19a19fea4Smochel@digitalimplant.org /* 29a19fea4Smochel@digitalimplant.org * klist.c - Routines for manipulating klists. 39a19fea4Smochel@digitalimplant.org * 4c3bb7fadSGreg Kroah-Hartman * Copyright (C) 2005 Patrick Mochel 5c3bb7fadSGreg Kroah-Hartman * 6c3bb7fadSGreg Kroah-Hartman * This file is released under the GPL v2. 79a19fea4Smochel@digitalimplant.org * 89a19fea4Smochel@digitalimplant.org * This klist interface provides a couple of structures that wrap around 9c3bb7fadSGreg Kroah-Hartman * struct list_head to provide explicit list "head" (struct klist) and list 10c3bb7fadSGreg Kroah-Hartman * "node" (struct klist_node) objects. For struct klist, a spinlock is 11c3bb7fadSGreg Kroah-Hartman * included that protects access to the actual list itself. struct 129a19fea4Smochel@digitalimplant.org * klist_node provides a pointer to the klist that owns it and a kref 139a19fea4Smochel@digitalimplant.org * reference count that indicates the number of current users of that node 149a19fea4Smochel@digitalimplant.org * in the list. 159a19fea4Smochel@digitalimplant.org * 169a19fea4Smochel@digitalimplant.org * The entire point is to provide an interface for iterating over a list 179a19fea4Smochel@digitalimplant.org * that is safe and allows for modification of the list during the 189a19fea4Smochel@digitalimplant.org * iteration (e.g. insertion and removal), including modification of the 199a19fea4Smochel@digitalimplant.org * current node on the list. 209a19fea4Smochel@digitalimplant.org * 219a19fea4Smochel@digitalimplant.org * It works using a 3rd object type - struct klist_iter - that is declared 229a19fea4Smochel@digitalimplant.org * and initialized before an iteration. klist_next() is used to acquire the 239a19fea4Smochel@digitalimplant.org * next element in the list. It returns NULL if there are no more items. 24c3bb7fadSGreg Kroah-Hartman * Internally, that routine takes the klist's lock, decrements the 25c3bb7fadSGreg Kroah-Hartman * reference count of the previous klist_node and increments the count of 26c3bb7fadSGreg Kroah-Hartman * the next klist_node. It then drops the lock and returns. 279a19fea4Smochel@digitalimplant.org * 289a19fea4Smochel@digitalimplant.org * There are primitives for adding and removing nodes to/from a klist. 299a19fea4Smochel@digitalimplant.org * When deleting, klist_del() will simply decrement the reference count. 309a19fea4Smochel@digitalimplant.org * Only when the count goes to 0 is the node removed from the list. 31c3bb7fadSGreg Kroah-Hartman * klist_remove() will try to delete the node from the list and block until 32c3bb7fadSGreg Kroah-Hartman * it is actually removed. This is useful for objects (like devices) that 33c3bb7fadSGreg Kroah-Hartman * have been removed from the system and must be freed (but must wait until 34c3bb7fadSGreg Kroah-Hartman * all accessors have finished). 359a19fea4Smochel@digitalimplant.org */ 369a19fea4Smochel@digitalimplant.org 379a19fea4Smochel@digitalimplant.org #include <linux/klist.h> 388bc3bcc9SPaul Gortmaker #include <linux/export.h> 39210272a2SMatthew Wilcox #include <linux/sched.h> 409a19fea4Smochel@digitalimplant.org 41a1ed5b0cSTejun Heo /* 42a1ed5b0cSTejun Heo * Use the lowest bit of n_klist to mark deleted nodes and exclude 43a1ed5b0cSTejun Heo * dead ones from iteration. 