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authorPaul Durrant <pdurrant@amazon.com>2019-12-11 15:29:55 +0000
committerJuergen Gross <jgross@suse.com>2019-12-20 13:44:42 +0100
commit1ee54195a305fae3955642af8528bdf67496d353 (patch)
treeadc856cbc0bd8f1778f74658178d38f4d6242595 /include/xen/interface
parent672b7763cb2c723fd6f92a3879cc60d2fb11e56a (diff)
xen/interface: re-define FRONT/BACK_RING_ATTACH()
Currently these macros are defined to re-initialize a front/back ring (respectively) to values read from the shared ring in such a way that any requests/responses that are added to the shared ring whilst the front/back is detached will be skipped over. This, in general, is not a desirable semantic since most frontend implementations will eventually block waiting for a response which would either never appear or never be processed. Since the macros are currently unused, take this opportunity to re-define them to re-initialize a front/back ring using specified values. This also allows FRONT/BACK_RING_INIT() to be re-defined in terms of FRONT/BACK_RING_ATTACH() using a specified value of 0. NOTE: BACK_RING_ATTACH() will be used directly in a subsequent patch. Signed-off-by: Paul Durrant <pdurrant@amazon.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Juergen Gross <jgross@suse.com>
Diffstat (limited to 'include/xen/interface')
-rw-r--r--include/xen/interface/io/ring.h29
1 files changed, 9 insertions, 20 deletions
diff --git a/include/xen/interface/io/ring.h b/include/xen/interface/io/ring.h
index 3f40501fc60b..2af7a1cd6658 100644
--- a/include/xen/interface/io/ring.h
+++ b/include/xen/interface/io/ring.h
@@ -125,35 +125,24 @@ struct __name##_back_ring { \
memset((_s)->pad, 0, sizeof((_s)->pad)); \
} while(0)
-#define FRONT_RING_INIT(_r, _s, __size) do { \
- (_r)->req_prod_pvt = 0; \
- (_r)->rsp_cons = 0; \
+#define FRONT_RING_ATTACH(_r, _s, _i, __size) do { \
+ (_r)->req_prod_pvt = (_i); \
+ (_r)->rsp_cons = (_i); \
(_r)->nr_ents = __RING_SIZE(_s, __size); \
(_r)->sring = (_s); \
} while (0)
-#define BACK_RING_INIT(_r, _s, __size) do { \
- (_r)->rsp_prod_pvt = 0; \
- (_r)->req_cons = 0; \
- (_r)->nr_ents = __RING_SIZE(_s, __size); \
- (_r)->sring = (_s); \
-} while (0)
+#define FRONT_RING_INIT(_r, _s, __size) FRONT_RING_ATTACH(_r, _s, 0, __size)
-/* Initialize to existing shared indexes -- for recovery */
-#define FRONT_RING_ATTACH(_r, _s, __size) do { \
- (_r)->sring = (_s); \
- (_r)->req_prod_pvt = (_s)->req_prod; \
- (_r)->rsp_cons = (_s)->rsp_prod; \
+#define BACK_RING_ATTACH(_r, _s, _i, __size) do { \
+ (_r)->rsp_prod_pvt = (_i); \
+ (_r)->req_cons = (_i); \
(_r)->nr_ents = __RING_SIZE(_s, __size); \
-} while (0)
-
-#define BACK_RING_ATTACH(_r, _s, __size) do { \
(_r)->sring = (_s); \
- (_r)->rsp_prod_pvt = (_s)->rsp_prod; \
- (_r)->req_cons = (_s)->req_prod; \
- (_r)->nr_ents = __RING_SIZE(_s, __size); \
} while (0)
+#define BACK_RING_INIT(_r, _s, __size) BACK_RING_ATTACH(_r, _s, 0, __size)
+
/* How big is this ring? */
#define RING_SIZE(_r) \
((_r)->nr_ents)