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(struct timer_list *t)
134 {
135 	LIST_HEAD(list);
136 	struct cw1200_queue *queue =
137 		from_timer(queue, t, gc);
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 = kcalloc(map_capacity, sizeof(int),
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 	timer_setup(&queue->gc, cw1200_queue_gc, 0);
183 
184 	queue->pool = kcalloc(capacity, sizeof(struct cw1200_queue_item),
185 			      GFP_KERNEL);
186 	if (!queue->pool)
187 		return -ENOMEM;
188 
189 	queue->link_map_cache = kcalloc(stats->map_capacity, sizeof(int),
190 					GFP_KERNEL);
191 	if (!queue->link_map_cache) {
192 		kfree(queue->pool);
193 		queue->pool = NULL;
194 		return -ENOMEM;
195 	}
196 
197 	for (i = 0; i < capacity; ++i)
198 		list_add_tail(&queue->pool[i].head, &queue->free_pool);
199 
200 	return 0;
201 }
202 
203 int cw1200_queue_clear(struct cw1200_queue *queue)
204 {
205 	int i;
206 	LIST_HEAD(gc_list);
207 	struct cw1200_queue_stats *stats = queue->stats;
208 	struct cw1200_queue_item *item, *tmp;
209 
210 	spin_lock_bh(&queue->lock);
211 	queue->generation++;
212 	list_splice_tail_init(&queue->queue, &queue->pending);
213 	list_for_each_entry_safe(item, tmp, &queue->pending, head) {
214 		WARN_ON(!item->skb);
215 		cw1200_queue_register_post_gc(&gc_list, item);
216 		item->skb = NULL;
217 		list_move_tail(&item->head, &queue->free_pool);
218 	}
219 	queue->num_queued = 0;
220 	queue->num_pending = 0;
221 
222 	spin_lock_bh(&stats->lock);
223 	for (i = 0; i < stats->map_capacity; ++i) {
224 		stats->num_queued -= queue->link_map_cache[i];
225 		stats->link_map_cache[i] -= queue->link_map_cache[i];
226 		queue->link_map_cache[i] = 0;
227 	}
228 	spin_unlock_bh(&stats->lock);
229 	if (queue->overfull) {
230 		queue->overfull = false;
231 		__cw1200_queue_unlock(queue);
232 	}
233 	spin_unlock_bh(&queue->lock);
234 	wake_up(&stats->wait_link_id_empty);
235 	cw1200_queue_post_gc(stats, &gc_list);
236 	return 0;
237 }
238 
239 void cw1200_queue_stats_deinit(struct cw1200_queue_stats *stats)
240 {
241 	kfree(stats->link_map_cache);
242 	stats->link_map_cache = NULL;
243 }
244 
245 void cw1200_queue_deinit(struct cw1200_queue *queue)
246 {
247 	cw1200_queue_clear(queue);
248 	del_timer_sync(&queue->gc);
249 	INIT_LIST_HEAD(&queue->free_pool);
250 	kfree(queue->pool);
251 	kfree(queue->link_map_cache);
252 	queue->pool = NULL;
253 	queue->link_map_cache = NULL;
254 	queue->capacity = 0;
255 }
256 
257 size_t cw1200_queue_get_num_queued(struct cw1200_queue *queue,
258 				   u32 link_id_map)
259 {
260 	size_t ret;
261 	int i, bit;
262 	size_t map_capacity = queue->stats->map_capacity;
263 
264 	if (!link_id_map)
265 		return 0;
266 
267 	spin_lock_bh(&queue->lock);
268 	if (link_id_map == (u32)-1) {
269 		ret = queue->num_queued - queue->num_pending;
270 	} else {
271 		ret = 0;
272 		for (i = 0, bit = 1; i < map_capacity; ++i, bit <<= 1) {
273 			if (link_id_map & bit)
274 				ret += queue->link_map_cache[i];
275 		}
276 	}
277 	spin_unlock_bh(&queue->lock);
278 	return ret;
279 }
280 
281 int cw1200_queue_put(struct cw1200_queue *queue,
282 		     struct sk_buff *skb,
283 		     struct cw1200_txpriv *txpriv)
284 {
285 	int ret = 0;
286 	struct cw1200_queue_stats *stats = queue->stats;
287 
288 	if (txpriv->link_id >= queue->stats->map_capacity)
289 		return -EINVAL;
290 
291 	spin_lock_bh(&queue->lock);
292 	if (!WARN_ON(list_empty(&queue->free_pool))) {
293 		struct cw1200_queue_item *item = list_first_entry(
294 			&queue->free_pool, struct cw1200_queue_item, head);
295 		BUG_ON(item->skb);
296 
297 		list_move_tail(&item->head, &queue->queue);
298 		item->skb = skb;
299 		item->txpriv = *txpriv;
300 		item->generation = 0;
301 		item->packet_id = cw1200_queue_mk_packet_id(queue->generation,
302 							    queue->queue_id,
303 							    item->generation,
304 							    item - queue->pool);
305 		item->queue_timestamp = jiffies;
306 
307 		++queue->num_queued;
308 		++queue->link_map_cache[txpriv->link_id];
309 
310 		spin_lock_bh(&stats->lock);
311 		++stats->num_queued;
312 		++stats->link_map_cache[txpriv->link_id];
313 		spin_unlock_bh(&stats->lock);
314 
315 		/* TX may happen in parallel sometimes.