44a1ed5b0cSTejun Heo */ 45a1ed5b0cSTejun Heo #define KNODE_DEAD 1LU 46a1ed5b0cSTejun Heo #define KNODE_KLIST_MASK ~KNODE_DEAD 47a1ed5b0cSTejun Heo 48a1ed5b0cSTejun Heo static struct klist *knode_klist(struct klist_node *knode) 49a1ed5b0cSTejun Heo { 50a1ed5b0cSTejun Heo return (struct klist *) 51a1ed5b0cSTejun Heo ((unsigned long)knode->n_klist & KNODE_KLIST_MASK); 52a1ed5b0cSTejun Heo } 53a1ed5b0cSTejun Heo 54a1ed5b0cSTejun Heo static bool knode_dead(struct klist_node *knode) 55a1ed5b0cSTejun Heo { 56a1ed5b0cSTejun Heo return (unsigned long)knode->n_klist & KNODE_DEAD; 57a1ed5b0cSTejun Heo } 58a1ed5b0cSTejun Heo 59a1ed5b0cSTejun Heo static void knode_set_klist(struct klist_node *knode, struct klist *klist) 60a1ed5b0cSTejun Heo { 61a1ed5b0cSTejun Heo knode->n_klist = klist; 62a1ed5b0cSTejun Heo /* no knode deserves to start its life dead */ 63a1ed5b0cSTejun Heo WARN_ON(knode_dead(knode)); 64a1ed5b0cSTejun Heo } 65a1ed5b0cSTejun Heo 66a1ed5b0cSTejun Heo static void knode_kill(struct klist_node *knode) 67a1ed5b0cSTejun Heo { 68a1ed5b0cSTejun Heo /* and no knode should die twice ever either, see we're very humane */ 69a1ed5b0cSTejun Heo WARN_ON(knode_dead(knode)); 70a1ed5b0cSTejun Heo *(unsigned long *)&knode->n_klist |= KNODE_DEAD; 71a1ed5b0cSTejun Heo } 729a19fea4Smochel@digitalimplant.org 739a19fea4Smochel@digitalimplant.org /** 749a19fea4Smochel@digitalimplant.org * klist_init - Initialize a klist structure. 759a19fea4Smochel@digitalimplant.org * @k: The klist we're initializing. 7634bb61f9SJames Bottomley * @get: The get function for the embedding object (NULL if none) 7734bb61f9SJames Bottomley * @put: The put function for the embedding object (NULL if none) 7834bb61f9SJames Bottomley * 7934bb61f9SJames Bottomley * Initialises the klist structure. If the klist_node structures are 8034bb61f9SJames Bottomley * going to be embedded in refcounted objects (necessary for safe 8134bb61f9SJames Bottomley * deletion) then the get/put arguments are used to initialise 8234bb61f9SJames Bottomley * functions that take and release references on the embedding 8334bb61f9SJames Bottomley * objects. 849a19fea4Smochel@digitalimplant.org */ 8534bb61f9SJames Bottomley void klist_init(struct klist *k, void (*get)(struct klist_node *), 8634bb61f9SJames Bottomley void (*put)(struct klist_node *)) 879a19fea4Smochel@digitalimplant.org { 889a19fea4Smochel@digitalimplant.org INIT_LIST_HEAD(&k->k_list); 899a19fea4Smochel@digitalimplant.org spin_lock_init(&k->k_lock); 9034bb61f9SJames Bottomley k->get = get; 9134bb61f9SJames Bottomley k->put = put; 929a19fea4Smochel@digitalimplant.org } 939a19fea4Smochel@digitalimplant.org EXPORT_SYMBOL_GPL(klist_init); 949a19fea4Smochel@digitalimplant.org 959a19fea4Smochel@digitalimplant.org static void add_head(struct klist *k, struct klist_node *n) 969a19fea4Smochel@digitalimplant.org { 979a19fea4Smochel@digitalimplant.org spin_lock(&k->k_lock); 989a19fea4Smochel@digitalimplant.org list_add(&n->n_node, &k->k_list); 999a19fea4Smochel@digitalimplant.org spin_unlock(&k->k_lock); 1009a19fea4Smochel@digitalimplant.org } 1019a19fea4Smochel@digitalimplant.org 1029a19fea4Smochel@digitalimplant.org static void add_tail(struct klist *k, struct klist_node *n) 1039a19fea4Smochel@digitalimplant.org { 1049a19fea4Smochel@digitalimplant.org spin_lock(&k->k_lock); 1059a19fea4Smochel@digitalimplant.org list_add_tail(&n->n_node, &k->k_list); 1069a19fea4Smochel@digitalimplant.org spin_unlock(&k->k_lock); 1079a19fea4Smochel@digitalimplant.org } 1089a19fea4Smochel@digitalimplant.org 1099a19fea4Smochel@digitalimplant.org