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Message-ID: <20080124135112.32b5c1c7@deepthought>
Date: Thu, 24 Jan 2008 13:51:12 -0800
From: Stephen Hemminger <shemminger@...ux-foundation.org>
To: David Miller <davem@...emloft.net>
Cc: kaber@...sh.net, netdev@...r.kernel.org
Subject: [PATCH] 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: Stephen Hemminger <shemminger@...tta.com>
--- a/include/linux/netlink.h 2008-01-24 13:39:40.000000000 -0800
+++ b/include/linux/netlink.h 2008-01-24 13:42:05.000000000 -0800
@@ -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
--- a/net/ipv4/fib_trie.c 2008-01-24 13:39:40.000000000 -0800
+++ b/net/ipv4/fib_trie.c 2008-01-24 13:44:26.000000000 -0800
@@ -1743,6 +1743,19 @@ static struct leaf *trie_nextleaf(struct
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.
*/
@@ -1848,7 +1861,7 @@ static int fn_trie_dump_fa(t_key key, in
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 */
@@ -1869,12 +1882,12 @@ static int fn_trie_dump_fa(t_key key, in
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;
}
@@ -1885,7 +1898,7 @@ static int fn_trie_dump_leaf(struct leaf
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 */
@@ -1896,19 +1909,19 @@ static int fn_trie_dump_leaf(struct leaf
}
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;
}
@@ -1918,35 +1931,37 @@ static int fn_trie_dump(struct fib_table
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 {
+ /* Normally, continue from last key, but if that is missing
+ * fallback to using slow rescan
+ */
l = fib_find_node(t, key);
- if (!l) {
- /* The table changed during the dump, rather than
- * giving partial data, just make application retry.
- */
- rcu_read_unlock();
- return -EBUSY;
- }
+ 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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