In overwrite mode, start will be set to head in perf_mmap__read_init.
Therefore, it is no need to set the start one more in
overwrite_rb_find_range and *start can be used as head instead of
passing head to overwrite_rb_find_range.
Signed-off-by: Yisheng Xie <xieyishe...@huawei.com>
---
tools/perf/util/mmap.c | 15 +++++++--------
1 file changed, 7 insertions(+), 8 deletions(-)
diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
index 91531a7..6751ac9 100644
--- a/tools/perf/util/mmap.c
+++ b/tools/perf/util/mmap.c
@@ -223,19 +223,18 @@ int perf_mmap__mmap(struct perf_mmap *map, struct
mmap_params *mp, int fd)
return 0;
}
-static int overwrite_rb_find_range(void *buf, int mask, u64 head, u64 *start,
u64 *end)
+static int overwrite_rb_find_range(void *buf, int mask, u64 *start, u64 *end)
{
struct perf_event_header *pheader;
- u64 evt_head = head;
+ u64 evt_head = *start;
int size = mask + 1;
- pr_debug2("overwrite_rb_find_range: buf=%p, head=%"PRIx64"\n", buf,
head);
- pheader = (struct perf_event_header *)(buf + (head & mask));
- *start = head;
+ pr_debug2("%s: buf=%p, start=%"PRIx64"\n", __func__, buf, *start);
+ pheader = (struct perf_event_header *)(buf + (*start & mask));
while (true) {
- if (evt_head - head >= (unsigned int)size) {
+ if (evt_head - *start >= (unsigned int)size) {
pr_debug("Finished reading overwrite ring buffer:
rewind\n");
- if (evt_head - head > (unsigned int)size)
+ if (evt_head - *start > (unsigned int)size)
evt_head -= pheader->size;
*end = evt_head;
return 0;
@@ -287,7 +286,7 @@ int perf_mmap__read_init(struct perf_mmap *md, bool
overwrite,
* Backward ring buffer is full. We still have a chance to read
* most of data from it.
*/
- if (overwrite_rb_find_range(data, md->mask, head, startp, endp))
+ if (overwrite_rb_find_range(data, md->mask, startp, endp))
return -EINVAL;
}
--
1.7.12.4
