[PATCH] lib: Add support for DIF CRC - Kernel

This is a discussion on [PATCH] lib: Add support for DIF CRC - Kernel ; Add support for the T10 Data Integrity Field CRC. Signed-off-by: Martin K. Petersen diff -r f5ec697e8b10 include/linux/crc-t10dif.h --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/include/linux/crc-t10dif.h Tue Jan 29 13:26:19 2008 -0500 @@ -0,0 +1,9 @@ +#ifndef _LINUX_CRC_T10DIF_H +#define ...

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Thread: [PATCH] lib: Add support for DIF CRC

  1. [PATCH] lib: Add support for DIF CRC


    Add support for the T10 Data Integrity Field CRC.

    Signed-off-by: Martin K. Petersen

    diff -r f5ec697e8b10 include/linux/crc-t10dif.h
    --- /dev/null Thu Jan 01 00:00:00 1970 +0000
    +++ b/include/linux/crc-t10dif.h Tue Jan 29 13:26:19 2008 -0500
    @@ -0,0 +1,9 @@
    +#ifndef _LINUX_CRC_T10DIF_H
    +#define _LINUX_CRC_T10DIF_H
    +
    +#include
    +
    +const __u16 t10_dif_crc_table[256];
    +__u16 crc_t10dif(unsigned char const *, size_t);
    +
    +#endif
    diff -r f5ec697e8b10 lib/Kconfig
    --- a/lib/Kconfig Tue Jan 29 12:11:57 2008 -0500
    +++ b/lib/Kconfig Tue Jan 29 13:26:19 2008 -0500
    @@ -22,6 +22,13 @@ config CRC16
    modules require CRC16 functions, but a module built outside
    the kernel tree does. Such modules that use library CRC16
    functions require M here.
    +
    +config CRC_T10DIF
    + tristate "CRC calculation for the T10 Data Integrity Field"
    + help
    + This option is only needed if a module that's not in the
    + kernel tree needs to calculate CRC checks for use with the
    + SCSI data integrity subsystem.

