[xen staging] xen/public: add new macro to ring.h

[patchbot@xxxxxxx]

commit 6cf1398ba9e3f8ea64d58930288a6dffbdb7c207
Author:     Juergen Gross <jgross@xxxxxxxx>
AuthorDate: Thu Apr 28 09:58:42 2022 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Apr 28 09:58:42 2022 +0200

    xen/public: add new macro to ring.h
    
    For the initialization of a ring page by the frontend two macros are
    available in ring.h: SHARED_RING_INIT() and FRONT_RING_INIT().
    
    All known users use always both of them in direct sequence.
    
    Add another macro XEN_FRONT_RING_INIT() combining the two macros.
    
    Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/include/public/io/ring.h | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/xen/include/public/io/ring.h b/xen/include/public/io/ring.h
index 277af36e61..ab3439bd58 100644
--- a/xen/include/public/io/ring.h
+++ b/xen/include/public/io/ring.h
@@ -95,9 +95,8 @@ typedef unsigned int RING_IDX;
  * of the shared memory area (PAGE_SIZE, for instance). To initialise
  * the front half:
  *
- *     mytag_front_ring_t front_ring;
- *     SHARED_RING_INIT((mytag_sring_t *)shared_page);
- *     FRONT_RING_INIT(&front_ring, (mytag_sring_t *)shared_page, PAGE_SIZE);
+ *     mytag_front_ring_t ring;
+ *     XEN_FRONT_RING_INIT(&ring, (mytag_sring_t *)shared_page, PAGE_SIZE);
  *
  * Initializing the back follows similarly (note that only the front
  * initializes the shared ring):
@@ -184,6 +183,11 @@ typedef struct __name##_back_ring __name##_back_ring_t
 
 #define FRONT_RING_INIT(_r, _s, __size) FRONT_RING_ATTACH(_r, _s, 0, __size)
 
+#define XEN_FRONT_RING_INIT(r, s, size) do {                            \
+    SHARED_RING_INIT(s);                                                \
+    FRONT_RING_INIT(r, s, size);                                        \
+} while (0)
+
 #define BACK_RING_ATTACH(_r, _s, _i, __size) do {                       \
     (_r)->rsp_prod_pvt = (_i);                                          \
     (_r)->req_cons = (_i);                                              \
--
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