Commit 7e4d784f authored by Stanislav Fomichev's avatar Stanislav Fomichev Committed by Jakub Kicinski
Browse files

net: hold netdev instance lock during rtnetlink operations 



To preserve the atomicity, hold the lock while applying multiple
attributes. The major issue with a full conversion to the instance
lock are software nesting devices (bonding/team/vrf/etc). Those
devices call into the core stack for their lower (potentially
real hw) devices. To avoid explicitly wrapping all those places
into instance lock/unlock, introduce new API boundaries:

- (some) existing dev_xxx calls are now considered "external"
  (to drivers) APIs and they transparently grab the instance
  lock if needed (dev_api.c)
- new netif_xxx calls are internal core stack API (naming is
  sketchy, I've tried netdev_xxx_locked per Jakub's suggestion,
  but it feels a bit verbose; but happy to get back to this
  naming scheme if this is the preference)

This avoids touching most of the existing ioctl/sysfs/drivers paths.

Note the special handling of ndo_xxx_slave operations: I exploit
the fact that none of the drivers that call these functions
need/use instance lock. At the same time, they use dev_xxx
APIs, so the lower device has to be unlocked.

Changes in unregister_netdevice_many_notify (to protect dev->state
with instance lock) trigger lockdep - the loop over close_list
(mostly from cleanup_net) introduces spurious ordering issues.
netdev_lock_cmp_fn has a justification on why it's ok to suppress
for now.

Cc: Saeed Mahameed <saeed@kernel.org>
Signed-off-by: default avatarStanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250305163732.2766420-7-sdf@fomichev.me


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent cae03e5b

include/linux/netdevice.h

+34 −6
Original line number Diff line number Diff line
@@ -2620,16 +2620,35 @@ static inline void netdev_for_each_tx_queue(struct net_device *dev, 
		f(dev, &dev->_tx[i], arg);

}



static inline int netdev_lock_cmp_fn(const struct lockdep_map *a,

				     const struct lockdep_map *b)

{

	/* Only lower devices currently grab the instance lock, so no

	 * real ordering issues can occur. In the near future, only

	 * hardware devices will grab instance lock which also does not

	 * involve any ordering. Suppress lockdep ordering warnings

	 * until (if) we start grabbing instance lock on pure SW

	 * devices (bond/team/veth/etc).

	 */

	if (a == b)

		return 0;

	return -1;

}



#define netdev_lockdep_set_classes(dev)				\

{								\

	static struct lock_class_key qdisc_tx_busylock_key;	\

	static struct lock_class_key qdisc_xmit_lock_key;	\

	static struct lock_class_key dev_addr_list_lock_key;	\

	static struct lock_class_key dev_instance_lock_key;	\

	unsigned int i;						\

								\

	(dev)->qdisc_tx_busylock = &qdisc_tx_busylock_key;	\

	lockdep_set_class(&(dev)->addr_list_lock,		\

			  &dev_addr_list_lock_key);		\

	lockdep_set_class(&(dev)->lock,				\

			  &dev_instance_lock_key);		\

	lock_set_cmp_fn(&dev->lock, netdev_lock_cmp_fn, NULL);	\

	for (i = 0; i < (dev)->num_tx_queues; i++)		\

		lockdep_set_class(&(dev)->_tx[i]._xmit_lock,	\

				  &qdisc_xmit_lock_key);	\
@@ -2776,6 +2795,12 @@ static inline void netdev_unlock_ops(struct net_device *dev) 
		netdev_unlock(dev);

}



static inline void netdev_ops_assert_locked(struct net_device *dev)

{

	if (netdev_need_ops_lock(dev))

		lockdep_assert_held(&dev->lock);

}



void netif_napi_set_irq_locked(struct napi_struct *napi, int irq);



static inline void netif_napi_set_irq(struct napi_struct *napi, int irq)
@@ -3350,7 +3375,9 @@ 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 netif_open(struct net_device *dev, struct netlink_ext_ack *extack);

