doc: Update rcu_assign_pointer() definition in whatisRCU.txt
The rcu_assign_pointer() macro has changed over time, and the version
in Documentation/RCU/whatisRCU.txt has not kept up. This commit brings
it into 2017, albeit in a simplified fashion.
Reported-by: Andrea Parri <parri.andrea@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
diff --git a/Documentation/RCU/whatisRCU.txt b/Documentation/RCU/whatisRCU.txt
index 5cbd8b2..6b03370 100644
--- a/Documentation/RCU/whatisRCU.txt
+++ b/Documentation/RCU/whatisRCU.txt
@@ -587,20 +587,21 @@
write_unlock(&rcu_gp_mutex);
}
-[You can ignore rcu_assign_pointer() and rcu_dereference() without
-missing much. But here they are anyway. And whatever you do, don't
-forget about them when submitting patches making use of RCU!]
+[You can ignore rcu_assign_pointer() and rcu_dereference() without missing
+much. But here are simplified versions anyway. And whatever you do,
+don't forget about them when submitting patches making use of RCU!]
- #define rcu_assign_pointer(p, v) ({ \
- smp_wmb(); \
- (p) = (v); \
- })
+ #define rcu_assign_pointer(p, v) \
+ ({ \
+ smp_store_release(&(p), (v)); \
+ })
- #define rcu_dereference(p) ({ \
- typeof(p) _________p1 = p; \
- smp_read_barrier_depends(); \
- (_________p1); \
- })
+ #define rcu_dereference(p) \
+ ({ \
+ typeof(p) _________p1 = p; \
+ smp_read_barrier_depends(); \
+ (_________p1); \
+ })
The rcu_read_lock() and rcu_read_unlock() primitive read-acquire