hdq driver for OMAP2430/3430

[linux-kernel-docs/linux-2.6.git] / lib / klist.c

diff --git a/lib/klist.c b/lib/klist.c
index cca37f9..bbdd301 100644 (file)
--- a/lib/klist.c
+++ b/lib/klist.c
@@ -37,6 +37,37 @@
 #include <linux/klist.h>
 #include <linux/module.h>
 
+/*
+ * Use the lowest bit of n_klist to mark deleted nodes and exclude
+ * dead ones from iteration.
+ */
+#define KNODE_DEAD             1LU
+#define KNODE_KLIST_MASK       ~KNODE_DEAD
+
+static struct klist *knode_klist(struct klist_node *knode)
+{
+       return (struct klist *)
+               ((unsigned long)knode->n_klist & KNODE_KLIST_MASK);
+}
+
+static bool knode_dead(struct klist_node *knode)
+{
+       return (unsigned long)knode->n_klist & KNODE_DEAD;
+}
+
+static void knode_set_klist(struct klist_node *knode, struct klist *klist)
+{
+       knode->n_klist = klist;
+       /* no knode deserves to start its life dead */
+       WARN_ON(knode_dead(knode));
+}
+
+static void knode_kill(struct klist_node *knode)
+{
+       /* and no knode should die twice ever either, see we're very humane */
+       WARN_ON(knode_dead(knode));
+       *(unsigned long *)&knode->n_klist |= KNODE_DEAD;
+}
 
 /**
  * klist_init - Initialize a klist structure.
@@ -79,7 +110,7 @@ static void klist_node_init(struct klist *k, struct klist_node *n)
        INIT_LIST_HEAD(&n->n_node);
        init_completion(&n->n_removed);
        kref_init(&n->n_ref);
-       n->n_klist = k;
+       knode_set_klist(n, k);
        if (k->get)
                k->get(n);
 }
@@ -115,7 +146,7 @@ EXPORT_SYMBOL_GPL(klist_add_tail);
  */
 void klist_add_after(struct klist_node *n, struct klist_node *pos)
 {
-       struct klist *k = pos->n_klist;
+       struct klist *k = knode_klist(pos);
 
        klist_node_init(k, n);
        spin_lock(&k->k_lock);
@@ -131,7 +162,7 @@ EXPORT_SYMBOL_GPL(klist_add_after);
  */
 void klist_add_before(struct klist_node *n, struct klist_node *pos)
 {
-       struct klist *k = pos->n_klist;
+       struct klist *k = knode_klist(pos);
 
        klist_node_init(k, n);
        spin_lock(&k->k_lock);
@@ -144,9 +175,10 @@ static void klist_release(struct kref *kref)
 {
        struct klist_node *n = container_of(kref, struct klist_node, n_ref);
 
+       WARN_ON(!knode_dead(n));
        list_del(&n->n_node);
        complete(&n->n_removed);
-       n->n_klist = NULL;
+       knode_set_klist(n, NULL);
 }
 
 static int klist_dec_and_del(struct klist_node *n)
@@ -154,22 +186,29 @@ static int klist_dec_and_del(struct klist_node *n)
        return kref_put(&n->n_ref, klist_release);
 }
 
-/**
- * klist_del - Decrement the reference count of node and try to remove.
- * @n: node we're deleting.
- */
-void klist_del(struct klist_node *n)
+static void klist_put(struct klist_node *n, bool kill)
 {
-       struct klist *k = n->n_klist;
+       struct klist *k = knode_klist(n);
        void (*put)(struct klist_node *) = k->put;
 
        spin_lock(&k->k_lock);
+       if (kill)
+               knode_kill(n);
        if (!klist_dec_and_del(n))
                put = NULL;
        spin_unlock(&k->k_lock);
        if (put)
                put(n);
 }
+
+/**
+ * klist_del - Decrement the reference count of node and try to remove.
+ * @n: node we're deleting.
+ */
+void klist_del(struct klist_node *n)
+{
+       klist_put(n, true);
+}
 EXPORT_SYMBOL_GPL(klist_del);
 
 /**
@@ -206,7 +245,6 @@ void klist_iter_init_node(struct klist *k, struct klist_iter *i,
                          struct klist_node *n)
 {
        i->i_klist = k;
-       i->i_head = &k->k_list;
        i->i_cur = n;
        if (n)
                kref_get(&n->n_ref);
@@ -237,7 +275,7 @@ EXPORT_SYMBOL_GPL(klist_iter_init);
 void klist_iter_exit(struct klist_iter *i)
 {
        if (i->i_cur) {
-               klist_del(i->i_cur);
+               klist_put(i->i_cur, false);
                i->i_cur = NULL;
        }
 }
@@ -258,27 +296,33 @@ static struct klist_node *to_klist_node(struct list_head *n)
  */
 struct klist_node *klist_next(struct klist_iter *i)
 {
-       struct list_head *next;
-       struct klist_node *lnode = i->i_cur;
-       struct klist_node *knode = NULL;
        void (*put)(struct klist_node *) = i->i_klist->put;
+       struct klist_node *last = i->i_cur;
+       struct klist_node *next;
 
        spin_lock(&i->i_klist->k_lock);
-       if (lnode) {
-               next = lnode->n_node.next;
-               if (!klist_dec_and_del(lnode))
+
+       if (last) {
+               next = to_klist_node(last->n_node.next);
+               if (!klist_dec_and_del(last))
                        put = NULL;
        } else
-               next = i->i_head->next;
+               next = to_klist_node(i->i_klist->k_list.next);
 
-       if (next != i->i_head) {
-               knode = to_klist_node(next);
-               kref_get(&knode->n_ref);
+       i->i_cur = NULL;
+       while (next != to_klist_node(&i->i_klist->k_list)) {
+               if (likely(!knode_dead(next))) {
+                       kref_get(&next->n_ref);
+                       i->i_cur = next;
+                       break;
+               }
+               next = to_klist_node(next->n_node.next);
        }
-       i->i_cur = knode;
+
        spin_unlock(&i->i_klist->k_lock);
-       if (put && lnode)
-               put(lnode);
-       return knode;
+
+       if (put && last)
+               put(last);
+       return i->i_cur;
 }
 EXPORT_SYMBOL_GPL(klist_next);