linux-kernel - Re: [PATCH v1 09/17] perf c2c: Clean up some defensive gets and make asan clean

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Message-ID: <aS3UK1QYkf5vD7Mp@x1>
Date: Mon, 1 Dec 2025 14:45:15 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Ian Rogers <irogers@...gle.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	James Clark <james.clark@...aro.org>,
	Collin Funk <collin.funk1@...il.com>,
	Dmitry Vyukov <dvyukov@...gle.com>, Andi Kleen <ak@...ux.intel.com>,
	Thomas Falcon <thomas.falcon@...el.com>, Leo Yan <leo.yan@....com>,
	Yicong Yang <yangyicong@...ilicon.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Masami Hiramatsu (Google)" <mhiramat@...nel.org>,
	Stephen Brennan <stephen.s.brennan@...cle.com>,
	Haibo Xu <haibo1.xu@...el.com>, linux-kernel@...r.kernel.org,
	linux-perf-users@...r.kernel.org
Subject: Re: [PATCH v1 09/17] perf c2c: Clean up some defensive gets and make
 asan clean

On Sat, Nov 22, 2025 at 12:19:21AM -0800, Ian Rogers wrote:
> To deal with histogram code that had missing gets the c2c code had
> some defensive gets. Those other issues were cleaned up by the
> reference count checker, clean them up for the c2c command here.

Reviewed-by: Arnaldo Carvalho de Melo <acme@...hat.com>

- Arnaldo
 
> Signed-off-by: Ian Rogers <irogers@...gle.com>
> ---
>  tools/perf/builtin-c2c.c | 36 ++++++++++++++----------------------
>  1 file changed, 14 insertions(+), 22 deletions(-)
> 
> diff --git a/tools/perf/builtin-c2c.c b/tools/perf/builtin-c2c.c
> index 14c3823f8fed..d390ae4e3ec8 100644
> --- a/tools/perf/builtin-c2c.c
> +++ b/tools/perf/builtin-c2c.c
> @@ -322,7 +322,7 @@ static int process_sample_event(const struct perf_tool *tool __maybe_unused,
>  	struct c2c_stats stats = { .nr_entries = 0, };
>  	struct hist_entry *he;
>  	struct addr_location al;
> -	struct mem_info *mi, *mi_dup;
> +	struct mem_info *mi = NULL;
>  	struct callchain_cursor *cursor;
>  	int ret;
>  
> @@ -349,20 +349,15 @@ static int process_sample_event(const struct perf_tool *tool __maybe_unused,
>  		goto out;
>  	}
>  
> -	/*
> -	 * The mi object is released in hists__add_entry_ops,
> -	 * if it gets sorted out into existing data, so we need
> -	 * to take the copy now.
> -	 */
> -	mi_dup = mem_info__get(mi);
> -
>  	c2c_decode_stats(&stats, mi);
>  
>  	he = hists__add_entry_ops(&c2c_hists->hists, &c2c_entry_ops,
>  				  &al, NULL, NULL, mi, NULL,
>  				  sample, true);
> -	if (he == NULL)
> -		goto free_mi;
> +	if (he == NULL) {
> +		ret = -ENOMEM;
> +		goto out;
> +	}
>  
>  	c2c_he = container_of(he, struct c2c_hist_entry, he);
>  	c2c_add_stats(&c2c_he->stats, &stats);
> @@ -393,17 +388,19 @@ static int process_sample_event(const struct perf_tool *tool __maybe_unused,
>  		int cpu = sample->cpu == (unsigned int) -1 ? 0 : sample->cpu;
>  		int node = c2c.cpu2node[cpu];
>  
> -		mi = mi_dup;
> -
>  		c2c_hists = he__get_c2c_hists(he, c2c.cl_sort, 2, machine->env);
> -		if (!c2c_hists)
> -			goto free_mi;
> +		if (!c2c_hists) {
> +			ret = -ENOMEM;
> +			goto out;
> +		}
>  
>  		he = hists__add_entry_ops(&c2c_hists->hists, &c2c_entry_ops,
>  					  &al, NULL, NULL, mi, NULL,
>  					  sample, true);
> -		if (he == NULL)
> -			goto free_mi;
> +		if (he == NULL) {
> +			ret = -ENOMEM;
> +			goto out;
> +		}
>  
>  		c2c_he = container_of(he, struct c2c_hist_entry, he);
>  		c2c_add_stats(&c2c_he->stats, &stats);
> @@ -421,14 +418,9 @@ static int process_sample_event(const struct perf_tool *tool __maybe_unused,
>  	}
>  
>  out:
> +	mem_info__put(mi);
>  	addr_location__exit(&al);
>  	return ret;
> -
> -free_mi:
> -	mem_info__put(mi_dup);
> -	mem_info__put(mi);
> -	ret = -ENOMEM;
> -	goto out;
>  }
>  
>  static const char * const c2c_usage[] = {
> -- 
> 2.52.0.rc2.455.g230fcf2819-goog