Re: [PATCH 4/5] perf stat: Avoid segv if core.user_cpus isn't set.

From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Ian Rogers <irogers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@kernel.org>, Namhyung Kim <namhyung@kernel.org>,
	Mathieu Poirier <mathieu.poirier@linaro.org>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Mike Leach <mike.leach@linaro.org>, Leo Yan <leo.yan@linaro.org>,
	John Garry <john.garry@huawei.com>, Will Deacon <will@kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
	Yonghong Song <yhs@fb.com>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>, Kajol Jain <kjain@linux.ibm.com>,
	James Clark <james.clark@arm.com>,
	German Gomez <german.gomez@arm.com>,
	Adrian Hunter <adrian.hunter@intel.com>,
	Riccardo Mancini <rickyman7@gmail.com>,
	Andi Kleen <ak@linux.intel.com>,
	Alexey Bayduraev <alexey.v.bayduraev@linux.intel.com>,
	Alexander Antonov <alexander.antonov@linux.intel.com>,
	linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
	coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org,
	netdev@vger.kernel.org, bpf@vger.kernel.org,
	Stephane Eranian <eranian@google.com>
Subject: Re: [PATCH 4/5] perf stat: Avoid segv if core.user_cpus isn't set.
Date: Mon, 28 Mar 2022 17:32:31 -0300	[thread overview]
Message-ID: <YkIbXzCYEutqxQRE@kernel.org> (raw)
In-Reply-To: <20220328062414.1893550-5-irogers@google.com>

Em Sun, Mar 27, 2022 at 11:24:13PM -0700, Ian Rogers escreveu:
> Passing null to perf_cpu_map__max doesn't make sense as there is no
> valid max. Avoid this problem by null checking in
> perf_stat_init_aggr_mode.

Applying this one after changing user_cpus back to cpus as this is a fix
independent of this patchset.

In the future, please try to have such patches at the beginning of the
series, so that  they can get cherry-picked more easily.

- Arnaldo

> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
>  tools/perf/builtin-stat.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> index 5bee529f7656..ecd5cf4fd872 100644
> --- a/tools/perf/builtin-stat.c
> +++ b/tools/perf/builtin-stat.c
> @@ -1472,7 +1472,10 @@ static int perf_stat_init_aggr_mode(void)
>  	 * taking the highest cpu number to be the size of
>  	 * the aggregation translate cpumap.
>  	 */
> -	nr = perf_cpu_map__max(evsel_list->core.user_cpus).cpu;
> +	if (evsel_list->core.user_cpus)
> +		nr = perf_cpu_map__max(evsel_list->core.user_cpus).cpu;
> +	else
> +		nr = 0;
>  	stat_config.cpus_aggr_map = cpu_aggr_map__empty_new(nr + 1);
>  	return stat_config.cpus_aggr_map ? 0 : -ENOMEM;
>  }
> -- 
> 2.35.1.1021.g381101b075-goog

-- 

- Arnaldo