2015-08-26 08:38:13

by Wang Nan

Subject: [PATCH] perf tools: Don't set cmdline_group_boundary if no evsel is collected

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/[email protected]

Signed-off-by: Wang Nan <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Zefan Li <[email protected]>
Cc: [email protected]
Cc: Arnaldo Carvalho de Melo <[email protected]>
---
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) {
+ last = perf_evlist__last(evlist);
+ last->cmdline_group_boundary = true;
+ }
return 0;
}

--
1.8.3.4

2015-08-27 11:27:46

by Wang Nan

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/[email protected]
>
> Signed-off-by: Wang Nan <[email protected]>
> Cc: Alexei Starovoitov <[email protected]>
> Cc: Masami Hiramatsu <[email protected]>
> Cc: Namhyung Kim <[email protected]>
> Cc: Zefan Li <[email protected]>
> Cc: [email protected]
> Cc: Arnaldo Carvalho de Melo <[email protected]>
> ---
> 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;
> }
>