Blame view
lib/klist.c
10.4 KB
8092f73c5 treewide: Replace... |
1 |
// SPDX-License-Identifier: GPL-2.0-only |
9a19fea43 [PATCH] Add initi... |
2 |
/* |
c3bb7fada klist: fix coding... |
3 |
* klist.c - Routines for manipulating klists. |
9a19fea43 [PATCH] Add initi... |
4 |
* |
c3bb7fada klist: fix coding... |
5 |
* Copyright (C) 2005 Patrick Mochel |
9a19fea43 [PATCH] Add initi... |
6 |
* |
c3bb7fada klist: fix coding... |
7 8 9 10 11 12 13 |
* 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. |
9a19fea43 [PATCH] Add initi... |
14 |
* |
c3bb7fada klist: fix coding... |
15 16 17 18 |
* 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. |
9a19fea43 [PATCH] Add initi... |
19 |
* |
c3bb7fada klist: fix coding... |
20 21 22 23 24 25 |
* 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. |
9a19fea43 [PATCH] Add initi... |
26 |
* |
c3bb7fada klist: fix coding... |
27 28 29 30 31 32 33 |
* 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). |
9a19fea43 [PATCH] Add initi... |
34 35 36 |
*/ #include <linux/klist.h> |
8bc3bcc93 lib: reduce the u... |
37 |
#include <linux/export.h> |
210272a28 driver core: Remo... |
38 |
#include <linux/sched.h> |
9a19fea43 [PATCH] Add initi... |
39 |
|
a1ed5b0cf klist: don't iter... |
40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 |
/* * 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; } |
9a19fea43 [PATCH] Add initi... |
71 72 |
/** |
c3bb7fada klist: fix coding... |
73 74 75 76 |
* klist_init - Initialize a klist structure. * @k: The klist we're initializing. * @get: The get function for the embedding object (NULL if none) * @put: The put function for the embedding object (NULL if none) |
34bb61f9d [PATCH] fix klist... |
77 78 79 80 81 82 |
* * Initialises the klist structure. If the klist_node structures are * going to be embedded in refcounted objects (necessary for safe * deletion) then the get/put arguments are used to initialise * functions that take and release references on the embedding * objects. |
9a19fea43 [PATCH] Add initi... |
83 |
*/ |
c3bb7fada klist: fix coding... |
84 |
void klist_init(struct klist *k, void (*get)(struct klist_node *), |
34bb61f9d [PATCH] fix klist... |
85 |
void (*put)(struct klist_node *)) |
9a19fea43 [PATCH] Add initi... |
86 87 88 |
{ INIT_LIST_HEAD(&k->k_list); spin_lock_init(&k->k_lock); |
34bb61f9d [PATCH] fix klist... |
89 90 |
k->get = get; k->put = put; |
9a19fea43 [PATCH] Add initi... |
91 |
} |
9a19fea43 [PATCH] Add initi... |
92 |
EXPORT_SYMBOL_GPL(klist_init); |
c3bb7fada klist: fix coding... |
93 |
static void add_head(struct klist *k, struct klist_node *n) |
9a19fea43 [PATCH] Add initi... |
94 95 96 97 98 |
{ spin_lock(&k->k_lock); list_add(&n->n_node, &k->k_list); spin_unlock(&k->k_lock); } |
c3bb7fada klist: fix coding... |
99 |
static void add_tail(struct klist *k, struct klist_node *n) |
9a19fea43 [PATCH] Add initi... |
100 101 102 103 104 |
{ spin_lock(&k->k_lock); list_add_tail(&n->n_node, &k->k_list); spin_unlock(&k->k_lock); } |
c3bb7fada klist: fix coding... |
105 |
