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authorIan Rogers <irogers@google.com>2022-03-17 16:16:43 -0700
committerArnaldo Carvalho de Melo <acme@redhat.com>2022-03-18 18:39:09 -0300
commit8b464eac9765dfc84d0327fa3f3668faa439d1ce (patch)
tree33b01cedf3690cd112774f742caa9bf470d3cd6f
parent3cf6a32f3f2a45944dd5be5c6ac4deb46bcd3bee (diff)
downloadlinux-8b464eac9765dfc84d0327fa3f3668faa439d1ce.tar.gz
perf evlist: Avoid iteration for empty evlist.
As seen with 'perf stat --null ..' and reported in: https://lore.kernel.org/lkml/YjCLcpcX2peeQVCH@kernel.org/ v2. Avoids setting evsel in the empty list case as suggested by Jiri Olsa. Committer testing: Before: $ perf stat --null sleep 1 Segmentation fault (core dumped) $ After: $ perf stat --null sleep 1 Performance counter stats for 'sleep 1': 1.010340646 seconds time elapsed 0.001420000 seconds user 0.000000000 seconds sys $ Fixes: 472832d2c000b961 ("perf evlist: Refactor evlist__for_each_cpu()") Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Ian Rogers <irogers@google.com> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Acked-by: Jiri Olsa <jolsa@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Ian Rogers <irogers@google.com> Cc: Namhyung Kim <namhyung@kernel.org> Link: https://lore.kernel.org/r/20220317231643.550902-1-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
-rw-r--r--tools/perf/util/evlist.c28
1 files changed, 17 insertions, 11 deletions
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index eaad04e1672a..41a66a48cbdf 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -346,7 +346,7 @@ struct evlist_cpu_iterator evlist__cpu_begin(struct evlist *evlist, struct affin
{
struct evlist_cpu_iterator itr = {
.container = evlist,
- .evsel = evlist__first(evlist),
+ .evsel = NULL,
.cpu_map_idx = 0,
.evlist_cpu_map_idx = 0,
.evlist_cpu_map_nr = perf_cpu_map__nr(evlist->core.all_cpus),
@@ -354,16 +354,22 @@ struct evlist_cpu_iterator evlist__cpu_begin(struct evlist *evlist, struct affin
.affinity = affinity,
};
- if (itr.affinity) {
- itr.cpu = perf_cpu_map__cpu(evlist->core.all_cpus, 0);
- affinity__set(itr.affinity, itr.cpu.cpu);
- itr.cpu_map_idx = perf_cpu_map__idx(itr.evsel->core.cpus, itr.cpu);
- /*
- * If this CPU isn't in the evsel's cpu map then advance through
- * the list.
- */
- if (itr.cpu_map_idx == -1)
- evlist_cpu_iterator__next(&itr);
+ if (evlist__empty(evlist)) {
+ /* Ensure the empty list doesn't iterate. */
+ itr.evlist_cpu_map_idx = itr.evlist_cpu_map_nr;
+ } else {
+ itr.evsel = evlist__first(evlist);
+ if (itr.affinity) {
+ itr.cpu = perf_cpu_map__cpu(evlist->core.all_cpus, 0);
+ affinity__set(itr.affinity, itr.cpu.cpu);
+ itr.cpu_map_idx = perf_cpu_map__idx(itr.evsel->core.cpus, itr.cpu);
+ /*
+ * If this CPU isn't in the evsel's cpu map then advance
+ * through the list.
+ */
+ if (itr.cpu_map_idx == -1)
+ evlist_cpu_iterator__next(&itr);
+ }
}
return itr;
}