ia64/linux-2.6.18-xen.hg

annotate lib/klist.c @ 740:bf8b1ee634e2

balloon: Fix the build by including <linux/init.h>

Signed-off-by: Keir Fraser <keir.fraser@citrix.com>
author Keir Fraser <keir.fraser@citrix.com>
date Tue Nov 25 11:19:41 2008 +0000 (2008-11-25)
parents 831230e53067
children
rev   line source
ian@0 1 /*
ian@0 2 * klist.c - Routines for manipulating klists.
ian@0 3 *
ian@0 4 *
ian@0 5 * This klist interface provides a couple of structures that wrap around
ian@0 6 * struct list_head to provide explicit list "head" (struct klist) and
ian@0 7 * list "node" (struct klist_node) objects. For struct klist, a spinlock
ian@0 8 * is included that protects access to the actual list itself. struct
ian@0 9 * klist_node provides a pointer to the klist that owns it and a kref
ian@0 10 * reference count that indicates the number of current users of that node
ian@0 11 * in the list.
ian@0 12 *
ian@0 13 * The entire point is to provide an interface for iterating over a list
ian@0 14 * that is safe and allows for modification of the list during the
ian@0 15 * iteration (e.g. insertion and removal), including modification of the
ian@0 16 * current node on the list.
ian@0 17 *
ian@0 18 * It works using a 3rd object type - struct klist_iter - that is declared
ian@0 19 * and initialized before an iteration. klist_next() is used to acquire the
ian@0 20 * next element in the list. It returns NULL if there are no more items.
ian@0 21 * Internally, that routine takes the klist's lock, decrements the reference
ian@0 22 * count of the previous klist_node and increments the count of the next
ian@0 23 * klist_node. It then drops the lock and returns.
ian@0 24 *
ian@0 25 * There are primitives for adding and removing nodes to/from a klist.
ian@0 26 * When deleting, klist_del() will simply decrement the reference count.
ian@0 27 * Only when the count goes to 0 is the node removed from the list.
ian@0 28 * klist_remove() will try to delete the node from the list and block
ian@0 29 * until it is actually removed. This is useful for objects (like devices)
ian@0 30 * that have been removed from the system and must be freed (but must wait
ian@0 31 * until all accessors have finished).
ian@0 32 *
ian@0 33 * Copyright (C) 2005 Patrick Mochel
ian@0 34 *
ian@0 35 * This file is released under the GPL v2.
ian@0 36 */
ian@0 37
ian@0 38 #include <linux/klist.h>
ian@0 39 #include <linux/module.h>
ian@0 40
ian@0 41
ian@0 42 /**
ian@0 43 * klist_init - Initialize a klist structure.
ian@0 44 * @k: The klist we're initializing.
ian@0 45 * @get: The get function for the embedding object (NULL if none)
ian@0 46 * @put: The put function for the embedding object (NULL if none)
ian@0 47 *
ian@0 48 * Initialises the klist structure. If the klist_node structures are
ian@0 49 * going to be embedded in refcounted objects (necessary for safe
ian@0 50 * deletion) then the get/put arguments are used to initialise
ian@0 51 * functions that take and release references on the embedding
ian@0 52 * objects.
ian@0 53 */
ian@0 54
ian@0 55 void klist_init(struct klist * k, void (*get)(struct klist_node *),
ian@0 56 void (*put)(struct klist_node *))
ian@0 57 {
ian@0 58 INIT_LIST_HEAD(&k->k_list);
ian@0 59 spin_lock_init(&k->k_lock);
ian@0 60 k->get = get;
ian@0 61 k->put = put;
ian@0 62 }
ian@0 63
ian@0 64 EXPORT_SYMBOL_GPL(klist_init);
ian@0 65
ian@0 66
ian@0 67 static void add_head(struct klist * k, struct klist_node * n)
ian@0 68 {
ian@0 69 spin_lock(&k->k_lock);
ian@0 70 list_add(&n->n_node, &k->k_list);
ian@0 71 spin_unlock(&k->k_lock);
ian@0 72 }
ian@0 73
ian@0 74 static void add_tail(struct klist * k, struct klist_node * n)
ian@0 75 {
ian@0 76 spin_lock(&k->k_lock);
ian@0 77 list_add_tail(&n->n_node, &k->k_list);
ian@0 78 spin_unlock(&k->k_lock);
ian@0 79 }
ian@0 80
ian@0 81
ian@0 82 static void klist_node_init(struct klist * k, struct klist_node * n)
ian@0 83 {
ian@0 84 INIT_LIST_HEAD(&n->n_node);
ian@0 85 init_completion(&n->n_removed);
ian@0 86 kref_init(&n->n_ref);
ian@0 87 n->n_klist = k;
ian@0 88 if (k->get)
ian@0 89 k->get(n);
ian@0 90 }
ian@0 91
ian@0 92
ian@0 93 /**
ian@0 94 * klist_add_head - Initialize a klist_node and add it to front.
