Re: [RFC][PATCH] Put size in array to get rid of barriers in grow_ary()

["Paul E. McKenney" <paulmck@us.ibm.com>]

On Mon, Sep 13, 2004 at 08:40:15PM +0200, Manfred Spraul wrote:
> Paul E. McKenney wrote:
> 
> >And here, finally, is the updated patch.  Still untested.
> >
> >Thoughts?
> >
> > 
> >
> Looks good.
> I've even tried to test it, but doesn't compile with -rc1-bk11 due to 
> missing rcu_assign_pointer.

My bad!  It needs the rcu_assign_pointer() patch as pre-req.

http://marc.theaimsgroup.com/?l=linux-kernel&m=109459678719365&w=2

Below is the part of that patch that is actually supplies
rcu_assign_pointer(), which should be all that is needed.

						Thanx, Paul

diff -urpN -X ../dontdiff linux-2.5/include/linux/rcupdate.h linux-2.5-rap/include/linux/rcupdate.h
--- linux-2.5/include/linux/rcupdate.h	Tue Sep  7 10:04:29 2004
+++ linux-2.5-rap/include/linux/rcupdate.h	Tue Sep  7 12:12:09 2004
@@ -238,6 +238,24 @@ static inline int rcu_pending(int cpu)
 				(_________p1); \
 				})
 
+/**
+ * rcu_assign_pointer - assign (publicize) a pointer to a newly
+ * initialized structure that will be dereferenced by RCU read-side
+ * critical sections.  Returns the value assigned.
+ *
+ * Inserts memory barriers on architectures that require them
+ * (pretty much all of them other than x86), and also prevents
+ * the compiler from reordering the code that initializes the
+ * structure after the pointer assignment.  More importantly, this
+ * call documents which pointers will be dereferenced by RCU read-side
+ * code.
+ */
+
+#define rcu_assign_pointer(p, v)	({ \
+						smp_wmb(); \
+						(p) = (v); \
+					})
+
 extern void rcu_init(void);
 extern void rcu_check_callbacks(int cpu, int user);
 extern void rcu_restart_cpu(int cpu);