From b267b179648e46ea8e2a44f7314a23eb6aee1d6c Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Wed, 12 Sep 2007 13:48:45 +0200 Subject: [PATCH] [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: Eric W. Biederman Signed-off-by: David S. Miller --- net/core/dev.c | 48 +++++++++++++++++++++++++++++++++++------------- 1 file changed, 35 insertions(+), 13 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index 3a3d5ee73909..520ef7b20862 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -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 -- 2.39.2