[Xen-devel] [PATCH] xen: notifier: refine 'notifier_head', use 'list_head' directly

[Baodong Chen <chenbaodong@xxxxxxxxxx>]

Signed-off-by: Baodong Chen <chenbaodong@xxxxxxxxxx>
---
 xen/common/notifier.c      | 25 ++++++-------------------
 xen/include/xen/notifier.h | 21 +++++++++++++++------
 2 files changed, 21 insertions(+), 25 deletions(-)

diff --git a/xen/common/notifier.c b/xen/common/notifier.c
index 34488a8..f959a79 100644
--- a/xen/common/notifier.c
+++ b/xen/common/notifier.c
@@ -21,10 +21,10 @@
 void __init notifier_chain_register(
     struct notifier_head *nh, struct notifier_block *n)
 {
-    struct list_head *chain = &nh->head.chain;
+    struct list_head *chain = &nh->head;
     struct notifier_block *nb;
 
-    while ( chain->next != &nh->head.chain )
+    while ( chain->next != &nh->head )
     {
         nb = list_entry(chain->next, struct notifier_block, chain);
         if ( n->priority > nb->priority )
@@ -35,19 +35,6 @@ void __init notifier_chain_register(
     list_add(&n->chain, chain);
 }
 
-/**
- * notifier_chain_unregister - Remove notifier from a raw notifier chain
- * @nh: Pointer to head of the raw notifier chain
- * @n: Entry to remove from notifier chain
- *
- * Removes a notifier from a raw notifier chain.
- * All locking must be provided by the caller.
- */
-void __init notifier_chain_unregister(
-    struct notifier_head *nh, struct notifier_block *n)
-{
-    list_del(&n->chain);
-}
 
 /**
  * notifier_call_chain - Informs the registered notifiers about an event.
@@ -71,16 +58,16 @@ int notifier_call_chain(
 {
     int ret = NOTIFY_DONE;
     struct list_head *cursor;
-    struct notifier_block *nb;
+    struct notifier_block *nb = NULL;
     bool_t reverse = !!(val & NOTIFY_REVERSE);
 
-    cursor = &(pcursor && *pcursor ? *pcursor : &nh->head)->chain;
+    cursor = (pcursor && *pcursor ? &(*pcursor)->chain : &nh->head);
 
     do {
         cursor = reverse ? cursor->prev : cursor->next;
-        nb = list_entry(cursor, struct notifier_block, chain);
-        if ( cursor == &nh->head.chain )
+        if ( cursor == &nh->head )
             break;
+        nb = list_entry(cursor, struct notifier_block, chain);
         ret = nb->notifier_call(nb, val, v);
     } while ( !(ret & NOTIFY_STOP_MASK) );
 
diff --git a/xen/include/xen/notifier.h b/xen/include/xen/notifier.h
index d1ff9b1..b1961cb 100644
--- a/xen/include/xen/notifier.h
+++ b/xen/include/xen/notifier.h
@@ -29,18 +29,27 @@ struct notifier_block {
 };
 
 struct notifier_head {
-    struct notifier_block head;
+    struct list_head head;
 };
 
-#define NOTIFIER_INIT(name) { .head.chain = LIST_HEAD_INIT(name.head.chain) }
+#define NOTIFIER_HEAD(name)                                                    
\
+  struct notifier_head name = {.head = LIST_HEAD_INIT(name.head)}
 
-#define NOTIFIER_HEAD(name) \
-    struct notifier_head name = NOTIFIER_INIT(name)
 
 void notifier_chain_register(
     struct notifier_head *nh, struct notifier_block *nb);
-void notifier_chain_unregister(
-    struct notifier_head *nh, struct notifier_block *nb);
+
+/**
+ * notifier_chain_unregister - Remove notifier from a raw notifier chain
+ * @n: Entry to remove from notifier chain
+ *
+ * Removes a notifier from a raw notifier chain.
+ * All locking must be provided by the caller.
+ */
+static inline void notifier_chain_unregister(struct notifier_block *n)
+{
+    list_del(&n->chain);
+}
 
 int notifier_call_chain(
     struct notifier_head *nh, unsigned long val, void *v,
-- 
2.7.4


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