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

void netif_close(struct net_device *dev);

void dev_close(struct net_device *dev);

void dev_close_many(struct list_head *head, bool unlink);

int dev_setup_tc(struct net_device *dev, enum tc_setup_type type,
@@ -4211,25 +4238,26 @@ int dev_ethtool(struct net *net, struct ifreq *ifr, void __user *userdata); 
unsigned int dev_get_flags(const struct net_device *);

int __dev_change_flags(struct net_device *dev, unsigned int flags,

		       struct netlink_ext_ack *extack);

int netif_change_flags(struct net_device *dev, unsigned int flags,

		       struct netlink_ext_ack *extack);

int dev_change_flags(struct net_device *dev, unsigned int flags,

		     struct netlink_ext_ack *extack);

int netif_set_alias(struct net_device *dev, const char *alias, size_t len);

int dev_set_alias(struct net_device *, const char *, size_t);

int dev_get_alias(const struct net_device *, char *, size_t);

int __dev_change_net_namespace(struct net_device *dev, struct net *net,

int netif_change_net_namespace(struct net_device *dev, struct net *net,

			       const char *pat, int new_ifindex,

			       struct netlink_ext_ack *extack);

static inline

int dev_change_net_namespace(struct net_device *dev, struct net *net,

			     const char *pat)

{

	return __dev_change_net_namespace(dev, net, pat, 0, NULL);

}

			     const char *pat);

int __dev_set_mtu(struct net_device *, int);

int dev_set_mtu(struct net_device *, int);

int dev_pre_changeaddr_notify(struct net_device *dev, const char *addr,

			      struct netlink_ext_ack *extack);

int dev_set_mac_address(struct net_device *dev, struct sockaddr *sa,

			struct netlink_ext_ack *extack);

int netif_set_mac_address_user(struct net_device *dev, struct sockaddr *sa,

			       struct netlink_ext_ack *extack);

int dev_set_mac_address_user(struct net_device *dev, struct sockaddr *sa,

			     struct netlink_ext_ack *extack);

int dev_get_mac_address(struct sockaddr *sa, struct net *net, char *dev_name);

net/core/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -9,7 +9,7 @@ obj-y := sock.o request_sock.o skbuff.o datagram.o stream.o scm.o \ 


obj-$(CONFIG_SYSCTL) += sysctl_net_core.o



obj-y		     += dev.o dev_addr_lists.o dst.o netevent.o \

obj-y		     += dev.o dev_api.o dev_addr_lists.o dst.o netevent.o \

			neighbour.o rtnetlink.o utils.o link_watch.o filter.o \

			sock_diag.o dev_ioctl.o tso.o sock_reuseport.o \

			fib_notifier.o xdp.o flow_offload.o gro.o \

net/core/dev.c

+29 −125
Original line number Diff line number Diff line
@@ -1371,15 +1371,7 @@ static int dev_get_valid_name(struct net *net, struct net_device *dev, 
	return ret < 0 ? ret : 0;

}



/**

 *	dev_change_name - change name of a device

 *	@dev: device

 *	@newname: name (or format string) must be at least IFNAMSIZ

 *

 *	Change name of a device, can pass format strings "eth%d".

 *	for wildcarding.

 */

int dev_change_name(struct net_device *dev, const char *newname)

int netif_change_name(struct net_device *dev, const char *newname)

{

	struct net *net = dev_net(dev);

	unsigned char old_assign_type;
@@ -1449,15 +1441,7 @@ int dev_change_name(struct net_device *dev, const char *newname) 
	return err;

}



/**

 *	dev_set_alias - change ifalias of a device

 *	@dev: device

 *	@alias: name up to IFALIASZ

 *	@len: limit of bytes to copy from info

 *

 *	Set ifalias for a device,

 */

int dev_set_alias(struct net_device *dev, const char *alias, size_t len)

int netif_set_alias(struct net_device *dev, const char *alias, size_t len)

{

	struct dev_ifalias *new_alias = NULL;
@@ -1483,7 +1467,6 @@ int dev_set_alias(struct net_device *dev, const char *alias, size_t len) 


	return len;

}

EXPORT_SYMBOL(dev_set_alias);



/**

 *	dev_get_alias - get ifalias of a device
@@ -1627,10 +1610,10 @@ static int __dev_open(struct net_device *dev, struct netlink_ext_ack *extack) 
	if (ret)

		return ret;



	netdev_lock_ops(dev);



	set_bit(__LINK_STATE_START, &dev->state);



	netdev_ops_assert_locked(dev);



	if (ops->ndo_validate_addr)

		ret = ops->ndo_validate_addr(dev);
@@ -1648,25 +1631,10 @@ static int __dev_open(struct net_device *dev, struct netlink_ext_ack *extack) 
		add_device_randomness(dev->dev_addr, dev->addr_len);

	}



	netdev_unlock_ops(dev);



	return ret;

}



/**

 *	dev_open	- prepare an interface for use.

