sched: fix cpu hotplug, cleanup

[pandora-kernel.git] / kernel / notifier.c

diff --git a/kernel/notifier.c b/kernel/notifier.c
index 4253f47..823be11 100644 (file)
--- a/kernel/notifier.c
+++ b/kernel/notifier.c
@@ -4,6 +4,7 @@
 #include <linux/notifier.h>
 #include <linux/rcupdate.h>
 #include <linux/vmalloc.h>
+#include <linux/reboot.h>
 
 /*
  *     Notifier list for kernel code which wants to be called
@@ -30,6 +31,21 @@ static int notifier_chain_register(struct notifier_block **nl,
        return 0;
 }
 
+static int notifier_chain_cond_register(struct notifier_block **nl,
+               struct notifier_block *n)
+{
+       while ((*nl) != NULL) {
+               if ((*nl) == n)
+                       return 0;
+               if (n->priority > (*nl)->priority)
+                       break;
+               nl = &((*nl)->next);
+       }
+       n->next = *nl;
+       rcu_assign_pointer(*nl, n);
+       return 0;
+}
+
 static int notifier_chain_unregister(struct notifier_block **nl,
                struct notifier_block *n)
 {
@@ -203,6 +219,29 @@ int blocking_notifier_chain_register(struct blocking_notifier_head *nh,
 }
 EXPORT_SYMBOL_GPL(blocking_notifier_chain_register);
 
+/**
+ *     blocking_notifier_chain_cond_register - Cond add notifier to a blocking notifier chain
+ *     @nh: Pointer to head of the blocking notifier chain
+ *     @n: New entry in notifier chain
+ *
+ *     Adds a notifier to a blocking notifier chain, only if not already
+ *     present in the chain.
+ *     Must be called in process context.
+ *
+ *     Currently always returns zero.
+ */
+int blocking_notifier_chain_cond_register(struct blocking_notifier_head *nh,
+               struct notifier_block *n)
+{
+       int ret;
+
+       down_write(&nh->rwsem);
+       ret = notifier_chain_cond_register(&nh->head, n);
+       up_write(&nh->rwsem);
+       return ret;
+}
+EXPORT_SYMBOL_GPL(blocking_notifier_chain_cond_register);
+
 /**
  *     blocking_notifier_chain_unregister - Remove notifier from a blocking notifier chain
  *     @nh: Pointer to head of the blocking notifier chain