On Tue, Mar 06, 2018 at 07:44:23PM +0800, Yisheng Xie wrote: > 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.
it conflicts a little with recent cleanup from Kan Liang,, https://marc.info/?t=152035082800001&r=1&w=2 otherwise it looks ok to me jirka > > 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 >
