locking/atomics: build atomic headers as required
Andrew and Ingo report that the check-atomics.sh script is simply too
slow to run for every kernel build, and it's impractical to make it
faster without rewriting it in something other than shell.
Rather than committing the generated headers, let's regenerate these
as-required, if we change the data or scripts used to generate the
atomic headers, or when building from a pristine tree.
That ensures they're always up-to-date, allows them to be built in
parallel, and avoid redundant rebuilds, which is a 2-8s saving per
incremental build. Since the results are not committed, it's very
obvious that they should not be modified directly. If we need to
generate more headers in future, it's easy to extend Makefile.genheader
to permit this.
I've verified that this works in the cases we previously had issues with
(out-of-tree builds and where scripts have no execute permissions), and
have tested these cases for both x86_64 and arm64.
The diffstat looks nice, at least...
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-kernel@vger.kernel.org
10 files changed
