bpf_perf_object__next folded the last element in the list test with the
empty list test. However, this meant that offsets were computed against
null and that a struct list_head was compared against a struct
bpf_perf_object. Working around this with clang's undefined behavior
sanitizer required -fno-sanitize=null and -fno-sanitize=object-size.
Remove the undefined behavior by using the regular Linux list APIs and
handling the starting case separately from the end testing case. Looking
at uses like bpf_perf_object__for_each, as the constant NULL or non-NULL
argument can be constant propagated the code is no less efficient.
Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
---
tools/perf/util/bpf-loader.c | 18 +++++++-----------
1 file changed, 7 insertions(+), 11 deletions(-)
diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index f8ad581ea247..cdd6463a5b68 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -63,20 +63,16 @@ static struct hashmap *bpf_map_hash;
static struct bpf_perf_object *
bpf_perf_object__next(struct bpf_perf_object *prev)
{
- struct bpf_perf_object *next;
-
- if (!prev)
- next = list_first_entry(&bpf_objects_list,
- struct bpf_perf_object,
- list);
- else
- next = list_next_entry(prev, list);
+ if (!prev) {
+ if (list_empty(&bpf_objects_list))
+ return NULL;
- /* Empty list is noticed here so don't need checking on entry. */
- if (&next->list == &bpf_objects_list)
+ return list_first_entry(&bpf_objects_list, struct bpf_perf_object, list);
+ }
+ if (list_is_last(&prev->list, &bpf_objects_list))
return NULL;
- return next;
+ return list_next_entry(prev, list);
}
#define bpf_perf_object__for_each(perf_obj, tmp) \
--
2.37.1.359.gd136c6c3e2-goog
