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Message-ID: <55DEF395.30201@huawei.com>
Date: Thu, 27 Aug 2015 19:25:09 +0800
From: "Wangnan (F)" <wangnan0@...wei.com>
To: <acme@...hat.com>
CC: <linux-kernel@...r.kernel.org>,
Alexei Starovoitov <ast@...mgrid.com>,
Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
Namhyung Kim <namhyung@...nel.org>,
Zefan Li <lizefan@...wei.com>, <pi3orama@....com>
Subject: Re: [PATCH] perf tools: Don't set cmdline_group_boundary if no evsel
is collected
On 2015/8/26 16:32, Wang Nan wrote:
> If parse_events__scanner() collects no entry, perf_evlist__last(evlist)
> is invalid. Then setting of cmdline_group_boundary touches invalid.
>
> It could happend in currect BPF implementation. See [1]. Although it
> can be fixed, for safety reason it whould be better to introduce this
> check.
>
> [1]: http://lkml.kernel.org/n/1436445342-1402-19-git-send-email-wangnan0@huawei.com
>
> Signed-off-by: Wang Nan <wangnan0@...wei.com>
> Cc: Alexei Starovoitov <ast@...mgrid.com>
> Cc: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
> Cc: Namhyung Kim <namhyung@...nel.org>
> Cc: Zefan Li <lizefan@...wei.com>
> Cc: pi3orama@....com
> Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
> ---
> tools/perf/util/parse-events.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
> index cce3e43..02609da 100644
> --- a/tools/perf/util/parse-events.c
> +++ b/tools/perf/util/parse-events.c
> @@ -1171,9 +1171,11 @@ int parse_events(struct perf_evlist *evlist, const char *str,
>
> perf_evlist__splice_list_tail(evlist, &data.list, entries);
> evlist->nr_groups += data.nr_groups;
> - last = perf_evlist__last(evlist);
> - last->cmdline_group_boundary = true;
>
> + if (entries > 0) {
Now I think chinking this before list splice should be better. Plase
ignore this patch.
Thank you.
> + last = perf_evlist__last(evlist);
> + last->cmdline_group_boundary = true;
> + }
> return 0;
> }
>
--
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