[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: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index cbccafd..35851c9 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -1758,6 +1758,19 @@
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 @@
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 @@
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 @@
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 @@
}
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 @@
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;