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Message-ID: <8f62965ad89f82b0f4bd73d6e5acf352dc2b767e.camel@linux.intel.com>
Date: Tue, 17 Jul 2018 18:43:05 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Coly Li <colyli@...e.de>, linux-kernel@...r.kernel.org
Cc: linux-bcache@...r.kernel.org, linux-block@...r.kernel.org,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Michael Lyle <mlyle@...e.org>,
Kent Overstreet <kent.overstreet@...il.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Thomas Gleixner <tglx@...utronix.de>,
Kate Stewart <kstewart@...uxfoundation.org>,
Eric Biggers <ebiggers3@...il.com>
Subject: Re: [PATCH v3 1/3] lib: add crc64 calculation routines
On Tue, 2018-07-17 at 22:55 +0800, Coly Li wrote:
> This patch adds the re-write crc64 calculation routines for Linux
> kernel.
> The CRC64 polynomical arithmetic follows ECMA-182 specification,
> inspired
> by CRC paper of Dr. Ross N. Williams
> (see http://www.ross.net/crc/download/crc_v3.txt) and other public
> domain
> implementations.
>
> All the changes work in this way,
> - When Linux kernel is built, host program lib/gen_crc64table.c will
> be
> compiled to lib/gen_crc64table and executed.
> - The output of gen_crc64table execution is an array called as lookup
> table (a.k.a POLY 0x42f0e1eba9ea369) which contain 256 64bits-long
> numbers, this talbe is dumped into header file lib/crc64table.h.
> - Then the header file is included by lib/crc64.c for normal 64bit crc
> calculation.
> - Function declaration of the crc64 calculation routines is placed in
> include/linux/crc64.h
Thanks for an update! My comments below.
> Co-developed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
As required by coding style this tag should be accompanied with SoB of
co-developer(s).
> +u64 __pure crc64_update(u64 crc, const void *_p, size_t len);
For sake of consistency I would name _len as well.
> + * Normal 64bit CRC calculation.
I think 64-bit form is slightly better and more often
$ git grep -n -w 64bit | wc -l
809
$ git grep -n -w 64-bit | wc -l
2957
> + * crc64table[256] is the lookup table of a table-driver 64bit CRC
Ditto.
> + * Copyright 2018 SUSE Linux.
> + * Author: Coly Li <colyli@...e.de>
> + *
This (blank comment) line is not needed.
> +u64 __pure crc64_update(u64 crc, const void *_p, size_t len)
_len ?
> + * Copyright 2018 SUSE Linux.
> + * Author: Coly Li <colyli@...e.de>
> + *
Not needed line.
> +#include <inttypes.h>
> +#include <stdio.h>
+ blank line? Would separate groups of headers logically.
> +#include <linux/swab.h>
> +static int64_t crc64_table[256] = {0,};
I guess {0} would work as well (no comma).
> + printf("#include <uapi/linux/types.h>\n");
> + printf("#include <linux/cache.h>\n\n");
Do wee need these? CRC32 case seems fine without.
--
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Intel Finland Oy
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