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net: Add non-RCU dev_getbyhwaddr() helper

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Add dedicated helper for finding devices by hardware address when
holding rtnl_lock, similar to existing dev_getbyhwaddr_rcu(). This prevents
PROVE_LOCKING warnings when rtnl_lock is held but RCU read lock is not.

Extract common address comparison logic into dev_addr_cmp().

The context about this change could be found in the following
discussion:

Link: https://lore.kernel.org/all/20250206-scarlet-ermine-of-improvement-1fcac5@leitao/

Cc: kuniyu@amazon.com
Cc: ushankar@purestorage.com
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250218-arm_fix_selftest-v5-1-d3d6892db9e1@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Breno Leitao 2025-02-18 05:49:30 -08:00 • committed by Jakub Kicinski
parent 606572eb22
commit 4b5a28b38c
2 changed files with 36 additions and 3 deletions
include/linux
netdevice.h
net/core
dev.c

2
include/linux/netdevice.h
View file

@ -3275,6 +3275,8 @@ static inline struct net_device *first_net_device_rcu(struct net *net)
} }
int netdev_boot_setup_check(struct net_device *dev); int netdev_boot_setup_check(struct net_device *dev);
struct net_device *dev_getbyhwaddr(struct net *net, unsigned short type,
const char *hwaddr);
struct net_device *dev_getbyhwaddr_rcu(struct net *net, unsigned short type, struct net_device *dev_getbyhwaddr_rcu(struct net *net, unsigned short type,
const char *hwaddr); const char *hwaddr);
struct net_device *dev_getfirstbyhwtype(struct net *net, unsigned short type); struct net_device *dev_getfirstbyhwtype(struct net *net, unsigned short type);

37
net/core/dev.c
View file

@ -1121,6 +1121,12 @@ out:
return ret; return ret;
} }
static bool dev_addr_cmp(struct net_device *dev, unsigned short type,
const char *ha)
{
return dev->type == type && !memcmp(dev->dev_addr, ha, dev->addr_len);
}
/** /**
* dev_getbyhwaddr_rcu - find a device by its hardware address * dev_getbyhwaddr_rcu - find a device by its hardware address
* @net: the applicable net namespace * @net: the applicable net namespace
@ -1129,7 +1135,7 @@ out:
* *
* Search for an interface by MAC address. Returns NULL if the device * Search for an interface by MAC address. Returns NULL if the device
* is not found or a pointer to the device. * is not found or a pointer to the device.
* The caller must hold RCU or RTNL. * The caller must hold RCU.
* The returned device has not had its ref count increased * The returned device has not had its ref count increased
* and the caller must therefore be careful about locking * and the caller must therefore be careful about locking
* *
@ -1141,14 +1147,39 @@ struct net_device *dev_getbyhwaddr_rcu(struct net *net, unsigned short type,
struct net_device *dev; struct net_device *dev;
for_each_netdev_rcu(net, dev) for_each_netdev_rcu(net, dev)
if (dev->type == type && if (dev_addr_cmp(dev, type, ha))
!memcmp(dev->dev_addr, ha, dev->addr_len))
return dev; return dev;
return NULL; return NULL;
} }
EXPORT_SYMBOL(dev_getbyhwaddr_rcu); EXPORT_SYMBOL(dev_getbyhwaddr_rcu);
/**
* dev_getbyhwaddr() - find a device by its hardware address
* @net: the applicable net namespace
* @type: media type of device
* @ha: hardware address
*
* Similar to dev_getbyhwaddr_rcu(), but the owner needs to hold
* rtnl_lock.
*
* Context: rtnl_lock() must be held.
* Return: pointer to the net_device, or NULL if not found
*/
struct net_device *dev_getbyhwaddr(struct net *net, unsigned short type,
const char *ha)
{
struct net_device *dev;
ASSERT_RTNL();
for_each_netdev(net, dev)
if (dev_addr_cmp(dev, type, ha))
return dev;
return NULL;
}
EXPORT_SYMBOL(dev_getbyhwaddr);
struct net_device *dev_getfirstbyhwtype(struct net *net, unsigned short type) struct net_device *dev_getfirstbyhwtype(struct net *net, unsigned short type)
{ {
struct net_device *dev, *ret = NULL; struct net_device *dev, *ret = NULL;