static void klist_node_init(struct klist *k, struct klist_node *n) 1109a19fea4Smochel@digitalimplant.org { 1119a19fea4Smochel@digitalimplant.org INIT_LIST_HEAD(&n->n_node); 1129a19fea4Smochel@digitalimplant.org kref_init(&n->n_ref); 113a1ed5b0cSTejun Heo knode_set_klist(n, k); 11434bb61f9SJames Bottomley if (k->get) 11534bb61f9SJames Bottomley k->get(n); 1169a19fea4Smochel@digitalimplant.org } 1179a19fea4Smochel@digitalimplant.org 1189a19fea4Smochel@digitalimplant.org /** 1199a19fea4Smochel@digitalimplant.org * klist_add_head - Initialize a klist_node and add it to front. 1209a19fea4Smochel@digitalimplant.org * @n: node we're adding. 121d856f1e3SJames Bottomley * @k: klist it's going on. 1229a19fea4Smochel@digitalimplant.org */ 123d856f1e3SJames Bottomley void klist_add_head(struct klist_node *n, struct klist *k) 1249a19fea4Smochel@digitalimplant.org { 1259a19fea4Smochel@digitalimplant.org klist_node_init(k, n); 1269a19fea4Smochel@digitalimplant.org add_head(k, n); 1279a19fea4Smochel@digitalimplant.org } 1289a19fea4Smochel@digitalimplant.org EXPORT_SYMBOL_GPL(klist_add_head); 1299a19fea4Smochel@digitalimplant.org 1309a19fea4Smochel@digitalimplant.org /** 1319a19fea4Smochel@digitalimplant.org * klist_add_tail - Initialize a klist_node and add it to back. 1329a19fea4Smochel@digitalimplant.org * @n: node we're adding. 133d856f1e3SJames Bottomley * @k: klist it's going on. 1349a19fea4Smochel@digitalimplant.org */ 135d856f1e3SJames Bottomley void klist_add_tail(struct klist_node *n, struct klist *k) 1369a19fea4Smochel@digitalimplant.org { 1379a19fea4Smochel@digitalimplant.org klist_node_init(k, n); 1389a19fea4Smochel@digitalimplant.org add_tail(k, n); 1399a19fea4Smochel@digitalimplant.org } 1409a19fea4Smochel@digitalimplant.org EXPORT_SYMBOL_GPL(klist_add_tail); 1419a19fea4Smochel@digitalimplant.org 14293dd4001STejun Heo /** 143*0f9859caSKen Helias * klist_add_behind - Init a klist_node and add it after an existing node 14493dd4001STejun Heo * @n: node we're adding. 14593dd4001STejun Heo * @pos: node to put @n after 14693dd4001STejun Heo */ 147*0f9859caSKen Helias void klist_add_behind(struct klist_node *n, struct klist_node *pos) 14893dd4001STejun Heo { 149a1ed5b0cSTejun Heo struct klist *k = knode_klist(pos); 15093dd4001STejun Heo 15193dd4001STejun Heo klist_node_init(k, n); 15293dd4001STejun Heo spin_lock(&k->k_lock); 15393dd4001STejun Heo list_add(&n->n_node, &pos->n_node); 15493dd4001STejun Heo spin_unlock(&k->k_lock); 15593dd4001STejun Heo } 156*0f9859caSKen Helias EXPORT_SYMBOL_GPL(klist_add_behind); 15793dd4001STejun Heo 15893dd4001STejun Heo /** 15993dd4001STejun Heo * klist_add_before - Init a klist_node and add it before an existing node 16093dd4001STejun Heo * @n: node we're adding. 16193dd4001STejun Heo * @pos: node to put @n after 16293dd4001STejun Heo */ 16393dd4001STejun Heo void klist_add_before(struct klist_node *n, struct klist_node *pos) 16493dd4001STejun Heo { 165a1ed5b0cSTejun Heo struct klist *k = knode_klist(pos); 16693dd4001STejun Heo 16793dd4001STejun Heo klist_node_init(k, n); 16893dd4001STejun Heo spin_lock(&k->k_lock); 16993dd4001STejun Heo list_add_tail(&n->n_node, &pos->n_node); 17093dd4001STejun Heo spin_unlock(&k->k_lock); 17193dd4001STejun Heo } 17293dd4001STejun Heo EXPORT_SYMBOL_GPL(klist_add_before); 17393dd4001STejun Heo 174210272a2SMatthew Wilcox struct klist_waiter { 175210272a2SMatthew Wilcox struct list_head