linux-kernel - Re: [PATCH v2 09/10] perf dwarf-aux: fix __die_find_scope

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Message-ID: <aLKpAxq5QQIwD_Z_@google.com>
Date: Sat, 30 Aug 2025 00:32:19 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Zecheng Li <zecheng@...gle.com>
Cc: 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>, Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	"Liang, Kan" <kan.liang@...ux.intel.com>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Xu Liu <xliuprof@...gle.com>, linux-perf-users@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 09/10] perf dwarf-aux: fix __die_find_scope_cb for
 namespaces

On Mon, Aug 25, 2025 at 07:58:17PM +0000, Zecheng Li wrote:
> Currently __die_find_scope_cb goes to check siblings when the DIE
> doesn't include the given PC. However namespaces don't have a PC and
> could contain children that have that PC. When we encounter a namespace,
> we should check both its children and siblings.
> 
> Signed-off-by: Zecheng Li <zecheng@...gle.com>

Reviewed-by: Namhyung Kim <namhyung@...nel.org>

Thanks,
Namhyung

> ---
>  tools/perf/util/dwarf-aux.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
> index 56e1b5690dc4..013862ea8924 100644
> --- a/tools/perf/util/dwarf-aux.c
> +++ b/tools/perf/util/dwarf-aux.c
> @@ -1962,6 +1962,7 @@ struct find_scope_data {
>  static int __die_find_scope_cb(Dwarf_Die *die_mem, void *arg)
>  {
>  	struct find_scope_data *data = arg;
> +	int tag = dwarf_tag(die_mem);
>  
>  	if (dwarf_haspc(die_mem, data->pc)) {
>  		Dwarf_Die *tmp;
> @@ -1975,6 +1976,14 @@ static int __die_find_scope_cb(Dwarf_Die *die_mem, void *arg)
>  		data->nr++;
>  		return DIE_FIND_CB_CHILD;
>  	}
> +
> +	/*
> +	 * If the DIE doesn't have the PC, we still need to check its children
> +	 * and siblings if it's a container like a namespace.
> +	 */
> +	if (tag == DW_TAG_namespace)
> +		return DIE_FIND_CB_CONTINUE;
> +
>  	return DIE_FIND_CB_SIBLING;
>  }
>  
> -- 
> 2.51.0.261.g7ce5a0a67e-goog
>