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a910e4a9 SP |
1 | /* |
2 | * O(1) TX queue with built-in allocator for ST-Ericsson CW1200 drivers | |
3 | * | |
4 | * Copyright (c) 2010, ST-Ericsson | |
5 | * Author: Dmitry Tarnyagin <dmitry.tarnyagin@lockless.no> | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License version 2 as | |
9 | * published by the Free Software Foundation. | |
10 | */ | |
11 | ||
12 | #include <net/mac80211.h> | |
13 | #include <linux/sched.h> | |
14 | #include "queue.h" | |
15 | #include "cw1200.h" | |
16 | #include "debug.h" | |
17 | ||
18 | /* private */ struct cw1200_queue_item | |
19 | { | |
20 | struct list_head head; | |
21 | struct sk_buff *skb; | |
22 | u32 packet_id; | |
23 | unsigned long queue_timestamp; | |
24 | unsigned long xmit_timestamp; | |
25 | struct cw1200_txpriv txpriv; | |
26 | u8 generation; | |
27 | }; | |
28 | ||
29 | static inline void __cw1200_queue_lock(struct cw1200_queue *queue) | |
30 | { | |
31 | struct cw1200_queue_stats *stats = queue->stats; | |
32 | if (queue->tx_locked_cnt++ == 0) { | |
33 | pr_debug("[TX] Queue %d is locked.\n", | |
34 | queue->queue_id); | |
35 | ieee80211_stop_queue(stats->priv->hw, queue->queue_id); | |
36 | } | |
37 | } | |
38 | ||
39 | static inline void __cw1200_queue_unlock(struct cw1200_queue *queue) | |
40 | { | |
41 | struct cw1200_queue_stats *stats = queue->stats; | |
42 | BUG_ON(!queue->tx_locked_cnt); | |
43 | if (--queue->tx_locked_cnt == 0) { | |
44 | pr_debug("[TX] Queue %d is unlocked.\n", | |
45 | queue->queue_id); | |
46 | ieee80211_wake_queue(stats->priv->hw, queue->queue_id); | |
47 | } | |
48 | } | |
49 | ||
50 | static inline void cw1200_queue_parse_id(u32 packet_id, u8 *queue_generation, | |
51 | u8 *queue_id, u8 *item_generation, | |
52 | u8 *item_id) | |
53 | { | |
54 | *item_id = (packet_id >> 0) & 0xFF; | |
55 | *item_generation = (packet_id >> 8) & 0xFF; | |
56 | *queue_id = (packet_id >> 16) & 0xFF; | |
57 | *queue_generation = (packet_id >> 24) & 0xFF; | |
58 | } | |
59 | ||
60 | static inline u32 cw1200_queue_mk_packet_id(u8 queue_generation, u8 queue_id, | |
61 | u8 item_generation, u8 item_id) | |
62 | { | |
63 | return ((u32)item_id << 0) | | |
64 | ((u32)item_generation << 8) | | |
65 | ((u32)queue_id << 16) | | |
66 | ((u32)queue_generation << 24); | |
67 | } | |
68 | ||
69 | static void cw1200_queue_post_gc(struct cw1200_queue_stats *stats, | |
70 | struct list_head *gc_list) | |
71 | { | |
72 | struct cw1200_queue_item *item, *tmp; | |
73 | ||
74 | list_for_each_entry_safe(item, tmp, gc_list, head) { | |
75 | list_del(&item->head); | |
76 | stats->skb_dtor(stats->priv, item->skb, &item->txpriv); | |
77 | kfree(item); | |
78 | } | |
79 | } | |
80 | ||
81 | static void cw1200_queue_register_post_gc(struct list_head *gc_list, | |
82 | struct cw1200_queue_item *item) | |
83 | { | |
84 | struct cw1200_queue_item *gc_item; | |
85 | gc_item = kmalloc(sizeof(struct cw1200_queue_item), | |
86 | GFP_ATOMIC); | |
87 | BUG_ON(!gc_item); | |
88 | memcpy(gc_item, item, sizeof(struct cw1200_queue_item)); | |
89 | list_add_tail(&gc_item->head, gc_list); | |
90 | } | |
91 | ||
92 | static void __cw1200_queue_gc(struct cw1200_queue *queue, | |
93 | struct list_head *head, | |
