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Commit 941666c2 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net: RCU conversion of dev_getbyhwaddr() and arp_ioctl() 



Le dimanche 05 décembre 2010 à 09:19 +0100, Eric Dumazet a écrit :

> Hmm..
>
> If somebody can explain why RTNL is held in arp_ioctl() (and therefore
> in arp_req_delete()), we might first remove RTNL use in arp_ioctl() so
> that your patch can be applied.
>
> Right now it is not good, because RTNL wont be necessarly held when you
> are going to call arp_invalidate() ?

While doing this analysis, I found a refcount bug in llc, I'll send a
patch for net-2.6

Meanwhile, here is the patch for net-next-2.6

Your patch then can be applied after mine.

Thanks

[PATCH] net: RCU conversion of dev_getbyhwaddr() and arp_ioctl()

dev_getbyhwaddr() was called under RTNL.

Rename it to dev_getbyhwaddr_rcu() and change all its caller to now use
RCU locking instead of RTNL.

Change arp_ioctl() to use RCU instead of RTNL locking.

Note: this fix a dev refcount bug in llc

Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a2d4b65d

include/linux/netdevice.h

+2 −1
Original line number Diff line number Diff line
@@ -1360,7 +1360,8 @@ static inline struct net_device *first_net_device(struct net *net) 


extern int 			netdev_boot_setup_check(struct net_device *dev);

extern unsigned long		netdev_boot_base(const char *prefix, int unit);

extern struct net_device    *dev_getbyhwaddr(struct net *net, unsigned short type, char *hwaddr);

extern struct net_device *dev_getbyhwaddr_rcu(struct net *net, unsigned short type,

					      const char *hwaddr);

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

extern struct net_device *__dev_getfirstbyhwtype(struct net *net, unsigned short type);

extern void		dev_add_pack(struct packet_type *pt);

net/core/dev.c

+7 −10
Original line number Diff line number Diff line
@@ -743,34 +743,31 @@ struct net_device *dev_get_by_index(struct net *net, int ifindex) 
EXPORT_SYMBOL(dev_get_by_index);



/**

 *	dev_getbyhwaddr - find a device by its hardware address

 *	dev_getbyhwaddr_rcu - find a device by its hardware address

 *	@net: the applicable net namespace

 *	@type: media type of device

 *	@ha: hardware address

 *

 *	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 the

 *	rtnl semaphore. The returned device has not had its ref count increased

 *	is not found or a pointer to the device. The caller must hold RCU

 *	The returned device has not had its ref count increased

 *	and the caller must therefore be careful about locking

 *

 *	BUGS:

 *	If the API was consistent this would be __dev_get_by_hwaddr

 */



struct net_device *dev_getbyhwaddr(struct net *net, unsigned short type, char *ha)

struct net_device *dev_getbyhwaddr_rcu(struct net *net, unsigned short type,

				       const char *ha)

{

	struct net_device *dev;



	ASSERT_RTNL();



	for_each_netdev(net, dev)

	for_each_netdev_rcu(net, dev)

		if (dev->type == type &&

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

			return dev;



	return NULL;

}

EXPORT_SYMBOL(dev_getbyhwaddr);

EXPORT_SYMBOL(dev_getbyhwaddr_rcu);



struct net_device *__dev_getfirstbyhwtype(struct net *net, unsigned short type)

{

net/ieee802154/af_ieee802154.c

+3 −3
Original line number Diff line number Diff line
@@ -52,11 +52,11 @@ struct net_device *ieee802154_get_dev(struct net *net, 


	switch (addr->addr_type) {

	case IEEE802154_ADDR_LONG:

		rtnl_lock();

		dev = dev_getbyhwaddr(net, ARPHRD_IEEE802154, addr->hwaddr);

		rcu_read_lock();

		dev = dev_getbyhwaddr_rcu(net, ARPHRD_IEEE802154, addr->hwaddr);

		if (dev)

			dev_hold(dev);

		rtnl_unlock();

		rcu_read_unlock();

		break;

	case IEEE802154_ADDR_SHORT:

		if (addr->pan_id == 0xffff ||

net/ipv4/arp.c

+9 −8
Original line number Diff line number Diff line
@@ -1017,13 +1017,14 @@ static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on) 
		IPV4_DEVCONF_ALL(net, PROXY_ARP) = on;

		return 0;

	}

	if (__in_dev_get_rtnl(dev)) {

		IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on);

	if (__in_dev_get_rcu(dev)) {

		IN_DEV_CONF_SET(__in_dev_get_rcu(dev), PROXY_ARP, on);

		return 0;

	}

	return -ENXIO;

}



/* must be called with rcu_read_lock() */

static int arp_req_set_public(struct net *net, struct arpreq *r,

		struct net_device *dev)

{
@@ -1033,7 +1034,7 @@ static int arp_req_set_public(struct net *net, struct arpreq *r, 
	if (mask && mask != htonl(0xFFFFFFFF))

		return -EINVAL;

	if (!dev && (r->arp_flags & ATF_COM)) {

		dev = dev_getbyhwaddr(net, r->arp_ha.sa_family,

		dev = dev_getbyhwaddr_rcu(net, r->arp_ha.sa_family,

				      r->arp_ha.sa_data);

		if (!dev)

			return -ENODEV;
@@ -1225,10 +1226,10 @@ int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg) 
	if (!(r.arp_flags & ATF_NETMASK))

		((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr =

							   htonl(0xFFFFFFFFUL);

	rtnl_lock();

	rcu_read_lock();

	if (r.arp_dev[0]) {

		err = -ENODEV;

		dev = __dev_get_by_name(net, r.arp_dev);

		dev = dev_get_by_name_rcu(net, r.arp_dev);

		if (dev == NULL)

			goto out;
@@ -1252,12 +1253,12 @@ int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg) 
		break;

	case SIOCGARP:

		err = arp_req_get(&r, dev);

		if (!err && copy_to_user(arg, &r, sizeof(r)))

			err = -EFAULT;

		break;

	}

out:

	rtnl_unlock();

	rcu_read_unlock();

	if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r)))

		err = -EFAULT;

	return err;

}

net/llc/af_llc.c

+6 −5
Original line number Diff line number Diff line
@@ -316,9 +316,9 @@ static int llc_ui_bind(struct socket *sock, struct sockaddr *uaddr, int addrlen) 
	if (unlikely(addr->sllc_family != AF_LLC))

		goto out;

	rc = -ENODEV;

	rtnl_lock();

	rcu_read_lock();

	if (sk->sk_bound_dev_if) {

		llc->dev = dev_get_by_index(&init_net, sk->sk_bound_dev_if);

		llc->dev = dev_get_by_index_rcu(&init_net, sk->sk_bound_dev_if);

		if (llc->dev) {

			if (!addr->sllc_arphrd)

				addr->sllc_arphrd = llc->dev->type;
@@ -329,14 +329,15 @@ static int llc_ui_bind(struct socket *sock, struct sockaddr *uaddr, int addrlen) 
			    !llc_mac_match(addr->sllc_mac,

					   llc->dev->dev_addr)) {

				rc = -EINVAL;

				dev_put(llc->dev);

				llc->dev = NULL;

			}

		}

	} else

		llc->dev = dev_getbyhwaddr(&init_net, addr->sllc_arphrd,

		llc->dev = dev_getbyhwaddr_rcu(&init_net, addr->sllc_arphrd,

					   addr->sllc_mac);

	rtnl_unlock();

	if (llc->dev)

		dev_hold(llc->dev);

	rcu_read_unlock();

	if (!llc->dev)

		goto out;

	if (!addr->sllc_sap) {