[Xen-devel] [PATCH] make protocol specific usage of shared sring explicit

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

I don't think protocol specific data't really belongs in this header
but since it is already there and we seem to be stuck with it lets at
least make the users explicit lest people get caught out by future new
fields moving the pad field around.

This is the Xen portion of this change. The kernel portion will be
sent separately. There is no dependency between the two.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Cc: Daniel Stodden <daniel.stodden@xxxxxxxxxx>
Cc: Dongxiao Xu <dongxiao.xu@xxxxxxxxx>

diff -r aecf092da748 -r 9fb06660a061 tools/blktap2/drivers/tapdisk-vbd.c
--- a/tools/blktap2/drivers/tapdisk-vbd.c       Wed Jun 30 22:12:54 2010 +0100
+++ b/tools/blktap2/drivers/tapdisk-vbd.c       Thu Jul 01 10:20:07 2010 +0100
@@ -1684,7 +1684,7 @@
        if (!vbd->ring.sring)
                return -EINVAL;
 
-       switch (vbd->ring.sring->pad[0]) {
+       switch (vbd->ring.sring->private.tapif_user.msg) {
        case 0:
                return 0;
 
diff -r aecf092da748 -r 9fb06660a061 xen/include/public/io/ring.h
--- a/xen/include/public/io/ring.h      Wed Jun 30 22:12:54 2010 +0100
+++ b/xen/include/public/io/ring.h      Thu Jul 01 10:20:07 2010 +0100
@@ -103,8 +103,16 @@
 struct __name##_sring {                                                 \
     RING_IDX req_prod, req_event;                                       \
     RING_IDX rsp_prod, rsp_event;                                       \
-    uint8_t  netfront_smartpoll_active;                                 \
-    uint8_t  pad[47];                                                   \
+    union {                                                             \
+        struct {                                                        \
+            uint8_t smartpoll_active;                                   \
+        } netif;                                                        \
+        struct {                                                        \
+            uint8_t msg;                                                \
+        } tapif_user;                                                   \
+        uint8_t pvt_pad[4];                                             \
+    } private;                                                          \
+    uint8_t pad[44];                                                    \
     union __name##_sring_entry ring[1]; /* variable-length */           \
 };                                                                      \
                                                                         \

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel