As noted by Konstantin Khlebnikov, gcc can split assignment of
constants to long variables (https://lkml.org/lkml/2013/1/15/141),
though assignment of NULL (0) is OK. Assuming that a gcc bug is
fixed (http://gcc.gnu.org/bugzilla/attachment.cgi?id=29169&action=diff
has a patch), making the store be volatile keeps gcc from splitting.
This commit therefore applies ACCESS_ONCE() to CMM_STORE_SHARED(),
which is the underlying primitive used by rcu_assign_pointer().
Signed-off-by: Paul E. McKenney <paul...@linux.vnet.ibm.com>
diff --git a/urcu/system.h b/urcu/system.h
index 2a45f22..7a1887e 100644
--- a/urcu/system.h
+++ b/urcu/system.h
@@ -49,7 +49,7 @@
*/
#define CMM_STORE_SHARED(x, v) \
({ \
- __typeof__(x) _v = _CMM_STORE_SHARED(x, v); \
+ __typeof__(x) CMM_ACCESS_ONCE(_v) = _CMM_STORE_SHARED(x, v);
\
cmm_smp_wmc(); \
_v; \
})
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