linux-kernel - Re: [PATCH] kbuild: set EXIT trap before creating temporary directory

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Date:   Tue, 2 Aug 2022 10:52:08 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Masahiro Yamada <masahiroy@...nel.org>
Cc:     linux-kbuild@...r.kernel.org,
        David Laight <David.Laight@...lab.com>,
        Michal Marek <michal.lkml@...kovi.net>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kbuild: set EXIT trap before creating temporary directory

On Wed, Jul 27, 2022 at 8:17 PM Masahiro Yamada <masahiroy@...nel.org> wrote:
>
> Swap the order of 'mkdir' and 'trap' just in case the subshell is
> interrupted between 'mkdir' and 'trap' although the effect might be
> subtle.
>
> Please not this is not a perfect solution to avoid the left-over tmp
> directory. There are more cases that miss to remove the tmp directory,
> for example:
>
>  - When interrupted, dash does not invoke the EXIT trap (bash does)
>
>  - 'rm' command might be interrupted before removing the directory
>
> I am not addressing all the cases since the tmp directory is harmless
> after all.
>
> Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>

Thanks for the patch!
Reviewed-by: Nick Desaulniers <ndesaulniers@...gle.com>

> ---
>
>  scripts/Kconfig.include   | 2 +-
>  scripts/Makefile.compiler | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/scripts/Kconfig.include b/scripts/Kconfig.include
> index c1f4222d223d..a0ccceb22cf8 100644
> --- a/scripts/Kconfig.include
> +++ b/scripts/Kconfig.include
> @@ -25,7 +25,7 @@ failure = $(if-success,$(1),n,y)
>
>  # $(cc-option,<flag>)
>  # Return y if the compiler supports <flag>, n otherwise
> -cc-option = $(success,mkdir .tmp_$$; trap "rm -rf .tmp_$$" EXIT; $(CC) -Werror $(CLANG_FLAGS) $(1) -c -x c /dev/null -o .tmp_$$/tmp.o)
> +cc-option = $(success,trap "rm -rf .tmp_$$" EXIT; mkdir .tmp_$$; $(CC) -Werror $(CLANG_FLAGS) $(1) -c -x c /dev/null -o .tmp_$$/tmp.o)
>
>  # $(ld-option,<flag>)
>  # Return y if the linker supports <flag>, n otherwise
> diff --git a/scripts/Makefile.compiler b/scripts/Makefile.compiler
> index 86ecd2ac874c..94d0d40cddb3 100644
> --- a/scripts/Makefile.compiler
> +++ b/scripts/Makefile.compiler
> @@ -21,8 +21,8 @@ TMPOUT = $(if $(KBUILD_EXTMOD),$(firstword $(KBUILD_EXTMOD))/).tmp_$$$$
>  # automatically cleaned up.
>  try-run = $(shell set -e;              \
>         TMP=$(TMPOUT)/tmp;              \
> -       mkdir -p $(TMPOUT);             \
>         trap "rm -rf $(TMPOUT)" EXIT;   \
> +       mkdir -p $(TMPOUT);             \
>         if ($(1)) >/dev/null 2>&1;      \
>         then echo "$(2)";               \
>         else echo "$(3)";               \
> --
> 2.34.1
>


-- 
Thanks,
~Nick Desaulniers