linux-kernel - [PATCH 1/3] perf pmu: Dynamically allocate tool PMU

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Message-Id: <20250225164639.522741-2-james.clark@linaro.org>
Date: Tue, 25 Feb 2025 16:46:28 +0000
From: James Clark <james.clark@...aro.org>
To: linux-perf-users@...r.kernel.org,
	irogers@...gle.com,
	namhyung@...nel.org,
	cyy@...self.name
Cc: James Clark <james.clark@...aro.org>,
	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>,
	Adrian Hunter <adrian.hunter@...el.com>,
	"Liang, Kan" <kan.liang@...ux.intel.com>,
	Yoshihiro Furudera <fj5100bi@...itsu.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Weilin Wang <weilin.wang@...el.com>,
	Junhao He <hejunhao3@...wei.com>,
	Jean-Philippe Romain <jean-philippe.romain@...s.st.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/3] perf pmu: Dynamically allocate tool PMU

perf_pmus__destroy() treats all PMUs as allocated and free's them so we
can't have any static PMUs that are added to the PMU lists. Fix it by
allocating the tool PMU in the same way as the others. Current users of
the tool PMU already use find_pmu() and not perf_pmus__tool_pmu(), so
rename the function to add 'new' to avoid it being misused in the
future.

perf_pmus__fake_pmu() can remain as static as it's not added to the
PMU lists.

Fixes the following error:

  $ perf bench internals pmu-scan

  # Running 'internals/pmu-scan' benchmark:
  Computing performance of sysfs PMU event scan for 100 times
  munmap_chunk(): invalid pointer
  Aborted (core dumped)

Fixes: 240505b2d0ad ("perf tool_pmu: Factor tool events into their own PMU")
Signed-off-by: James Clark <james.clark@...aro.org>
---
 tools/perf/util/pmus.c     |  2 +-
 tools/perf/util/tool_pmu.c | 23 +++++++++++------------
 tools/perf/util/tool_pmu.h |  2 +-
 3 files changed, 13 insertions(+), 14 deletions(-)

diff --git a/tools/perf/util/pmus.c b/tools/perf/util/pmus.c
index 8a0a919415d4..c1815edaca37 100644
--- a/tools/perf/util/pmus.c
+++ b/tools/perf/util/pmus.c
@@ -268,7 +268,7 @@ static void pmu_read_sysfs(unsigned int to_read_types)
 
 	if ((to_read_types & PERF_TOOL_PMU_TYPE_TOOL_MASK) != 0 &&
 	    (read_pmu_types & PERF_TOOL_PMU_TYPE_TOOL_MASK) == 0) {
-		tool_pmu = perf_pmus__tool_pmu();
+		tool_pmu = perf_pmus__new_tool_pmu();
 		list_add_tail(&tool_pmu->list, &other_pmus);
 	}
 	if ((to_read_types & PERF_TOOL_PMU_TYPE_HWMON_MASK) != 0 &&
diff --git a/tools/perf/util/tool_pmu.c b/tools/perf/util/tool_pmu.c
index 3a68debe7143..45eae810b205 100644
--- a/tools/perf/util/tool_pmu.c
+++ b/tools/perf/util/tool_pmu.c
@@ -490,17 +490,16 @@ int evsel__tool_pmu_read(struct evsel *evsel, int cpu_map_idx, int thread)
 	return 0;
 }
 
-struct perf_pmu *perf_pmus__tool_pmu(void)
+struct perf_pmu *perf_pmus__new_tool_pmu(void)
 {
-	static struct perf_pmu tool = {
-		.name = "tool",
-		.type = PERF_PMU_TYPE_TOOL,
-		.aliases = LIST_HEAD_INIT(tool.aliases),
-		.caps = LIST_HEAD_INIT(tool.caps),
-		.format = LIST_HEAD_INIT(tool.format),
-	};
-	if (!tool.events_table)
-		tool.events_table = find_core_events_table("common", "common");
-
-	return &tool;
+	struct perf_pmu *tool = zalloc(sizeof(struct perf_pmu));
+
+	tool->name = strdup("tool");
+	tool->type = PERF_PMU_TYPE_TOOL;
+	INIT_LIST_HEAD(&tool->aliases);
+	INIT_LIST_HEAD(&tool->caps);
+	INIT_LIST_HEAD(&tool->format);
+	tool->events_table = find_core_events_table("common", "common");
+
+	return tool;
 }
diff --git a/tools/perf/util/tool_pmu.h b/tools/perf/util/tool_pmu.h
index a60184859080..268f05064d03 100644
--- a/tools/perf/util/tool_pmu.h
+++ b/tools/perf/util/tool_pmu.h
@@ -51,6 +51,6 @@ int evsel__tool_pmu_open(struct evsel *evsel,
 			 int start_cpu_map_idx, int end_cpu_map_idx);
 int evsel__tool_pmu_read(struct evsel *evsel, int cpu_map_idx, int thread);
 
-struct perf_pmu *perf_pmus__tool_pmu(void);
+struct perf_pmu *perf_pmus__new_tool_pmu(void);
 
 #endif /* __TOOL_PMU_H */
-- 
2.34.1