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Commit f3d9832e authored by David Ahern's avatar David Ahern Committed by David S. Miller
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ipv6: addrconf: cleanup locking in ipv6_add_addr 



ipv6_add_addr is called in process context with rtnl lock held
(e.g., manual config of an address) or during softirq processing
(e.g., autoconf and address from a router advertisement).

Currently, ipv6_add_addr calls rcu_read_lock_bh shortly after entry
and does not call unlock until exit, minus the call around the address
validator notifier. Similarly, addrconf_hash_lock is taken after the
validator notifier and held until exit. This forces the allocation of
inet6_ifaddr to always be atomic.

Refactor ipv6_add_addr as follows:
1. add an input boolean to discriminate the call path (process context
   or softirq). This new flag controls whether the alloc can be done
   with GFP_KERNEL or GFP_ATOMIC.

2. Move the rcu_read_lock_bh and unlock calls only around functions that
   do rcu updates.

3. Remove the in6_dev_hold and put added by 3ad7d246 ("Ipvlan should
   return an error when an address is already in use."). This was done
   presumably because rcu_read_unlock_bh needs to be called before calling
   the validator. Since rcu_read_lock is not needed before the validator
   runs revert the hold and put added by 3ad7d246 and only do the
   hold when setting ifp->idev.

4. move duplicate address check and insertion of new address in the global
   address hash into a helper. The helper is called after an ifa is
   allocated and filled in.

This allows the ifa for manually configured addresses to be done with
GFP_KERNEL and reduces the overall amount of time with rcu_read_lock held
and hash table spinlock held.

Signed-off-by: default avatarDavid Ahern <dsahern@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 6b1f8eda

net/ipv6/addrconf.c

+60 −44
Original line number Diff line number Diff line
@@ -957,18 +957,43 @@ static u32 inet6_addr_hash(const struct in6_addr *addr) 
	return hash_32(ipv6_addr_hash(addr), IN6_ADDR_HSIZE_SHIFT);

}



static int ipv6_add_addr_hash(struct net_device *dev, struct inet6_ifaddr *ifa)

{

	unsigned int hash;

	int err = 0;



	spin_lock(&addrconf_hash_lock);



	/* Ignore adding duplicate addresses on an interface */

	if (ipv6_chk_same_addr(dev_net(dev), &ifa->addr, dev)) {

		ADBG("ipv6_add_addr: already assigned\n");

		err = -EEXIST;

		goto out;

	}



	/* Add to big hash table */

	hash = inet6_addr_hash(&ifa->addr);

	hlist_add_head_rcu(&ifa->addr_lst, &inet6_addr_lst[hash]);



out:

	spin_unlock(&addrconf_hash_lock);



	return err;

}



/* On success it returns ifp with increased reference count */



static struct inet6_ifaddr *

ipv6_add_addr(struct inet6_dev *idev, const struct in6_addr *addr,

	      const struct in6_addr *peer_addr, int pfxlen,

	      int scope, u32 flags, u32 valid_lft, u32 prefered_lft)

	      int scope, u32 flags, u32 valid_lft, u32 prefered_lft,

	      bool can_block)

{

	gfp_t gfp_flags = can_block ? GFP_KERNEL : GFP_ATOMIC;

	struct net *net = dev_net(idev->dev);

	struct inet6_ifaddr *ifa = NULL;

	struct rt6_info *rt;

	struct rt6_info *rt = NULL;

	struct in6_validator_info i6vi;

	unsigned int hash;

	int err = 0;

	int addr_type = ipv6_addr_type(addr);
@@ -978,42 +1003,24 @@ ipv6_add_addr(struct inet6_dev *idev, const struct in6_addr *addr, 
	     addr_type & IPV6_ADDR_LOOPBACK))

		return ERR_PTR(-EADDRNOTAVAIL);



	rcu_read_lock_bh();



	in6_dev_hold(idev);



	if (idev->dead) {

		err = -ENODEV;			/*XXX*/

		goto out2;

		goto out;

	}



	if (idev->cnf.disable_ipv6) {

		err = -EACCES;

		goto out2;

		goto out;

	}



	i6vi.i6vi_addr = *addr;

	i6vi.i6vi_dev = idev;

	rcu_read_unlock_bh();



	err = inet6addr_validator_notifier_call_chain(NETDEV_UP, &i6vi);



	rcu_read_lock_bh();

	err = notifier_to_errno(err);

	if (err)

		goto out2;



	spin_lock(&addrconf_hash_lock);



	/* Ignore adding duplicate addresses on an interface */

	if (ipv6_chk_same_addr(dev_net(idev->dev), addr, idev->dev)) {

		ADBG("ipv6_add_addr: already assigned\n");

		err = -EEXIST;

	if (err < 0)

		goto out;

