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-rw-r--r--include/linux/klist.h53
-rw-r--r--lib/Makefile7
-rw-r--r--lib/klist.c248
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 @@
1/*
2 * klist.h - Some generic list helpers, extending struct list_head a bit.
3 *
4 * Implementations are found in lib/klist.c
5 *
6 *
7 * Copyright (C) 2005 Patrick Mochel
8 *
9 * This file is rleased under the GPL v2.
10 */
11
12#include <linux/spinlock.h>
13#include <linux/completion.h>
14#include <linux/kref.h>
15#include <linux/list.h>
16
17
18struct klist {
19 spinlock_t k_lock;
20 struct list_head k_list;
21};
22
23
24extern void klist_init(struct klist * k);
25
26
27struct klist_node {
28 struct klist * n_klist;
29 struct list_head n_node;
30 struct kref n_ref;
31 struct completion n_removed;
32};
33
34extern void klist_add_tail(struct klist * k, struct klist_node * n);
35extern void klist_add_head(struct klist * k, struct klist_node * n);
36
37extern void klist_del(struct klist_node * n);
38extern void klist_remove(struct klist_node * n);
39
40
41struct klist_iter {
42 struct klist * i_klist;
43 struct list_head * i_head;
44 struct klist_node * i_cur;
45};
46
47
48extern void klist_iter_init(struct klist * k, struct klist_iter * i);
49extern void klist_iter_init_node(struct klist * k, struct klist_iter * i,
50 struct klist_node * n);
51extern void klist_iter_exit(struct klist_iter * i);
52extern struct klist_node * klist_next(struct klist_iter * i);
53
diff --git a/lib/Makefile b/lib/Makefile
index 7c70db79c0e0..9eccea9429a7 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -4,9 +4,10 @@
4 4
5lib-y := errno.o ctype.o string.o vsprintf.o cmdline.o \ 5lib-y := errno.o ctype.o string.o vsprintf.o cmdline.o \
6 bust_spinlocks.o rbtree.o radix-tree.o dump_stack.o \ 6 bust_spinlocks.o rbtree.o radix-tree.o dump_stack.o \
7 kobject.o kref.o idr.o div64.o int_sqrt.o \ 7 idr.o div64.o int_sqrt.o bitmap.o extable.o prio_tree.o \
8 bitmap.o extable.o kobject_uevent.o prio_tree.o sha1.o \ 8 sha1.o halfmd4.o
9 halfmd4.o 9
10lib-y += kobject.o kref.o kobject_uevent.o klist.o
10 11
11obj-y += sort.o parser.o 12obj-y += sort.o parser.o
12 13
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 @@
1/*
2 * klist.c - Routines for manipulating klists.
3 *
4 *
5 * This klist interface provides a couple of structures that wrap around
6 * struct list_head to provide explicit list "head" (struct klist) and
7 * list "node" (struct klist_node) objects. For struct klist, a spinlock
8 * is included that protects access to the actual list itself. struct
9 * klist_node provides a pointer to the klist that owns it and a kref
10 * reference count that indicates the number of current users of that node
11 * in the list.
12 *
13 * The entire point is to provide an interface for iterating over a list
14 * that is safe and allows for modification of the list during the
15 * iteration (e.g. insertion and removal), including modification of the
16 * current node on the list.
17 *
18 * It works using a 3rd object type - struct klist_iter - that is declared
19 * and initialized before an iteration. klist_next() is used to acquire the
20 * next element in the list. It returns NULL if there are no more items.
21 * Internally, that routine takes the klist's lock, decrements the reference
22 * count of the previous klist_node and increments the count of the next
23 * klist_node. It then drops the lock and returns.
24 *
25 * There are primitives for adding and removing nodes to/from a klist.
26 * When deleting, klist_del() will simply decrement the reference count.
27 * Only when the count goes to 0 is the node removed from the list.
28 * klist_remove() will try to delete the node from the list and block
29 * until it is actually removed. This is useful for objects (like devices)
30 * that have been removed from the system and must be freed (but must wait
31 * until all accessors have finished).
32 *
33 * Copyright (C) 2005 Patrick Mochel
34 *
35 * This file is released under the GPL v2.
36 */
37
38#include <linux/klist.h>
39#include <linux/module.h>
40
41
42/**
43 * klist_init - Initialize a klist structure.
44 * @k: The klist we're initializing.
45 */
46
47void klist_init(struct klist * k)
48{
49 INIT_LIST_HEAD(&k->k_list);
50 spin_lock_init(&k->k_lock);
51}
52
53EXPORT_SYMBOL_GPL(klist_init);
54
55
56static void add_head(struct klist * k, struct klist_node * n)
57{
58 spin_lock(&k->k_lock);
59 list_add(&n->n_node, &k->k_list);
60 spin_unlock(&k->k_lock);
61}
62
63static void add_tail(struct klist * k, struct klist_node * n)
64{
65 spin_lock(&k->k_lock);
66 list_add_tail(&n->n_node, &k->k_list);
67 spin_unlock(&k->k_lock);
68}
69
70
71static void klist_node_init(struct klist * k, struct klist_node * n)
72{
73 INIT_LIST_HEAD(&n->n_node);
74 init_completion(&n->n_removed);
75 kref_init(&n->n_ref);
76 n->n_klist = k;
77}
78
79
80/**
81 * klist_add_head - Initialize a klist_node and add it to front.
