

 *	@net: network namespace to allocate the device name in

 *	@name: name format string

 *	@buf:  scratch buffer and result name string

 *

 *	Passed a format string - eg "lt%d" it will try and find a suitable

 *	id. It scans list of devices to build up a free map, then chooses
@@ -752,18 +753,13 @@ int dev_valid_name(const char *name) 
 *	Returns the number of the unit assigned or a negative errno code.

 */



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

static int __dev_alloc_name(struct net *net, const char *name, char *buf)

{

	int i = 0;

	char buf[IFNAMSIZ];

	const char *p;

	const int max_netdevices = 8*PAGE_SIZE;

	long *inuse;

	struct net_device *d;

	struct net *net;



	BUG_ON(!dev->nd_net);

	net = dev->nd_net;



	p = strnchr(name, IFNAMSIZ-1, '%');

	if (p) {
@@ -787,7 +783,7 @@ int dev_alloc_name(struct net_device *dev, const char *name) 
				continue;



			/*  avoid cases where sscanf is not exact inverse of printf */

			snprintf(buf, sizeof(buf), name, i);

			snprintf(buf, IFNAMSIZ, name, i);

			if (!strncmp(buf, d->name, IFNAMSIZ))

				set_bit(i, inuse);

		}
@@ -796,11 +792,9 @@ int dev_alloc_name(struct net_device *dev, const char *name) 
		free_page((unsigned long) inuse);

	}



	snprintf(buf, sizeof(buf), name, i);

	if (!__dev_get_by_name(net, buf)) {

		strlcpy(dev->name, buf, IFNAMSIZ);

	snprintf(buf, IFNAMSIZ, name, i);

	if (!__dev_get_by_name(net, buf))

		return i;

	}



	/* It is possible to run out of possible slots

	 * when the name is long and there isn't enough space left
@@ -809,6 +803,34 @@ int dev_alloc_name(struct net_device *dev, const char *name) 
	return -ENFILE;

}



/**

 *	dev_alloc_name - allocate a name for a device

 *	@dev: device

 *	@name: name format string

 *

 *	Passed a format string - eg "lt%d" it will try and find a suitable

 *	id. It scans list of devices to build up a free map, then chooses

 *	the first empty slot. The caller must hold the dev_base or rtnl lock

 *	while allocating the name and adding the device in order to avoid

 *	duplicates.

 *	Limited to bits_per_byte * page size devices (ie 32K on most platforms).

 *	Returns the number of the unit assigned or a negative errno code.

 */



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

{

	char buf[IFNAMSIZ];

	struct net *net;

	int ret;



	BUG_ON(!dev->nd_net);

	net = dev->nd_net;

	ret = __dev_alloc_name(net, name, buf);

	if (ret >= 0)

		strlcpy(dev->name, buf, IFNAMSIZ);

	return ret;

}





/**

 *	dev_change_name - change name of a device