Messages in this thread | | | Date | Wed, 2 Sep 2015 13:54:15 +0200 | From | Jiri Olsa <> | Subject | Re: [PATCH] perf tools: Don't write to evsel if parser doesn't collect evsel |
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On Wed, Sep 02, 2015 at 02:53:58PM +0800, Wangnan (F) wrote: > 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");
we need to unify error printing in this object ;-) with this one it's 3
__WARN_printf(... fprintf(stderr,... printf(... WARN_ONCE(...
;-)
> >+ > > 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))
why is it better than to check evlist->nr_entries? evlist->nr_entries is equivalent to !list_empty(&evlist->entries) in here, right?
jirka
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