316 		 * Leave extra queue slots so we don't overflow.
317 		 */
318 		if (queue->overfull == false &&
319 		    queue->num_queued >=
320 		    (queue->capacity - (num_present_cpus() - 1))) {
321 			queue->overfull = true;
322 			__cw1200_queue_lock(queue);
323 			mod_timer(&queue->gc, jiffies);
324 		}
325 	} else {
326 		ret = -ENOENT;
327 	}
328 	spin_unlock_bh(&queue->lock);
329 	return ret;
330 }
331 
332 int cw1200_queue_get(struct cw1200_queue *queue,
333 		     u32 link_id_map,
334 		     struct wsm_tx **tx,
335 		     struct ieee80211_tx_info **tx_info,
336 		     const struct cw1200_txpriv **txpriv)
337 {
338 	int ret = -ENOENT;
339 	struct cw1200_queue_item *item;
340 	struct cw1200_queue_stats *stats = queue->stats;
341 	bool wakeup_stats = false;
342 
343 	spin_lock_bh(&queue->lock);
344 	list_for_each_entry(item, &queue->queue, head) {
345 		if (link_id_map & BIT(item->txpriv.link_id)) {
346 			ret = 0;
347 			break;
348 		}
349 	}
350 
351 	if (!WARN_ON(ret)) {
352 		*tx = (struct wsm_tx *)item->skb->data;
353 		*tx_info = IEEE80211_SKB_CB(item->skb);
354 		*txpriv = &item->txpriv;
355 		(*tx)->packet_id = item->packet_id;
356 		list_move_tail(&item->head, &queue->pending);
357 		++queue->num_pending;
358 		--queue->link_map_cache[item->txpriv.link_id];
359 		item->xmit_timestamp = jiffies;
360 
361 		spin_lock_bh(&stats->lock);
362 		--stats->num_queued;
363 		if (!--stats->link_map_cache[item->txpriv.link_id])
364 			wakeup_stats = true;
365 		spin_unlock_bh(&stats->lock);
366 	}
367 	spin_unlock_bh(&queue->lock);
368 	if (wakeup_stats)
369 		wake_up(&stats->wait_link_id_empty);
370 	return ret;
371 }
372 
373 int cw1200_queue_requeue(struct cw1200_queue *queue, u32 packet_id)
374 {
375 	int ret = 0;
376 	u8 queue_generation, queue_id, item_generation, item_id;
377 	struct cw1200_queue_item *item;
378 	struct cw1200_queue_stats *stats = queue->stats;
379 
380 	cw1200_queue_parse_id(packet_id, &queue_generation, &queue_id,
381 			      &item_generation, &item_id);
382 
383 	item = &queue->pool[item_id];
384 
385 	spin_lock_bh(&queue->lock);
386 	BUG_ON(queue_id != queue->queue_id);
387 	if (queue_generation != queue->generation) {
388 		ret = -ENOENT;
389 	} else if (item_id >= (unsigned) queue->capacity) {
390 		WARN_ON(1);
391 		ret = -EINVAL;
392 	} else if (item->generation != item_generation) {
393 		WARN_ON(1);
394 		ret = -ENOENT;
395 	} else {
396 		--queue->num_pending;
397 		++queue->link_map_cache[item->txpriv.link_id];
398 
399 		spin_lock_bh(&stats->lock);
400 		++stats->num_queued;
401 		++stats->link_map_cache[item->txpriv.link_id];
402 		spin_unlock_bh(&stats->lock);
403 
404 		item->generation = ++item_generation;
405 		item->packet_id = cw1200_queue_mk_packet_id(queue_generation,
406 							    queue_id,
407 							    item_generation,
408 							    item_id);
409 		list_move(&item->head, &queue->queue);
410 	}
411 	spin_unlock_bh(&queue->lock);
412 	return ret;
413 }
414 
415 int cw1200_queue_requeue_all(struct cw1200_queue *queue)
416 {
417 	struct cw1200_queue_item *item, *tmp;
418 	struct cw1200_queue_stats *stats = queue->stats;
419 	spin_lock_bh(&queue->lock);
420 
421 	list_for_each_entry_safe_reverse(item, tmp, &queue->pending, head) {
422 		--queue->num_pending;
423 		++queue->link_map_cache[item->txpriv.link_id];
424 
425 		spin_lock_bh(&stats->lock);
426 		++stats->num_queued;
427 		++stats->link_map_cache[item->txpriv.link_id];
428 		spin_unlock_bh(&stats->lock);
429 
430 		++item->generation;
431 		item->packet_id = cw1200_queue_mk_packet_id(queue->generation,
432 							    queue->queue_id,
433 							    item->generation,
434 							    item - queue->pool);
435 		list_move(&item->head, &queue->queue);
436 	}
437 	spin_unlock_bh(&queue->lock);
438 
439 	return 0;
440 }
441 
442 int cw1200_queue_remove(struct cw1200_queue *queue, u32 packet_id)
443 {
444 	int ret = 0;
445 	u8 queue_generation, queue_id, item_generation, item_id;
446 	struct cw1200_queue_item *item;
447 	struct cw1200_queue_stats *stats = queue->stats;
448 	struct sk_buff *gc_skb = NULL;
449 	struct cw1200_txpriv gc_txpriv;
450 
451 	cw1200_queue_parse_id(packet_id, &queue_generation, &queue_id,
452 			      &item_generation, &item_id);
453 
454 	item = &queue->pool[item_id];
455 
456 	spin_lock_bh(&queue->lock);
457 	BUG_ON(queue_id != queue->queue_id);
458 	if (queue_generation != queue->generation) {
459 		ret = -ENOENT;
460 	} else if (item_id >= (unsigned) queue->capacity) {
461 		WARN_ON(1);
462 		ret = -EINVAL;
463 	} else if (item->generation != item_generation) {
464 		WARN_ON(1);
465 		ret = -ENOENT;
466 	} else {
467 		gc_txpriv = item->txpriv;
468 		gc_skb = item->skb;
469 		item->skb = NULL;
470 		--queue->num_pending;
471 		--queue->num_queued;
472 		++queue->num_sent;
473 		++item->generation;
474 		/* Do not use list_move_tail here, but list_move:
475 		 * try to utilize cache row.
