diff options
| -rw-r--r-- | include/linux/klist.h | 3 | ||||
| -rw-r--r-- | lib/klist.c | 96 |
2 files changed, 71 insertions, 28 deletions
diff --git a/include/linux/klist.h b/include/linux/klist.h index 06c338ef7f1..8ea98db223e 100644 --- a/include/linux/klist.h +++ b/include/linux/klist.h @@ -38,7 +38,7 @@ extern void klist_init(struct klist *k, void (*get)(struct klist_node *), void (*put)(struct klist_node *)); struct klist_node { - struct klist *n_klist; + void *n_klist; /* never access directly */ struct list_head n_node; struct kref n_ref; struct completion n_removed; @@ -57,7 +57,6 @@ extern int klist_node_attached(struct klist_node *n); struct klist_iter { struct klist *i_klist; - struct list_head *i_head; struct klist_node *i_cur; }; diff --git a/lib/klist.c b/lib/klist.c index cca37f96faa..bbdd3015c2c 100644 --- 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); |