linux-kernel - [PATCH v3 0/4] lib/string_helpers: fix precision issues and introduce tests

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Message-Id: <1446136250-11507-1-git-send-email-vkuznets@redhat.com>
Date:	Thu, 29 Oct 2015 17:30:46 +0100
From:	Vitaly Kuznetsov <vkuznets@...hat.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Rasmus Villemoes <linux@...musvillemoes.dk>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	James Bottomley <JBottomley@...n.com>,
	Kees Cook <keescook@...omium.org>, linux-kernel@...r.kernel.org
Subject: [PATCH v3 0/4] lib/string_helpers: fix precision issues and introduce tests

Linux always lies about your storage size when it has 4k sectors and its
size is big enough. E.g. a device with 8192 4k sectors will be reported as
"32.7 MB/32 MiB" while "33.5 MB/32 MiB" is expected. This series is
supposed to fix the issue by fixing calculation precision in
string_get_size() for all possible inputs.

PATCH 1/4 is a preparatory change, PATCH 2/4 adds additional protection
against blk_size=0 (nobody is supposed to call string_get_size() with
with blk_size=0, but better safe than sorry), PATCH 3/4 re-factors
string_get_size() fixing the issue, PATCH 4/4 introduces tests for
string_get_size().

PATCH 4/4 was previously sent as part of "lib/string_helpers.c: fix
infinite loop in string_get_size()" series but it is still not merged
upstream. In this submission I improve it and add additional tests to it.

Changes since v2:
- Separate blk_size check from Patch 3/4 to new Patch 2/4 [Andy Shevchenko]
- Slightly change the algorithm in Patch 3/4 [Rasmus Villemoes]

Vitaly Kuznetsov (4):
  lib/string_helpers: change blk_size to u32 for string_get_size()
    interface
  lib/string_helpers.c: protect string_get_size() against blk_size=0
  lib/string_helpers.c: don't lose precision in string_get_size()
  lib/test-string_helpers.c: add string_get_size() tests

 include/linux/string_helpers.h |  2 +-
 lib/string_helpers.c           | 38 ++++++++++++++-------------
 lib/test-string_helpers.c      | 58 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 79 insertions(+), 19 deletions(-)

-- 
2.4.3

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