X-Git-Url: https://git.lttng.org/?a=blobdiff_plain;f=libringbuffer%2Fbackend.h;h=feefc7a3229f1314cf6813b1f05178a0cc6176e8;hb=172d6b687981b2606a5ad9caffba5686be96ff28;hp=d4824d63fc713bb97451298e115edd34f87bab78;hpb=35897f8b2d311b756b81657dad9c53ef1c0fad8a;p=lttng-ust.git

diff --git a/libringbuffer/backend.h b/libringbuffer/backend.h
index d4824d63..feefc7a3 100644
--- a/libringbuffer/backend.h
+++ b/libringbuffer/backend.h
@@ -1,14 +1,26 @@
-#ifndef _LINUX_RING_BUFFER_BACKEND_H
-#define _LINUX_RING_BUFFER_BACKEND_H
+#ifndef _LTTNG_RING_BUFFER_BACKEND_H
+#define _LTTNG_RING_BUFFER_BACKEND_H
 
 /*
- * linux/ringbuffer/backend.h
- *
- * Copyright (C) 2008-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * libringbuffer/backend.h
  *
  * Ring buffer backend (API).
  *
- * Dual LGPL v2.1/GPL v2 license.
+ * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; only
+ * version 2.1 of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  *
  * Credits to Steven Rostedt for proposing to use an extra-subbuffer owned by
  * the reader in flight recorder mode.
@@ -72,6 +84,8 @@ void lib_ring_buffer_write(const struct lttng_ust_lib_ring_buffer_config *config
 	struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages;
 	unsigned long sb_bindex, id;
 
+	if (caa_unlikely(!len))
+		return;
 	offset &= chanb->buf_size - 1;
 	sbidx = offset >> chanb->subbuf_size_order;
 	id = shmp_index(handle, bufb->buf_wsb, sbidx)->id;
@@ -122,4 +136,4 @@ unsigned long lib_ring_buffer_get_records_unread(
 	return records_unread;
 }
 
-#endif /* _LINUX_RING_BUFFER_BACKEND_H */
+#endif /* _LTTNG_RING_BUFFER_BACKEND_H */