Commit 4b5a28b3 authored by Breno Leitao's avatar Breno Leitao Committed by Jakub Kicinski
Browse files

net: Add non-RCU dev_getbyhwaddr() helper 

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: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarBreno Leitao <leitao@debian.org>
Reviewed-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250218-arm_fix_selftest-v5-1-d3d6892db9e1@debian.org


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 606572eb

include/linux/netdevice.h

+2 −0
Original line number Diff line number Diff line
@@ -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);

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,

				       const char *hwaddr);

struct net_device *dev_getfirstbyhwtype(struct net *net, unsigned short type);

net/core/dev.c

+34 −3
Original line number Diff line number Diff line
@@ -1121,6 +1121,12 @@ int netdev_get_name(struct net *net, char *name, int ifindex) 
	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

 *	@net: the applicable net namespace
@@ -1129,7 +1135,7 @@ int netdev_get_name(struct net *net, char *name, int ifindex) 
 *

 *	Search for an interface by MAC address. Returns NULL if 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

 *	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;



	for_each_netdev_rcu(net, dev)

		if (dev->type == type &&

		    !memcmp(dev->dev_addr, ha, dev->addr_len))

		if (dev_addr_cmp(dev, type, ha))

			return dev;



	return NULL;

}

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, *ret = NULL;