On 18 July 2018 at 02:12, Eric Biggers [off-list ref] wrote:

Hi Krzysztof,

On Tue, Jul 17, 2018 at 06:05:35PM +0200, Krzysztof Kozlowski wrote:

quoted

Hi,

Kernel defines same polynomial for CRC-32 in few places.
This is unnecessary duplication of the same value. Also this might
be error-prone for future code - every driver will define the
polynomial again.

This is an attempt to unify definition of polynomial.  Few obvious
hard-coded locations are fixed with define.

All series depend on each 1/6 and 2/6.

This could be merged in two different merge windows (1st lib/crc and then
the rest) or taken through one tree.

It would be nice to get some testing. Only generic lib/crc, bunzip, xz_crc32
and Freescale's Ethernet driver were tested on HW.  Rest got just different
builds.

Best regards,
Krzysztof

Krzysztof Kozlowski (6):
  lib/crc: Move polynomial definition to separate header
  lib/crc: Use consistent naming for CRC-32 polynomials
  crypto: stm32_crc32 - Use existing define with polynomial
  net: ethernet: Use existing define with polynomial
  staging: rtl: Use existing define with polynomial
  lib: Use existing define with polynomial

 drivers/crypto/stm32/stm32_crc32.c               | 11 ++++-------
 drivers/net/ethernet/amd/xgbe/xgbe-dev.c         |  4 ++--
 drivers/net/ethernet/apple/bmac.c                |  8 ++------
 drivers/net/ethernet/broadcom/tg3.c              |  3 ++-
 drivers/net/ethernet/freescale/fec_main.c        |  4 ++--
 drivers/net/ethernet/freescale/fs_enet/fec.h     |  3 ---
 drivers/net/ethernet/freescale/fs_enet/mac-fec.c |  3 ++-
 drivers/net/ethernet/micrel/ks8851_mll.c         |  3 ++-
 drivers/net/ethernet/synopsys/dwc-xlgmac-hw.c    |  4 ++--
 drivers/staging/rtl8712/rtl871x_security.c       |  5 ++---
 drivers/staging/rtl8723bs/core/rtw_security.c    |  5 ++---
 include/linux/crc32poly.h                        | 20 ++++++++++++++++++++
 lib/crc32.c                                      | 11 ++++++-----
 lib/crc32defs.h                                  | 14 --------------
 lib/decompress_bunzip2.c                         |  3 ++-
 lib/gen_crc32table.c                             |  5 +++--
 lib/xz/xz_crc32.c                                |  3 ++-
 17 files changed, 55 insertions(+), 54 deletions(-)
 create mode 100644 include/linux/crc32poly.h

Did you check whether any of these users can be converted to use the CRC
implementations in lib/, so they wouldn't need the polynomial definition
themselves?

I did not check but that's interesting point... The Ethernet drivers
(xgbe, tg3, fec, ks8851, dwc-xlgmac) look like could be converted to
generic implementation. The apple/bmac looks weird. The rtl WiFi
drivers in long term can be converted to use generic lib80211 for
encryption (see commit 0d4876f4e977 ("staging:r8188eu: Use lib80211 to
encrypt (TKIP) tx frames")) but that is much bigger task. The
remaining use the polynomials in different aspect:
1. XZ and BUNZIP use it to create CRC tables - probably generic
gen_crc32table.c could be used,
2. stm32_crc32.c uses it to initialize HW CRC accelerator.

I can work on Freescale FEC, xz and bunzip code because these I can
test but I would prefer to do it as follow up.

Best regards,
Krzysztof