diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
index 8c1d033638c2478a3edf82dde8fdd1bba5f81235..2933942abfe252edf0c5f6387cc23bb54a602f5b 100644
--- a/tools/perf/util/mmap.c
+++ b/tools/perf/util/mmap.c
@@ -76,8 +76,9 @@ static union perf_event *perf_mmap__read(struct perf_mmap *map,
  * perf_mmap__read_done()
  */
 union perf_event *perf_mmap__read_event(struct perf_mmap *map,
-					bool overwrite,
-					u64 *startp, u64 end)
+					bool overwrite __maybe_unused,
+					u64 *startp __maybe_unused,
+					u64 end __maybe_unused)
 {
 	union perf_event *event;
 
@@ -87,17 +88,14 @@ union perf_event *perf_mmap__read_event(struct perf_mmap *map,
 	if (!refcount_read(&map->refcnt))
 		return NULL;
 
-	if (startp == NULL)
-		return NULL;
-
 	/* non-overwirte doesn't pause the ringbuffer */
-	if (!overwrite)
-		end = perf_mmap__read_head(map);
+	if (!map->overwrite)
+		map->end = perf_mmap__read_head(map);
 
-	event = perf_mmap__read(map, startp, end);
+	event = perf_mmap__read(map, &map->start, map->end);
 
-	if (!overwrite)
-		map->prev = *startp;
+	if (!map->overwrite)
+		map->prev = map->start;
 
 	return event;
 }