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

[Gaurav Sharma <sgaurav00719@gmail.com>]

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)