Clean up notifier-chain interface and use new interface in CPU hotplug.

Signed-off-by: Keir Fraser <keir.fraser@citrix.com>

1 files changed, 51 insertions, 115 deletions

diff --git a/xen/common/notifier.c b/xen/common/notifier.c
index fe1c507a7a..ea1ebdeffe 100644
--- a/xen/common/notifier.c
+++ b/xen/common/notifier.c
@@ -10,147 +10,83 @@
 #include <xen/config.h>
 #include <xen/init.h>
 #include <xen/notifier.h>
-#include <xen/rcupdate.h>
-
-/*
- * Notifier chain core routines.  The exported routines below
- * are layered on top of these, with appropriate locking added.
- */
-
-static int notifier_chain_register(
-    struct notifier_block **nl, struct notifier_block *n)
-{
-    while ( (*nl) != NULL )
-    {
-        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)
-{
-    while ( (*nl) != NULL )
-    {
-        if ( (*nl) == n )
-        {
-            rcu_assign_pointer(*nl, n->next);
-            return 0;
-        }
-        nl = &((*nl)->next);
-    }
-    return -ENOENT;
-}
-
-/**
- * notifier_call_chain - Informs the registered notifiers about an event.
- * @nl:  Pointer to head of the blocking notifier chain
- * @val:  Value passed unmodified to notifier function
- * @v:  Pointer passed unmodified to notifier function
- * @nr_to_call: Number of notifier functions to be called. Don't care
- *   value of this parameter is -1.
- * @nr_calls: Records the number of notifications sent. Don't care
- *   value of this field is NULL.
- * @returns: notifier_call_chain returns the value returned by the
- *   last notifier function called.
- */
-static int notifier_call_chain(
-    struct notifier_block **nl, unsigned long val, void *v,
-    int nr_to_call, int *nr_calls)
-{
-    int ret = NOTIFY_DONE;
-    struct notifier_block *nb, *next_nb;
-
-    if ( nr_calls )
-        *nr_calls = 0;
-
-    nb = rcu_dereference(*nl);
-
-    while ( nb && nr_to_call )
-    {
-        next_nb = rcu_dereference(nb->next);
-        ret = nb->notifier_call(nb, val, v);
-
-        if ( nr_calls )
-            (*nr_calls)++;
-
-        if ( (ret & NOTIFY_STOP_MASK) == NOTIFY_STOP_MASK )
-            break;
-        nb = next_nb;
-        nr_to_call--;
-    }
-    return ret;
-}
-
-/*
- * Raw notifier chain routines.  There is no protection;
- * the caller must provide it.  Use at your own risk!
- */
 
 /**
- * raw_notifier_chain_register - Add notifier to a raw notifier chain
+ * notifier_chain_register - Add notifier to a raw notifier chain
  * @nh: Pointer to head of the raw notifier chain
  * @n: New entry in notifier chain
  *
  * Adds a notifier to a raw notifier chain.
  * All locking must be provided by the caller.
- *
- * Currently always returns zero.
  */
-int raw_notifier_chain_register(
-    struct raw_notifier_head *nh, struct notifier_block *n)
+void notifier_chain_register(
+    struct notifier_head *nh, struct notifier_block *n)
 {
-    return notifier_chain_register(&nh->head, n);
+    struct list_head *chain = &nh->head.chain;
+    struct notifier_block *nb;
+
+    while ( chain->next != &nh->head.chain )
+    {
+        nb = list_entry(chain->next, struct notifier_block, chain);
+        if ( n->priority > nb->priority )
+            break;
+        chain = chain->next;
+    }
+
+    list_add(&n->chain, chain);
 }
 
 /**
- * raw_notifier_chain_unregister - Remove notifier from a raw notifier 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.
- *
- * Returns zero on success or %-ENOENT on failure.
  */
-int raw_notifier_chain_unregister(
-    struct raw_notifier_head *nh, struct notifier_block *n)
+void notifier_chain_unregister(
+    struct notifier_head *nh, struct notifier_block *n)
 {
-    return notifier_chain_unregister(&nh->head, n);
+    list_del(&n->chain);
 }
 
 /**
- * __raw_notifier_call_chain - Call functions in a raw notifier chain
+ * notifier_call_chain - Informs the registered notifiers about an event.
  * @nh: Pointer to head of the raw notifier chain
- * @val: Value passed unmodified to notifier function
- * @v: Pointer passed unmodified to notifier function
- * @nr_to_call: See comment for notifier_call_chain.
- * @nr_calls: See comment for notifier_call_chain
+ * @val:  Value passed unmodified to notifier function
+ * @v:  Pointer passed unmodified to notifier function
+ * @pcursor: If non-NULL, position in chain to start from. Also updated on
+ *           return to indicate how far notifications got before stopping.
  *
- * Calls each function in a notifier chain in turn.  The functions
- * run in an undefined context.
- * All locking must be provided by the caller.
+ * Calls each function in a notifier chain in turn.  The functions run in an
+ * undefined context. All locking must be provided by the caller.
  *
- * If the return value of the notifier can be and'ed
- * with %NOTIFY_STOP_MASK then raw_notifier_call_chain()
- * will return immediately, with the return value of
- * the notifier function which halted execution.
- * Otherwise the return value is the return value
- * of the last notifier function called.
+ * If the return value of the notifier can be and'ed with %NOTIFY_STOP_MASK
+ * then notifier_call_chain() will return immediately, with teh return value of
+ * the notifier function which halted execution. Otherwise the return value is
+ * the return value of the last notifier function called.
  */
-int __raw_notifier_call_chain(
-    struct raw_notifier_head *nh, unsigned long val, void *v,
-    int nr_to_call, int *nr_calls)
+int notifier_call_chain(
+    struct notifier_head *nh, unsigned long val, void *v,
+    struct notifier_block **pcursor)
 {
-    return notifier_call_chain(&nh->head, val, v, nr_to_call, nr_calls);
-}
+    int ret = NOTIFY_DONE;
+    struct list_head *cursor;
+    struct notifier_block *nb;
+    bool_t reverse = !!(val & NOTIFY_REVERSE);
 
-int raw_notifier_call_chain(
-    struct raw_notifier_head *nh, unsigned long val, void *v)
-{
-    return __raw_notifier_call_chain(nh, val, v, -1, NULL);
+    cursor = &(pcursor && *pcursor ? *pcursor : &nh->head)->chain;
+
+    do {
+        cursor = reverse ? cursor->prev : cursor->next;
+        nb = list_entry(cursor, struct notifier_block, chain);
+        if ( cursor == &nh->head.chain )
+            break;
+        ret = nb->notifier_call(nb, val, v);
+    } while ( !(ret & NOTIFY_STOP_MASK) );
+
+    if ( pcursor )
+        *pcursor = nb;
+
+    return ret;
 }