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authorMichael S. Tsirkin <mst@redhat.com>2015-12-27 19:02:16 +0300
committerMichael S. Tsirkin <mst@redhat.com>2016-01-12 21:47:03 +0300
commit506b02eb1cf79838b76c6e3e43171cf960f01fc8 (patch)
tree4e89ac8ba0cfe3752e005aaf49f9706176d92fe8 /include/xen
parent5bb0c9be2ac9a98513d43969e2b5c3d02cb271c8 (diff)
downloadlinux-506b02eb1cf79838b76c6e3e43171cf960f01fc8.tar.xz
xen/io: use virt_xxx barriers
include/xen/interface/io/ring.h uses full memory barriers to communicate with the other side. For guests compiled with CONFIG_SMP, smp_wmb and smp_mb would be sufficient, so mb() and wmb() here are only needed if a non-SMP guest runs on an SMP host. Switch to virt_xxx barriers which serve this exact purpose. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Acked-by: David Vrabel <david.vrabel@citrix.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Diffstat (limited to 'include/xen')
-rw-r--r--include/xen/interface/io/ring.h16
1 files changed, 8 insertions, 8 deletions
diff --git a/include/xen/interface/io/ring.h b/include/xen/interface/io/ring.h
index 7dc685b4057d..21f4fbd55e48 100644
--- a/include/xen/interface/io/ring.h
+++ b/include/xen/interface/io/ring.h
@@ -208,12 +208,12 @@ struct __name##_back_ring { \
#define RING_PUSH_REQUESTS(_r) do { \
- wmb(); /* back sees requests /before/ updated producer index */ \
+ virt_wmb(); /* back sees requests /before/ updated producer index */ \
(_r)->sring->req_prod = (_r)->req_prod_pvt; \
} while (0)
#define RING_PUSH_RESPONSES(_r) do { \
- wmb(); /* front sees responses /before/ updated producer index */ \
+ virt_wmb(); /* front sees responses /before/ updated producer index */ \
(_r)->sring->rsp_prod = (_r)->rsp_prod_pvt; \
} while (0)
@@ -250,9 +250,9 @@ struct __name##_back_ring { \
#define RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(_r, _notify) do { \
RING_IDX __old = (_r)->sring->req_prod; \
RING_IDX __new = (_r)->req_prod_pvt; \
- wmb(); /* back sees requests /before/ updated producer index */ \
+ virt_wmb(); /* back sees requests /before/ updated producer index */ \
(_r)->sring->req_prod = __new; \
- mb(); /* back sees new requests /before/ we check req_event */ \
+ virt_mb(); /* back sees new requests /before/ we check req_event */ \
(_notify) = ((RING_IDX)(__new - (_r)->sring->req_event) < \
(RING_IDX)(__new - __old)); \
} while (0)
@@ -260,9 +260,9 @@ struct __name##_back_ring { \
#define RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(_r, _notify) do { \
RING_IDX __old = (_r)->sring->rsp_prod; \
RING_IDX __new = (_r)->rsp_prod_pvt; \
- wmb(); /* front sees responses /before/ updated producer index */ \
+ virt_wmb(); /* front sees responses /before/ updated producer index */ \
(_r)->sring->rsp_prod = __new; \
- mb(); /* front sees new responses /before/ we check rsp_event */ \
+ virt_mb(); /* front sees new responses /before/ we check rsp_event */ \
(_notify) = ((RING_IDX)(__new - (_r)->sring->rsp_event) < \
(RING_IDX)(__new - __old)); \
} while (0)
@@ -271,7 +271,7 @@ struct __name##_back_ring { \
(_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \
if (_work_to_do) break; \
(_r)->sring->req_event = (_r)->req_cons + 1; \
- mb(); \
+ virt_mb(); \
(_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \
} while (0)
@@ -279,7 +279,7 @@ struct __name##_back_ring { \
(_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \
if (_work_to_do) break; \
(_r)->sring->rsp_event = (_r)->rsp_cons + 1; \
- mb(); \
+ virt_mb(); \
(_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \
} while (0)