Commit 71d67e66 authored by Stephen Hemminger's avatar Stephen Hemminger Committed by David S. Miller
Browse files

[IPV4] fib_trie: rescan if key is lost during dump 



Normally during a dump the key of the last dumped entry is used for
continuation, but since lock is dropped it might be lost. In that case
fallback to the old counter based N^2 behaviour.  This means the dump
will end up skipping some routes which matches what FIB_HASH does.

Signed-off-by: default avatarStephen Hemminger <shemminger@vyatta.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 9fe7c712

include/linux/netlink.h

+1 −1
Original line number Diff line number Diff line
@@ -219,7 +219,7 @@ struct netlink_callback 
	int		(*dump)(struct sk_buff * skb, struct netlink_callback *cb);

	int		(*done)(struct netlink_callback *cb);

	int		family;

	long		args[5];

	long		args[6];

};



struct netlink_notify

net/ipv4/fib_trie.c

+32 −17
Original line number Diff line number Diff line
@@ -1758,6 +1758,19 @@ static struct leaf *trie_nextleaf(struct leaf *l) 
	return leaf_walk_rcu(p, c);

}



static struct leaf *trie_leafindex(struct trie *t, int index)

{

	struct leaf *l = trie_firstleaf(t);



	while (index-- > 0) {

		l = trie_nextleaf(l);

		if (!l)

			break;

	}

	return l;

}





/*

 * Caller must hold RTNL.

 */
@@ -1863,7 +1876,7 @@ static int fn_trie_dump_fa(t_key key, int plen, struct list_head *fah, 
	struct fib_alias *fa;

	__be32 xkey = htonl(key);



	s_i = cb->args[4];

	s_i = cb->args[5];

	i = 0;



	/* rcu_read_lock is hold by caller */
@@ -1884,12 +1897,12 @@ static int fn_trie_dump_fa(t_key key, int plen, struct list_head *fah, 
				  plen,

				  fa->fa_tos,

				  fa->fa_info, NLM_F_MULTI) < 0) {

			cb->args[4] = i;

			cb->args[5] = i;

			return -1;

		}

		i++;

	}

	cb->args[4] = i;

	cb->args[5] = i;

	return skb->len;

}
@@ -1900,7 +1913,7 @@ static int fn_trie_dump_leaf(struct leaf *l, struct fib_table *tb, 
	struct hlist_node *node;

	int i, s_i;



	s_i = cb->args[3];

	s_i = cb->args[4];

	i = 0;



	/* rcu_read_lock is hold by caller */
@@ -1911,19 +1924,19 @@ static int fn_trie_dump_leaf(struct leaf *l, struct fib_table *tb, 
		}



		if (i > s_i)

			cb->args[4] = 0;

			cb->args[5] = 0;



		if (list_empty(&li->falh))

			continue;



		if (fn_trie_dump_fa(l->key, li->plen, &li->falh, tb, skb, cb) < 0) {

			cb->args[3] = i;

			cb->args[4] = i;

			return -1;

		}

		i++;

	}



	cb->args[3] = i;

	cb->args[4] = i;

	return skb->len;

}
@@ -1933,35 +1946,37 @@ static int fn_trie_dump(struct fib_table *tb, struct sk_buff *skb, 
	struct leaf *l;

	struct trie *t = (struct trie *) tb->tb_data;

	t_key key = cb->args[2];

	int count = cb->args[3];



	rcu_read_lock();

	/* Dump starting at last key.

	 * Note: 0.0.0.0/0 (ie default) is first key.

	 */

	if (!key)

	if (count == 0)

		l = trie_firstleaf(t);

	else {

		l = fib_find_node(t, key);

		if (!l) {

			/* The table changed during the dump, rather than

			 * giving partial data, just make application retry.

		/* Normally, continue from last key, but if that is missing

		 * fallback to using slow rescan

		 */

			rcu_read_unlock();

			return -EBUSY;

		}

		l = fib_find_node(t, key);

		if (!l)

			l = trie_leafindex(t, count);

	}



	while (l) {

		cb->args[2] = l->key;

		if (fn_trie_dump_leaf(l, tb, skb, cb) < 0) {

			cb->args[3] = count;

			rcu_read_unlock();

			return -1;

		}



		++count;

		l = trie_nextleaf(l);

		memset(&cb->args[3], 0,

		       sizeof(cb->args) - 3*sizeof(cb->args[0]));

		memset(&cb->args[4], 0,

		       sizeof(cb->args) - 4*sizeof(cb->args[0]));

	}

	cb->args[3] = count;

	rcu_read_unlock();



	return skb->len;

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