94 | bool unlock) | |
95 | { | |
96 | struct cw1200_queue_stats *stats = queue->stats; | |
97 | struct cw1200_queue_item *item = NULL, *tmp; | |
98 | bool wakeup_stats = false; | |
99 | ||
100 | list_for_each_entry_safe(item, tmp, &queue->queue, head) { | |
101 | if (jiffies - item->queue_timestamp < queue->ttl) | |
102 | break; | |
103 | --queue->num_queued; | |
104 | --queue->link_map_cache[item->txpriv.link_id]; | |
105 | spin_lock_bh(&stats->lock); | |
106 | --stats->num_queued; | |
107 | if (!--stats->link_map_cache[item->txpriv.link_id]) | |
108 | wakeup_stats = true; | |
109 | spin_unlock_bh(&stats->lock); | |
110 | cw1200_debug_tx_ttl(stats->priv); | |
111 | cw1200_queue_register_post_gc(head, item); | |
112 | item->skb = NULL; | |
113 | list_move_tail(&item->head, &queue->free_pool); | |
114 | } | |
115 | ||
116 | if (wakeup_stats) | |
117 | wake_up(&stats->wait_link_id_empty); | |
118 | ||
119 | if (queue->overfull) { | |
120 | if (queue->num_queued <= (queue->capacity >> 1)) { | |
121 | queue->overfull = false; | |
122 | if (unlock) | |
123 | __cw1200_queue_unlock(queue); | |
124 | } else if (item) { | |
125 | unsigned long tmo = item->queue_timestamp + queue->ttl; | |
126 | mod_timer(&queue->gc, tmo); | |
127 | cw1200_pm_stay_awake(&stats->priv->pm_state, | |
128 | tmo - jiffies); | |
129 | } | |
130 | } | |
131 | } | |
132 | ||
133 | static void cw1200_queue_gc(unsigned long arg) | |
134 | { | |
135 | LIST_HEAD(list); | |
136 | struct cw1200_queue *queue = | |
137 | (struct cw1200_queue *)arg; | |
138 | ||
139 | spin_lock_bh(&queue->lock); | |
140 | __cw1200_queue_gc(queue, &list, true); | |
141 | spin_unlock_bh(&queue->lock); | |
142 | cw1200_queue_post_gc(queue->stats, &list); | |
143 | } | |
144 | ||
145 | int cw1200_queue_stats_init(struct cw1200_queue_stats *stats, | |
146 | size_t map_capacity, | |
147 | cw1200_queue_skb_dtor_t skb_dtor, | |
148 | struct cw1200_common *priv) | |
149 | { | |
150 | memset(stats, 0, sizeof(*stats)); | |
151 | stats->map_capacity = map_capacity; | |
152 | stats->skb_dtor = skb_dtor; | |
153 | stats->priv = priv; | |
154 | spin_lock_init(&stats->lock); | |
155 | init_waitqueue_head(&stats->wait_link_id_empty); | |
156 | ||
157 | stats->link_map_cache = kzalloc(sizeof(int) * map_capacity, | |
158 | GFP_KERNEL); | |
159 | if (!stats->link_map_cache) | |
160 | return -ENOMEM; | |
161 | ||
162 | return 0; | |
163 | } | |
164 | ||
165 | int cw1200_queue_init(struct cw1200_queue *queue, | |
166 | struct cw1200_queue_stats *stats, | |
167 | u8 queue_id, | |
168 | size_t capacity, | |
169 | unsigned long ttl) | |
170 | { | |
171 | size_t i; | |
172 | ||
173 | memset(queue, 0, sizeof(*queue)); | |
174 | queue->stats = stats; | |
175 | queue->capacity = capacity; | |
176 | queue->queue_id = queue_id; | |
177 | queue->ttl = ttl; | |
178 | INIT_LIST_HEAD(&queue->queue); | |
179 | INIT_LIST_HEAD(&queue->pending); | |
180 | INIT_LIST_HEAD(&queue->free_pool); | |
181 | spin_lock_init(&queue->lock); | |
182 | init_timer(&queue->gc); | |
183 | queue->gc.data = (unsigned long)queue; | |
184 | queue->gc.function = cw1200_queue_gc; | |
185 | ||
186 | queue->pool = kzalloc(sizeof(struct cw1200_queue_item) * capacity, | |
187 | GFP_KERNEL); | |
188 | if (!queue->pool) | |
