[PATCH V2] tools/perf: Add perf binary dependent rule for shellcheck log in Makefile.perf

[Athira Rajeev <atrajeev@linux.vnet.ibm.com>]

Add rule in new Makefile "tests/Makefile.tests" for running
shellcheck on shell test scripts. This automates below shellcheck
into the build.

	$ for F in $(find tests/shell/ -perm -o=x -name '*.sh'); do shellcheck -S warning $F; done

Condition for shellcheck is added in Makefile.perf to avoid build
breakage in the absence of shellcheck binary. Update Makefile.perf
to contain new rule for "SHELLCHECK_TEST" which is for making
shellcheck test as a dependency on perf binary. Added
"tests/Makefile.tests" to run shellcheck on shellscripts in
tests/shell. The make rule "SHLLCHECK_RUN" ensures that, every
time during make, shellcheck will be run only on modified files
during subsequent invocations. By this, if any newly added shell
scripts or fixes in existing scripts breaks coding/formatting
style, it will get captured during the perf build.

Example build failure with present scripts in tests/shell:

	INSTALL libsubcmd_headers
	INSTALL libperf_headers
	INSTALL libapi_headers
	INSTALL libsymbol_headers
	INSTALL libbpf_headers
	make[3]: *** [/root/athira/namhyung/perf-tools-next/tools/perf/tests/Makefile.tests:17: output/tests/shell/record_sideband.dep] Error 1
	make[3]: *** Waiting for unfinished jobs....
	make[3]: *** [/root/athira/namhyung/perf-tools-next/tools/perf/tests/Makefile.tests:17: output/tests/shell/test_arm_coresight.dep] Error 1
	make[3]: *** [/root/athira/namhyung/perf-tools-next/tools/perf/tests/Makefile.tests:17: output/tests/shell/lock_contention.dep] Error 1
	make[2]: *** [Makefile.perf:675: SHELLCHECK_TEST] Error 2
	make[1]: *** [Makefile.perf:238: sub-make] Error 2
	make: *** [Makefile:70: all] Error 2

After this, for testing, changed "tests/shell/record.sh" to
break shellcheck format. In the next make run, it is
also captured:

	make[3]: *** [/root/athira/namhyung/perf-tools-next/tools/perf/tests/Makefile.tests:17: output/tests/shell/record_sideband.dep] Error 1
	make[3]: *** Waiting for unfinished jobs....
	make[3]: *** [/root/athira/namhyung/perf-tools-next/tools/perf/tests/Makefile.tests:17: output/tests/shell/record.dep] Error 1
	make[3]: *** [/root/athira/namhyung/perf-tools-next/tools/perf/tests/Makefile.tests:17: output/tests/shell/test_arm_coresight.dep] Error 1
	make[3]: *** [/root/athira/namhyung/perf-tools-next/tools/perf/tests/Makefile.tests:17: output/tests/shell/lock_contention.dep] Error 1
	make[2]: *** [Makefile.perf:675: SHELLCHECK_TEST] Error 2
	make[1]: *** [Makefile.perf:238: sub-make] Error 2
	make: *** [Makefile:70: all] Error 2

Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
---
Changelog:
 v1 -> v2:
 Version1 had shellcheck in feature check which is not
 required since shellcheck is already a binary. Presence
 of binary can be checked using:
 $(shell command -v shellcheck)
 Addressed these changes as suggested by Namhyung in V2
 Feature test logic is removed in V2. Also added example
 for build breakage when shellcheck fails in commit message

 tools/perf/Makefile.perf        | 14 +++++++++++++-
 tools/perf/tests/Makefile.tests | 24 ++++++++++++++++++++++++
 2 files changed, 37 insertions(+), 1 deletion(-)
 create mode 100644 tools/perf/tests/Makefile.tests

diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index 98604e396ac3..56a66ca253ab 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -667,7 +667,18 @@ $(PERF_IN): prepare FORCE
 $(PMU_EVENTS_IN): FORCE prepare
 	$(Q)$(MAKE) -f $(srctree)/tools/build/Makefile.build dir=pmu-events obj=pmu-events
 
-$(OUTPUT)perf: $(PERFLIBS) $(PERF_IN) $(PMU_EVENTS_IN)
+# Runs shellcheck on perf test shell scripts
+
+SHELLCHECK := $(shell command -v shellcheck)
+ifneq ($(SHELLCHECK),)
+SHELLCHECK_TEST: FORCE prepare
+	$(Q)$(MAKE) -f $(srctree)/tools/perf/tests/Makefile.tests
+else
+SHELLCHECK_TEST:
+	@:
+endif
+
+$(OUTPUT)perf: $(PERFLIBS) $(PERF_IN) $(PMU_EVENTS_IN) SHELLCHECK_TEST
 	$(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) \
 		$(PERF_IN) $(PMU_EVENTS_IN) $(LIBS) -o $@
 
@@ -1130,6 +1141,7 @@ bpf-skel-clean:
 	$(call QUIET_CLEAN, bpf-skel) $(RM) -r $(SKEL_TMP_OUT) $(SKELETONS)
 
 clean:: $(LIBAPI)-clean $(LIBBPF)-clean $(LIBSUBCMD)-clean $(LIBSYMBOL)-clean $(LIBPERF)-clean fixdep-clean python-clean bpf-skel-clean tests-coresight-targets-clean
+	$(Q)$(MAKE) -f $(srctree)/tools/perf/tests/Makefile.tests clean
 	$(call QUIET_CLEAN, core-objs)  $(RM) $(LIBPERF_A) $(OUTPUT)perf-archive $(OUTPUT)perf-iostat $(LANG_BINDINGS)
 	$(Q)find $(or $(OUTPUT),.) -name '*.o' -delete -o -name '\.*.cmd' -delete -o -name '\.*.d' -delete
 	$(Q)$(RM) $(OUTPUT).config-detected
diff --git a/tools/perf/tests/Makefile.tests b/tools/perf/tests/Makefile.tests
new file mode 100644
index 000000000000..8011e99768a3
--- /dev/null
+++ b/tools/perf/tests/Makefile.tests
@@ -0,0 +1,24 @@
+# SPDX-License-Identifier: GPL-2.0
+# Athira Rajeev <atrajeev@linux.vnet.ibm.com>, 2023
+
+PROGS = $(subst ./,,$(shell find tests/shell -perm -o=x -type f -name '*.sh'))
+DEPS = $(addprefix output/,$(addsuffix .dep,$(basename $(PROGS))))
+DIRS = $(shell echo $(dir $(DEPS)) | xargs -n1 | sort -u | xargs)
+
+.PHONY: all
+all: SHELLCHECK_RUN
+	@:
+
+SHELLCHECK_RUN: $(DEPS) $(DIRS)
+
+output/%.dep: %.sh | $(DIRS)
+	$(call rule_mkdir)
+	$(eval input_file := $(subst output/,./,$(patsubst %.dep, %.sh, $@)))
+	$(Q)$(call frecho-cmd,test)@shellcheck -S warning ${input_file} 1> $@.log && ([[ ! -s $@.log ]])
+	$(Q)$(call frecho-cmd,test)@touch $@
+	$(Q)$(call frecho-cmd,test)@rm -rf $@.log
+$(DIRS):
+	@mkdir -p $@
+
+clean:
+	@rm -rf output
-- 
2.31.1