Commit b4b036b4 authored by Kan Liang's avatar Kan Liang Committed by Arnaldo Carvalho de Melo

perf mmap: Discard 'prev' in perf_mmap__read()

The 'start' and 'prev' variables are duplicates in perf_mmap__read().

Use 'map->prev' to replace 'start' in perf_mmap__read_*().
Suggested-by: default avatarWang Nan <wangnan0@huawei.com>
Signed-off-by: default avatarKan Liang <kan.liang@intel.com>
Acked-by: default avatarJiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1516310792-208685-7-git-send-email-kan.liang@intel.comSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 189f2cc9
......@@ -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)
......
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