list; 176210272a2SMatthew Wilcox struct klist_node *node; 177210272a2SMatthew Wilcox struct task_struct *process; 178210272a2SMatthew Wilcox int woken; 179210272a2SMatthew Wilcox }; 180210272a2SMatthew Wilcox 181210272a2SMatthew Wilcox static DEFINE_SPINLOCK(klist_remove_lock); 182210272a2SMatthew Wilcox static LIST_HEAD(klist_remove_waiters); 183210272a2SMatthew Wilcox 1849a19fea4Smochel@digitalimplant.org static void klist_release(struct kref *kref) 1859a19fea4Smochel@digitalimplant.org { 186210272a2SMatthew Wilcox struct klist_waiter *waiter, *tmp; 1879a19fea4Smochel@digitalimplant.org struct klist_node *n = container_of(kref, struct klist_node, n_ref); 1887e9f4b2dSAlan Stern 189a1ed5b0cSTejun Heo WARN_ON(!knode_dead(n)); 1909a19fea4Smochel@digitalimplant.org list_del(&n->n_node); 191210272a2SMatthew Wilcox spin_lock(&klist_remove_lock); 192210272a2SMatthew Wilcox list_for_each_entry_safe(waiter, tmp, &klist_remove_waiters, list) { 193210272a2SMatthew Wilcox if (waiter->node != n) 194210272a2SMatthew Wilcox continue; 195210272a2SMatthew Wilcox 196ac5a2962Swang, biao list_del(&waiter->list); 197210272a2SMatthew Wilcox waiter->woken = 1; 198210272a2SMatthew Wilcox mb(); 199210272a2SMatthew Wilcox wake_up_process(waiter->process); 200210272a2SMatthew Wilcox } 201210272a2SMatthew Wilcox spin_unlock(&klist_remove_lock); 202a1ed5b0cSTejun Heo knode_set_klist(n, NULL); 2039a19fea4Smochel@digitalimplant.org } 2049a19fea4Smochel@digitalimplant.org 2059a19fea4Smochel@digitalimplant.org static int klist_dec_and_del(struct klist_node *n) 2069a19fea4Smochel@digitalimplant.org { 2079a19fea4Smochel@digitalimplant.org return kref_put(&n->n_ref, klist_release); 2089a19fea4Smochel@digitalimplant.org } 2099a19fea4Smochel@digitalimplant.org 210a1ed5b0cSTejun Heo static void klist_put(struct klist_node *n, bool kill) 211a1ed5b0cSTejun Heo { 212a1ed5b0cSTejun Heo struct klist *k = knode_klist(n); 213a1ed5b0cSTejun Heo void (*put)(struct klist_node *) = k->put; 214a1ed5b0cSTejun Heo 215a1ed5b0cSTejun Heo spin_lock(&k->k_lock); 216a1ed5b0cSTejun Heo if (kill) 217a1ed5b0cSTejun Heo knode_kill(n); 218a1ed5b0cSTejun Heo if (!klist_dec_and_del(n)) 219a1ed5b0cSTejun Heo put = NULL; 220a1ed5b0cSTejun Heo spin_unlock(&k->k_lock); 221a1ed5b0cSTejun Heo if (put) 222a1ed5b0cSTejun Heo put(n); 223a1ed5b0cSTejun Heo } 224a1ed5b0cSTejun Heo 2259a19fea4Smochel@digitalimplant.org /** 2269a19fea4Smochel@digitalimplant.org * klist_del - Decrement the reference count of node and try to remove. 2279a19fea4Smochel@digitalimplant.org * @n: node we're deleting. 2289a19fea4Smochel@digitalimplant.org */ 2299a19fea4Smochel@digitalimplant.org void klist_del(struct klist_node *n) 2309a19fea4Smochel@digitalimplant.org { 231a1ed5b0cSTejun Heo klist_put(n, true); 2329a19fea4Smochel@digitalimplant.org } 2339a19fea4Smochel@digitalimplant.org EXPORT_SYMBOL_GPL(klist_del); 2349a19fea4Smochel@digitalimplant.org 2359a19fea4Smochel@digitalimplant.org /** 2369a19fea4Smochel@digitalimplant.org * klist_remove - Decrement the refcount of node and wait for it to go away. 2379a19fea4Smochel@digitalimplant.org * @n: node we're removing. 