189 | return -ENOMEM; | |
190 | ||
191 | queue->link_map_cache = kzalloc(sizeof(int) * stats->map_capacity, | |
192 | GFP_KERNEL); | |
193 | if (!queue->link_map_cache) { | |
194 | kfree(queue->pool); | |
195 | queue->pool = NULL; | |
196 | return -ENOMEM; | |
197 | } | |
198 | ||
199 | for (i = 0; i < capacity; ++i) | |
200 | list_add_tail(&queue->pool[i].head, &queue->free_pool); | |
201 | ||
202 | return 0; | |
203 | } | |
204 | ||
205 | int cw1200_queue_clear(struct cw1200_queue *queue) | |
206 | { | |
207 | int i; | |
208 | LIST_HEAD(gc_list); | |
209 | struct cw1200_queue_stats *stats = queue->stats; | |
210 | struct cw1200_queue_item *item, *tmp; | |
211 | ||
212 | spin_lock_bh(&queue->lock); | |
213 | queue->generation++; | |
214 | list_splice_tail_init(&queue->queue, &queue->pending); | |
215 | list_for_each_entry_safe(item, tmp, &queue->pending, head) { | |
216 | WARN_ON(!item->skb); | |
217 | cw1200_queue_register_post_gc(&gc_list, item); | |
218 | item->skb = NULL; | |
219 | list_move_tail(&item->head, &queue->free_pool); | |
220 | } | |
221 | queue->num_queued = 0; | |
222 | queue->num_pending = 0; | |
223 | ||
224 | spin_lock_bh(&stats->lock); | |
225 | for (i = 0; i < stats->map_capacity; ++i) { | |
226 | stats->num_queued -= queue->link_map_cache[i]; | |
227 | stats->link_map_cache[i] -= queue->link_map_cache[i]; | |
228 | queue->link_map_cache[i] = 0; | |
229 | } | |
230 | spin_unlock_bh(&stats->lock); | |
231 | if (queue->overfull) { | |
232 | queue->overfull = false; | |
233 | __cw1200_queue_unlock(queue); | |
234 | } | |
235 | spin_unlock_bh(&queue->lock); | |
236 | wake_up(&stats->wait_link_id_empty); | |
237 | cw1200_queue_post_gc(stats, &gc_list); | |
238 | return 0; | |
239 | } | |
240 | ||
241 | void cw1200_queue_stats_deinit(struct cw1200_queue_stats *stats) | |
242 | { | |
243 | kfree(stats->link_map_cache); | |
244 | stats->link_map_cache = NULL; | |
245 | } | |
246 | ||
247 | void cw1200_queue_deinit(struct cw1200_queue *queue) | |
248 | { | |
249 | cw1200_queue_clear(queue); | |
250 | del_timer_sync(&queue->gc); | |
251 | INIT_LIST_HEAD(&queue->free_pool); | |
252 | kfree(queue->pool); | |
253 | kfree(queue->link_map_cache); | |
254 | queue->pool = NULL; | |
255 | queue->link_map_cache = NULL; | |
256 | queue->capacity = 0; | |
257 | } | |
258 | ||
259 | size_t cw1200_queue_get_num_queued(struct cw1200_queue *queue, | |
260 | u32 link_id_map) | |
261 | { | |
262 | size_t ret; | |
263 | int i, bit; | |
264 | size_t map_capacity = queue->stats->map_capacity; | |
265 | ||
266 | if (!link_id_map) | |
267 | return 0; | |
268 | ||
269 | spin_lock_bh(&queue->lock); | |
270 | if (link_id_map == (u32)-1) { | |
271 | ret = queue->num_queued - queue->num_pending; | |
272 | } else { | |
273 | ret = 0; | |
274 | for (i = 0, bit = 1; i < map_capacity; ++i, bit <<= 1) { | |
275 | if (link_id_map & bit) | |
276 | ret += queue->link_map_cache[i]; | |
277 | } | |
278 | } | |
279 | spin_unlock_bh(&queue->lock); | |
280 | return ret; | |
281 | } | |
282 | ||
283 | int cw1200_queue_put(struct cw1200_queue *queue, | |
284 | struct sk_buff *skb, | |
285 | struct cw1200_txpriv *txpriv) | |
286 | { | |
287 | int ret = 0; | |
288 | LIST_HEAD(gc_list); | |
289 | struct cw1200_queue_stats *stats = queue->stats; | |
