Re: [PATCH] perf tools: Don't set leader if parser doesn't collect an evsel

[Wangnan (F)]

On 2015/9/2 10:53, Wang Nan wrote:
> Similar to patch 'perf tools: Don't set cmdline_group_boundary if no
> evsel is collected', in case when parser collects no evsel (at this
> point it shouldn't happen), parse_events__set_leader() is not safe.
>
> This patch checks list_empty becore calling __perf_evlist__set_leader()
> for safty reason.
>
> Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> Cc: Alexei Starovoitov <ast@xxxxxxxxxxxx>
> Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
> Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
> Cc: Zefan Li <lizefan@xxxxxxxxxx>
> Cc: pi3orama@xxxxxxx
> ---
>
> I'd like to queue this patch into my next pull request. Since it is not
> a real bug, it may be dropped.

I think merging this into patch 2/31 should be better. If we decide to 
drop then
only one patch should be considered.

> ---
>   tools/perf/util/parse-events.c | 3 +++
>   1 file changed, 3 insertions(+)
>
> diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
> index f2c0317..836d226 100644
> --- a/tools/perf/util/parse-events.c
> +++ b/tools/perf/util/parse-events.c
> @@ -793,6 +793,9 @@ void parse_events__set_leader(char *name, struct list_head *list)
>   {
>   	struct perf_evsel *leader;
>   
> +	if (list_empty(list))
> +		return;
> +
>   	__perf_evlist__set_leader(list);
>   	leader = list_entry(list->next, struct perf_evsel, node);
>   	leader->group_name = name ? strdup(name) : NULL;


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