2389a19fea4Smochel@digitalimplant.org */ 2399a19fea4Smochel@digitalimplant.org void klist_remove(struct klist_node *n) 2409a19fea4Smochel@digitalimplant.org { 241210272a2SMatthew Wilcox struct klist_waiter waiter; 242210272a2SMatthew Wilcox 243210272a2SMatthew Wilcox waiter.node = n; 244210272a2SMatthew Wilcox waiter.process = current; 245210272a2SMatthew Wilcox waiter.woken = 0; 246210272a2SMatthew Wilcox spin_lock(&klist_remove_lock); 247210272a2SMatthew Wilcox list_add(&waiter.list, &klist_remove_waiters); 248210272a2SMatthew Wilcox spin_unlock(&klist_remove_lock); 249210272a2SMatthew Wilcox 2507e9f4b2dSAlan Stern klist_del(n); 251210272a2SMatthew Wilcox 252210272a2SMatthew Wilcox for (;;) { 253210272a2SMatthew Wilcox set_current_state(TASK_UNINTERRUPTIBLE); 254210272a2SMatthew Wilcox if (waiter.woken) 255210272a2SMatthew Wilcox break; 256210272a2SMatthew Wilcox schedule(); 257210272a2SMatthew Wilcox } 258210272a2SMatthew Wilcox __set_current_state(TASK_RUNNING); 2599a19fea4Smochel@digitalimplant.org } 2609a19fea4Smochel@digitalimplant.org EXPORT_SYMBOL_GPL(klist_remove); 2619a19fea4Smochel@digitalimplant.org 2629a19fea4Smochel@digitalimplant.org /** 2638b0c250bSmochel@digitalimplant.org * klist_node_attached - Say whether a node is bound to a list or not. 2648b0c250bSmochel@digitalimplant.org * @n: Node that we're testing. 2658b0c250bSmochel@digitalimplant.org */ 2668b0c250bSmochel@digitalimplant.org int klist_node_attached(struct klist_node *n) 2678b0c250bSmochel@digitalimplant.org { 2688b0c250bSmochel@digitalimplant.org return (n->n_klist != NULL); 2698b0c250bSmochel@digitalimplant.org } 2708b0c250bSmochel@digitalimplant.org EXPORT_SYMBOL_GPL(klist_node_attached); 2718b0c250bSmochel@digitalimplant.org 2728b0c250bSmochel@digitalimplant.org /** 2739a19fea4Smochel@digitalimplant.org * klist_iter_init_node - Initialize a klist_iter structure. 2749a19fea4Smochel@digitalimplant.org * @k: klist we're iterating. 2759a19fea4Smochel@digitalimplant.org * @i: klist_iter we're filling. 2769a19fea4Smochel@digitalimplant.org * @n: node to start with. 2779a19fea4Smochel@digitalimplant.org * 2789a19fea4Smochel@digitalimplant.org * Similar to klist_iter_init(), but starts the action off with @n, 2799a19fea4Smochel@digitalimplant.org * instead of with the list head. 2809a19fea4Smochel@digitalimplant.org */ 281c3bb7fadSGreg Kroah-Hartman void klist_iter_init_node(struct klist *k, struct klist_iter *i, 282c3bb7fadSGreg Kroah-Hartman struct klist_node *n) 2839a19fea4Smochel@digitalimplant.org { 2849a19fea4Smochel@digitalimplant.org i->i_klist = k; 2859a19fea4Smochel@digitalimplant.org i->i_cur = n; 286e22dafbcSFrank Pavlic if (n) 287e22dafbcSFrank Pavlic kref_get(&n->n_ref); 2889a19fea4Smochel@digitalimplant.org } 2899a19fea4Smochel@digitalimplant.org EXPORT_SYMBOL_GPL(klist_iter_init_node); 2909a19fea4Smochel@digitalimplant.org 2919a19fea4Smochel@digitalimplant.org /** 2929a19fea4Smochel@digitalimplant.org * klist_iter_init - Iniitalize a klist_iter structure. 2939a19fea4Smochel@digitalimplant.org * @k: klist we're iterating. 2949a19fea4Smochel@digitalimplant.org * @i: klist_iter structure we're filling. 2959a19fea4Smochel@digitalimplant.org * 2969a19fea4Smochel@digitalimplant.org * Similar to klist_iter_init_node(), but start with the list head. 2979a19fea4Smochel@digitalimplant.org */ 2989a19fea4Smochel@digitalimplant.org void klist_iter_init(struct klist *k, struct klist_iter *i) 2999a19fea4Smochel@digitalimplant.org { 3009a19fea4Smochel@digitalimplant.org klist_iter_init_node(k, i, NULL); 3019a19fea4Smochel@digitalimplant.org } 3029a19fea4Smochel@digitalimplant.org EXPORT_SYMBOL_GPL(klist_iter_init); 3039a19fea4Smochel@digitalimplant.org 3049a19fea4Smochel@digitalimplant.org /** 3059a19fea4Smochel@digitalimplant.org * klist_iter_exit - Finish a list iteration. 