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xenstore: make producer/consumer volatile

PATCH In review Christoph Egger 2 participants 2 messages Jul 28, 2008

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Christoph Egger

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#0 lore raw

PATCH 1/1 xenstore: make producer/consumer volatile

Hi!

Don't allow the compiler to play around with producer/consumer shared across domains.

Keir: Please apply this also to Xen 3.2-testing.

Signed-off-by Christoph Egger <[email protected]>
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AMD Saxony, Dresden, Germany
Operating System Research Center

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xen/include/public/io/xs_wire.h +2 -2
diff -r 37fae02cc335 xen/include/public/io/xs_wire.h
@@ -106,8 +106,8 @@ struct xenstore_domain_interface {
 struct xenstore_domain_interface {
     char req[XENSTORE_RING_SIZE]; /* Requests to xenstore daemon. */
     char rsp[XENSTORE_RING_SIZE]; /* Replies and async watch events. */
-    XENSTORE_RING_IDX req_cons, req_prod;
-    XENSTORE_RING_IDX rsp_cons, rsp_prod;
+    volatile XENSTORE_RING_IDX req_cons, req_prod;
+    volatile XENSTORE_RING_IDX rsp_cons, rsp_prod;
 };
 
 /* Violating this is very bad.  See docs/misc/xenstore.txt. */

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#1 lore raw
Quoted 8 lines · Christoph Egger

Hi!

Don't allow the compiler to play around with producer/consumer shared across domains.

Keir: Please apply this also to Xen 3.2-testing.

Signed-off-by Christoph Egger <[email protected]>

We don't use volatile. If extra ordering constraints are required then the access code should be amended to include extra barriers.

-- Keir