Messages in this thread | | | Date | Wed, 2 Sep 2015 14:53:58 +0800 | From | "Wangnan (F)" <> | Subject | Re: [PATCH] perf tools: Don't write to evsel if parser doesn't collect evsel |
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Sorry, forget to CC kernel mailing list...
On 2015/9/2 14:49, Wang Nan wrote: > If parse_events__scanner() collects no entry, perf_evlist__last(evlist) > is invalid. > > Although it shouldn't happen at this point, before calling > perf_evlist__last(), we should ensure the list is not empty for safety > reason. > > There are 3 places need this checking: > > 1. Before setting cmdline_group_boundary; > 2. Before __perf_evlist__set_leader(); > 3. In foreach_evsel_in_last_glob. > > Signed-off-by: Wang Nan <wangnan0@huawei.com> > Cc: Arnaldo Carvalho de Melo <acme@redhat.com> > Cc: Alexei Starovoitov <ast@plumgrid.com> > Cc: Jiri Olsa <jolsa@kernel.org> > Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> > Cc: Namhyung Kim <namhyung@kernel.org> > Cc: Zefan Li <lizefan@huawei.com> > Cc: pi3orama@163.com > --- > > Merge all 3 list_empty() test together into one patch. > > Add warning messages. > > Improve commit message. > > --- > tools/perf/util/parse-events.c | 22 +++++++++++++++++++--- > 1 file changed, 19 insertions(+), 3 deletions(-) > > diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c > index d826e6f..069848d 100644 > --- a/tools/perf/util/parse-events.c > +++ b/tools/perf/util/parse-events.c > @@ -793,6 +793,11 @@ void parse_events__set_leader(char *name, struct list_head *list) > { > struct perf_evsel *leader; > > + if (list_empty(list)) { > + __WARN_printf("WARNING: failed to set leader: empty list"); > + return; > + } > + > __perf_evlist__set_leader(list); > leader = list_entry(list->next, struct perf_evsel, node); > leader->group_name = name ? strdup(name) : NULL; > @@ -1143,10 +1148,15 @@ int parse_events(struct perf_evlist *evlist, const char *str, > int entries = data.idx - evlist->nr_entries; > struct perf_evsel *last; > > + if (!list_empty(&data.list)) { > + last = list_entry(data.list.prev, > + struct perf_evsel, node); > + last->cmdline_group_boundary = true; > + } else > + __WARN_printf("WARNING: event parser found nothing"); > + > 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; > > return 0; > } > @@ -1252,7 +1262,13 @@ foreach_evsel_in_last_glob(struct perf_evlist *evlist, > struct perf_evsel *last = NULL; > int err; > > - if (evlist->nr_entries > 0) > + /* > + * Don't return when list_empty, give func a chance to report > + * error when it found last == NULL. > + * > + * So no need to WARN here, let *func do this. > + */ > + if (!list_empty(&evlist->entries)) > last = perf_evlist__last(evlist); > > do {
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