static void klist_node_init(struct klist *k, struct klist_node *n) |
9a19fea43 [PATCH] Add initi... |
106 107 |
{ INIT_LIST_HEAD(&n->n_node); |
9a19fea43 [PATCH] Add initi... |
108 |
kref_init(&n->n_ref); |
a1ed5b0cf klist: don't iter... |
109 |
knode_set_klist(n, k); |
34bb61f9d [PATCH] fix klist... |
110 111 |
if (k->get) k->get(n); |
9a19fea43 [PATCH] Add initi... |
112 |
} |
9a19fea43 [PATCH] Add initi... |
113 |
/** |
c3bb7fada klist: fix coding... |
114 115 116 |
* klist_add_head - Initialize a klist_node and add it to front. * @n: node we're adding. * @k: klist it's going on. |
9a19fea43 [PATCH] Add initi... |
117 |
*/ |
c3bb7fada klist: fix coding... |
118 |
void klist_add_head(struct klist_node *n, struct klist *k) |
9a19fea43 [PATCH] Add initi... |
119 120 121 122 |
{ klist_node_init(k, n); add_head(k, n); } |
9a19fea43 [PATCH] Add initi... |
123 |
EXPORT_SYMBOL_GPL(klist_add_head); |
9a19fea43 [PATCH] Add initi... |
124 |
/** |
c3bb7fada klist: fix coding... |
125 126 127 |
* klist_add_tail - Initialize a klist_node and add it to back. * @n: node we're adding. * @k: klist it's going on. |
9a19fea43 [PATCH] Add initi... |
128 |
*/ |
c3bb7fada klist: fix coding... |
129 |
void klist_add_tail(struct klist_node *n, struct klist *k) |
9a19fea43 [PATCH] Add initi... |
130 131 132 133 |
{ klist_node_init(k, n); add_tail(k, n); } |
9a19fea43 [PATCH] Add initi... |
134 |
EXPORT_SYMBOL_GPL(klist_add_tail); |
93dd40013 klist: implement ... |
135 |
/** |
0f9859ca9 klist: use same n... |
136 |
* klist_add_behind - Init a klist_node and add it after an existing node |
93dd40013 klist: implement ... |
137 138 139 |
* @n: node we're adding. * @pos: node to put @n after */ |
0f9859ca9 klist: use same n... |
140 |
void klist_add_behind(struct klist_node *n, struct klist_node *pos) |
93dd40013 klist: implement ... |
141 |
{ |
a1ed5b0cf klist: don't iter... |
142 |
struct klist *k = knode_klist(pos); |
93dd40013 klist: implement ... |
143 144 145 146 147 148 |
klist_node_init(k, n); spin_lock(&k->k_lock); list_add(&n->n_node, &pos->n_node); spin_unlock(&k->k_lock); } |
0f9859ca9 klist: use same n... |
149 |
EXPORT_SYMBOL_GPL(klist_add_behind); |
93dd40013 klist: implement ... |
150 151 152 153 154 155 156 157 |
/** * klist_add_before - Init a klist_node and add it before an existing node * @n: node we're adding. * @pos: node to put @n after */ void klist_add_before(struct klist_node *n, struct klist_node *pos) { |
a1ed5b0cf klist: don't iter... |
158 |
struct klist *k = knode_klist(pos); |
93dd40013 klist: implement ... |
159 160 161 162 163 164 165 |
klist_node_init(k, n); spin_lock(&k->k_lock); list_add_tail(&n->n_node, &pos->n_node); spin_unlock(&k->k_lock); } EXPORT_SYMBOL_GPL(klist_add_before); |
210272a28 driver core: Remo... |
166 167 168 169 170 171 172 173 174 |
struct klist_waiter { struct list_head list; struct klist_node *node; struct task_struct *process; int woken; }; static DEFINE_SPINLOCK(klist_remove_lock); static LIST_HEAD(klist_remove_waiters); |
c3bb7fada klist: fix coding... |
175 |
