On Fri, Mar 27, 2026 at 07:16:32AM +0100, Christoph Hellwig wrote:

Hi all,

the XOR library used for the RAID5 parity is a bit of a mess right now.
The main file sits in crypto/ despite not being cryptography and not
using the crypto API, with the generic implementations sitting in
include/asm-generic and the arch implementations sitting in an asm/
header in theory.  The latter doesn't work for many cases, so
architectures often build the code directly into the core kernel, or
create another module for the architecture code.

Changes this to a single module in lib/ that also contains the
architecture optimizations, similar to the library work Eric Biggers
has done for the CRC and crypto libraries later.  After that it changes
to better calling conventions that allow for smarter architecture
implementations (although none is contained here yet), and uses
static_call to avoid indirection function call overhead.

A git tree is also available here:

    git://git.infradead.org/users/hch/misc.git xor-improvements

Gitweb:

    https://git.infradead.org/?p=users/hch/misc.git;a=shortlog;h=refs/heads/xor-improvements

Changes since v3:
 - switch away from lockdep_assert_preemption_enabled() again
 - fix a @ reference in a kerneldoc comment.
 - build the arm4regs implementation also without kernel-mode neon
   support
 - fix a pre-existing issue about mismatched attributes on arm64's
   xor_block_inner_neon
 - reject 0-sized xor request and adjust the kunit test case to not
   generate them

Reviewed-by: Eric Biggers <ebiggers@kernel.org>

But yes, as Andrew mentioned there are two "xor: add a better public
API" patches.  They should be folded together.

- Eric