linux-kernel - [PATCH v1 5/5] perf cpumap: Add checking for reference counter

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Message-Id: <20240925195325.426533-6-leo.yan@arm.com>
Date: Wed, 25 Sep 2024 20:53:25 +0100
From: Leo Yan <leo.yan@....com>
To: Arnaldo Carvalho de Melo <acme@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	"Liang, Kan" <kan.liang@...ux.intel.com>,
	James Clark <james.clark@...aro.org>,
	linux-perf-users@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Leo Yan <leo.yan@....com>
Subject: [PATCH v1 5/5] perf cpumap: Add checking for reference counter

For the CPU map merging and intersection cases, add an extra check for
the reference counter before releasing the last CPU map.

Signed-off-by: Leo Yan <leo.yan@....com>
---
 tools/perf/tests/cpumap.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/tools/perf/tests/cpumap.c b/tools/perf/tests/cpumap.c
index d5b6c450f5c9..0bcf603a0ccf 100644
--- a/tools/perf/tests/cpumap.c
+++ b/tools/perf/tests/cpumap.c
@@ -168,6 +168,16 @@ static int __test__cpu_map_merge(const char *lhs, const char *rhs, int nr, const
 	TEST_ASSERT_VAL("failed to merge map: bad result", !strcmp(buf, expected));
 	perf_cpu_map__put(a);
 	perf_cpu_map__put(b);
+
+	/*
+	 * If 'b' is a superset of 'a', 'c' points to the same map with the
+	 * map 'b'. In this case, the two owners 'b' and 'c' both point to the
+	 * same map. The owner 'b' has released the resource above but 'c'
+	 * still keeps the ownership, so the reference counter should be 1.
+	 */
+	TEST_ASSERT_VAL("unexpected refcnt: bad result",
+			refcount_read(perf_cpu_map__refcnt(c)) == 1);
+
 	perf_cpu_map__put(c);
 	return 0;
 }
@@ -208,6 +218,16 @@ static int __test__cpu_map_intersect(const char *lhs, const char *rhs, int nr, c
 	TEST_ASSERT_VAL("failed to intersect map: bad result", !strcmp(buf, expected));
 	perf_cpu_map__put(a);
 	perf_cpu_map__put(b);
+
+	/*
+	 * If 'b' is a subset of 'a', 'c' points to the same map with the
+	 * map 'b'. In this case, the two owners 'b' and 'c' both point to the
+	 * same map. The owner 'b' has released the resource above but 'c'
+	 * still keeps the ownership, so the reference counter should be 1.
+	 */
+	TEST_ASSERT_VAL("unexpected refcnt: bad result",
+			refcount_read(perf_cpu_map__refcnt(c)) == 1);
+
 	perf_cpu_map__put(c);
 	return 0;
 }
-- 
2.34.1