X-Git-Url: http://git.lttng.org/?p=lttng-ust.git;a=blobdiff_plain;f=libringbuffer%2Ffrontend_internal.h;h=4ad921ec0ec8263086cddbf1c11044110dc672f6;hp=323a8df7f98cd7e5d3aba69302c6c291799b8bbd;hb=beca55a1aa4ff272188d7c37c19eb0540f811c8b;hpb=f6d8019ea6fbda4df5d746fd20fa5d596e7b0556

diff --git a/libringbuffer/frontend_internal.h b/libringbuffer/frontend_internal.h
index 323a8df7..4ad921ec 100644
--- a/libringbuffer/frontend_internal.h
+++ b/libringbuffer/frontend_internal.h
@@ -205,6 +205,32 @@ void lib_ring_buffer_reserve_push_reader(struct lttng_ust_lib_ring_buffer *buf,
 					      consumed_new) != consumed_old));
 }
 
+static inline
+void lib_ring_buffer_clear_reader(struct lttng_ust_lib_ring_buffer *buf,
+				  struct lttng_ust_shm_handle *handle)
+{
+	struct channel *chan;
+	const struct lttng_ust_lib_ring_buffer_config *config;
+	unsigned long offset, consumed_old, consumed_new;
+
+	chan = shmp(handle, buf->backend.chan);
+	if (!chan)
+		return;
+	config = &chan->backend.config;
+
+	do {
+		offset = v_read(config, &buf->offset);
+		consumed_old = uatomic_read(&buf->consumed);
+		if (caa_unlikely(subbuf_trunc(offset, chan)
+			      - subbuf_trunc(consumed_old, chan)
+			     > 0))
+			consumed_new = subbuf_trunc(offset, chan);
+		else
+			return;
+	} while (caa_unlikely(uatomic_cmpxchg(&buf->consumed, consumed_old,
+					      consumed_new) != consumed_old));
+}
+
 static inline
 int lib_ring_buffer_pending_data(const struct lttng_ust_lib_ring_buffer_config *config,
 				 struct lttng_ust_lib_ring_buffer *buf,