 *	@dev: device to open

 *	@extack: netlink extended ack

 *

 *	Takes a device from down to up state. The device's private open

 *	function is invoked and then the multicast lists are loaded. Finally

 *	the device is moved into the up state and a %NETDEV_UP message is

 *	sent to the netdev notifier chain.

 *

 *	Calling this function on an active interface is a nop. On a failure

 *	a negative errno code is returned.

 */

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

int netif_open(struct net_device *dev, struct netlink_ext_ack *extack)

{

	int ret;
@@ -1682,7 +1650,6 @@ int dev_open(struct net_device *dev, struct netlink_ext_ack *extack) 


	return ret;

}

EXPORT_SYMBOL(dev_open);



static void __dev_close_many(struct list_head *head)

{
@@ -1721,18 +1688,13 @@ static void __dev_close_many(struct list_head *head) 
		 *	event.

		 */



		/* TODO: move the lock up before clearing __LINK_STATE_START.

		 * Generates spurious lockdep warning.

		 */

		netdev_lock_ops(dev);

		netdev_ops_assert_locked(dev);



		if (ops->ndo_stop)

			ops->ndo_stop(dev);



		netif_set_up(dev, false);

		netpoll_poll_enable(dev);



		netdev_unlock_ops(dev);

	}

}
@@ -1765,16 +1727,7 @@ void dev_close_many(struct list_head *head, bool unlink) 
}

EXPORT_SYMBOL(dev_close_many);



/**

 *	dev_close - shutdown an interface.

 *	@dev: device to shutdown

 *

 *	This function moves an active device into down state. A

 *	%NETDEV_GOING_DOWN is sent to the netdev notifier chain. The device

 *	is then deactivated and finally a %NETDEV_DOWN is sent to the notifier

 *	chain.

 */

void dev_close(struct net_device *dev)

void netif_close(struct net_device *dev)

{

	if (dev->flags & IFF_UP) {

		LIST_HEAD(single);
@@ -1784,7 +1737,6 @@ void dev_close(struct net_device *dev) 
		list_del(&single);

	}

}

EXPORT_SYMBOL(dev_close);



int dev_setup_tc(struct net_device *dev, enum tc_setup_type type,

		 void *type_data)
@@ -9479,16 +9431,7 @@ void __dev_notify_flags(struct net_device *dev, unsigned int old_flags, 
	}

}



/**

 *	dev_change_flags - change device settings

 *	@dev: device

 *	@flags: device state flags

 *	@extack: netlink extended ack

 *

 *	Change settings on device based state flags. The flags are

 *	in the userspace exported format.

 */

int dev_change_flags(struct net_device *dev, unsigned int flags,

int netif_change_flags(struct net_device *dev, unsigned int flags,

		       struct netlink_ext_ack *extack)

{

	int ret;
@@ -9502,7 +9445,6 @@ int dev_change_flags(struct net_device *dev, unsigned int flags, 
	__dev_notify_flags(dev, old_flags, changes, 0, NULL);

	return ret;

}

EXPORT_SYMBOL(dev_change_flags);



int __dev_set_mtu(struct net_device *dev, int new_mtu)

{
@@ -9534,14 +9476,14 @@ int dev_validate_mtu(struct net_device *dev, int new_mtu, 
}



/**

 *	dev_set_mtu_ext - Change maximum transfer unit

 *	netif_set_mtu_ext - Change maximum transfer unit

 *	@dev: device

 *	@new_mtu: new transfer unit

 *	@extack: netlink extended ack

 *

 *	Change the maximum transfer size of the network device.

 */

int dev_set_mtu_ext(struct net_device *dev, int new_mtu,

int netif_set_mtu_ext(struct net_device *dev, int new_mtu,

		      struct netlink_ext_ack *extack)

{

	int err, orig_mtu;
@@ -9586,19 +9528,14 @@ int dev_set_mtu(struct net_device *dev, int new_mtu) 
	int err;



	memset(&extack, 0, sizeof(extack));

	err = dev_set_mtu_ext(dev, new_mtu, &extack);

	err = netif_set_mtu_ext(dev, new_mtu, &extack);

	if (err && extack._msg)

		net_err_ratelimited("%s: %s\n", dev->name, extack._msg);

	return err;

}

EXPORT_SYMBOL(dev_set_mtu);



/**

 *	dev_change_tx_queue_len - Change TX queue length of a netdevice

 *	@dev: device

 *	@new_len: new tx queue length

 */

int dev_change_tx_queue_len(struct net_device *dev, unsigned long new_len)

int netif_change_tx_queue_len(struct net_device *dev, unsigned long new_len)

