Hello Giovanni,

On Thu, 3 Aug 2023 at 11:51, Giovanni Cabiddu
[off-list ref] wrote:

Hi Ard,

On Tue, Jul 18, 2023 at 01:58:27PM +0100, Ard Biesheuvel wrote:

quoted

This reverts commit a368f43d6e3a001e684e9191a27df384fbff12f5.

"zlib-deflate" was introduced 6 years ago, but it does not have any
users. So let's remove the generic implementation and the test vectors,
but retain the "zlib-deflate" entry in the testmgr code to avoid
introducing warning messages on systems that implement zlib-deflate in
hardware.

Note that RFC 1950 which forms the basis of this algorithm dates back to
1996, and predates RFC 1951, on which the existing IPcomp is based and
which we have supported in the kernel since 2003. So it seems rather
unlikely that we will ever grow the need to support zlib-deflate.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

Support for zlib-deflate was added for [1] but that work was not
completed.

Any clue why zlib_deflate was chosen in this case?

/me also notes that this is another occurrence of the antipattern
where we use an asynchronous API and subsequently sleep on the
completion.

Based on [2], either we leave this SW implementation or we remove the HW
implementations in the QAT [3] and in the Hisilicon Zip [4] drivers.

That would work for me as well - dead code is just busywork.

[1] https://patchwork.kernel.org/project/linux-btrfs/patch/1467083180-111750-1-git-send-email-weigang.li@intel.com/
[2] https://lore.kernel.org/lkml/ZIw%2Fjtxdg6O1O0j3@gondor.apana.org.au/ (local)
[3] https://elixir.bootlin.com/linux/latest/source/drivers/crypto/intel/qat/qat_common/qat_comp_algs.c#L457
[4] https://elixir.bootlin.com/linux/latest/source/drivers/crypto/hisilicon/zip/zip_crypto.c#L754

Regards,

--
Giovanni