ian@0 95 * @n: node we're adding.
ian@0 96 * @k: klist it's going on.
ian@0 97 */
ian@0 98
ian@0 99 void klist_add_head(struct klist_node * n, struct klist * k)
ian@0 100 {
ian@0 101 klist_node_init(k, n);
ian@0 102 add_head(k, n);
ian@0 103 }
ian@0 104
ian@0 105 EXPORT_SYMBOL_GPL(klist_add_head);
ian@0 106
ian@0 107
ian@0 108 /**
ian@0 109 * klist_add_tail - Initialize a klist_node and add it to back.
ian@0 110 * @n: node we're adding.
ian@0 111 * @k: klist it's going on.
ian@0 112 */
ian@0 113
ian@0 114 void klist_add_tail(struct klist_node * n, struct klist * k)
ian@0 115 {
ian@0 116 klist_node_init(k, n);
ian@0 117 add_tail(k, n);
ian@0 118 }
ian@0 119
ian@0 120 EXPORT_SYMBOL_GPL(klist_add_tail);
ian@0 121
ian@0 122
ian@0 123 static void klist_release(struct kref * kref)
ian@0 124 {
ian@0 125 struct klist_node * n = container_of(kref, struct klist_node, n_ref);
ian@0 126 void (*put)(struct klist_node *) = n->n_klist->put;
ian@0 127 list_del(&n->n_node);
ian@0 128 complete(&n->n_removed);
ian@0 129 n->n_klist = NULL;
ian@0 130 if (put)
ian@0 131 put(n);
ian@0 132 }
ian@0 133
ian@0 134 static int klist_dec_and_del(struct klist_node * n)
ian@0 135 {
ian@0 136 return kref_put(&n->n_ref, klist_release);
ian@0 137 }
ian@0 138
ian@0 139
ian@0 140 /**
ian@0 141 * klist_del - Decrement the reference count of node and try to remove.
ian@0 142 * @n: node we're deleting.
ian@0 143 */
ian@0 144
ian@0 145 void klist_del(struct klist_node * n)
ian@0 146 {
ian@0 147 struct klist * k = n->n_klist;
ian@0 148
ian@0 149 spin_lock(&k->k_lock);
ian@0 150 klist_dec_and_del(n);
ian@0 151 spin_unlock(&k->k_lock);
ian@0 152 }
ian@0 153
ian@0 154 EXPORT_SYMBOL_GPL(klist_del);
ian@0 155
ian@0 156
ian@0 157 /**
ian@0 158 * klist_remove - Decrement the refcount of node and wait for it to go away.
ian@0 159 * @n: node we're removing.
ian@0 160 */
ian@0 161
ian@0 162 void klist_remove(struct klist_node * n)
ian@0 163 {
ian@0 164 struct klist * k = n->n_klist;
ian@0 165 spin_lock(&k->k_lock);
ian@0 166 klist_dec_and_del(n);
ian@0 167 spin_unlock(&k->k_lock);
ian@0 168 wait_for_completion(&n->n_removed);
ian@0 169 }
ian@0 170
ian@0 171 EXPORT_SYMBOL_GPL(klist_remove);
ian@0 172
ian@0 173
ian@0 174 /**
ian@0 175 * klist_node_attached - Say whether a node is bound to a list or not.
ian@0 176 * @n: Node that we're testing.