static void klist_release(struct kref *kref) |
9a19fea43 [PATCH] Add initi... |
176 |
{ |
210272a28 driver core: Remo... |
177 |
struct klist_waiter *waiter, *tmp; |
c3bb7fada klist: fix coding... |
178 |
struct klist_node *n = container_of(kref, struct klist_node, n_ref); |
7e9f4b2d3 Driver core: Don'... |
179 |
|
a1ed5b0cf klist: don't iter... |
180 |
WARN_ON(!knode_dead(n)); |
9a19fea43 [PATCH] Add initi... |
181 |
list_del(&n->n_node); |
210272a28 driver core: Remo... |
182 183 184 185 |
spin_lock(&klist_remove_lock); list_for_each_entry_safe(waiter, tmp, &klist_remove_waiters, list) { if (waiter->node != n) continue; |
ac5a2962b klist: del waiter... |
186 |
list_del(&waiter->list); |
210272a28 driver core: Remo... |
187 188 189 |
waiter->woken = 1; mb(); wake_up_process(waiter->process); |
210272a28 driver core: Remo... |
190 191 |
} spin_unlock(&klist_remove_lock); |
a1ed5b0cf klist: don't iter... |
192 |
knode_set_klist(n, NULL); |
9a19fea43 [PATCH] Add initi... |
193 |
} |
c3bb7fada klist: fix coding... |
194 |
static int klist_dec_and_del(struct klist_node *n) |
9a19fea43 [PATCH] Add initi... |
195 196 197 |
{ return kref_put(&n->n_ref, klist_release); } |
a1ed5b0cf klist: don't iter... |
198 |
static void klist_put(struct klist_node *n, bool kill) |
9a19fea43 [PATCH] Add initi... |
199 |
{ |
a1ed5b0cf klist: don't iter... |
200 |
struct klist *k = knode_klist(n); |
7e9f4b2d3 Driver core: Don'... |
201 |
void (*put)(struct klist_node *) = k->put; |
9a19fea43 [PATCH] Add initi... |
202 203 |
spin_lock(&k->k_lock); |
a1ed5b0cf klist: don't iter... |
204 205 |
if (kill) knode_kill(n); |
7e9f4b2d3 Driver core: Don'... |
206 207 |
if (!klist_dec_and_del(n)) put = NULL; |
9a19fea43 [PATCH] Add initi... |
208 |
spin_unlock(&k->k_lock); |
7e9f4b2d3 Driver core: Don'... |
209 210 |
if (put) put(n); |
9a19fea43 [PATCH] Add initi... |
211 |
} |
a1ed5b0cf klist: don't iter... |
212 213 214 215 216 217 218 219 220 |
/** * 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); } |
9a19fea43 [PATCH] Add initi... |
221 |
EXPORT_SYMBOL_GPL(klist_del); |
9a19fea43 [PATCH] Add initi... |
222 |
/** |
c3bb7fada klist: fix coding... |
223 224 |
* klist_remove - Decrement the refcount of node and wait for it to go away. * @n: node we're removing. |
9a19fea43 [PATCH] Add initi... |
225 |
*/ |
c3bb7fada klist: fix coding... |
226 |
void klist_remove(struct klist_node *n) |
9a19fea43 [PATCH] Add initi... |
227 |
{ |
210272a28 driver core: Remo... |
228 229 230 231 232 233 234 235 |
struct klist_waiter waiter; waiter.node = n; waiter.process = current; waiter.woken = 0; spin_lock(&klist_remove_lock); list_add(&waiter.list, &klist_remove_waiters); spin_unlock(&klist_remove_lock); |
7e9f4b2d3 Driver core: Don'... |
236 |
klist_del(n); |
210272a28 driver core: Remo... |
237 238 239 240 241 242 243 244 |
for (;;) { set_current_state(TASK_UNINTERRUPTIBLE); if (waiter.woken) break; schedule(); } __set_current_state(TASK_RUNNING); |
9a19fea43 [PATCH] Add initi... |
245 |
} |
9a19fea43 [PATCH] Add initi... |
246 |
