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Commit 2e997d8b authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'ipv6-addrlabel-avoid-dirtying-ip6addrlbl_entry' 



Eric Dumazet says:

====================
ipv6: addrlabel: avoid dirtying ip6addrlbl_entry

The refcount on ip6addrlbl_entry is only used to make sure ip6addrlbl_entry
does not disappear while ip6addrlbl_get() is allocating an skb.

We can instead allocate skb first, then use RCU, so that we no longer need
to refcount these structures.
====================

Acked-by: default avatarMartin KaFai Lau <kafai@fb.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents 1ee87d7a 2809c095

net/ipv6/addrlabel.c

+17 −52
Original line number Diff line number Diff line
@@ -18,7 +18,6 @@ 
#include <linux/if_addrlabel.h>

#include <linux/netlink.h>

#include <linux/rtnetlink.h>

#include <linux/refcount.h>



#if 0

#define ADDRLABEL(x...) printk(x)
@@ -36,7 +35,6 @@ struct ip6addrlbl_entry { 
	int addrtype;

	u32 label;

	struct hlist_node list;

	refcount_t refcnt;

	struct rcu_head rcu;

};
@@ -111,28 +109,6 @@ static const __net_initconst struct ip6addrlbl_init_table 
	}

};



/* Object management */

static inline void ip6addrlbl_free(struct ip6addrlbl_entry *p)

{

	kfree(p);

}



static void ip6addrlbl_free_rcu(struct rcu_head *h)

{

	ip6addrlbl_free(container_of(h, struct ip6addrlbl_entry, rcu));

}



static bool ip6addrlbl_hold(struct ip6addrlbl_entry *p)

{

	return refcount_inc_not_zero(&p->refcnt);

}



static inline void ip6addrlbl_put(struct ip6addrlbl_entry *p)

{

	if (refcount_dec_and_test(&p->refcnt))

		call_rcu(&p->rcu, ip6addrlbl_free_rcu);

}



/* Find label */

static bool __ip6addrlbl_match(const struct ip6addrlbl_entry *p,

			       const struct in6_addr *addr,
@@ -219,7 +195,6 @@ static struct ip6addrlbl_entry *ip6addrlbl_alloc(const struct in6_addr *prefix, 
	newp->addrtype = addrtype;

	newp->label = label;

	INIT_HLIST_NODE(&newp->list);

	refcount_set(&newp->refcnt, 1);

	return newp;

}
@@ -243,7 +218,7 @@ static int __ip6addrlbl_add(struct net *net, struct ip6addrlbl_entry *newp, 
				goto out;

			}

			hlist_replace_rcu(&p->list, &newp->list);

			ip6addrlbl_put(p);

			kfree_rcu(p, rcu);

			goto out;

		} else if ((p->prefixlen == newp->prefixlen && !p->ifindex) ||

			   (p->prefixlen < newp->prefixlen)) {
@@ -281,7 +256,7 @@ static int ip6addrlbl_add(struct net *net, 
	ret = __ip6addrlbl_add(net, newp, replace);

	spin_unlock(&net->ipv6.ip6addrlbl_table.lock);

	if (ret)

		ip6addrlbl_free(newp);

		kfree(newp);

	return ret;

}
@@ -302,7 +277,7 @@ static int __ip6addrlbl_del(struct net *net, 
		    p->ifindex == ifindex &&

		    ipv6_addr_equal(&p->prefix, prefix)) {

			hlist_del_rcu(&p->list);

			ip6addrlbl_put(p);

			kfree_rcu(p, rcu);

			ret = 0;

			break;

		}
@@ -360,7 +335,7 @@ static void __net_exit ip6addrlbl_net_exit(struct net *net) 
	spin_lock(&net->ipv6.ip6addrlbl_table.lock);

	hlist_for_each_entry_safe(p, n, &net->ipv6.ip6addrlbl_table.head, list) {

		hlist_del_rcu(&p->list);

		ip6addrlbl_put(p);

		kfree_rcu(p, rcu);

	}

	spin_unlock(&net->ipv6.ip6addrlbl_table.lock);

}
@@ -546,38 +521,28 @@ static int ip6addrlbl_get(struct sk_buff *in_skb, struct nlmsghdr *nlh, 
		return -EINVAL;

	addr = nla_data(tb[IFAL_ADDRESS]);



	rcu_read_lock();

	p = __ipv6_addr_label(net, addr, ipv6_addr_type(addr), ifal->ifal_index);

	if (p && !ip6addrlbl_hold(p))

		p = NULL;

	lseq = net->ipv6.ip6addrlbl_table.seq;

	rcu_read_unlock();



	if (!p) {

		err = -ESRCH;

		goto out;

	}



	skb = nlmsg_new(ip6addrlbl_msgsize(), GFP_KERNEL);

	if (!skb) {

		ip6addrlbl_put(p);

	if (!skb)

		return -ENOBUFS;

	}



	err = -ESRCH;



	rcu_read_lock();

	p = __ipv6_addr_label(net, addr, ipv6_addr_type(addr), ifal->ifal_index);

	lseq = net->ipv6.ip6addrlbl_table.seq;

	if (p)

		err = ip6addrlbl_fill(skb, p, lseq,

			      NETLINK_CB(in_skb).portid, nlh->nlmsg_seq,

				      NETLINK_CB(in_skb).portid,

				      nlh->nlmsg_seq,

				      RTM_NEWADDRLABEL, 0);



	ip6addrlbl_put(p);

	rcu_read_unlock();



	if (err < 0) {

		WARN_ON(err == -EMSGSIZE);

		kfree_skb(skb);

		goto out;

	}



	} else {

		err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);

out:

	}

	return err;

}