636 	struct perf_mmap *md = &evlist->mmap[idx];  in perf_evlist__mmap_read()  local
637 	u64 head = perf_mmap__read_head(md);  in perf_evlist__mmap_read()
638 	u64 old = md->prev;  in perf_evlist__mmap_read()
639 	unsigned char *data = md->base + page_size;  in perf_evlist__mmap_read()
652 		if (diff > md->mask / 2 || diff < 0) {  in perf_evlist__mmap_read()
665 		event = (union perf_event *)&data[old & md->mask];  in perf_evlist__mmap_read()
672 		if ((old & md->mask) + size != ((old + size) & md->mask)) {  in perf_evlist__mmap_read()
675 			void *dst = md->event_copy;  in perf_evlist__mmap_read()
678 				cpy = min(md->mask + 1 - (offset & md->mask), len);  in perf_evlist__mmap_read()
679 				memcpy(dst, &data[offset & md->mask], cpy);  in perf_evlist__mmap_read()
685 			event = (union perf_event *) md->event_copy;  in perf_evlist__mmap_read()
691 	md->prev = old;  in perf_evlist__mmap_read()
696 static bool perf_mmap__empty(struct perf_mmap *md)  in perf_mmap__empty()  argument
698 	return perf_mmap__read_head(md) == md->prev;  in perf_mmap__empty()
716 	struct perf_mmap *md = &evlist->mmap[idx];  in perf_evlist__mmap_consume()  local
719 		u64 old = md->prev;  in perf_evlist__mmap_consume()
721 		perf_mmap__write_tail(md, old);  in perf_evlist__mmap_consume()
724 	if (md->refcnt == 1 && perf_mmap__empty(md))  in perf_evlist__mmap_consume()