290 | ||
291 | if (txpriv->link_id >= queue->stats->map_capacity) | |
292 | return -EINVAL; | |
293 | ||
294 | spin_lock_bh(&queue->lock); | |
295 | if (!WARN_ON(list_empty(&queue->free_pool))) { | |
296 | struct cw1200_queue_item *item = list_first_entry( | |
297 | &queue->free_pool, struct cw1200_queue_item, head); | |
298 | BUG_ON(item->skb); | |
299 | ||
300 | list_move_tail(&item->head, &queue->queue); | |
301 | item->skb = skb; | |
302 | item->txpriv = *txpriv; | |
303 | item->generation = 0; | |
304 | item->packet_id = cw1200_queue_mk_packet_id(queue->generation, | |
305 | queue->queue_id, | |
306 | item->generation, | |
307 | item - queue->pool); | |
308 | item->queue_timestamp = jiffies; | |
309 | ||
310 | ++queue->num_queued; | |
311 | ++queue->link_map_cache[txpriv->link_id]; | |
312 | ||
313 | spin_lock_bh(&stats->lock); | |
314 | ++stats->num_queued; | |
315 | ++stats->link_map_cache[txpriv->link_id]; | |
316 | spin_unlock_bh(&stats->lock); | |
317 | ||
318 | /* TX may happen in parallel sometimes. | |
319 | * Leave extra queue slots so we don't overflow. | |
320 | */ | |
321 | if (queue->overfull == false && | |
322 | queue->num_queued >= | |
323 | (queue->capacity - (num_present_cpus() - 1))) { | |
324 | queue->overfull = true; | |
325 | __cw1200_queue_lock(queue); | |
326 | mod_timer(&queue->gc, jiffies); | |
327 | } | |
328 | } else { | |
329 | ret = -ENOENT; | |
330 | } | |
331 | spin_unlock_bh(&queue->lock); | |
332 | return ret; | |
333 | } | |
334 | ||
335 | int cw1200_queue_get(struct cw1200_queue *queue, | |
336 | u32 link_id_map, | |
337 | struct wsm_tx **tx, | |
338 | struct ieee80211_tx_info **tx_info, | |
339 | const struct cw1200_txpriv **txpriv) | |
340 | { | |
341 | int ret = -ENOENT; | |
342 | struct cw1200_queue_item *item; | |
343 | struct cw1200_queue_stats *stats = queue->stats; | |
344 | bool wakeup_stats = false; | |
345 | ||
346 | spin_lock_bh(&queue->lock); | |
347 | list_for_each_entry(item, &queue->queue, head) { | |
348 | if (link_id_map & BIT(item->txpriv.link_id)) { | |
349 | ret = 0; | |
350 | break; | |
351 | } | |
352 | } | |
353 | ||
354 | if (!WARN_ON(ret)) { | |
355 | *tx = (struct wsm_tx *)item->skb->data; | |
356 | *tx_info = IEEE80211_SKB_CB(item->skb); | |
357 | *txpriv = &item->txpriv; | |
7258416c | 358 | (*tx)->packet_id = item->packet_id; |
a910e4a9 SP |
359 | list_move_tail(&item->head, &queue->pending); |
360 | ++queue->num_pending; | |
361 | --queue->link_map_cache[item->txpriv.link_id]; | |
362 | item->xmit_timestamp = jiffies; | |
363 | ||
364 | spin_lock_bh(&stats->lock); | |
365 | --stats->num_queued; | |
366 | if (!--stats->link_map_cache[item->txpriv.link_id]) | |
367 | wakeup_stats = true; | |
368 | spin_unlock_bh(&stats->lock); | |
369 | } | |
370 | spin_unlock_bh(&queue->lock); | |
371 | if (wakeup_stats) | |
372 | wake_up(&stats->wait_link_id_empty); | |
373 | return ret; | |
374 | } | |
375 | ||
376 | int cw1200_queue_requeue(struct cw1200_queue *queue, u32 packet_id) | |
377 | { | |
378 | int ret = 0; | |
379 | u8 queue_generation, queue_id, item_generation, item_id; | |
380 | struct cw1200_queue_item *item; | |
381 | struct cw1200_queue_stats *stats = queue->stats; | |
382 | ||