{

	unsigned int orig_len = dev->tx_queue_len;

	int res;
@@ -9625,12 +9562,7 @@ int dev_change_tx_queue_len(struct net_device *dev, unsigned long new_len) 
	return res;

}



/**

 *	dev_set_group - Change group this device belongs to

 *	@dev: device

 *	@new_group: group this device should belong to

 */

void dev_set_group(struct net_device *dev, int new_group)

void netif_set_group(struct net_device *dev, int new_group)

{

	dev->group = new_group;

}
@@ -9693,7 +9625,7 @@ EXPORT_SYMBOL(dev_set_mac_address); 


DECLARE_RWSEM(dev_addr_sem);



int dev_set_mac_address_user(struct net_device *dev, struct sockaddr *sa,

int netif_set_mac_address_user(struct net_device *dev, struct sockaddr *sa,

			       struct netlink_ext_ack *extack)

{

	int ret;
@@ -9703,7 +9635,6 @@ int dev_set_mac_address_user(struct net_device *dev, struct sockaddr *sa, 
	up_write(&dev_addr_sem);

	return ret;

}

EXPORT_SYMBOL(dev_set_mac_address_user);



int dev_get_mac_address(struct sockaddr *sa, struct net *net, char *dev_name)

{
@@ -9733,14 +9664,7 @@ int dev_get_mac_address(struct sockaddr *sa, struct net *net, char *dev_name) 
}

EXPORT_SYMBOL(dev_get_mac_address);



/**

 *	dev_change_carrier - Change device carrier

 *	@dev: device

 *	@new_carrier: new value

 *

 *	Change device carrier

 */

int dev_change_carrier(struct net_device *dev, bool new_carrier)

int netif_change_carrier(struct net_device *dev, bool new_carrier)

{

	const struct net_device_ops *ops = dev->netdev_ops;
@@ -9851,13 +9775,7 @@ bool netdev_port_same_parent_id(struct net_device *a, struct net_device *b) 
}

EXPORT_SYMBOL(netdev_port_same_parent_id);



/**

 *	dev_change_proto_down - set carrier according to proto_down.

 *

 *	@dev: device

 *	@proto_down: new value

 */

int dev_change_proto_down(struct net_device *dev, bool proto_down)

int netif_change_proto_down(struct net_device *dev, bool proto_down)

{

	if (!dev->change_proto_down)

		return -EOPNOTSUPP;
@@ -9872,14 +9790,14 @@ int dev_change_proto_down(struct net_device *dev, bool proto_down) 
}



/**

 *	dev_change_proto_down_reason - proto down reason

 *	netdev_change_proto_down_reason_locked - proto down reason

 *

 *	@dev: device

 *	@mask: proto down mask

 *	@value: proto down value

 */

void dev_change_proto_down_reason(struct net_device *dev, unsigned long mask,

				  u32 value)

void netdev_change_proto_down_reason_locked(struct net_device *dev,

					    unsigned long mask, u32 value)

{

	u32 proto_down_reason;

	int b;
@@ -10687,6 +10605,7 @@ int __netdev_update_features(struct net_device *dev) 
	int err = -1;



	ASSERT_RTNL();

	netdev_ops_assert_locked(dev);



	features = netdev_get_wanted_features(dev);
@@ -12036,11 +11955,14 @@ void unregister_netdevice_many_notify(struct list_head *head, 
	}



	/* If device is running, close it first. */

	list_for_each_entry(dev, head, unreg_list)

	list_for_each_entry(dev, head, unreg_list) {

		list_add_tail(&dev->close_list, &close_head);

		netdev_lock_ops(dev);

	}

	dev_close_many(&close_head, true);



	list_for_each_entry(dev, head, unreg_list) {

		netdev_unlock_ops(dev);

		/* And unlink it from device chain. */

		unlist_netdevice(dev);

		netdev_lock(dev);
@@ -12153,24 +12075,7 @@ void unregister_netdev(struct net_device *dev) 
}

EXPORT_SYMBOL(unregister_netdev);



/**

 *	__dev_change_net_namespace - move device to different nethost namespace

 *	@dev: device

 *	@net: network namespace

 *	@pat: If not NULL name pattern to try if the current device name

 *	      is already taken in the destination network namespace.

 *	@new_ifindex: If not zero, specifies device index in the target

 *	              namespace.

