Merge branch 'for-3.11/drivers' of git://git.kernel.dk/linux-block

[karo-tx-linux.git] / include / xen / interface / io / ring.h

diff --git a/include/xen/interface/io/ring.h b/include/xen/interface/io/ring.h
index 75271b9a8f61bedcec5a18465b5a9ca8e84a38c7..7d28aff605c7eb600c4c3bfe93b8b5f1edbaebfe 100644 (file)
--- a/include/xen/interface/io/ring.h
+++ b/include/xen/interface/io/ring.h
@@ -188,6 +188,11 @@ struct __name##_back_ring {                                                \
 #define RING_REQUEST_CONS_OVERFLOW(_r, _cons)                          \
     (((_cons) - (_r)->rsp_prod_pvt) >= RING_SIZE(_r))
 
+/* Ill-behaved frontend determination: Can there be this many requests? */
+#define RING_REQUEST_PROD_OVERFLOW(_r, _prod)               \
+    (((_prod) - (_r)->rsp_prod_pvt) > RING_SIZE(_r))
+
+
 #define RING_PUSH_REQUESTS(_r) do {                                    \
     wmb(); /* back sees requests /before/ updated producer index */    \
     (_r)->sring->req_prod = (_r)->req_prod_pvt;                                \