    config CRC_ITU_T
    tristate "CRC ITU-T V.41 functions"
    diff -r f5ec697e8b10 lib/Makefile
    --- a/lib/Makefile Tue Jan 29 12:11:57 2008 -0500
    +++ b/lib/Makefile Tue Jan 29 13:26:19 2008 -0500
    @@ -44,6 +44,7 @@ obj-$(CONFIG_BITREVERSE) += bitrev.o
    obj-$(CONFIG_BITREVERSE) += bitrev.o
    obj-$(CONFIG_CRC_CCITT) += crc-ccitt.o
    obj-$(CONFIG_CRC16) += crc16.o
    +obj-$(CONFIG_CRC_T10DIF)+= crc-t10dif.o
    obj-$(CONFIG_CRC_ITU_T) += crc-itu-t.o
    obj-$(CONFIG_CRC32) += crc32.o
    obj-$(CONFIG_CRC7) += crc7.o
    diff -r f5ec697e8b10 lib/crc-t10dif.c
    --- /dev/null Thu Jan 01 00:00:00 1970 +0000
    +++ b/lib/crc-t10dif.c Tue Jan 29 13:26:19 2008 -0500
    @@ -0,0 +1,68 @@
    +/*
    + * T10 Data Integrity Field CRC16 calculation
    + *
    + * Copyright (c) 2007 Oracle Corporation. All rights reserved.
    + * Written by Martin K. Petersen
    + *
    + * This source code is licensed under the GNU General Public License,
    + * Version 2. See the file COPYING for more details.
    + */
    +
    +#include
    +#include
    +#include
    +
    +/* Table generated using the following polynomium:
    + * x^16 + x^15 + x^11 + x^9 + x^8 + x^7 + x^5 + x^4 + x^2 + x + 1
    + * gt: 0x8bb7
    + */
    +const __u16 t10_dif_crc_table[256] = {
    + 0x0000, 0x8BB7, 0x9CD9, 0x176E, 0xB205, 0x39B2, 0x2EDC, 0xA56B,
    + 0xEFBD, 0x640A, 0x7364, 0xF8D3, 0x5DB8, 0xD60F, 0xC161, 0x4AD6,
    + 0x54CD, 0xDF7A, 0xC814, 0x43A3, 0xE6C8, 0x6D7F, 0x7A11, 0xF1A6,
    + 0xBB70, 0x30C7, 0x27A9, 0xAC1E, 0x0975, 0x82C2, 0x95AC, 0x1E1B,
    + 0xA99A, 0x222D, 0x3543, 0xBEF4, 0x1B9F, 0x9028, 0x8746, 0x0CF1,
    + 0x4627, 0xCD90, 0xDAFE, 0x5149, 0xF422, 0x7F95, 0x68FB, 0xE34C,
    + 0xFD57, 0x76E0, 0x618E, 0xEA39, 0x4F52, 0xC4E5, 0xD38B, 0x583C,
    + 0x12EA, 0x995D, 0x8E33, 0x0584, 0xA0EF, 0x2B58, 0x3C36, 0xB781,
    + 0xD883, 0x5334, 0x445A, 0xCFED, 0x6A86, 0xE131, 0xF65F, 0x7DE8,
    + 0x373E, 0xBC89, 0xABE7, 0x2050, 0x853B, 0x0E8C, 0x19E2, 0x9255,
    + 0x8C4E, 0x07F9, 0x1097, 0x9B20, 0x3E4B, 0xB5FC, 0xA292, 0x2925,
    + 0x63F3, 0xE844, 0xFF2A, 0x749D, 0xD1F6, 0x5A41, 0x4D2F, 0xC698,
    + 0x7119, 0xFAAE, 0xEDC0, 0x6677, 0xC31C, 0x48AB, 0x5FC5, 0xD472,
    + 0x9EA4, 0x1513, 0x027D, 0x89CA, 0x2CA1, 0xA716, 0xB078, 0x3BCF,
    + 0x25D4, 0xAE63, 0xB90D, 0x32BA, 0x97D1, 0x1C66, 0x0B08, 0x80BF,
    + 0xCA69, 0x41DE, 0x56B0, 0xDD07, 0x786C, 0xF3DB, 0xE4B5, 0x6F02,
    + 0x3AB1, 0xB106, 0xA668, 0x2DDF, 0x88B4, 0x0303, 0x146D, 0x9FDA,
    + 0xD50C, 0x5EBB, 0x49D5, 0xC262, 0x6709, 0xECBE, 0xFBD0, 0x7067,
    + 0x6E7C, 0xE5CB, 0xF2A5, 0x7912, 0xDC79, 0x57CE, 0x40A0, 0xCB17,
    + 0x81C1, 0x0A76, 0x1D18, 0x96AF, 0x33C4, 0xB873, 0xAF1D, 0x24AA,
    + 0x932B, 0x189C, 0x0FF2, 0x8445, 0x212E, 0xAA99, 0xBDF7, 0x3640,
    + 0x7C96, 0xF721, 0xE04F, 0x6BF8, 0xCE93, 0x4524, 0x524A, 0xD9FD,
    + 0xC7E6, 0x4C51, 0x5B3F, 0xD088, 0x75E3, 0xFE54, 0xE93A, 0x628D,
    + 0x285B, 0xA3EC, 0xB482, 0x3F35, 0x9A5E, 0x11E9, 0x0687, 0x8D30,
    + 0xE232, 0x6985, 0x7EEB, 0xF55C, 0x5037, 0xDB80, 0xCCEE, 0x4759,
    + 0x0D8F, 0x8638, 0x9156, 0x1AE1, 0xBF8A, 0x343D, 0x2353, 0xA8E4,
    + 0xB6FF, 0x3D48, 0x2A26, 0xA191, 0x04FA, 0x8F4D, 0x9823, 0x1394,
    + 0x5942, 0xD2F5, 0xC59B, 0x4E2C, 0xEB47, 0x60F0, 0x779E, 0xFC29,
    + 0x4BA8, 0xC01F, 0xD771, 0x5CC6, 0xF9AD, 0x721A, 0x6574, 0xEEC3,
    + 0xA415, 0x2FA2, 0x38CC, 0xB37B, 0x1610, 0x9DA7, 0x8AC9, 0x017E,
    + 0x1F65, 0x94D2, 0x83BC, 0x080B, 0xAD60, 0x26D7, 0x31B9, 0xBA0E,
    + 0xF0D8, 0x7B6F, 0x6C01, 0xE7B6, 0x42DD, 0xC96A, 0xDE04, 0x55B3
    +};
    +
    +__u16 crc_t10dif(const unsigned char *buffer, size_t len)
    +{
    + __u16 crc = 0;
    + unsigned int i;
    +
    + for (i=0 ; i < len ; i++)
    + crc = (crc << 8) ^ t10_dif_crc_table[((crc >> 8) ^ buffer[i]) & 0xff];
    +
    + return crc;
    +}
    +
    +EXPORT_SYMBOL(crc_t10dif);
    +
    +MODULE_DESCRIPTION("T10 DIF CRC calculation");
    +MODULE_LICENSE("GPL");
    --
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  2. Re: [PATCH] lib: Add support for DIF CRC


    On Jan 30 2008 02:00, Martin K. Petersen wrote:
    >diff -r f5ec697e8b10 include/linux/crc-t10dif.h
    >--- /dev/null Thu Jan 01 00:00:00 1970 +0000
    >+++ b/include/linux/crc-t10dif.h Tue Jan 29 13:26:19 2008 -0500
    >@@ -0,0 +1,9 @@
    >+#ifndef _LINUX_CRC_T10DIF_H
    >+#define _LINUX_CRC_T10DIF_H
    >+
    >+#include
    >+
    >+const __u16 t10_dif_crc_table[256];
    >+__u16 crc_t10dif(unsigned char const *, size_t);
    >+
    >+const __u16 t10_dif_crc_table[256] = {

    ....
    >+};
    >+
    >+__u16 crc_t10dif(const unsigned char *buffer, size_t len)
    >+{

    ....
    >+}
    >+
    >+EXPORT_SYMBOL(crc_t10dif);



    One minor nitpick still: if t10_dif_crc_table is not EXPORT_SYMBOLed,
    it should be static, since I do not see a reason to only make it
    available to built-in code.

    So either make the table static too, or EXPORT it. I am not sure if
    any code needs to access the table directly, though, so I'd be going
    for the static.
    --
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