82 * @k: klist it's going on.
83 * @n: node we're adding.
84 */
85
86void klist_add_head(struct klist * k, struct klist_node * n)
87{
88 klist_node_init(k, n);
89 add_head(k, n);
90}
91
92EXPORT_SYMBOL_GPL(klist_add_head);
93
94
95/**
96 * klist_add_tail - Initialize a klist_node and add it to back.
97 * @k: klist it's going on.
98 * @n: node we're adding.
99 */
100
101void klist_add_tail(struct klist * k, struct klist_node * n)
102{
103 klist_node_init(k, n);
104 add_tail(k, n);
105}
106
107EXPORT_SYMBOL_GPL(klist_add_tail);
108
109
110static void klist_release(struct kref * kref)
111{
112 struct klist_node * n = container_of(kref, struct klist_node, n_ref);
113 list_del(&n->n_node);
114 complete(&n->n_removed);
115}
116
117static int klist_dec_and_del(struct klist_node * n)
118{
119 return kref_put(&n->n_ref, klist_release);
120}
121
122
123/**
124 * klist_del - Decrement the reference count of node and try to remove.
125 * @n: node we're deleting.
126 */
127
128void klist_del(struct klist_node * n)
129{
130 struct klist * k = n->n_klist;
131
132 spin_lock(&k->k_lock);
133 klist_dec_and_del(n);
134 spin_unlock(&k->k_lock);
135}
136
137EXPORT_SYMBOL_GPL(klist_del);
138
139
140/**
141 * klist_remove - Decrement the refcount of node and wait for it to go away.
142 * @n: node we're removing.
143 */
144
145void klist_remove(struct klist_node * n)
146{
147 spin_lock(&n->n_klist->k_lock);
148 klist_dec_and_del(n);
149 spin_unlock(&n->n_klist->k_lock);
150 wait_for_completion(&n->n_removed);
151}
152
153EXPORT_SYMBOL_GPL(klist_remove);
154
155
156/**
157 * klist_iter_init_node - Initialize a klist_iter structure.
158 * @k: klist we're iterating.
159 * @i: klist_iter we're filling.
160 * @n: node to start with.
161 *
162 * Similar to klist_iter_init(), but starts the action off with @n,
163 * instead of with the list head.
164 */
165
166void klist_iter_init_node(struct klist * k, struct klist_iter * i, struct klist_node * n)
167{
168 i->i_klist = k;
169 i->i_head = &k->k_list;
170 i->i_cur = n;
171}
172
173EXPORT_SYMBOL_GPL(klist_iter_init_node);
174
175
176/**
177 * klist_iter_init - Iniitalize a klist_iter structure.
178 * @k: klist we're iterating.
179 * @i: klist_iter structure we're filling.
180 *
181 * Similar to klist_iter_init_node(), but start with the list head.
182 */
183
184void klist_iter_init(struct klist * k, struct klist_iter * i)
185{
186 klist_iter_init_node(k, i, NULL);
187}
188
189EXPORT_SYMBOL_GPL(klist_iter_init);
190
191
192/**
193 * klist_iter_exit - Finish a list iteration.
194 * @i: Iterator structure.
195 *
196 * Must be called when done iterating over list, as it decrements the
197 * refcount of the current node. Necessary in case iteration exited before
198 * the end of the list was reached, and always good form.
199 */
200
201void klist_iter_exit(struct klist_iter * i)
202{
203 if (i->i_cur) {
204 klist_del(i->i_cur);
205 i->i_cur = NULL;
206 }
207}
208
209EXPORT_SYMBOL_GPL(klist_iter_exit);
210
211
212static struct klist_node * to_klist_node(struct list_head * n)
213{
214 return container_of(n, struct klist_node, n_node);
215}
216
217
218/**
219 * klist_next - Ante up next node in list.
220 * @i: Iterator structure.
221 *
222 * First grab list lock. Decrement the reference count of the previous
223 * node, if there was one. Grab the next node, increment its reference
224 * count, drop the lock, and return that next node.
225 */
226
227struct klist_node * klist_next(struct klist_iter * i)
228{
229 struct list_head * next;
230 struct klist_node * knode = NULL;
231
232 spin_lock(&i->i_klist->k_lock);
233 if (i->i_cur) {
234 next = i->i_cur->n_node.next;
235 klist_dec_and_del(i->i_cur);
236 } else
237 next = i->i_head->next;
238
239 if (next != i->i_head) {
240 knode = to_klist_node(next);
241 kref_get(&knode->n_ref);
242 }
243 i->i_cur = knode;
244 spin_unlock(&i->i_klist->k_lock);
245 return knode;
246}
247
248EXPORT_SYMBOL_GPL(klist_next);
generated by cgit v1.2.2 (git 2.25.0) at 2024-11-23 03:36:45 -0500