diff options
| -rw-r--r-- | include/linux/klist.h | 53 | ||||
| -rw-r--r-- | lib/Makefile | 7 | ||||
| -rw-r--r-- | lib/klist.c | 248 |
3 files changed, 305 insertions, 3 deletions
diff --git a/include/linux/klist.h b/include/linux/klist.h new file mode 100644 index 000000000000..fb52f9d9d611 --- /dev/null +++ b/include/linux/klist.h @@ -0,0 +1,53 @@ +/* + * klist.h - Some generic list helpers, extending struct list_head a bit. + * + * Implementations are found in lib/klist.c + * + * + * Copyright (C) 2005 Patrick Mochel + * + * This file is rleased under the GPL v2. + */ + +#include <linux/spinlock.h> +#include <linux/completion.h> +#include <linux/kref.h> +#include <linux/list.h> + + +struct klist { + spinlock_t k_lock; + struct list_head k_list; +}; + + +extern void klist_init(struct klist * k); + + +struct klist_node { + struct klist * n_klist; + struct list_head n_node; + struct kref n_ref; + struct completion n_removed; +}; + +extern void klist_add_tail(struct klist * k, struct klist_node * n); +extern void klist_add_head(struct klist * k, struct klist_node * n); + +extern void klist_del(struct klist_node * n); +extern void klist_remove(struct klist_node * n); + + +struct klist_iter { + struct klist * i_klist; + struct list_head * i_head; + struct klist_node * i_cur; +}; + + +extern void klist_iter_init(struct klist * k, struct klist_iter * i); +extern void klist_iter_init_node(struct klist * k, struct klist_iter * i, + struct klist_node * n); +extern void klist_iter_exit(struct klist_iter * i); +extern struct klist_node * klist_next(struct klist_iter * i); + diff --git a/lib/Makefile b/lib/Makefile index 7c70db79c0e0..9eccea9429a7 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -4,9 +4,10 @@ lib-y := errno.o ctype.o string.o vsprintf.o cmdline.o \ bust_spinlocks.o rbtree.o radix-tree.o dump_stack.o \ - kobject.o kref.o idr.o div64.o int_sqrt.o \ - bitmap.o extable.o kobject_uevent.o prio_tree.o sha1.o \ - halfmd4.o + idr.o div64.o int_sqrt.o bitmap.o extable.o prio_tree.o \ + sha1.o halfmd4.o + +lib-y += kobject.o kref.o kobject_uevent.o klist.o obj-y += sort.o parser.o diff --git a/lib/klist.c b/lib/klist.c new file mode 100644 index 000000000000..6f760424648b --- /dev/null +++ b/lib/klist.c @@ -0,0 +1,248 @@ +/* + * klist.c - Routines for manipulating klists. + * + * + * This klist interface provides a couple of structures that wrap around + * struct list_head to provide explicit list "head" (struct klist) and + * list "node" (struct klist_node) objects. For struct klist, a spinlock + * is included that protects access to the actual list itself. struct + * klist_node provides a pointer to the klist that owns it and a kref + * reference count that indicates the number of current users of that node + * in the list. + * + * The entire point is to provide an interface for iterating over a list + * that is safe and allows for modification of the list during the + * iteration (e.g. insertion and removal), including modification of the + * current node on the list. + * + * It works using a 3rd object type - struct klist_iter - that is declared + * and initialized before an iteration. klist_next() is used to acquire the + * next element in the list. It returns NULL if there are no more items. + * Internally, that routine takes the klist's lock, decrements the reference + * count of the previous klist_node and increments the count of the next + * klist_node. It then drops the lock and returns. + * + * There are primitives for adding and removing nodes to/from a klist. + * When deleting, klist_del() will simply decrement the reference count. + * Only when the count goes to 0 is the node removed from the list. + * klist_remove() will try to delete the node from the list and block + * until it is actually removed. This is useful for objects (like devices) + * that have been removed from the system and must be freed (but must wait + * until all accessors have finished). + * + * Copyright (C) 2005 Patrick Mochel + * + * This file is released under the GPL v2. + */ + +#include <linux/klist.h> +#include <linux/module.h> + + +/** + * klist_init - Initialize a klist structure. + * @k: The klist we're initializing. + */ + +void klist_init(struct klist * k) +{ + INIT_LIST_HEAD(&k->k_list); + spin_lock_init(&k->k_lock); +} + +EXPORT_SYMBOL_GPL(klist_init); + + +static void add_head(struct klist * k, struct klist_node * n) +{ + spin_lock(&k->k_lock); + list_add(&n->n_node, &k->k_list); + spin_unlock(&k->k_lock); +} + +static void add_tail(struct klist * k, struct klist_node * n) +{ + spin_lock(&k->k_lock); + list_add_tail(&n->n_node, &k->k_list); + spin_unlock(&k->k_lock); +} + + +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; +} + + +/** + * klist_add_head - Initialize a klist_node and add it to front. + * @k: klist it's going on. + * @n: node we're adding. + */ + +void klist_add_head(struct klist * k, struct klist_node * n) +{ + klist_node_init(k, n); + add_head(k, n); +} + +EXPORT_SYMBOL_GPL(klist_add_head); + + +/** + * klist_add_tail - Initialize a klist_node and add it to back. + * @k: klist it's going on. + * @n: node we're adding. + */ + +void klist_add_tail(struct klist * k, struct klist_node * n) +{ + klist_node_init(k, n); + add_tail(k, n); +} + +EXPORT_SYMBOL_GPL(klist_add_tail); + + +static void klist_release(struct kref * kref) +{ + struct klist_node * n = container_of(kref, struct klist_node, n_ref); + list_del(&n->n_node); + complete(&n->n_removed); +} + +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) +{ + struct klist * k = n->n_klist; + + spin_lock(&k->k_lock); + klist_dec_and_del(n); + spin_unlock(&k->k_lock); +} + +EXPORT_SYMBOL_GPL(klist_del); + + +/** + * klist_remove - Decrement the refcount of node and wait for it to go away. + * @n: node we're removing. + */ + +void klist_remove(struct klist_node * n) +{ + spin_lock(&n->n_klist->k_lock); + klist_dec_and_del(n); + spin_unlock(&n->n_klist->k_lock); + wait_for_completion(&n->n_removed); +} + +EXPORT_SYMBOL_GPL(klist_remove); + + +/** + * klist_iter_init_node - Initialize a klist_iter structure. + * @k: klist we're iterating. + * @i: klist_iter we're filling. + * @n: node to start with. + * + * Similar to klist_iter_init(), but starts the action off with @n, + * instead of with the list head. + */ + +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; +} + +EXPORT_SYMBOL_GPL(klist_iter_init_node); + + +/** + * klist_iter_init - Iniitalize a klist_iter structure. + * @k: klist we're iterating. + * @i: klist_iter structure we're filling. + * + * Similar to klist_iter_init_node(), but start with the list head. + */ + +void klist_iter_init(struct klist * k, struct klist_iter * i) +{ + klist_iter_init_node(k, i, NULL); +} + +EXPORT_SYMBOL_GPL(klist_iter_init); + + +/** + * klist_iter_exit - Finish a list iteration. + * @i: Iterator structure. + * + * Must be called when done iterating over list, as it decrements the + * refcount of the current node. Necessary in case iteration exited before + * the end of the list was reached, and always good form. + */ + +void klist_iter_exit(struct klist_iter * i) +{ + if (i->i_cur) { + klist_del(i->i_cur); + i->i_cur = NULL; + } +} + +EXPORT_SYMBOL_GPL(klist_iter_exit); + + +static struct klist_node * to_klist_node(struct list_head * n) +{ + return container_of(n, struct klist_node, n_node); +} + + +/** + * klist_next - Ante up next node in list. + * @i: Iterator structure. + * + * First grab list lock. Decrement the reference count of the previous + * node, if there was one. Grab the next node, increment its reference + * count, drop the lock, and return that next node. + */ + +struct klist_node * klist_next(struct klist_iter * i) +{ + struct list_head * next; + struct klist_node * knode = NULL; + + spin_lock(&i->i_klist->k_lock); + if (i->i_cur) { + next = i->i_cur->n_node.next; + klist_dec_and_del(i->i_cur); + } else + next = i->i_head->next; + + if (next != i->i_head) { + knode = to_klist_node(next); + kref_get(&knode->n_ref); + } + i->i_cur = knode; + spin_unlock(&i->i_klist->k_lock); + return knode; +} + +EXPORT_SYMBOL_GPL(klist_next); |