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

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Date:   Fri, 15 Mar 2019 18:53:51 +0300
From:   Yury Norov <yury.norov@...il.com>
To:     Yury Norov <yury.norov@...il.com>
Cc:     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>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/5] lib: rework bitmap_parselist and tests

Ping?

On Wed, Feb 20, 2019 at 11:36:59AM +0300, Yury Norov wrote:
> 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