476 		 */
477 		list_move(&item->head, &queue->free_pool);
478 
479 		if (queue->overfull &&
480 		    (queue->num_queued <= (queue->capacity >> 1))) {
481 			queue->overfull = false;
482 			__cw1200_queue_unlock(queue);
483 		}
484 	}
485 	spin_unlock_bh(&queue->lock);
486 
487 	if (gc_skb)
488 		stats->skb_dtor(stats->priv, gc_skb, &gc_txpriv);
489 
490 	return ret;
491 }
492 
493 int cw1200_queue_get_skb(struct cw1200_queue *queue, u32 packet_id,
494 			 struct sk_buff **skb,
495 			 const struct cw1200_txpriv **txpriv)
496 {
497 	int ret = 0;
498 	u8 queue_generation, queue_id, item_generation, item_id;
499 	struct cw1200_queue_item *item;
500 	cw1200_queue_parse_id(packet_id, &queue_generation, &queue_id,
501 			      &item_generation, &item_id);
502 
503 	item = &queue->pool[item_id];
504 
505 	spin_lock_bh(&queue->lock);
506 	BUG_ON(queue_id != queue->queue_id);
507 	if (queue_generation != queue->generation) {
508 		ret = -ENOENT;
509 	} else if (item_id >= (unsigned) queue->capacity) {
510 		WARN_ON(1);
511 		ret = -EINVAL;
512 	} else if (item->generation != item_generation) {
513 		WARN_ON(1);
514 		ret = -ENOENT;
515 	} else {
516 		*skb = item->skb;
517 		*txpriv = &item->txpriv;
518 	}
519 	spin_unlock_bh(&queue->lock);
520 	return ret;
521 }
522 
523 void cw1200_queue_lock(struct cw1200_queue *queue)
524 {
525 	spin_lock_bh(&queue->lock);
526 	__cw1200_queue_lock(queue);
527 	spin_unlock_bh(&queue->lock);
528 }
529 
530 void cw1200_queue_unlock(struct cw1200_queue *queue)
531 {
532 	spin_lock_bh(&queue->lock);
533 	__cw1200_queue_unlock(queue);
534 	spin_unlock_bh(&queue->lock);
535 }
536 
537 bool cw1200_queue_get_xmit_timestamp(struct cw1200_queue *queue,
538 				     unsigned long *timestamp,
539 				     u32 pending_frame_id)
540 {
541 	struct cw1200_queue_item *item;
542 	bool ret;
543 
544 	spin_lock_bh(&queue->lock);
545 	ret = !list_empty(&queue->pending);
546 	if (ret) {
547 		list_for_each_entry(item, &queue->pending, head) {
548 			if (item->packet_id != pending_frame_id)
549 				if (time_before(item->xmit_timestamp,
550 						*timestamp))
551 					*timestamp = item->xmit_timestamp;
552 		}
553 	}
554 	spin_unlock_bh(&queue->lock);
555 	return ret;
556 }
557 
558 bool cw1200_queue_stats_is_empty(struct cw1200_queue_stats *stats,
559 				 u32 link_id_map)
560 {
561 	bool empty = true;
562 
563 	spin_lock_bh(&stats->lock);
564 	if (link_id_map == (u32)-1) {
565 		empty = stats->num_queued == 0;
566 	} else {
567 		int i;
568 		for (i = 0; i < stats->map_capacity; ++i) {
569 			if (link_id_map & BIT(i)) {
570 				if (stats->link_map_cache[i]) {
571 					empty = false;
572 					break;
573 				}
574 			}
575 		}
576 	}
577 	spin_unlock_bh(&stats->lock);
578 
579 	return empty;
580 }
581