[PATCH 3.2 22/24] ipv6: fib: fix fib dump restart

[Ben Hutchings <ben@decadent.org.uk>]

3.2.68-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Dumazet <edumazet@google.com>

commit fa809e2fd6e317226c046202a88520962672eac0 upstream.

Commit 2bec5a369ee79576a3 (ipv6: fib: fix crash when changing large fib
while dumping it) introduced ability to restart the dump at tree root,
but failed to skip correctly a count of already dumped entries. Code
didn't match Patrick intent.

We must skip exactly the number of already dumped entries.

Note that like other /proc/net files or netlink producers, we could
still dump some duplicates entries.

Reported-by: Debabrata Banerjee <dbavatar@gmail.com>
Reported-by: Josh Hunt <johunt@akamai.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 net/ipv6/ip6_fib.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -1276,8 +1276,8 @@ static int fib6_walk_continue(struct fib
 			if (w->leaf && fn->fn_flags&RTN_RTINFO) {
 				int err;
 
-				if (w->count < w->skip) {
-					w->count++;
+				if (w->skip) {
+					w->skip--;
 					continue;
 				}