linux-kernel - [PATCH v4 08/35] perf pmu: Add CPU map for "cpu" PMUs

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Message-Id: <20230526215410.2435674-9-irogers@google.com>
Date:   Fri, 26 May 2023 14:53:43 -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 08/35] perf pmu: Add CPU map for "cpu" PMUs

A typical "cpu" PMU has no "cpus" or "cpumask" file meaning the CPU
map is set to NULL, which also encodes an empty CPU map. Update
pmu_cpumask so that if the "cpu" PMU fails to load a CPU map, use a
default of all online PMUs.

Remove const from cpu_map__online for the sake of reference counting.

Signed-off-by: Ian Rogers <irogers@...gle.com>
Reviewed-by: Kan Liang <kan.liang@...ux.intel.com>
---
 tools/perf/util/cpumap.c | 4 ++--
 tools/perf/util/cpumap.h | 4 ++--
 tools/perf/util/pmu.c    | 2 +-
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/tools/perf/util/cpumap.c b/tools/perf/util/cpumap.c
index 75d9c73e0184..75c5bed37805 100644
--- a/tools/perf/util/cpumap.c
+++ b/tools/perf/util/cpumap.c
@@ -663,9 +663,9 @@ size_t cpu_map__snprint_mask(struct perf_cpu_map *map, char *buf, size_t size)
 	return ptr - buf;
 }
 
-const struct perf_cpu_map *cpu_map__online(void) /* thread unsafe */
+struct perf_cpu_map *cpu_map__online(void) /* thread unsafe */
 {
-	static const struct perf_cpu_map *online = NULL;
+	static struct perf_cpu_map *online;
 
 	if (!online)
 		online = perf_cpu_map__new(NULL); /* from /sys/devices/system/cpu/online */
diff --git a/tools/perf/util/cpumap.h b/tools/perf/util/cpumap.h
index e3426541e0aa..05201b31810c 100644
--- a/tools/perf/util/cpumap.h
+++ b/tools/perf/util/cpumap.h
@@ -48,7 +48,7 @@ struct perf_cpu_map *cpu_map__new_data(const struct perf_record_cpu_map_data *da
 size_t cpu_map__snprint(struct perf_cpu_map *map, char *buf, size_t size);
 size_t cpu_map__snprint_mask(struct perf_cpu_map *map, char *buf, size_t size);
 size_t cpu_map__fprintf(struct perf_cpu_map *map, FILE *fp);
-const struct perf_cpu_map *cpu_map__online(void); /* thread unsafe */
+struct perf_cpu_map *cpu_map__online(void); /* thread unsafe */
 
 int cpu__setup_cpunode_map(void);
 
@@ -59,7 +59,7 @@ struct perf_cpu cpu__max_present_cpu(void);
 /**
  * cpu_map__is_dummy - Events associated with a pid, rather than a CPU, use a single dummy map with an entry of -1.
  */
-static inline bool cpu_map__is_dummy(struct perf_cpu_map *cpus)
+static inline bool cpu_map__is_dummy(const struct perf_cpu_map *cpus)
 {
 	return perf_cpu_map__nr(cpus) == 1 && perf_cpu_map__cpu(cpus, 0).cpu == -1;
 }
diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index e8c0762c311a..d992f5242d99 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -610,7 +610,7 @@ static struct perf_cpu_map *pmu_cpumask(int dirfd, const char *name)
 			return cpus;
 	}
 
-	return NULL;
+	return !strcmp(name, "cpu") ? perf_cpu_map__get(cpu_map__online()) : NULL;
 }
 
 static bool pmu_is_uncore(int dirfd, const char *name)
-- 
2.41.0.rc0.172.g3f132b7071-goog