[PATCH] perf build: prevent "argument list too long" error

[Markus Mayer]

Due to a recent change, building perf may result in a build error when
it is trying to "prune orphans". The file list passed to "rm" may exceed
what the shell can handle. The build will then abort with an error like
this:

  TEST    [...]/arm64/build/linux-custom/tools/perf/pmu-events/metric_test.log
make[5]: /bin/sh: Argument list too long
make[5]: *** [pmu-events/Build:217: prune_orphans] Error 127
make[5]: *** Waiting for unfinished jobs....
make[4]: *** [Makefile.perf:773: [...]/tools/perf/pmu-events/pmu-events-in.o] Error 2
make[4]: *** Waiting for unfinished jobs....
make[3]: *** [Makefile.perf:289: sub-make] Error 2

Processing the arguments via "xargs", instead of passing the list of
files directly to "rm" via the shell, prevents this issue.

Fixes: 36a1b0061a5 (perf build: Reduce pmu-events related copying and mkdirs)
Signed-off-by: Markus Mayer <mmayer@xxxxxxxxxxxx>
---
 tools/perf/pmu-events/Build | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/perf/pmu-events/Build b/tools/perf/pmu-events/Build
index 63c65788d442..dc5f94862a3b 100644
--- a/tools/perf/pmu-events/Build
+++ b/tools/perf/pmu-events/Build
@@ -214,7 +214,8 @@ ifneq ($(strip $(ORPHAN_FILES)),)
 quiet_cmd_rm  = RM      $^
 
 prune_orphans: $(ORPHAN_FILES)
-	$(Q)$(call echo-cmd,rm)rm -f $^
+	# The list of files can be long. Use xargs to prevent issues.
+	$(Q)$(call echo-cmd,rm)echo "$^" | xargs rm -f
 
 JEVENTS_DEPS += prune_orphans
 endif
-- 
2.52.0