383 | cw1200_queue_parse_id(packet_id, &queue_generation, &queue_id, | |
384 | &item_generation, &item_id); | |
385 | ||
386 | item = &queue->pool[item_id]; | |
387 | ||
388 | spin_lock_bh(&queue->lock); | |
389 | BUG_ON(queue_id != queue->queue_id); | |
390 | if (queue_generation != queue->generation) { | |
391 | ret = -ENOENT; | |
392 | } else if (item_id >= (unsigned) queue->capacity) { | |
393 | WARN_ON(1); | |
394 | ret = -EINVAL; | |
395 | } else if (item->generation != item_generation) { | |
396 | WARN_ON(1); | |
397 | ret = -ENOENT; | |
398 | } else { | |
399 | --queue->num_pending; | |
400 | ++queue->link_map_cache[item->txpriv.link_id]; | |
401 | ||
402 | spin_lock_bh(&stats->lock); | |
403 | ++stats->num_queued; | |
404 | ++stats->link_map_cache[item->txpriv.link_id]; | |
405 | spin_unlock_bh(&stats->lock); | |
406 | ||
407 | item->generation = ++item_generation; | |
408 | item->packet_id = cw1200_queue_mk_packet_id(queue_generation, | |
409 | queue_id, | |
410 | item_generation, | |
411 | item_id); | |
412 | list_move(&item->head, &queue->queue); | |
413 | } | |
414 | spin_unlock_bh(&queue->lock); | |
415 | return ret; | |
416 | } | |
417 | ||
418 | int cw1200_queue_requeue_all(struct cw1200_queue *queue) | |
419 | { | |
420 | struct cw1200_queue_item *item, *tmp; | |
421 | struct cw1200_queue_stats *stats = queue->stats; | |
422 | spin_lock_bh(&queue->lock); | |
423 | ||
424 | list_for_each_entry_safe_reverse(item, tmp, &queue->pending, head) { | |
425 | --queue->num_pending; | |
426 | ++queue->link_map_cache[item->txpriv.link_id]; | |
427 | ||
428 | spin_lock_bh(&stats->lock); | |
429 | ++stats->num_queued; | |
430 | ++stats->link_map_cache[item->txpriv.link_id]; | |
431 | spin_unlock_bh(&stats->lock); | |
432 | ||
433 | ++item->generation; | |
434 | item->packet_id = cw1200_queue_mk_packet_id(queue->generation, | |
435 | queue->queue_id, | |
436 | item->generation, | |
437 | item - queue->pool); | |
438 | list_move(&item->head, &queue->queue); | |
439 | } | |
440 | spin_unlock_bh(&queue->lock); | |
441 | ||
442 | return 0; | |
443 | } | |
444 | ||
445 | int cw1200_queue_remove(struct cw1200_queue *queue, u32 packet_id) | |
446 | { | |
447 | int ret = 0; | |
448 | u8 queue_generation, queue_id, item_generation, item_id; | |
449 | struct cw1200_queue_item *item; | |
450 | struct cw1200_queue_stats *stats = queue->stats; | |
451 | struct sk_buff *gc_skb = NULL; | |
452 | struct cw1200_txpriv gc_txpriv; | |
453 | ||
454 | cw1200_queue_parse_id(packet_id, &queue_generation, &queue_id, | |
455 | &item_generation, &item_id); | |
456 | ||
457 | item = &queue->pool[item_id]; | |
458 | ||
459 | spin_lock_bh(&queue->lock); | |
460 | BUG_ON(queue_id != queue->queue_id); | |
461 | if (queue_generation != queue->generation) { | |
462 | ret = -ENOENT; | |
463 | } else if (item_id >= (unsigned) queue->capacity) { | |
464 | WARN_ON(1); | |
465 | ret = -EINVAL; | |
466 | } else if (item->generation != item_generation) { | |
467 | WARN_ON(1); | |
468 | ret = -ENOENT; | |
469 | } else { | |
470 | gc_txpriv = item->txpriv; | |
471 | gc_skb = item->skb; | |
472 | item->skb = NULL; | |
473 | --queue->num_pending; | |
474 | --queue->num_queued; | |
475 | ++queue->num_sent; | |
476 | ++item->generation; | |
