ring-buffer: Up rb_iter_peek() loop count to 3

[pandora-kernel.git] / kernel / trace / ring_buffer.c

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index f5b7b5c..9f80280 100644 (file)
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2040,6 +2040,13 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
        write &= RB_WRITE_MASK;
        tail = write - length;
 
+       /*
+        * If this is the first commit on the page, then it has the same
+        * timestamp as the page itself.
+        */
+       if (!tail)
+               delta = 0;
+
        /* See if we shot pass the end of this buffer page */
        if (unlikely(write > BUF_PAGE_SIZE))
                return rb_move_tail(cpu_buffer, length, tail,
@@ -2683,7 +2690,7 @@ unsigned long ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu)
        unsigned long flags;
        struct ring_buffer_per_cpu *cpu_buffer;
        struct buffer_page *bpage;
-       unsigned long ret;
+       unsigned long ret = 0;
 
        if (!cpumask_test_cpu(cpu, buffer->cpumask))
                return 0;
@@ -2698,7 +2705,8 @@ unsigned long ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu)
                bpage = cpu_buffer->reader_page;
        else
                bpage = rb_set_head_page(cpu_buffer);
-       ret = bpage->page->time_stamp;
+       if (bpage)
+               ret = bpage->page->time_stamp;
        raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
 
        return ret;
@@ -3005,6 +3013,8 @@ rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer)
         * Splice the empty reader page into the list around the head.
         */
        reader = rb_set_head_page(cpu_buffer);
+       if (!reader)
+               goto out;
        cpu_buffer->reader_page->list.next = rb_list_head(reader->list.next);
        cpu_buffer->reader_page->list.prev = reader->list.prev;
 
@@ -3236,12 +3246,14 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
                return NULL;
 
        /*
-        * We repeat when a time extend is encountered.
-        * Since the time extend is always attached to a data event,
-        * we should never loop more than once.
-        * (We never hit the following condition more than twice).
+        * We repeat when a time extend is encountered or we hit
+        * the end of the page. Since the time extend is always attached
+        * to a data event, we should never loop more than three times.
+        * Once for going to next page, once on time extend, and
+        * finally once to get the event.
+        * (We never hit the following condition more than thrice).
         */
-       if (RB_WARN_ON(cpu_buffer, ++nr_loops > 2))
+       if (RB_WARN_ON(cpu_buffer, ++nr_loops > 3))
                return NULL;
 
        if (rb_per_cpu_empty(cpu_buffer))