 *	@extack: netlink extended ack

 *

 *	This function shuts down a device interface and moves it

 *	to a new network namespace. On success 0 is returned, on

 *	a failure a netagive errno code is returned.

 *

 *	Callers must hold the rtnl semaphore.

 */



int __dev_change_net_namespace(struct net_device *dev, struct net *net,

int netif_change_net_namespace(struct net_device *dev, struct net *net,

			       const char *pat, int new_ifindex,

			       struct netlink_ext_ack *extack)

{
@@ -12256,7 +12161,7 @@ int __dev_change_net_namespace(struct net_device *dev, struct net *net, 
	 */



	/* If device is running close it first. */

	dev_close(dev);

	netif_close(dev);



	/* And unlink it from device chain */

	unlist_netdevice(dev);
@@ -12338,7 +12243,6 @@ int __dev_change_net_namespace(struct net_device *dev, struct net *net, 
out:

	return err;

}

EXPORT_SYMBOL_GPL(__dev_change_net_namespace);



static int dev_cpu_dead(unsigned int oldcpu)

{

net/core/dev.h

+9 −4
Original line number Diff line number Diff line
@@ -85,6 +85,7 @@ struct netdev_name_node { 
};



int netdev_get_name(struct net *net, char *name, int ifindex);

int netif_change_name(struct net_device *dev, const char *newname);

int dev_change_name(struct net_device *dev, const char *newname);



#define netdev_for_each_altname(dev, namenode)				\
@@ -98,7 +99,7 @@ int netdev_name_node_alt_destroy(struct net_device *dev, const char *name); 


int dev_validate_mtu(struct net_device *dev, int mtu,

		     struct netlink_ext_ack *extack);

int dev_set_mtu_ext(struct net_device *dev, int mtu,

int netif_set_mtu_ext(struct net_device *dev, int new_mtu,

		      struct netlink_ext_ack *extack);



int dev_get_phys_port_id(struct net_device *dev,
@@ -106,16 +107,20 @@ int dev_get_phys_port_id(struct net_device *dev, 
int dev_get_phys_port_name(struct net_device *dev,

			   char *name, size_t len);



int netif_change_proto_down(struct net_device *dev, bool proto_down);

int dev_change_proto_down(struct net_device *dev, bool proto_down);

void dev_change_proto_down_reason(struct net_device *dev, unsigned long mask,

				  u32 value);

void netdev_change_proto_down_reason_locked(struct net_device *dev,

					    unsigned long mask, u32 value);



typedef int (*bpf_op_t)(struct net_device *dev, struct netdev_bpf *bpf);

int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,

		      int fd, int expected_fd, u32 flags);



int netif_change_tx_queue_len(struct net_device *dev, unsigned long new_len);

int dev_change_tx_queue_len(struct net_device *dev, unsigned long new_len);

void netif_set_group(struct net_device *dev, int new_group);

void dev_set_group(struct net_device *dev, int new_group);

int netif_change_carrier(struct net_device *dev, bool new_carrier);

int dev_change_carrier(struct net_device *dev, bool new_carrier);



void __dev_set_rx_mode(struct net_device *dev);

net/core/dev_api.c

0 → 100644
+224 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-or-later

#include <linux/netdevice.h>



#include "dev.h"



/**

 * dev_change_name() - change name of a device

 * @dev: device

 * @newname: name (or format string) must be at least IFNAMSIZ

 *

 * Change name of a device, can pass format strings "eth%d".

 * for wildcarding.

 *

 * Return: 0 on success, -errno on failure.

 */

int dev_change_name(struct net_device *dev, const char *newname)

{

	int ret;



	netdev_lock_ops(dev);

	ret = netif_change_name(dev, newname);

	netdev_unlock_ops(dev);



	return ret;

}



/**

 * dev_set_alias() - change ifalias of a device

 * @dev: device

 * @alias: name up to IFALIASZ

 * @len: limit of bytes to copy from info

 *

 * Set ifalias for a device.

 *

 * Return: 0 on success, -errno on failure.

 */

int dev_set_alias(struct net_device *dev, const char *alias, size_t len)

{

	int ret;



	netdev_lock_ops(dev);

	ret = netif_set_alias(dev, alias, len);

	netdev_unlock_ops(dev);



	return ret;

}

EXPORT_SYMBOL(dev_set_alias);



/**

 * dev_change_flags() - change device settings

 * @dev: device

 * @flags: device state flags

 * @extack: netlink extended ack

 *

 * Change settings on device based state flags. The flags are

 * in the userspace exported format.

