[PATCH V2] tools/perf: Add includes for detected configs in Makefile.perf

[Ian Rogers]

On Fri, Sep 8, 2023 at 7:51 AM Athira Rajeev
<atrajeev at linux.vnet.ibm.com> wrote:
>
> Makefile.perf uses "CONFIG_*" checks in the code. Example the config
> for libtraceevent is used to set PYTHON_EXT_SRCS
>
>         ifeq ($(CONFIG_LIBTRACEEVENT),y)
>           PYTHON_EXT_SRCS := $(shell grep -v ^\# util/python-ext-sources)
>         else
>           PYTHON_EXT_SRCS := $(shell grep -v '^\#\|util/trace-event.c' util/python-ext-sources)
>         endif
>
> But this is not picking the value for CONFIG_LIBTRACEEVENT that is
> set using the settings in Makefile.config. Include the file
> ".config-detected" so that make will use the system detected
> configuration in the CONFIG checks. This will fix isues that
> could arise when other "CONFIG_*" checks are added to Makefile.perf
> in future as well.
>
> Signed-off-by: Athira Rajeev <atrajeev at linux.vnet.ibm.com>
> ---
> Changelog:
>  v1 -> v2:
>  Added $(OUTPUT) prefix to config-detected as pointed
>  out by Ian
>
>  tools/perf/Makefile.perf | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
> index 37af6df7b978..66b9dc61c32f 100644
> --- a/tools/perf/Makefile.perf
> +++ b/tools/perf/Makefile.perf
> @@ -351,6 +351,9 @@ export PYTHON_EXTBUILD_LIB PYTHON_EXTBUILD_TMP
>
>  python-clean := $(call QUIET_CLEAN, python) $(RM) -r $(PYTHON_EXTBUILD) $(OUTPUT)python/perf*.so
>
> +# Use the detected configuration
> +include $(OUTPUT).config-detected

The Makefile.build version also has a "-include" rather than "include"
in case the .config-detected file is missing. In Makefile.perf
including Makefile.config is optional:
https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/perf/Makefile.perf?h=perf-tools-next#n253

and there are certain targets that where we don't include it:
https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/perf/Makefile.perf?h=perf-tools-next#n200

So playing devil's advocate, if we ran "make clean" we'd remove
.config-detected:
https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/perf/Makefile.perf?h=perf-tools-next#n1131

If we then ran "make tags" then we wouldn't include Makefile.config
and so .config-detected wouldn't be generated and I think the build
would fail due to a missing include here. So I think this should be
-include or perhaps:

ifeq ($(config),1)
include $(OUTPUT).config-detected
endif

Thanks,
Ian

> +
>  ifeq ($(CONFIG_LIBTRACEEVENT),y)
>    PYTHON_EXT_SRCS := $(shell grep -v ^\# util/python-ext-sources)
>  else
> --
> 2.31.1
>