From: Yury Norov <yury.norov@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Dmitry Torokhov <dmitry.torokhov@gmail.com>,
"David S . Miller" <davem@davemloft.net>,
Stephen Rothwell <sfr@canb.auug.org.au>,
Amritha Nambiar <amritha.nambiar@intel.com>,
Willem de Bruijn <willemb@google.com>,
Kees Cook <keescook@chromium.org>,
Matthew Wilcox <willy@infradead.org>,
"Tobin C . Harding" <tobin@kernel.org>,
Will Deacon <will.deacon@arm.com>,
Miklos Szeredi <mszeredi@redhat.com>,
Vineet Gupta <vineet.gupta1@synopsys.com>,
Chris Wilson <chris@chris-wilson.co.uk>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
linux-kernel@vger.kernel.org
Cc: Yury Norov <ynorov@marvell.com>, Jens Axboe <axboe@kernel.dk>,
Steffen Klassert <steffen.klassert@secunet.com>
Subject: Re: [PATCH 0/7] lib: rework bitmap_parse
Date: Tue, 7 May 2019 14:04:21 -0700 [thread overview]
Message-ID: <20190507210421.GA8935@yury-thinkpad> (raw)
In-Reply-To: <20190501010636.30595-1-ynorov@marvell.com>
On Tue, Apr 30, 2019 at 06:06:29PM -0700, Yury Norov wrote:
> On top of next-20190418.
>
> Similarly to recently revisited bitmap_parselist() [1],
> bitmap_parse() is ineffective and overcomplicated. This
> series reworks it, aligns its interface with bitmap_parselist()
> and makes usage simpler.
>
> The series also adds a test for the function and fixes usage of it
> in cpumask_parse() according to new design - drops the calculating
> of length of an input string.
>
> The following users would also consider to drop the length argument,
> if possible:
> drivers/block/drbd/drbd_main.c:2608
> kernel/padata.c:924
> net/core/net-sysfs.c:726
> net/core/net-sysfs.c:1309
> net/core/net-sysfs.c:1391
>
> bitmap_parse() takes the array of numbers to be put into the map in
> the BE order which is reversed to the natural LE order for bitmaps.
> For example, to construct bitmap containing a bit on the position 42,
> we have to put a line '400,0'. Current implementation reads chunk
> one by one from the beginning ('400' before '0') and makes bitmap
> shift after each successful parse. It makes the complexity of the
> whole process as O(n^2). We can do it in reverse direction ('0'
> before '400') and avoid shifting, but it requires reverse parsing
> helpers.
>
> Tested on arm64 and BE mips.
Any comments?
> v1: https://lkml.org/lkml/2019/4/27/597
> v2:
> - strnchrnul() signature and description changed, ifdeffery and
> exporting removed;
> - test split for better demonstration of before/after changes;
> - minor naming and formatting issues fixed.
>
> [1] https://lkml.org/lkml/2019/4/16/66
>
> Yury Norov (7):
> lib/string: add strnchrnul()
> bitops: more BITS_TO_* macros
> lib: add test for bitmap_parse()
> lib: make bitmap_parse_user a wrapper on bitmap_parse
> lib: rework bitmap_parse()
> lib: new testcases for bitmap_parse{_user}
> cpumask: don't calculate length of the input string
>
> include/linux/bitmap.h | 8 +-
> include/linux/bitops.h | 5 +-
> include/linux/cpumask.h | 4 +-
> include/linux/string.h | 1 +
> lib/bitmap.c | 197 +++++++++++++++++------------------
> lib/string.c | 17 +++
> lib/test_bitmap.c | 102 +++++++++++++++++-
> tools/include/linux/bitops.h | 9 +-
> 8 files changed, 226 insertions(+), 117 deletions(-)
>
> --
> 2.17.1
prev parent reply other threads:[~2019-05-07 21:04 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-01 1:06 [PATCH 0/7] lib: rework bitmap_parse Yury Norov
2019-05-01 1:06 ` [PATCH 1/7] lib/string: add strnchrnul() Yury Norov
2019-05-08 8:47 ` Andy Shevchenko
2019-05-01 1:06 ` [PATCH 2/7] bitops: more BITS_TO_* macros Yury Norov
2019-05-08 8:47 ` Andy Shevchenko
2019-05-01 1:06 ` [PATCH 3/7] lib: add test for bitmap_parse() Yury Norov
2019-05-08 8:47 ` Andy Shevchenko
2019-05-01 1:06 ` [PATCH 4/7] lib: make bitmap_parse_user a wrapper on bitmap_parse Yury Norov
2019-05-08 8:47 ` Andy Shevchenko
2019-05-01 1:06 ` [PATCH 5/7] lib: rework bitmap_parse() Yury Norov
2019-05-08 8:46 ` Andy Shevchenko
2019-05-10 2:26 ` Yury Norov
2019-05-24 2:51 ` Andrew Morton
2019-05-01 1:06 ` [PATCH 6/7] lib: new testcases for bitmap_parse{_user} Yury Norov
2019-05-08 8:47 ` Andy Shevchenko
2019-05-01 1:06 ` [PATCH 7/7] cpumask: don't calculate length of the input string Yury Norov
2019-05-08 8:48 ` Andy Shevchenko
2019-05-07 21:04 ` Yury Norov [this message]
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