EXPORT_SYMBOL_GPL(klist_remove); |
9a19fea43 [PATCH] Add initi... |
247 |
/** |
c3bb7fada klist: fix coding... |
248 249 |
* klist_node_attached - Say whether a node is bound to a list or not. * @n: Node that we're testing. |
8b0c250be [PATCH] add klist... |
250 |
*/ |
c3bb7fada klist: fix coding... |
251 |
int klist_node_attached(struct klist_node *n) |
8b0c250be [PATCH] add klist... |
252 253 254 |
{ return (n->n_klist != NULL); } |
8b0c250be [PATCH] add klist... |
255 |
EXPORT_SYMBOL_GPL(klist_node_attached); |
8b0c250be [PATCH] add klist... |
256 |
/** |
c3bb7fada klist: fix coding... |
257 258 259 260 |
* 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. |
9a19fea43 [PATCH] Add initi... |
261 |
* |
c3bb7fada klist: fix coding... |
262 263 |
* Similar to klist_iter_init(), but starts the action off with @n, * instead of with the list head. |
9a19fea43 [PATCH] Add initi... |
264 |
*/ |
c3bb7fada klist: fix coding... |
265 266 |
void klist_iter_init_node(struct klist *k, struct klist_iter *i, struct klist_node *n) |
9a19fea43 [PATCH] Add initi... |
267 268 |
{ i->i_klist = k; |
00cd29b79 klist: fix starti... |
269 270 271 |
i->i_cur = NULL; if (n && kref_get_unless_zero(&n->n_ref)) i->i_cur = n; |
9a19fea43 [PATCH] Add initi... |
272 |
} |
9a19fea43 [PATCH] Add initi... |
273 |
EXPORT_SYMBOL_GPL(klist_iter_init_node); |
9a19fea43 [PATCH] Add initi... |
274 |
/** |
c3bb7fada klist: fix coding... |
275 276 277 |
* klist_iter_init - Iniitalize a klist_iter structure. * @k: klist we're iterating. * @i: klist_iter structure we're filling. |
9a19fea43 [PATCH] Add initi... |
278 |
* |
c3bb7fada klist: fix coding... |
279 |
* Similar to klist_iter_init_node(), but start with the list head. |
9a19fea43 [PATCH] Add initi... |
280 |
*/ |
c3bb7fada klist: fix coding... |
281 |
void klist_iter_init(struct klist *k, struct klist_iter *i) |
9a19fea43 [PATCH] Add initi... |
282 283 284 |
{ klist_iter_init_node(k, i, NULL); } |
9a19fea43 [PATCH] Add initi... |
285 |
EXPORT_SYMBOL_GPL(klist_iter_init); |
9a19fea43 [PATCH] Add initi... |
286 |
/** |
c3bb7fada klist: fix coding... |
287 288 |
* klist_iter_exit - Finish a list iteration. * @i: Iterator structure. |
9a19fea43 [PATCH] Add initi... |
289 |
* |
c3bb7fada klist: fix coding... |
290 291 292 |
* 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. |
9a19fea43 [PATCH] Add initi... |
293 |
*/ |
c3bb7fada klist: fix coding... |
294 |
void klist_iter_exit(struct klist_iter *i) |
9a19fea43 [PATCH] Add initi... |
295 296 |
{ if (i->i_cur) { |
a1ed5b0cf klist: don't iter... |
297 |
klist_put(i->i_cur, false); |
9a19fea43 [PATCH] Add initi... |
298 299 300 |
i->i_cur = NULL; } } |
9a19fea43 [PATCH] Add initi... |
301 |
EXPORT_SYMBOL_GPL(klist_iter_exit); |
c3bb7fada klist: fix coding... |
302 |
static struct klist_node *to_klist_node(struct list_head *n) |
9a19fea43 [PATCH] Add initi... |
303 304 305 |
{ return container_of(n, struct klist_node, n_node); } |
9a19fea43 [PATCH] Add initi... |
306 |
/** |
2e0fed7f7 klist: implement ... |