ian@0 177 */
ian@0 178
ian@0 179 int klist_node_attached(struct klist_node * n)
ian@0 180 {
ian@0 181 return (n->n_klist != NULL);
ian@0 182 }
ian@0 183
ian@0 184 EXPORT_SYMBOL_GPL(klist_node_attached);
ian@0 185
ian@0 186
ian@0 187 /**
ian@0 188 * klist_iter_init_node - Initialize a klist_iter structure.
ian@0 189 * @k: klist we're iterating.
ian@0 190 * @i: klist_iter we're filling.
ian@0 191 * @n: node to start with.
ian@0 192 *
ian@0 193 * Similar to klist_iter_init(), but starts the action off with @n,
ian@0 194 * instead of with the list head.
ian@0 195 */
ian@0 196
ian@0 197 void klist_iter_init_node(struct klist * k, struct klist_iter * i, struct klist_node * n)
ian@0 198 {
ian@0 199 i->i_klist = k;
ian@0 200 i->i_head = &k->k_list;
ian@0 201 i->i_cur = n;
ian@0 202 if (n)
ian@0 203 kref_get(&n->n_ref);
ian@0 204 }
ian@0 205
ian@0 206 EXPORT_SYMBOL_GPL(klist_iter_init_node);
ian@0 207
ian@0 208
ian@0 209 /**
ian@0 210 * klist_iter_init - Iniitalize a klist_iter structure.
ian@0 211 * @k: klist we're iterating.
ian@0 212 * @i: klist_iter structure we're filling.
ian@0 213 *
ian@0 214 * Similar to klist_iter_init_node(), but start with the list head.
ian@0 215 */
ian@0 216
ian@0 217 void klist_iter_init(struct klist * k, struct klist_iter * i)
ian@0 218 {
ian@0 219 klist_iter_init_node(k, i, NULL);
ian@0 220 }
ian@0 221
ian@0 222 EXPORT_SYMBOL_GPL(klist_iter_init);
ian@0 223
ian@0 224
ian@0 225 /**
ian@0 226 * klist_iter_exit - Finish a list iteration.
ian@0 227 * @i: Iterator structure.
ian@0 228 *
ian@0 229 * Must be called when done iterating over list, as it decrements the
ian@0 230 * refcount of the current node. Necessary in case iteration exited before
ian@0 231 * the end of the list was reached, and always good form.
ian@0 232 */
ian@0 233
ian@0 234 void klist_iter_exit(struct klist_iter * i)
ian@0 235 {
ian@0 236 if (i->i_cur) {
ian@0 237 klist_del(i->i_cur);
ian@0 238 i->i_cur = NULL;
ian@0 239 }
ian@0 240 }
ian@0 241
ian@0 242 EXPORT_SYMBOL_GPL(klist_iter_exit);
ian@0 243
ian@0 244
ian@0 245 static struct klist_node * to_klist_node(struct list_head * n)
ian@0 246 {
ian@0 247 return container_of(n, struct klist_node, n_node);
ian@0 248 }
ian@0 249
ian@0 250
ian@0 251 /**
ian@0 252 * klist_next - Ante up next node in list.
ian@0 253 * @i: Iterator structure.
ian@0 254 *
ian@0 255 * First grab list lock. Decrement the reference count of the previous
ian@0 256 * node, if there was one. Grab the next node, increment its reference
ian@0 257 * count, drop the lock, and return that next node.
ian@0 258 */
ian@0 259
ian@0 260 struct klist_node * klist_next(struct klist_iter * i)
ian@0 261 {
ian@0 262 struct list_head * next;
ian@0 263 struct klist_node * knode = NULL;
ian@0 264
ian@0 265 spin_lock(&i->i_klist->k_lock);
ian@0 266 if (i->i_cur) {
ian@0 267 next = i->i_cur->n_node.next;
ian@0 268 klist_dec_and_del(i->i_cur);
ian@0 269 } else
ian@0 270 next = i->i_head->next;
ian@0 271
ian@0 272 if (next != i->i_head) {
ian@0 273 knode = to_klist_node(next);
ian@0 274 kref_get(&knode->n_ref);
ian@0 275 }
ian@0 276 i->i_cur = knode;
ian@0 277 spin_unlock(&i->i_klist->k_lock);
ian@0 278 return knode;
ian@0 279 }
ian@0 280
ian@0 281 EXPORT_SYMBOL_GPL(klist_next);
ian@0 282
ian@0 283