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 <[email protected]> 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; \ }) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