	}



	ifa = kzalloc(sizeof(struct inet6_ifaddr), GFP_ATOMIC);



	ifa = kzalloc(sizeof(*ifa), gfp_flags);

	if (!ifa) {

		ADBG("ipv6_add_addr: malloc failed\n");

		err = -ENOBUFS;
@@ -1023,6 +1030,7 @@ ipv6_add_addr(struct inet6_dev *idev, const struct in6_addr *addr, 
	rt = addrconf_dst_alloc(idev, addr, false);

	if (IS_ERR(rt)) {

		err = PTR_ERR(rt);

		rt = NULL;

		goto out;

	}
@@ -1053,16 +1061,21 @@ ipv6_add_addr(struct inet6_dev *idev, const struct in6_addr *addr, 
	ifa->rt = rt;



	ifa->idev = idev;

	in6_dev_hold(idev);



	/* For caller */

	refcount_set(&ifa->refcnt, 1);



	/* Add to big hash table */

	hash = inet6_addr_hash(addr);

	rcu_read_lock_bh();



	hlist_add_head_rcu(&ifa->addr_lst, &inet6_addr_lst[hash]);

	spin_unlock(&addrconf_hash_lock);

	err = ipv6_add_addr_hash(idev->dev, ifa);

	if (err < 0) {

		rcu_read_unlock_bh();

		goto out;

	}



	write_lock(&idev->lock);



	/* Add to inet6_dev unicast addr list. */

	ipv6_link_dev_addr(idev, ifa);
@@ -1073,21 +1086,23 @@ ipv6_add_addr(struct inet6_dev *idev, const struct in6_addr *addr, 


	in6_ifa_hold(ifa);

	write_unlock(&idev->lock);

out2:



	rcu_read_unlock_bh();



	if (likely(err == 0))

	inet6addr_notifier_call_chain(NETDEV_UP, ifa);

	else {

out:

	if (unlikely(err < 0)) {

		if (rt)

			ip6_rt_put(rt);

		if (ifa) {

			if (ifa->idev)

				in6_dev_put(ifa->idev);

			kfree(ifa);

		in6_dev_put(idev);

		}

		ifa = ERR_PTR(err);

	}



	return ifa;

out:

	spin_unlock(&addrconf_hash_lock);

	goto out2;

}



enum cleanup_prefix_rt_t {
@@ -1334,7 +1349,7 @@ static int ipv6_create_tempaddr(struct inet6_ifaddr *ifp, struct inet6_ifaddr *i 


	ift = ipv6_add_addr(idev, &addr, NULL, tmp_plen,

			    ipv6_addr_scope(&addr), addr_flags,

			    tmp_valid_lft, tmp_prefered_lft);

			    tmp_valid_lft, tmp_prefered_lft, true);

	if (IS_ERR(ift)) {

		in6_ifa_put(ifp);

		in6_dev_put(idev);
@@ -2018,7 +2033,7 @@ void addrconf_dad_failure(struct inet6_ifaddr *ifp) 


		ifp2 = ipv6_add_addr(idev, &new_addr, NULL, pfxlen,

				     scope, flags, valid_lft,

				     preferred_lft);

				     preferred_lft, false);

		if (IS_ERR(ifp2))

			goto lock_errdad;
@@ -2476,7 +2491,7 @@ int addrconf_prefix_rcv_add_addr(struct net *net, struct net_device *dev, 
					    pinfo->prefix_len,

					    addr_type&IPV6_ADDR_SCOPE_MASK,

					    addr_flags, valid_lft,

					    prefered_lft);

					    prefered_lft, false);



		if (IS_ERR_OR_NULL(ifp))

			return -1;
@@ -2845,7 +2860,7 @@ static int inet6_addr_add(struct net *net, int ifindex, 
	}



	ifp = ipv6_add_addr(idev, pfx, peer_pfx, plen, scope, ifa_flags,

			    valid_lft, prefered_lft);

			    valid_lft, prefered_lft, true);



	if (!IS_ERR(ifp)) {

		if (!(ifa_flags & IFA_F_NOPREFIXROUTE)) {
@@ -2960,7 +2975,8 @@ static void add_addr(struct inet6_dev *idev, const struct in6_addr *addr, 


	ifp = ipv6_add_addr(idev, addr, NULL, plen,

			    scope, IFA_F_PERMANENT,

			    INFINITY_LIFE_TIME, INFINITY_LIFE_TIME);

			    INFINITY_LIFE_TIME, INFINITY_LIFE_TIME,

			    true);

	if (!IS_ERR(ifp)) {

		spin_lock_bh(&ifp->lock);

		ifp->flags &= ~IFA_F_TENTATIVE;
@@ -3060,7 +3076,7 @@ void addrconf_add_linklocal(struct inet6_dev *idev, 
#endif



	ifp = ipv6_add_addr(idev, addr, NULL, 64, IFA_LINK, addr_flags,

			    INFINITY_LIFE_TIME, INFINITY_LIFE_TIME);

			    INFINITY_LIFE_TIME, INFINITY_LIFE_TIME, true);

	if (!IS_ERR(ifp)) {

		addrconf_prefix_route(&ifp->addr, ifp->prefix_len, idev->dev, 0, 0);

		addrconf_dad_start(ifp);