Re: [PATCH] chainlint.pl: fix /proc/cpuinfo regexp

[Eric Sunshine <sunshine@sunshineco.com>]

On Tue, Nov 22, 2022 at 3:29 PM Andreas Hasenack via GitGitGadget
<gitgitgadget@gmail.com> wrote:
> git commit 29fb2ec384a867ca577335a12f4b45c184e7b642 introduced a
> function that gets the number of cores from /proc/cpuinfo on some
> systems, notably linux.

Thanks for diagnosing this problem and quickly submitting a patch.

I forgot to mention earlier that we typically cite other commits like this:

    29fb2ec384 (chainlint.pl: validate test scripts in parallel, 2022-09-01)

which you can generate automatically with:

    git log --pretty=reference -1 29fb2ec384

> The regexp it uses (^processor\s*:) fails to match the desired lines in
> the s390x architecture, where they look like this:
>
> processor 0: version = FF, identification = 148F67, machine = 2964
>
> As a result, on s390x that function returns 0 as the number of cores,
> and the chainlint.pl script exits without doing anything.

Makes sense. Well explained.

A separate problem is that chainlint.pl doesn't fall back to a
sensible non-zero value if ncores() returns 0 (or some other nonsense
value). That is, of course, outside the scope of the well-focused
problem fix which this standalone patch addresses. I may end up
submitting a fix separately to make it fall back sensibly.

> Signed-off-by: Andreas Hasenack <andreas.hasenack@canonical.com>
> ---
> diff --git a/t/chainlint.pl b/t/chainlint.pl
> @@ -656,7 +656,7 @@ sub ncores {
>         # Windows
>         return $ENV{NUMBER_OF_PROCESSORS} if exists($ENV{NUMBER_OF_PROCESSORS});
>         # Linux / MSYS2 / Cygwin / WSL
> -       do { local @ARGV='/proc/cpuinfo'; return scalar(grep(/^processor\s*:/, <>)); } if -r '/proc/cpuinfo';
> +       do { local @ARGV='/proc/cpuinfo'; return scalar(grep(/^processor[\s\d]*:/, <>)); } if -r '/proc/cpuinfo';
>         # macOS & BSD
>         return qx/sysctl -n hw.ncpu/ if $^O =~ /(?:^darwin$|bsd)/;
>         return 1;

As mentioned elsewhere[1], this code may eventually be dropped
altogether, but this fix is good to have in the meantime. Thanks.

[1]: https://lore.kernel.org/git/CAPig+cQrXb-YUSzmfgJ2PRoiOP3goVACRCrX9C39kf3oDH+BHg@mail.gmail.com/