 *

 * Return: 0 on success, -errno on failure.

 */

int dev_change_flags(struct net_device *dev, unsigned int flags,

		     struct netlink_ext_ack *extack)

{

	int ret;



	netdev_lock_ops(dev);

	ret = netif_change_flags(dev, flags, extack);

	netdev_unlock_ops(dev);



	return ret;

}

EXPORT_SYMBOL(dev_change_flags);



/**

 * dev_set_group() - change group this device belongs to

 * @dev: device

 * @new_group: group this device should belong to

 */

void dev_set_group(struct net_device *dev, int new_group)

{

	netdev_lock_ops(dev);

	netif_set_group(dev, new_group);

	netdev_unlock_ops(dev);

}



int dev_set_mac_address_user(struct net_device *dev, struct sockaddr *sa,

			     struct netlink_ext_ack *extack)

{

	int ret;



	netdev_lock_ops(dev);

	ret = netif_set_mac_address_user(dev, sa, extack);

	netdev_unlock_ops(dev);



	return ret;

}

EXPORT_SYMBOL(dev_set_mac_address_user);



/**

 * dev_change_net_namespace() - move device to different nethost namespace

 * @dev: device

 * @net: network namespace

 * @pat: If not NULL name pattern to try if the current device name

 *       is already taken in the destination network namespace.

 *

 * This function shuts down a device interface and moves it

 * to a new network namespace. On success 0 is returned, on

 * a failure a netagive errno code is returned.

 *

 * Callers must hold the rtnl semaphore.

 *

 * Return: 0 on success, -errno on failure.

 */

int dev_change_net_namespace(struct net_device *dev, struct net *net,

			     const char *pat)

{

	int ret;



	netdev_lock_ops(dev);

	ret = netif_change_net_namespace(dev, net, pat, 0, NULL);

	netdev_unlock_ops(dev);



	return ret;

}

EXPORT_SYMBOL_GPL(dev_change_net_namespace);



/**

 * dev_change_carrier() - change device carrier

 * @dev: device

 * @new_carrier: new value

 *

 * Change device carrier

 *

 * Return: 0 on success, -errno on failure.

 */

int dev_change_carrier(struct net_device *dev, bool new_carrier)

{

	int ret;



	netdev_lock_ops(dev);

	ret = netif_change_carrier(dev, new_carrier);

	netdev_unlock_ops(dev);



	return ret;

}



/**

 * dev_change_tx_queue_len() - change TX queue length of a netdevice

 * @dev: device

 * @new_len: new tx queue length

 *

 * Return: 0 on success, -errno on failure.

 */

int dev_change_tx_queue_len(struct net_device *dev, unsigned long new_len)

{

	int ret;



	netdev_lock_ops(dev);

	ret = netif_change_tx_queue_len(dev, new_len);

	netdev_unlock_ops(dev);



	return ret;

}



/**

 * dev_change_proto_down() - set carrier according to proto_down

 * @dev: device

 * @proto_down: new value

 *

 * Return: 0 on success, -errno on failure.

 */

int dev_change_proto_down(struct net_device *dev, bool proto_down)

{

	int ret;



	netdev_lock_ops(dev);

	ret = netif_change_proto_down(dev, proto_down);

	netdev_unlock_ops(dev);



	return ret;

}



/**

 * dev_open() - prepare an interface for use

 * @dev: device to open

 * @extack: netlink extended ack

 *

 * Takes a device from down to up state. The device's private open

 * function is invoked and then the multicast lists are loaded. Finally

 * the device is moved into the up state and a %NETDEV_UP message is

 * sent to the netdev notifier chain.

 *

 * Calling this function on an active interface is a nop. On a failure

 * a negative errno code is returned.

 *

 * Return: 0 on success, -errno on failure.

 */

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

{

	int ret;



	netdev_lock_ops(dev);

	ret = netif_open(dev, extack);

	netdev_unlock_ops(dev);



	return ret;

}

EXPORT_SYMBOL(dev_open);



/**

 * dev_close() - shutdown an interface

 * @dev: device to shutdown

 *

 * This function moves an active device into down state. A

 * %NETDEV_GOING_DOWN is sent to the netdev notifier chain. The device

 * is then deactivated and finally a %NETDEV_DOWN is sent to the notifier

 * chain.

 */

void dev_close(struct net_device *dev)

{

	netdev_lock_ops(dev);

	netif_close(dev);

	netdev_unlock_ops(dev);

}

EXPORT_SYMBOL(dev_close);