From: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Date: Sun, 8 Aug 2010 09:45:23 +0000 (+0300)
Subject: UBIFS: fix assertion warnings in comparison function
X-Git-Tag: v2.6.37-rc1~170^2~11
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1a9476a77083354005750c9df45ba9d71ad12c8c;p=pandora-kernel.git

UBIFS: fix assertion warnings in comparison function

When running the integrity test ('integck' from mtd-utils) on current
UBIFS on 2.6.35, I see that assertions in UBIFS 'list_sort()' comparison
functions trigger sometimes, e.g.:

UBIFS assert failed in data_nodes_cmp at 132 (pid 28311)

My investigation showed that this happens when 'list_sort()' calls the 'cmp()'
function with equivalent arguments. In this case, the 'struct list_head'
parameter, passed to 'cmp()' is bogus, and it does not belong to any element in
the original list.

And this issue seems to be introduced by commit:

commit 835cc0c8477fdbc59e0217891d6f11061b1ac4e2
Author: Don Mullis <don.mullis@gmail.com>
Date:   Fri Mar 5 13:43:15 2010 -0800

It is easy to work around the issue by doing:

if (a == b)
	return 0;

in UBIFS. It works, but 'lib_sort()' should nevertheless be fixed. Although it
is harmless to have this piece of code in UBIFS.

This patch adds that code to both UBIFS 'cmp()' functions:
'data_nodes_cmp()' and 'nondata_nodes_cmp()'.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
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