linux-kernel - [PATCH v2 0/5] lib: rework bitmap

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Date:   Wed, 20 Feb 2019 11:36:59 +0300
From:   Yury Norov <yury.norov@...il.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Arnd Bergmann <arnd@...db.de>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Kees Cook <keescook@...omium.org>,
        Matthew Wilcox <willy@...radead.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Cc:     Yury Norov <ynorov@...vell.com>, linux-kernel@...r.kernel.org,
        Yury Norov <yury.norov@...il.com>
Subject: [PATCH v2 0/5] lib: rework bitmap_parselist and tests

bitmap_parselist has been evolved from a pretty simple idea for long and
now lacks for refactoring. It is not structured, has nested loops and a
set of opaque-named variables. All this leads to extremely hard
understanding of the code. Once during the optimization of it I missed a
scenario which leads to kernel hangup. Tetsuo Handa spotted this and found
it simpler to rewrite the code instead fixing it. (Though, that attempt
had some flaws.)
https://lkml.org/lkml/2018/4/1/93 

Things are more complicated than they may be because bitmap_parselist()
is part of user interface, and its behavior should not change.

In this patchset 
 - __bitmap_parselist() is reworked (patches 2 and 3);
 - time measurement in test_bitmap_parselist switched to ktime_get
   (patch 4);
 - new tests introduced (patch 5), and
 - bitmap_parselist_user() testing enabled with the same testset as
   bitmap_parselist() (patch 6).

Patch 1 is a fix and may be applied separately.

V1: https://lkml.org/lkml/2018/12/23/50
v2: - use PTR_ERR() and ERR_PTR() where appropriate;
    - fix parser logic (last byte of string handling);
    - tests for bitmap_parselist_user() in patch 5.

Yury Norov (4):
  bitmap_parselist: don't calculate length of the input string
  bitmap_parselist: move non-parser logic to helpers
  bitmap_parselist: rework input string parser
  lib/test_bitmap: switch test_bitmap_parselist to ktime_get()
  lib/test_bitmap: add testcases for bitmap_parselist
  lib/test_bitmap: add tests for bitmap_parselist_user

 lib/bitmap.c      | 293 ++++++++++++++++++++++++++++++----------------
 lib/test_bitmap.c |  67 +++++++++--
 2 files changed, 245 insertions(+), 115 deletions(-)

-- 
2.17.1