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Commit c6d14c84 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net: Introduce for_each_netdev_rcu() iterator 



Adds RCU management to the list of netdevices.

Convert some for_each_netdev() users to RCU version, if
it can avoid read_lock-ing dev_base_lock

Ie:
	read_lock(&dev_base_loack);
	for_each_netdev(net, dev)
		some_action();
	read_unlock(&dev_base_lock);

becomes :

	rcu_read_lock();
	for_each_netdev_rcu(net, dev)
		some_action();
	rcu_read_unlock();


Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d0075634

include/linux/netdevice.h

+2 −0
Original line number Diff line number Diff line
@@ -1081,6 +1081,8 @@ extern rwlock_t dev_base_lock; /* Device list lock */ 


#define for_each_netdev(net, d)		\

		list_for_each_entry(d, &(net)->dev_base_head, dev_list)

#define for_each_netdev_rcu(net, d)		\

		list_for_each_entry_rcu(d, &(net)->dev_base_head, dev_list)

#define for_each_netdev_safe(net, d, n)	\

		list_for_each_entry_safe(d, n, &(net)->dev_base_head, dev_list)

#define for_each_netdev_continue(net, d)		\

net/core/dev.c

+16 −14
Original line number Diff line number Diff line
@@ -175,7 +175,7 @@ static struct list_head ptype_all __read_mostly; /* Taps */ 
 * The @dev_base_head list is protected by @dev_base_lock and the rtnl

 * semaphore.

 *

 * Pure readers hold dev_base_lock for reading.

 * Pure readers hold dev_base_lock for reading, or rcu_read_lock()

 *

 * Writers must hold the rtnl semaphore while they loop through the

 * dev_base_head list, and hold dev_base_lock for writing when they do the
@@ -212,7 +212,7 @@ static int list_netdevice(struct net_device *dev) 
	ASSERT_RTNL();



	write_lock_bh(&dev_base_lock);

	list_add_tail(&dev->dev_list, &net->dev_base_head);

	list_add_tail_rcu(&dev->dev_list, &net->dev_base_head);

	hlist_add_head_rcu(&dev->name_hlist, dev_name_hash(net, dev->name));

	hlist_add_head_rcu(&dev->index_hlist,

			   dev_index_hash(net, dev->ifindex));
@@ -229,7 +229,7 @@ static void unlist_netdevice(struct net_device *dev) 


	/* Unlink dev from the device chain */

	write_lock_bh(&dev_base_lock);

	list_del(&dev->dev_list);

	list_del_rcu(&dev->dev_list);

	hlist_del_rcu(&dev->name_hlist);

	hlist_del_rcu(&dev->index_hlist);

	write_unlock_bh(&dev_base_lock);
@@ -799,15 +799,15 @@ struct net_device *dev_get_by_flags(struct net *net, unsigned short if_flags, 
	struct net_device *dev, *ret;



	ret = NULL;

	read_lock(&dev_base_lock);

	for_each_netdev(net, dev) {

	rcu_read_lock();

	for_each_netdev_rcu(net, dev) {

		if (((dev->flags ^ if_flags) & mask) == 0) {

			dev_hold(dev);

			ret = dev;

			break;

		}

	}

	read_unlock(&dev_base_lock);

	rcu_read_unlock();

	return ret;

}

EXPORT_SYMBOL(dev_get_by_flags);
@@ -3077,18 +3077,18 @@ static int dev_ifconf(struct net *net, char __user *arg) 
 *	in detail.

 */

void *dev_seq_start(struct seq_file *seq, loff_t *pos)

	__acquires(dev_base_lock)

	__acquires(RCU)

{

	struct net *net = seq_file_net(seq);

	loff_t off;

	struct net_device *dev;



	read_lock(&dev_base_lock);

	rcu_read_lock();

	if (!*pos)

		return SEQ_START_TOKEN;



	off = 1;

	for_each_netdev(net, dev)

	for_each_netdev_rcu(net, dev)

		if (off++ == *pos)

			return dev;
@@ -3097,16 +3097,18 @@ void *dev_seq_start(struct seq_file *seq, loff_t *pos) 


void *dev_seq_next(struct seq_file *seq, void *v, loff_t *pos)

{

	struct net *net = seq_file_net(seq);

	struct net_device *dev = (v == SEQ_START_TOKEN) ?

				  first_net_device(seq_file_net(seq)) :

				  next_net_device((struct net_device *)v);



	++*pos;

	return v == SEQ_START_TOKEN ?

		first_net_device(net) : next_net_device((struct net_device *)v);

	return rcu_dereference(dev);

}



void dev_seq_stop(struct seq_file *seq, void *v)

	__releases(dev_base_lock)

	__releases(RCU)

{

	read_unlock(&dev_base_lock);

	rcu_read_unlock();

}



static void dev_seq_printf_stats(struct seq_file *seq, struct net_device *dev)

net/decnet/af_decnet.c

+3 −3
Original line number Diff line number Diff line
@@ -749,9 +749,9 @@ static int dn_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len) 


	if (!(saddr->sdn_flags & SDF_WILD)) {

		if (le16_to_cpu(saddr->sdn_nodeaddrl)) {

			read_lock(&dev_base_lock);

			rcu_read_lock();

			ldev = NULL;

			for_each_netdev(&init_net, dev) {

			for_each_netdev_rcu(&init_net, dev) {

				if (!dev->dn_ptr)

					continue;

				if (dn_dev_islocal(dev, dn_saddr2dn(saddr))) {
@@ -759,7 +759,7 @@ static int dn_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len) 
					break;

				}

			}

			read_unlock(&dev_base_lock);

			rcu_read_unlock();

			if (ldev == NULL)

				return -EADDRNOTAVAIL;

		}

net/decnet/dn_fib.c

+3 −3
Original line number Diff line number Diff line
@@ -607,8 +607,8 @@ static void dn_fib_del_ifaddr(struct dn_ifaddr *ifa) 
	ASSERT_RTNL();



	/* Scan device list */

	read_lock(&dev_base_lock);

	for_each_netdev(&init_net, dev) {

	rcu_read_lock();

	for_each_netdev_rcu(&init_net, dev) {

		dn_db = dev->dn_ptr;

		if (dn_db == NULL)

			continue;
@@ -619,7 +619,7 @@ static void dn_fib_del_ifaddr(struct dn_ifaddr *ifa) 
			}

		}

	}

	read_unlock(&dev_base_lock);

	rcu_read_unlock();



	if (found_it == 0) {

		fib_magic(RTM_DELROUTE, RTN_LOCAL, ifa->ifa_local, 16, ifa);

net/decnet/dn_route.c

+3 −3
Original line number Diff line number Diff line
@@ -908,8 +908,8 @@ static int dn_route_output_slow(struct dst_entry **pprt, const struct flowi *old 
			dev_put(dev_out);

			goto out;

		}

		read_lock(&dev_base_lock);

		for_each_netdev(&init_net, dev) {

		rcu_read_lock();

		for_each_netdev_rcu(&init_net, dev) {

			if (!dev->dn_ptr)

				continue;

			if (!dn_dev_islocal(dev, oldflp->fld_src))
@@ -922,7 +922,7 @@ static int dn_route_output_slow(struct dst_entry **pprt, const struct flowi *old 
			dev_out = dev;

			break;

		}

		read_unlock(&dev_base_lock);

		rcu_read_unlock();

		if (dev_out == NULL)

			goto out;

		dev_hold(dev_out);