xen/patches/linux-2.6.16.29/rcu_needs_cpu.patch

diff -pruN ../orig-linux-2.6.16.29/include/linux/rcupdate.h ./include/linux/rcupdate.h
--- ../orig-linux-2.6.16.29/include/linux/rcupdate.h	2006-09-12 19:02:10.000000000 +0100
+++ ./include/linux/rcupdate.h	2006-09-19 14:05:39.000000000 +0100
@@ -134,6 +134,7 @@ static inline void rcu_bh_qsctr_inc(int 
 }
 
 extern int rcu_pending(int cpu);
+extern int rcu_needs_cpu(int cpu);
 
 /**
  * rcu_read_lock - mark the beginning of an RCU read-side critical section.
diff -pruN ../orig-linux-2.6.16.29/kernel/rcupdate.c ./kernel/rcupdate.c
--- ../orig-linux-2.6.16.29/kernel/rcupdate.c	2006-09-12 19:02:10.000000000 +0100
+++ ./kernel/rcupdate.c	2006-09-19 14:05:39.000000000 +0100
@@ -485,6 +485,20 @@ int rcu_pending(int cpu)
 		__rcu_pending(&rcu_bh_ctrlblk, &per_cpu(rcu_bh_data, cpu));
 }
 
+/*
+ * Check to see if any future RCU-related work will need to be done
+ * by the current CPU, even if none need be done immediately, returning
+ * 1 if so.  This function is part of the RCU implementation; it is -not-
+ * an exported member of the RCU API.
+ */
+int rcu_needs_cpu(int cpu)
+{
+	struct rcu_data *rdp = &per_cpu(rcu_data, cpu);
+	struct rcu_data *rdp_bh = &per_cpu(rcu_bh_data, cpu);
+
+	return (!!rdp->curlist || !!rdp_bh->curlist || rcu_pending(cpu));
+}
+
 void rcu_check_callbacks(int cpu, int user)
 {
 	if (user ||