477 | /* Do not use list_move_tail here, but list_move: | |
478 | * try to utilize cache row. | |
479 | */ | |
480 | list_move(&item->head, &queue->free_pool); | |
481 | ||
482 | if (queue->overfull && | |
483 | (queue->num_queued <= (queue->capacity >> 1))) { | |
484 | queue->overfull = false; | |
485 | __cw1200_queue_unlock(queue); | |
486 | } | |
487 | } | |
488 | spin_unlock_bh(&queue->lock); | |
489 | ||
490 | if (gc_skb) | |
491 | stats->skb_dtor(stats->priv, gc_skb, &gc_txpriv); | |
492 | ||
493 | return ret; | |
494 | } | |
495 | ||
496 | int cw1200_queue_get_skb(struct cw1200_queue *queue, u32 packet_id, | |
497 | struct sk_buff **skb, | |
498 | const struct cw1200_txpriv **txpriv) | |
499 | { | |
500 | int ret = 0; | |
501 | u8 queue_generation, queue_id, item_generation, item_id; | |
502 | struct cw1200_queue_item *item; | |
503 | cw1200_queue_parse_id(packet_id, &queue_generation, &queue_id, | |
504 | &item_generation, &item_id); | |
505 | ||
506 | item = &queue->pool[item_id]; | |
507 | ||
508 | spin_lock_bh(&queue->lock); | |
509 | BUG_ON(queue_id != queue->queue_id); | |
510 | if (queue_generation != queue->generation) { | |
511 | ret = -ENOENT; | |
512 | } else if (item_id >= (unsigned) queue->capacity) { | |
513 | WARN_ON(1); | |
514 | ret = -EINVAL; | |
515 | } else if (item->generation != item_generation) { | |
516 | WARN_ON(1); | |
517 | ret = -ENOENT; | |
518 | } else { | |
519 | *skb = item->skb; | |
520 | *txpriv = &item->txpriv; | |
521 | } | |
522 | spin_unlock_bh(&queue->lock); | |
523 | return ret; | |
524 | } | |
525 | ||
526 | void cw1200_queue_lock(struct cw1200_queue *queue) | |
527 | { | |
528 | spin_lock_bh(&queue->lock); | |
529 | __cw1200_queue_lock(queue); | |
530 | spin_unlock_bh(&queue->lock); | |
531 | } | |
532 | ||
533 | void cw1200_queue_unlock(struct cw1200_queue *queue) | |
534 | { | |
535 | spin_lock_bh(&queue->lock); | |
536 | __cw1200_queue_unlock(queue); | |
537 | spin_unlock_bh(&queue->lock); | |
538 | } | |
539 | ||
540 | bool cw1200_queue_get_xmit_timestamp(struct cw1200_queue *queue, | |
541 | unsigned long *timestamp, | |
542 | u32 pending_frame_id) | |
543 | { | |
544 | struct cw1200_queue_item *item; | |
545 | bool ret; | |
546 | ||
547 | spin_lock_bh(&queue->lock); | |
548 | ret = !list_empty(&queue->pending); | |
549 | if (ret) { | |
550 | list_for_each_entry(item, &queue->pending, head) { | |
551 | if (item->packet_id != pending_frame_id) | |
552 | if (time_before(item->xmit_timestamp, | |
553 | *timestamp)) | |
554 | *timestamp = item->xmit_timestamp; | |
555 | } | |
556 | } | |
557 | spin_unlock_bh(&queue->lock); | |
558 | return ret; | |
559 | } | |
560 | ||
561 | bool cw1200_queue_stats_is_empty(struct cw1200_queue_stats *stats, | |
562 | u32 link_id_map) | |
563 | { | |
564 | bool empty = true; | |
565 | ||
566 | spin_lock_bh(&stats->lock); | |
567 | if (link_id_map == (u32)-1) { | |
568 | empty = stats->num_queued == 0; | |
569 | } else { | |
570 | int i; | |
571 | for (i = 0; i < stats->map_capacity; ++i) { | |
572 | if (link_id_map & BIT(i)) { | |
573 | if (stats->link_map_cache[i]) { | |
574 | empty = false; | |
575 | break; | |
576 | } | |
577 | } | |
578 | } | |
579 | } | |
580 | spin_unlock_bh(&stats->lock); | |
581 | ||
582 | return empty; | |
583 | } |