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-rw-r--r--kernel/trace/ring_buffer.c13
1 files changed, 10 insertions, 3 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 3d718add73c1..475338fda969 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -4012,6 +4012,7 @@ 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;
@@ -4038,10 +4039,14 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
* 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).
+ * 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.
*/
- if (RB_WARN_ON(cpu_buffer, ++nr_loops > 3))
+ if (++nr_loops > 3) {
+ RB_WARN_ON(cpu_buffer, !failed);
return NULL;
+ }
if (rb_per_cpu_empty(cpu_buffer))
return NULL;
@@ -4052,8 +4057,10 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
}
event = rb_iter_head_event(iter);
- if (!event)
+ if (!event) {
+ failed = true;
goto again;
+ }
switch (event->type_len) {
case RINGBUF_TYPE_PADDING: