X-Git-Url: http://git.liburcu.org/?p=lttng-modules.git;a=blobdiff_plain;f=lib%2Fringbuffer%2Ffrontend_internal.h;h=a1bfe558440c7d8f7f5af4d45395d6047fe334b7;hp=d02a73d32c2a46bc8a26469e1fddb0fb6eb762f1;hb=c245d0d3253680f0f8caf751ae99d10bd74034bf;hpb=ff0d3a20659704a3762b0394844f42a89afbe246

diff --git a/lib/ringbuffer/frontend_internal.h b/lib/ringbuffer/frontend_internal.h
index d02a73d3..a1bfe558 100644
--- a/lib/ringbuffer/frontend_internal.h
+++ b/lib/ringbuffer/frontend_internal.h
@@ -154,6 +154,8 @@ extern
 void lib_ring_buffer_switch_remote(struct lib_ring_buffer *buf);
 extern
 void lib_ring_buffer_switch_remote_empty(struct lib_ring_buffer *buf);
+extern
+void lib_ring_buffer_clear(struct lib_ring_buffer *buf);
 
 /* Buffer write helpers */
 
@@ -185,6 +187,30 @@ void lib_ring_buffer_reserve_push_reader(struct lib_ring_buffer *buf,
 					      consumed_new) != consumed_old));
 }
 
+/*
+ * Move consumed position to the beginning of subbuffer in which the
+ * write offset is.
+ */
+static inline
+void lib_ring_buffer_clear_reader(struct lib_ring_buffer *buf,
+				  struct channel *chan)
+{
+	const struct lib_ring_buffer_config *config = &chan->backend.config;
+	unsigned long offset, consumed_old, consumed_new;
+
+	do {
+		offset = v_read(config, &buf->offset);
+		consumed_old = atomic_long_read(&buf->consumed);
+		if (unlikely(subbuf_trunc(offset, chan)
+			      - subbuf_trunc(consumed_old, chan)
+			     > 0))
+			consumed_new = subbuf_trunc(offset, chan);
+		else
+			return;
+	} while (unlikely(atomic_long_cmpxchg(&buf->consumed, consumed_old,
+					      consumed_new) != consumed_old));
+}
+
 static inline
 int lib_ring_buffer_pending_data(const struct lib_ring_buffer_config *config,
 				 struct lib_ring_buffer *buf,