On 3/5/2018 3:20 PM, Arnaldo Carvalho de Melo wrote:
Em Mon, Mar 05, 2018 at 02:10:53PM -0500, kan.li...@linux.intel.com escreveu:
From: Kan Liang <kan.li...@linux.intel.com>

There are too many boilerplates for the perf_mmap__read*() interfaces.

Some of the data (e.g. 'start', 'end', 'overwrite') should be stored in
struct perf_mmap at initialization. They will be used later.

No functional change.

Signed-off-by: Kan Liang <kan.li...@linux.intel.com>
---
  tools/perf/util/mmap.c | 11 ++++++++---
  tools/perf/util/mmap.h |  3 +++
  2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
index 4f27c46..642b479 100644
--- a/tools/perf/util/mmap.c
+++ b/tools/perf/util/mmap.c
@@ -250,11 +250,14 @@ int perf_mmap__read_init(struct perf_mmap *md, bool 
overwrite,
*startp = overwrite ? head : old;
        *endp = overwrite ? old : head;

Why did you keep the above and haven't removed the startp/endp args?

The startp/endp are used by perf_mmap__read_event().
I don't want to make all the changes in a single patch. I think it's hard to review.
So I modified the interface one by one.
Only changing one interface will break the usage.
So the old 'startp/endp' and new 'md->start/md->end' will exist simultaneously in the first few patches. They have the same value.

Patch 1,3,4 add the new 'md->start/md->end' for the three interfaces.
Patch 2 uses the new 'md->start/md->end' for perf record.
Patch 5,6,7 remove the old 'startp/endp' for other perf tools/test and refine the interfaces.

Thanks,
Kan
to
ease the conversion somehow? I'll look at the other patches, but I think
we should change the function signature here and in the callers all at
once.

Sometimes this is ok, and probably this is one case.

- Arnaldo

+       md->overwrite = overwrite;
+       md->start = overwrite ? head : old;
+       md->end = overwrite ? old : head;
- if (*startp == *endp)
+       if (md->start == md->end)
                return -EAGAIN;
- size = *endp - *startp;
+       size = md->end - md->start;
        if (size > (unsigned long)(md->mask) + 1) {
                if (!overwrite) {
                        WARN_ONCE(1, "failed to keep up with mmap data. (warn only 
once)\n");
@@ -268,8 +271,10 @@ 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, head, &md->start, 
&md->end))
                        return -EINVAL;
+               *startp = md->start;
+               *endp = md->end;
        }
return 0;
diff --git a/tools/perf/util/mmap.h b/tools/perf/util/mmap.h
index ec7d3a24..9359e93 100644
--- a/tools/perf/util/mmap.h
+++ b/tools/perf/util/mmap.h
@@ -20,6 +20,9 @@ struct perf_mmap {
        int              fd;
        refcount_t       refcnt;
        u64              prev;
+       u64              start;
+       u64              end;
+       bool             overwrite;
        struct auxtrace_mmap auxtrace_mmap;
        char             event_copy[PERF_SAMPLE_MAX_SIZE] __aligned(8);
  };
--
2.4.11

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