Hi, Paul and Alpha hackers
memory barrier is expensive, I think it's worth that adding an if-statement
to avoid it when pointer == NULL.
This patch change nothing in UP or in other architectures for compiler's
optimization.
Thanks, Lai Jiangshan
Signed-off-by: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
---
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index d42dbec..8979f29 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -143,7 +143,8 @@ struct rcu_head {
#define rcu_dereference(p) ({ \
typeof(p) _________p1 = ACCESS_ONCE(p); \
- smp_read_barrier_depends(); \
+ if (_________p1) \
+ smp_read_barrier_depends(); \
(_________p1); \
})
--
To unsubscribe from this list: send the line "unsubscribe linux-arch" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
