Re: [PATCH] libperf: fix parallel build race with header install

[Ian Rogers]

On Tue, Apr 14, 2026 at 12:13 AM Gaurav Sharma <sgaurav00719@xxxxxxxxx> wrote:
>
> When perf is built with high parallelism (-j128), there is a race
> condition between the install_headers and libperf.a targets in the
> libperf sub-build. Both are invoked as targets of a single make
> invocation from Makefile.perf:
>
>   $(MAKE) -C $(LIBPERF_DIR) ... $@ install_headers
>
> The perf tool's exported CFLAGS includes -I$(LIBPERF_OUTPUT)/include
> which points to the header install destination. The coreutils install
> command creates the destination file (truncated) before writing content.
> If the compiler runs between file creation and content write, it
> includes an empty header, causing incomplete type and missing prototype
> errors in the libperf source files.
>
> Fix this by making the libperf compilation target depend on
> install_headers, ensuring all headers are fully installed before any
> source files are compiled.
>
> Fixes: 91009a3a9913 ("perf build: Install libperf locally when building")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Gaurav Sharma <mgsharm@xxxxxxxxxx>

I believe this was addressed by:
https://web.git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/commit/tools/lib/perf/Makefile?h=perf-tools-next&id=8c5b40678c63be6b85f1c2dc8c8b89d632faf988

Thanks,
Ian

> ---
>  tools/lib/perf/Makefile | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/lib/perf/Makefile b/tools/lib/perf/Makefile
> index 32301a1d8f0c..8372cd9919b7 100644
> --- a/tools/lib/perf/Makefile
> +++ b/tools/lib/perf/Makefile
> @@ -99,7 +99,7 @@ $(LIBAPI)-clean:
>         $(call QUIET_CLEAN, libapi)
>         $(Q)$(MAKE) -C $(LIB_DIR) O=$(OUTPUT) clean >/dev/null
>
> -$(LIBPERF_IN): FORCE
> +$(LIBPERF_IN): install_headers FORCE
>         $(Q)$(MAKE) $(build)=libperf
>
>  $(LIBPERF_A): $(LIBPERF_IN)
> --
> 2.50.1 (Apple Git-155)
>