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Subject[patch 49/59] IPV4: Fix the fib trie iterator to work with a single entry routing tables
-stable review patch.  If anyone has any objections, please let us know.
------------------
From: Eric W. Biederman <ebiederm@xmission.com>

In a kernel with trie routing enabled I had a simple routing setup
with only a single route to the outside world and no default
route. "ip route table list main" showed my the route just fine but
/proc/net/route was an empty file. What was going on?

Thinking it was a bug in something I did and I looked deeper. Eventually
I setup a second route and everything looked correct, huh? Finally I
realized that the it was just the iterator pair in fib_trie_get_first,
fib_trie_get_next just could not handle a routing table with a single entry.

So to save myself and others further confusion, here is a simple fix for
the fib proc iterator so it works even when there is only a single route
in a routing table.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Robert Olsson <robert.olsson@its.uu.se>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
---
net/ipv4/fib_trie.c | 21 ++++++++++++++++-----
1 file changed, 16 insertions(+), 5 deletions(-)
--- linux-2.6.19.2.orig/net/ipv4/fib_trie.c
+++ linux-2.6.19.2/net/ipv4/fib_trie.c
@@ -1989,6 +1989,10 @@ static struct node *fib_trie_get_next(st
unsigned cindex = iter->index;
struct tnode *p;

+ /* A single entry routing table */
+ if (!tn)
+ return NULL;
+
pr_debug("get_next iter={node=%p index=%d depth=%d}\n",
iter->tnode, iter->index, iter->depth);
rescan:
@@ -2037,11 +2041,18 @@ static struct node *fib_trie_get_first(s
if(!iter)
return NULL;

- if (n && IS_TNODE(n)) {
- iter->tnode = (struct tnode *) n;
- iter->trie = t;
- iter->index = 0;
- iter->depth = 1;
+ if (n) {
+ if (IS_TNODE(n)) {
+ iter->tnode = (struct tnode *) n;
+ iter->trie = t;
+ iter->index = 0;
+ iter->depth = 1;
+ } else {
+ iter->tnode = NULL;
+ iter->trie = t;
+ iter->index = 0;
+ iter->depth = 0;
+ }
return n;
}
return NULL;
--
-
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