Re: [PATCH] gcc-plugins: Require utsrelease.h before scripts target

[Guenter Roeck <linux@roeck-us.net>]

On Mon, May 23, 2022 at 01:02:22PM -0700, Kees Cook wrote:
> The "utsrelease.h" target was in parallel with the "scripts" target,
> which meant -j1 or unlucky parallel builds from a distclean state would
> fail to build the GCC plugins.
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Link: https://lore.kernel.org/linux-mm/202205230239.EZxeZ3Fv-lkp@intel.com
> Reported-by: Guenter Roeck <linux@roeck-us.net>
> Link: https://lore.kernel.org/lkml/YouX6g1T7w3FDeM8@cmpxchg.org
> Fixes: 61f60bac8c05 ("gcc-plugins: Change all version strings match kernel")
> Cc: Guenter Roeck <linux@roeck-us.net>
> Cc: Masahiro Yamada <masahiroy@kernel.org>
> Cc: linux-kbuild@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

I was able to reproduce the problem with the following change
in Makefile.

 include/generated/utsrelease.h: include/config/kernel.release FORCE
+       sleep 2
        $(call filechk,utsrelease.h)

With this patch, the problem is gone.

Tested-by: Guenter Roeck <linux@roeck-us.net>

Guenter

> ---
>  Makefile                     | 2 +-
>  scripts/gcc-plugins/Makefile | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index 91c91fcf3c24..c04420d5aa3d 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1175,7 +1175,7 @@ include/config/kernel.release: FORCE
>  # Carefully list dependencies so we do not try to build scripts twice
>  # in parallel
>  PHONY += scripts
> -scripts: scripts_basic scripts_dtc
> +scripts: include/generated/utsrelease.h scripts_basic scripts_dtc
>  	$(Q)$(MAKE) $(build)=$(@)
>  
>  # Things we need to do before we recursively start building the kernel
> diff --git a/scripts/gcc-plugins/Makefile b/scripts/gcc-plugins/Makefile
> index 6f0aecad5d67..c29334669a16 100644
> --- a/scripts/gcc-plugins/Makefile
> +++ b/scripts/gcc-plugins/Makefile
> @@ -64,5 +64,5 @@ $(foreach m, $(notdir $(plugin-multi)), $(eval $(obj)/$m: $(addprefix $(obj)/, $
>  quiet_cmd_plugin_cxx_o_c = HOSTCXX $@
>        cmd_plugin_cxx_o_c = $(HOSTCXX) $(plugin_cxxflags) -c -o $@ $<
>  
> -$(plugin-objs): $(obj)/%.o: $(src)/%.c FORCE
> +$(plugin-objs): $(obj)/%.o: $(src)/%.c $(objdir)/include/generated/utsrelease.h FORCE
>  	$(call if_changed_dep,plugin_cxx_o_c)
> -- 
> 2.32.0
>