307 308 309 310 311 312 313 314 315 316 317 318 |
* klist_prev - Ante up prev node in list. * @i: Iterator structure. * * First grab list lock. Decrement the reference count of the previous * node, if there was one. Grab the prev node, increment its reference * count, drop the lock, and return that prev node. */ struct klist_node *klist_prev(struct klist_iter *i) { void (*put)(struct klist_node *) = i->i_klist->put; struct klist_node *last = i->i_cur; struct klist_node *prev; |
624fa7790 scsi: klist: Make... |
319 |
unsigned long flags; |
2e0fed7f7 klist: implement ... |
320 |
|
624fa7790 scsi: klist: Make... |
321 |
spin_lock_irqsave(&i->i_klist->k_lock, flags); |
2e0fed7f7 klist: implement ... |
322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 |
if (last) { prev = to_klist_node(last->n_node.prev); if (!klist_dec_and_del(last)) put = NULL; } else prev = to_klist_node(i->i_klist->k_list.prev); i->i_cur = NULL; while (prev != to_klist_node(&i->i_klist->k_list)) { if (likely(!knode_dead(prev))) { kref_get(&prev->n_ref); i->i_cur = prev; break; } prev = to_klist_node(prev->n_node.prev); } |
624fa7790 scsi: klist: Make... |
339 |
spin_unlock_irqrestore(&i->i_klist->k_lock, flags); |
2e0fed7f7 klist: implement ... |
340 341 342 343 344 345 346 347 |
if (put && last) put(last); return i->i_cur; } EXPORT_SYMBOL_GPL(klist_prev); /** |
c3bb7fada klist: fix coding... |
348 349 |
* klist_next - Ante up next node in list. * @i: Iterator structure. |
9a19fea43 [PATCH] Add initi... |
350 |
* |
c3bb7fada klist: fix coding... |
351 352 353 |
* 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. |
9a19fea43 [PATCH] Add initi... |
354 |
*/ |
c3bb7fada klist: fix coding... |
355 |
struct klist_node *klist_next(struct klist_iter *i) |
9a19fea43 [PATCH] Add initi... |
356 |
{ |
7e9f4b2d3 Driver core: Don'... |
357 |
void (*put)(struct klist_node *) = i->i_klist->put; |
a1ed5b0cf klist: don't iter... |
358 359 |
struct klist_node *last = i->i_cur; struct klist_node *next; |
624fa7790 scsi: klist: Make... |
360 |
unsigned long flags; |
9a19fea43 [PATCH] Add initi... |
361 |
|
624fa7790 scsi: klist: Make... |
362 |
spin_lock_irqsave(&i->i_klist->k_lock, flags); |
a1ed5b0cf klist: don't iter... |
363 364 365 366 |
if (last) { next = to_klist_node(last->n_node.next); if (!klist_dec_and_del(last)) |
7e9f4b2d3 Driver core: Don'... |
367 |
put = NULL; |
9a19fea43 [PATCH] Add initi... |
368 |
} else |
a1ed5b0cf klist: don't iter... |
369 |
next = to_klist_node(i->i_klist->k_list.next); |
9a19fea43 [PATCH] Add initi... |
370 |
|
a1ed5b0cf klist: don't iter... |
371 372 373 374 375 376 377 378 |
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); |
9a19fea43 [PATCH] Add initi... |
379 |
} |
a1ed5b0cf klist: don't iter... |
380 |
|
624fa7790 scsi: klist: Make... |
381 |
spin_unlock_irqrestore(&i->i_klist->k_lock, flags); |
a1ed5b0cf klist: don't iter... |
382 383 384 385 |
if (put && last) put(last); return i->i_cur; |
9a19fea43 [PATCH] Add initi... |
386 |
} |
9a19fea43 [PATCH] Add initi... |
387 |
EXPORT_SYMBOL_GPL(klist_next); |