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-rw-r--r--kernel/trace/ring_buffer.c34
1 files changed, 13 insertions, 21 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 6f0b42ceeb00..b8e1ca48be50 100644
--- 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;