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

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

[Gaurav Sharma]

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@vger.kernel.org
Signed-off-by: Gaurav Sharma <mgsharm@amazon.com>
---
 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)

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

[sashiko-bot]

Sashiko AI review found 1 potential issue(s):
- [Medium] The patch breaks standalone compilation of `libperf` for unprivileged users and improperly pollutes the host filesystem for root users.
--

commit 208fe5b88e547b876734f4625a046aecb0847770
Author: Gaurav Sharma <sgaurav00719@gmail.com>

libperf: fix parallel build race with header install

This commit attempts to fix a race condition between the install_headers
and libperf.a targets when building with high parallelism. It does this
by making the libperf compilation target depend on install_headers.

> diff --git a/tools/lib/perf/Makefile b/tools/lib/perf/Makefile
> --- 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

Does this break standalone compilation of libperf for unprivileged users?

In a standalone build (e.g., make -C tools/lib/perf), variables like DESTDIR
and prefix default to empty strings. Because of this, it appears that
INSTALL_HDRS_PFX will evaluate to the absolute path /include/perf.

Won't forcing a standard compilation to execute system-level installation
steps abort the build with a 'Permission denied' error for unprivileged
users? For root users, will this unexpectedly write to /include/perf and
pollute the host's root filesystem outside of an explicit make install phase?

Would it be better to serialize the install_headers and compilation targets
in the caller (tools/perf/Makefile.perf) rather than within the library's
local build rules?

Serializing these targets in Makefile.perf would also resolve identical
pre-existing parallel build races in libapi, libbpf, libsubcmd, and
libsymbol which are not covered by this change.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260414071242.95637-1-mgsharm@amazon.com?part=1

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

[Ian Rogers]

On Tue, Apr 14, 2026 at 12:13 AM Gaurav Sharma <sgaurav00719@gmail.com> 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@vger.kernel.org
> Signed-off-by: Gaurav Sharma <mgsharm@amazon.com>

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)
>