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Date:   Fri, 28 Jul 2023 11:09:32 -0300
From:   Arnaldo Carvalho de Melo <acme@kernel.org>
To:     Namhyung Kim <namhyung@kernel.org>
Cc:     Jiri Olsa <jolsa@kernel.org>, Ian Rogers <irogers@google.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-perf-users@vger.kernel.org,
        Anup Sharma <anupnewsmail@gmail.com>, stable@vger.kernel.org
Subject: Re: [PATCH v2 1/2] perf build: Update build rule for generated files
Message-ID: <ZMPMHNjX2IxsLbAe@kernel.org>
References: <20230728022447.1323563-1-namhyung@kernel.org>
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Em Thu, Jul 27, 2023 at 07:24:46PM -0700, Namhyung Kim escreveu:
> The bison and flex generate C files from the source (.y and .l)
> files.  When O= option is used, they are saved in a separate directory
> but the default build rule assumes the .C files are in the source
> directory.  So it might read invalid file if there are generated files
> from an old version.  The same is true for the pmu-events files.
> 
> For example, the following command would cause a build failure:
> 
>   $ git checkout v6.3
>   $ make -C tools/perf  # build in the same directory
> 
>   $ git checkout v6.5-rc2
>   $ mkdir build  # create a build directory
>   $ make -C tools/perf O=build  # build in a different directory but it
>                                 # refers files in the source directory
> 
> Let's update the build rule to specify those cases explicitly to depend
> on the files in the output directory.
> 
> Note that it's not a complete fix and it needs the next patch for the
> include path too.

Applied, testing it on the container builds.

- Arnaldo
 
> Fixes: 80eeb67fe577 ("perf jevents: Program to convert JSON file")
> Cc: stable@vger.kernel.org
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---
>  tools/build/Makefile.build  | 10 ++++++++++
>  tools/perf/pmu-events/Build |  6 ++++++
>  2 files changed, 16 insertions(+)
> 
> diff --git a/tools/build/Makefile.build b/tools/build/Makefile.build
> index 89430338a3d9..fac42486a8cf 100644
> --- a/tools/build/Makefile.build
> +++ b/tools/build/Makefile.build
> @@ -117,6 +117,16 @@ $(OUTPUT)%.s: %.c FORCE
>  	$(call rule_mkdir)
>  	$(call if_changed_dep,cc_s_c)
>  
> +# bison and flex files are generated in the OUTPUT directory
> +# so it needs a separate rule to depend on them properly
> +$(OUTPUT)%-bison.o: $(OUTPUT)%-bison.c FORCE
> +	$(call rule_mkdir)
> +	$(call if_changed_dep,$(host)cc_o_c)
> +
> +$(OUTPUT)%-flex.o: $(OUTPUT)%-flex.c FORCE
> +	$(call rule_mkdir)
> +	$(call if_changed_dep,$(host)cc_o_c)
> +
>  # Gather build data:
>  #   obj-y        - list of build objects
>  #   subdir-y     - list of directories to nest
> diff --git a/tools/perf/pmu-events/Build b/tools/perf/pmu-events/Build
> index 150765f2baee..1d18bb89402e 100644
> --- a/tools/perf/pmu-events/Build
> +++ b/tools/perf/pmu-events/Build
> @@ -35,3 +35,9 @@ $(PMU_EVENTS_C): $(JSON) $(JSON_TEST) $(JEVENTS_PY) $(METRIC_PY) $(METRIC_TEST_L
>  	$(call rule_mkdir)
>  	$(Q)$(call echo-cmd,gen)$(PYTHON) $(JEVENTS_PY) $(JEVENTS_ARCH) $(JEVENTS_MODEL) pmu-events/arch $@
>  endif
> +
> +# pmu-events.c file is generated in the OUTPUT directory so it needs a
> +# separate rule to depend on it properly
> +$(OUTPUT)pmu-events/pmu-events.o: $(PMU_EVENTS_C)
> +	$(call rule_mkdir)
> +	$(call if_changed_dep,cc_o_c)
> -- 
> 2.41.0.487.g6d72f3e995-goog
> 

-- 

- Arnaldo