3069a19fea4Smochel@digitalimplant.org * @i: Iterator structure. 3079a19fea4Smochel@digitalimplant.org * 3089a19fea4Smochel@digitalimplant.org * Must be called when done iterating over list, as it decrements the 3099a19fea4Smochel@digitalimplant.org * refcount of the current node. Necessary in case iteration exited before 3109a19fea4Smochel@digitalimplant.org * the end of the list was reached, and always good form. 3119a19fea4Smochel@digitalimplant.org */ 3129a19fea4Smochel@digitalimplant.org void klist_iter_exit(struct klist_iter *i) 3139a19fea4Smochel@digitalimplant.org { 3149a19fea4Smochel@digitalimplant.org if (i->i_cur) { 315a1ed5b0cSTejun Heo klist_put(i->i_cur, false); 3169a19fea4Smochel@digitalimplant.org i->i_cur = NULL; 3179a19fea4Smochel@digitalimplant.org } 3189a19fea4Smochel@digitalimplant.org } 3199a19fea4Smochel@digitalimplant.org EXPORT_SYMBOL_GPL(klist_iter_exit); 3209a19fea4Smochel@digitalimplant.org 3219a19fea4Smochel@digitalimplant.org static struct klist_node *to_klist_node(struct list_head *n) 3229a19fea4Smochel@digitalimplant.org { 3239a19fea4Smochel@digitalimplant.org return container_of(n, struct klist_node, n_node); 3249a19fea4Smochel@digitalimplant.org } 3259a19fea4Smochel@digitalimplant.org 3269a19fea4Smochel@digitalimplant.org /** 3279a19fea4Smochel@digitalimplant.org * klist_next - Ante up next node in list. 3289a19fea4Smochel@digitalimplant.org * @i: Iterator structure. 3299a19fea4Smochel@digitalimplant.org * 3309a19fea4Smochel@digitalimplant.org * First grab list lock. Decrement the reference count of the previous 3319a19fea4Smochel@digitalimplant.org * node, if there was one. Grab the next node, increment its reference 3329a19fea4Smochel@digitalimplant.org * count, drop the lock, and return that next node. 3339a19fea4Smochel@digitalimplant.org */ 3349a19fea4Smochel@digitalimplant.org struct klist_node *klist_next(struct klist_iter *i) 3359a19fea4Smochel@digitalimplant.org { 3367e9f4b2dSAlan Stern void (*put)(struct klist_node *) = i->i_klist->put; 337a1ed5b0cSTejun Heo struct klist_node *last = i->i_cur; 338a1ed5b0cSTejun Heo struct klist_node *next; 3399a19fea4Smochel@digitalimplant.org 3409a19fea4Smochel@digitalimplant.org spin_lock(&i->i_klist->k_lock); 341a1ed5b0cSTejun Heo 342a1ed5b0cSTejun Heo if (last) { 343a1ed5b0cSTejun Heo next = to_klist_node(last->n_node.next); 344a1ed5b0cSTejun Heo if (!klist_dec_and_del(last)) 3457e9f4b2dSAlan Stern put = NULL; 3469a19fea4Smochel@digitalimplant.org } else 347a1ed5b0cSTejun Heo next = to_klist_node(i->i_klist->k_list.next); 3489a19fea4Smochel@digitalimplant.org 349a1ed5b0cSTejun Heo i->i_cur = NULL; 350a1ed5b0cSTejun Heo while (next != to_klist_node(&i->i_klist->k_list)) { 351a1ed5b0cSTejun Heo if (likely(!knode_dead(next))) { 352a1ed5b0cSTejun Heo kref_get(&next->n_ref); 353a1ed5b0cSTejun Heo i->i_cur = next; 354a1ed5b0cSTejun Heo break; 3559a19fea4Smochel@digitalimplant.org } 356a1ed5b0cSTejun Heo next = to_klist_node(next->n_node.next); 357a1ed5b0cSTejun Heo } 358a1ed5b0cSTejun Heo 3599a19fea4Smochel@digitalimplant.org spin_unlock(&i->i_klist->k_lock); 360a1ed5b0cSTejun Heo 361a1ed5b0cSTejun Heo if (put && last) 362a1ed5b0cSTejun Heo put(last); 363a1ed5b0cSTejun Heo return i->i_cur; 3649a19fea4Smochel@digitalimplant.org } 3659a19fea4Smochel@digitalimplant.org EXPORT_SYMBOL_GPL(klist_next); 366