Re: [PATCH stable 7.0] perf build: fix "argument list too long" in second location

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] The fix for the 'Argument list too long' build error is incomplete. It reduces the shell command length by removing the file list from the 'RM' output, but still embeds the full file list via `echo "$^"` within the shell command executed by Make. This means the build will still fail with the exact same E2BIG error if the number of files increases further or if the build directory has a long absolute path.
--

commit 3997e5cf292c966edf5b226f773ec398849158ff
Author: Markus Mayer <mmayer@broadcom.com>

perf build: fix "argument list too long" in second location

This commit addresses an "argument list too long" build error by replacing
the explicit file list in quiet_cmd_rm with a file count. It also moves a
comment about xargs above the rule.

> diff --git a/tools/perf/pmu-events/Build b/tools/perf/pmu-events/Build
> index dc5f94862a3bc..dc1df2d57ddc1 100644
> --- a/tools/perf/pmu-events/Build
> +++ b/tools/perf/pmu-events/Build
> @@ -211,10 +211,10 @@ ifneq ($(strip $(ORPHAN_FILES)),)
>  
>  # Message for $(call echo-cmd,rm). Generally cleaning files isn't part
>  # of a build step.
> -quiet_cmd_rm  = RM      $^
> +quiet_cmd_rm = RM      ...$(words $^) orphan file(s)...
>  
> +# The list of files can be long. Use xargs to prevent issues.
>  prune_orphans: $(ORPHAN_FILES)
> -	# The list of files can be long. Use xargs to prevent issues.
>  	$(Q)$(call echo-cmd,rm)echo "$^" | xargs rm -f

Is the fix for the argument list too long error complete here?

When Make executes a recipe containing shell operators (like |), it spawns
/bin/sh -c "<recipe>". The entire recipe string is passed as argv[2] to
the shell, which is subject to the Linux MAX_ARG_STRLEN limit.

By removing $^ from quiet_cmd_rm, this change reduces the size of the
recipe string, which might temporarily drop it below the limit for the
current number of files.

However, echo "$^" | xargs rm -f still embeds the full file list directly
into the shell argument. If the path lengths or file count grow further,
couldn't this still exceed MAX_ARG_STRLEN and break the build?

Would it be more robust to bypass the shell argument limits entirely, for
instance by using Make's $(file ...) function to write the list directly
to a file?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260513234639.128528-1-florian.fainelli@broadcom.com?part=1