From: Kan Liang <kan.li...@intel.com> The 'start' and 'prev' variables are duplicates in perf_mmap__read().
Use 'map->prev' to replace 'start' in perf_mmap__read_*(). Suggested-by: Wang Nan <wangn...@huawei.com> Signed-off-by: Kan Liang <kan.li...@intel.com> Acked-by: Jiri Olsa <jo...@kernel.org> Cc: Andi Kleen <a...@linux.intel.com> Cc: Jin Yao <yao....@linux.intel.com> Cc: Namhyung Kim <namhy...@kernel.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Wang Nan <wangn...@huawei.com> Link: http://lkml.kernel.org/r/1516310792-208685-7-git-send-email-kan.li...@intel.com Signed-off-by: Arnaldo Carvalho de Melo <a...@redhat.com> --- tools/perf/util/mmap.c | 28 ++++++++++------------------ 1 file changed, 10 insertions(+), 18 deletions(-) diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c index 38fa69dc635e..125bfda9d037 100644 --- a/tools/perf/util/mmap.c +++ b/tools/perf/util/mmap.c @@ -22,29 +22,27 @@ size_t perf_mmap__mmap_len(struct perf_mmap *map) /* When check_messup is true, 'end' must points to a good entry */ static union perf_event *perf_mmap__read(struct perf_mmap *map, - u64 start, u64 end, u64 *prev) + u64 *startp, u64 end) { unsigned char *data = map->base + page_size; union perf_event *event = NULL; - int diff = end - start; + int diff = end - *startp; if (diff >= (int)sizeof(event->header)) { size_t size; - event = (union perf_event *)&data[start & map->mask]; + event = (union perf_event *)&data[*startp & map->mask]; size = event->header.size; - if (size < sizeof(event->header) || diff < (int)size) { - event = NULL; - goto broken_event; - } + if (size < sizeof(event->header) || diff < (int)size) + return NULL; /* * Event straddles the mmap boundary -- header should always * be inside due to u64 alignment of output. */ - if ((start & map->mask) + size != ((start + size) & map->mask)) { - unsigned int offset = start; + if ((*startp & map->mask) + size != ((*startp + size) & map->mask)) { + unsigned int offset = *startp; unsigned int len = min(sizeof(*event), size), cpy; void *dst = map->event_copy; @@ -59,20 +57,15 @@ static union perf_event *perf_mmap__read(struct perf_mmap *map, event = (union perf_event *)map->event_copy; } - start += size; + *startp += size; } -broken_event: - if (prev) - *prev = start; - return event; } union perf_event *perf_mmap__read_forward(struct perf_mmap *map) { u64 head; - u64 old = map->prev; /* * Check if event was unmapped due to a POLLHUP/POLLERR. @@ -82,13 +75,12 @@ union perf_event *perf_mmap__read_forward(struct perf_mmap *map) head = perf_mmap__read_head(map); - return perf_mmap__read(map, old, head, &map->prev); + return perf_mmap__read(map, &map->prev, head); } union perf_event *perf_mmap__read_backward(struct perf_mmap *map) { u64 head, end; - u64 start = map->prev; /* * Check if event was unmapped due to a POLLHUP/POLLERR. @@ -118,7 +110,7 @@ union perf_event *perf_mmap__read_backward(struct perf_mmap *map) else end = head + map->mask + 1; - return perf_mmap__read(map, start, end, &map->prev); + return perf_mmap__read(map, &map->prev, end); } void perf_mmap__read_catchup(struct perf_mmap *map) -- 2.14.3
