linux-kernel - Re: [PATCH v2 3/3] perf cpumap: Add checking for reference counter

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Message-ID: <a584b2da-7463-41c4-885c-1ff13e69b08a@intel.com>
Date: Fri, 15 Nov 2024 10:49:01 +0200
From: Adrian Hunter <adrian.hunter@...el.com>
To: Leo Yan <leo.yan@....com>, Arnaldo Carvalho de Melo <acme@...nel.org>,
 Ian Rogers <irogers@...gle.com>, Namhyung Kim <namhyung@...nel.org>,
 Mark Rutland <mark.rutland@....com>,
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
 Jiri Olsa <jolsa@...nel.org>, "Liang, Kan" <kan.liang@...ux.intel.com>,
 James Clark <james.clark@...aro.org>, linux-perf-users@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/3] perf cpumap: Add checking for reference counter

On 7/11/24 14:53, Leo Yan wrote:
> For the CPU map merging test, add an extra check for the reference
> counter before releasing the last CPU map.
> 
> Signed-off-by: Leo Yan <leo.yan@....com>

Reviewed-by: Adrian Hunter <adrian.hunter@...el.com>

> ---
>  tools/perf/tests/cpumap.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/tools/perf/tests/cpumap.c b/tools/perf/tests/cpumap.c
> index f8187a801b8e..5ed7ff072ea3 100644
> --- a/tools/perf/tests/cpumap.c
> +++ b/tools/perf/tests/cpumap.c
> @@ -167,6 +167,15 @@ static int __test__cpu_map_merge(const char *lhs, const char *rhs, int nr, const
>  	cpu_map__snprint(a, buf, sizeof(buf));
>  	TEST_ASSERT_VAL("failed to merge map: bad result", !strcmp(buf, expected));
>  	perf_cpu_map__put(b);
> +
> +	/*
> +	 * If 'b' is a superset of 'a', 'a' points to the same map with the
> +	 * map 'b'. In this case, the owner 'b' has released the resource above
> +	 * but 'a' still keeps the ownership, the reference counter should be 1.
> +	 */
> +	TEST_ASSERT_VAL("unexpected refcnt: bad result",
> +			refcount_read(perf_cpu_map__refcnt(a)) == 1);
> +
>  	perf_cpu_map__put(a);
>  	return 0;
>  }