linux-kernel - [PATCH v4 26/35] perf pmus: Prefer perf_pmu__scan over perf_pmus__for_each

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Date:   Fri, 26 May 2023 14:54:01 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Suzuki K Poulose <suzuki.poulose@....com>,
        Mike Leach <mike.leach@...aro.org>,
        Leo Yan <leo.yan@...aro.org>,
        John Garry <john.g.garry@...cle.com>,
        Will Deacon <will@...nel.org>,
        James Clark <james.clark@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Kajol Jain <kjain@...ux.ibm.com>,
        Jing Zhang <renyu.zj@...ux.alibaba.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Zhengjun Xing <zhengjun.xing@...ux.intel.com>,
        Ravi Bangoria <ravi.bangoria@....com>,
        Madhavan Srinivasan <maddy@...ux.ibm.com>,
        Athira Rajeev <atrajeev@...ux.vnet.ibm.com>,
        Ming Wang <wangming01@...ngson.cn>,
        Huacai Chen <chenhuacai@...nel.org>,
        Sandipan Das <sandipan.das@....com>,
        Dmitrii Dolgov <9erthalion6@...il.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Ali Saidi <alisaidi@...zon.com>, Rob Herring <robh@...nel.org>,
        Thomas Richter <tmricht@...ux.ibm.com>,
        Kang Minchul <tegongkang@...il.com>,
        linux-kernel@...r.kernel.org, coresight@...ts.linaro.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-perf-users@...r.kernel.org
Subject: [PATCH v4 26/35] perf pmus: Prefer perf_pmu__scan over perf_pmus__for_each_pmu

perf_pmus__for_each_pmu doesn't lazily initialize pmus making its use
error prone. Just use perf_pmu__scan as this only impacts
non-performance critical tests.

Signed-off-by: Ian Rogers <irogers@...gle.com>
Reviewed-by: Kan Liang <kan.liang@...ux.intel.com>
---
 tools/perf/bench/pmu-scan.c     |  6 ++----
 tools/perf/tests/event_groups.c |  7 ++-----
 tools/perf/tests/parse-events.c | 11 ++++-------
 tools/perf/util/pmus.h          |  2 --
 4 files changed, 8 insertions(+), 18 deletions(-)

diff --git a/tools/perf/bench/pmu-scan.c b/tools/perf/bench/pmu-scan.c
index f0f007843bb8..f4a6c37cbe27 100644
--- a/tools/perf/bench/pmu-scan.c
+++ b/tools/perf/bench/pmu-scan.c
@@ -40,13 +40,11 @@ static struct pmu_scan_result *results;
 
 static int save_result(void)
 {
-	struct perf_pmu *pmu;
+	struct perf_pmu *pmu = NULL;
 	struct list_head *list;
 	struct pmu_scan_result *r;
 
-	perf_pmu__scan(NULL);
-
-	perf_pmus__for_each_pmu(pmu) {
+	while ((pmu = perf_pmu__scan(pmu)) != NULL) {
 		r = realloc(results, (nr_pmus + 1) * sizeof(*r));
 		if (r == NULL)
 			return -ENOMEM;
diff --git a/tools/perf/tests/event_groups.c b/tools/perf/tests/event_groups.c
index 029442b4e9c6..3d9a2b524bba 100644
--- a/tools/perf/tests/event_groups.c
+++ b/tools/perf/tests/event_groups.c
@@ -50,13 +50,10 @@ static int event_open(int type, unsigned long config, int group_fd)
 
 static int setup_uncore_event(void)
 {
-	struct perf_pmu *pmu;
+	struct perf_pmu *pmu = NULL;
 	int i, fd;
 
-	if (list_empty(&pmus))
-		perf_pmu__scan(NULL);
-
-	perf_pmus__for_each_pmu(pmu) {
+	while ((pmu = perf_pmu__scan(pmu)) != NULL) {
 		for (i = 0; i < NR_UNCORE_PMUS; i++) {
 			if (!strcmp(uncore_pmus[i].name, pmu->name)) {
 				pr_debug("Using %s for uncore pmu event\n", pmu->name);
diff --git a/tools/perf/tests/parse-events.c b/tools/perf/tests/parse-events.c
index 72a10bed84fd..277607ede060 100644
--- a/tools/perf/tests/parse-events.c
+++ b/tools/perf/tests/parse-events.c
@@ -108,11 +108,11 @@ static int test__checkevent_raw(struct evlist *evlist)
 	TEST_ASSERT_VAL("wrong number of entries", 0 != evlist->core.nr_entries);
 
 	perf_evlist__for_each_evsel(&evlist->core, evsel) {
-		struct perf_pmu *pmu;
+		struct perf_pmu *pmu = NULL;
 		bool type_matched = false;
 
 		TEST_ASSERT_VAL("wrong config", test_perf_config(evsel, 0x1a));
-		perf_pmus__for_each_pmu(pmu) {
+		while ((pmu = perf_pmu__scan(pmu)) != NULL) {
 			if (pmu->type == evsel->attr.type) {
 				TEST_ASSERT_VAL("PMU type expected once", !type_matched);
 				type_matched = true;
@@ -2243,13 +2243,10 @@ static int test__terms2(struct test_suite *test __maybe_unused, int subtest __ma
 
 static int test__pmu_events(struct test_suite *test __maybe_unused, int subtest __maybe_unused)
 {
-	struct perf_pmu *pmu;
+	struct perf_pmu *pmu = NULL;
 	int ret = TEST_OK;
 
-	if (list_empty(&pmus))
-		perf_pmu__scan(NULL);
-
-	perf_pmus__for_each_pmu(pmu) {
+	while ((pmu = perf_pmu__scan(pmu)) != NULL) {
 		struct stat st;
 		char path[PATH_MAX];
 		struct dirent *ent;
diff --git a/tools/perf/util/pmus.h b/tools/perf/util/pmus.h
index d475e2960c10..257de10788e8 100644
--- a/tools/perf/util/pmus.h
+++ b/tools/perf/util/pmus.h
@@ -5,8 +5,6 @@
 extern struct list_head pmus;
 struct perf_pmu;
 
-#define perf_pmus__for_each_pmu(pmu) list_for_each_entry(pmu, &pmus, list)
-
 const struct perf_pmu *perf_pmus__pmu_for_pmu_filter(const char *str);
 
 #endif /* __PMUS_H */
-- 
2.41.0.rc0.172.g3f132b7071-goog