[PATCH 7/9] perf intel-pt: Tidy old_buffer handling in intel_pt_get_trace()

[Adrian Hunter]

intel_pt_get_trace() fixes overlaps between the current buffer and the
previous buffer ('old_buffer'). However the previous buffer might not have
had usable data (no PSB) so the comparison must be made against the
previous buffer that had usable data. Tidy that by keeping a pointer for
that purpose in struct intel_pt_queue.

Signed-off-by: Adrian Hunter <adrian.hun...@intel.com>
---
 tools/perf/util/intel-pt.c | 24 +++++++++++-------------
 1 file changed, 11 insertions(+), 13 deletions(-)

diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index cfb3614f5def..9a4f9cdb752f 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -132,6 +132,7 @@ struct intel_pt_queue {
        struct intel_pt *pt;
        unsigned int queue_nr;
        struct auxtrace_buffer *buffer;
+       struct auxtrace_buffer *old_buffer;
        void *decoder;
        const struct intel_pt_state *state;
        struct ip_callchain *chain;
@@ -226,7 +227,8 @@ static int intel_pt_do_fix_overlap(struct intel_pt *pt, 
struct auxtrace_buffer *
 static int intel_pt_get_trace(struct intel_pt_buffer *b, void *data)
 {
        struct intel_pt_queue *ptq = data;
-       struct auxtrace_buffer *buffer = ptq->buffer, *old_buffer = buffer;
+       struct auxtrace_buffer *buffer = ptq->buffer;
+       struct auxtrace_buffer *old_buffer = ptq->old_buffer;
        struct auxtrace_queue *queue;
 
        if (ptq->stop) {
@@ -235,7 +237,7 @@ static int intel_pt_get_trace(struct intel_pt_buffer *b, 
void *data)
        }
 
        queue = &ptq->pt->queues.queue_array[ptq->queue_nr];
-next:
+
        buffer = auxtrace_buffer__next(queue, buffer);
        if (!buffer) {
                if (old_buffer)
@@ -267,16 +269,6 @@ static int intel_pt_get_trace(struct intel_pt_buffer *b, 
void *data)
        }
        b->ref_timestamp = buffer->reference;
 
-       /*
-        * If in snapshot mode and the buffer has no usable data, get next
-        * buffer and again check overlap against old_buffer.
-        */
-       if (ptq->pt->snapshot_mode && !b->len)
-               goto next;
-
-       if (old_buffer)
-               auxtrace_buffer__drop_data(old_buffer);
-
        if (!old_buffer || ptq->pt->sampling_mode || (ptq->pt->snapshot_mode &&
                                                      !buffer->consecutive)) {
                b->consecutive = false;
@@ -288,8 +280,14 @@ static int intel_pt_get_trace(struct intel_pt_buffer *b, 
void *data)
        if (ptq->step_through_buffers)
                ptq->stop = true;
 
-       if (!b->len)
+       if (b->len) {
+               if (old_buffer)
+                       auxtrace_buffer__drop_data(old_buffer);
+               ptq->old_buffer = buffer;
+       } else {
+               auxtrace_buffer__drop_data(buffer);
                return intel_pt_get_trace(b, data);
+       }
 
        return 0;
 }
-- 
1.9.1