X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=lib%2Fringbuffer%2Fbackend.h;fp=lib%2Fringbuffer%2Fbackend.h;h=b5c4fb264e4203ee72aef594705d04b18da7e4bd;hb=43b690e5e7b2b58166722a478767703886e91aaa;hp=826be933fe61bb45efbe96a7738823e3ae46af9e;hpb=8dfa3bb8897b8d9ac9b7ea33bebb7dad61b32d44;p=lttng-modules.git

diff --git a/lib/ringbuffer/backend.h b/lib/ringbuffer/backend.h
index 826be933..b5c4fb26 100644
--- a/lib/ringbuffer/backend.h
+++ b/lib/ringbuffer/backend.h
@@ -96,6 +96,8 @@ void lib_ring_buffer_write(const struct lib_ring_buffer_config *config,
 	struct lib_ring_buffer_backend_pages *rpages;
 	unsigned long sb_bindex, id;
 
+	if (unlikely(!len))
+		return;
 	offset &= chanb->buf_size - 1;
 	sbidx = offset >> chanb->subbuf_size_order;
 	index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT;
@@ -142,6 +144,8 @@ void lib_ring_buffer_memset(const struct lib_ring_buffer_config *config,
 	struct lib_ring_buffer_backend_pages *rpages;
 	unsigned long sb_bindex, id;
 
+	if (unlikely(!len))
+		return;
 	offset &= chanb->buf_size - 1;
 	sbidx = offset >> chanb->subbuf_size_order;
 	index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT;
@@ -189,6 +193,8 @@ void lib_ring_buffer_copy_from_user_inatomic(const struct lib_ring_buffer_config
 	unsigned long ret;
 	mm_segment_t old_fs = get_fs();
 
+	if (unlikely(!len))
+		return;
 	offset &= chanb->buf_size - 1;
 	sbidx = offset >> chanb->subbuf_size_order;
 	index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT;