Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi

[linux-2.6-microblaze.git] / kernel / trace / ring_buffer.c

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 6f0b42c..b8e1ca4 100644 (file)
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -193,7 +193,7 @@ rb_event_length(struct ring_buffer_event *event)
        case RINGBUF_TYPE_DATA:
                return rb_event_data_length(event);
        default:
-               BUG();
+               WARN_ON_ONCE(1);
        }
        /* not hit */
        return 0;
@@ -249,7 +249,7 @@ rb_event_data(struct ring_buffer_event *event)
 {
        if (extended_time(event))
                event = skip_time_extend(event);
-       BUG_ON(event->type_len > RINGBUF_TYPE_DATA_TYPE_LEN_MAX);
+       WARN_ON_ONCE(event->type_len > RINGBUF_TYPE_DATA_TYPE_LEN_MAX);
        /* If length is in len field, then array[0] has the data */
        if (event->type_len)
                return (void *)&event->array[0];
@@ -3727,7 +3727,7 @@ rb_update_read_stamp(struct ring_buffer_per_cpu *cpu_buffer,
                return;
 
        default:
-               BUG();
+               RB_WARN_ON(cpu_buffer, 1);
        }
        return;
 }
@@ -3757,7 +3757,7 @@ rb_update_iter_read_stamp(struct ring_buffer_iter *iter,
                return;
 
        default:
-               BUG();
+               RB_WARN_ON(iter->cpu_buffer, 1);
        }
        return;
 }
@@ -4020,7 +4020,7 @@ rb_buffer_peek(struct ring_buffer_per_cpu *cpu_buffer, u64 *ts,
                return event;
 
        default:
-               BUG();
+               RB_WARN_ON(cpu_buffer, 1);
        }
 
        return NULL;
@@ -4034,7 +4034,6 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
        struct ring_buffer_per_cpu *cpu_buffer;
        struct ring_buffer_event *event;
        int nr_loops = 0;
-       bool failed = false;
 
        if (ts)
                *ts = 0;
@@ -4056,19 +4055,14 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
                return NULL;
 
        /*
-        * 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 should never hit the following condition more than thrice,
-        * unless the buffer is very small, and there's a writer
-        * that is causing the reader to fail getting an event.
+        * As the writer can mess with what the iterator is trying
+        * to read, just give up if we fail to get an event after
+        * three tries. The iterator is not as reliable when reading
+        * the ring buffer with an active write as the consumer is.
+        * Do not warn if the three failures is reached.
         */
-       if (++nr_loops > 3) {
-               RB_WARN_ON(cpu_buffer, !failed);
+       if (++nr_loops > 3)
                return NULL;
-       }
 
        if (rb_per_cpu_empty(cpu_buffer))
                return NULL;
@@ -4079,10 +4073,8 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
        }
 
        event = rb_iter_head_event(iter);
-       if (!event) {
-               failed = true;
+       if (!event)
                goto again;
-       }
 
        switch (event->type_len) {
        case RINGBUF_TYPE_PADDING:
@@ -4117,7 +4109,7 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
                return event;
 
        default:
-               BUG();
+               RB_WARN_ON(cpu_buffer, 1);
        }
 
        return NULL;