diff options
| -rw-r--r-- | tools/perf/util/evlist.c | 29 |
1 files changed, 15 insertions, 14 deletions
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c index 96c71916e367..17cd01421e7f 100644 --- a/tools/perf/util/evlist.c +++ b/tools/perf/util/evlist.c @@ -679,30 +679,31 @@ static struct perf_evsel *perf_evlist__event2evsel(struct perf_evlist *evlist, return NULL; } +/* When check_messup is true, 'end' must points to a good entry */ static union perf_event * -perf_mmap__read(struct perf_mmap *md, bool overwrite, u64 head, - u64 old, u64 *prev) +perf_mmap__read(struct perf_mmap *md, bool check_messup, u64 start, + u64 end, u64 *prev) { unsigned char *data = md->base + page_size; union perf_event *event = NULL; - int diff = head - old; + int diff = end - start; - if (overwrite) { + if (check_messup) { /* * If we're further behind than half the buffer, there's a chance * the writer will bite our tail and mess up the samples under us. * - * If we somehow ended up ahead of the head, we got messed up. + * If we somehow ended up ahead of the 'end', we got messed up. * - * In either case, truncate and restart at head. + * In either case, truncate and restart at 'end'. */ if (diff > md->mask / 2 || diff < 0) { fprintf(stderr, "WARNING: failed to keep up with mmap data.\n"); /* - * head points to a known good entry, start there. + * 'end' points to a known good entry, start there. */ - old = head; + start = end; diff = 0; } } @@ -710,7 +711,7 @@ perf_mmap__read(struct perf_mmap *md, bool overwrite, u64 head, if (diff >= (int)sizeof(event->header)) { size_t size; - event = (union perf_event *)&data[old & md->mask]; + event = (union perf_event *)&data[start & md->mask]; size = event->header.size; if (size < sizeof(event->header) || diff < (int)size) { @@ -722,8 +723,8 @@ perf_mmap__read(struct perf_mmap *md, bool overwrite, u64 head, * Event straddles the mmap boundary -- header should always * be inside due to u64 alignment of output. */ - if ((old & md->mask) + size != ((old + size) & md->mask)) { - unsigned int offset = old; + if ((start & md->mask) + size != ((start + size) & md->mask)) { + unsigned int offset = start; unsigned int len = min(sizeof(*event), size), cpy; void *dst = md->event_copy; @@ -738,12 +739,12 @@ perf_mmap__read(struct perf_mmap *md, bool overwrite, u64 head, event = (union perf_event *) md->event_copy; } - old += size; + start += size; } broken_event: if (prev) - *prev = old; + *prev = start; return event; } @@ -762,7 +763,7 @@ union perf_event *perf_evlist__mmap_read(struct perf_evlist *evlist, int idx) head = perf_mmap__read_head(md); - return perf_mmap__read(md, evlist->overwrite, head, old, &md->prev); + return perf_mmap__read(md, evlist->overwrite, old, head, &md->prev); } static bool perf_mmap__empty(struct perf_mmap *md) |