packaging: Add the intial linux-rpi4 spec file
[platform/kernel/linux-rpi.git] / block / blk-rq-qos.c
1 // SPDX-License-Identifier: GPL-2.0
2
3 #include "blk-rq-qos.h"
4
5 /*
6  * Increment 'v', if 'v' is below 'below'. Returns true if we succeeded,
7  * false if 'v' + 1 would be bigger than 'below'.
8  */
9 static bool atomic_inc_below(atomic_t *v, unsigned int below)
10 {
11         unsigned int cur = atomic_read(v);
12
13         do {
14                 if (cur >= below)
15                         return false;
16         } while (!atomic_try_cmpxchg(v, &cur, cur + 1));
17
18         return true;
19 }
20
21 bool rq_wait_inc_below(struct rq_wait *rq_wait, unsigned int limit)
22 {
23         return atomic_inc_below(&rq_wait->inflight, limit);
24 }
25
26 void __rq_qos_cleanup(struct rq_qos *rqos, struct bio *bio)
27 {
28         do {
29                 if (rqos->ops->cleanup)
30                         rqos->ops->cleanup(rqos, bio);
31                 rqos = rqos->next;
32         } while (rqos);
33 }
34
35 void __rq_qos_done(struct rq_qos *rqos, struct request *rq)
36 {
37         do {
38                 if (rqos->ops->done)
39                         rqos->ops->done(rqos, rq);
40                 rqos = rqos->next;
41         } while (rqos);
42 }
43
44 void __rq_qos_issue(struct rq_qos *rqos, struct request *rq)
45 {
46         do {
47                 if (rqos->ops->issue)
48                         rqos->ops->issue(rqos, rq);
49                 rqos = rqos->next;
50         } while (rqos);
51 }
52
53 void __rq_qos_requeue(struct rq_qos *rqos, struct request *rq)
54 {
55         do {
56                 if (rqos->ops->requeue)
57                         rqos->ops->requeue(rqos, rq);
58                 rqos = rqos->next;
59         } while (rqos);
60 }
61
62 void __rq_qos_throttle(struct rq_qos *rqos, struct bio *bio)
63 {
64         do {
65                 if (rqos->ops->throttle)
66                         rqos->ops->throttle(rqos, bio);
67                 rqos = rqos->next;
68         } while (rqos);
69 }
70
71 void __rq_qos_track(struct rq_qos *rqos, struct request *rq, struct bio *bio)
72 {
73         do {
74                 if (rqos->ops->track)
75                         rqos->ops->track(rqos, rq, bio);
76                 rqos = rqos->next;
77         } while (rqos);
78 }
79
80 void __rq_qos_merge(struct rq_qos *rqos, struct request *rq, struct bio *bio)
81 {
82         do {
83                 if (rqos->ops->merge)
84                         rqos->ops->merge(rqos, rq, bio);
85                 rqos = rqos->next;
86         } while (rqos);
87 }
88
89 void __rq_qos_done_bio(struct rq_qos *rqos, struct bio *bio)
90 {
91         do {
92                 if (rqos->ops->done_bio)
93                         rqos->ops->done_bio(rqos, bio);
94                 rqos = rqos->next;
95         } while (rqos);
96 }
97
98 void __rq_qos_queue_depth_changed(struct rq_qos *rqos)
99 {
100         do {
101                 if (rqos->ops->queue_depth_changed)
102                         rqos->ops->queue_depth_changed(rqos);
103                 rqos = rqos->next;
104         } while (rqos);
105 }
106
107 /*
108  * Return true, if we can't increase the depth further by scaling
109  */
110 bool rq_depth_calc_max_depth(struct rq_depth *rqd)
111 {
112         unsigned int depth;
113         bool ret = false;
114
115         /*
116          * For QD=1 devices, this is a special case. It's important for those
117          * to have one request ready when one completes, so force a depth of
118          * 2 for those devices. On the backend, it'll be a depth of 1 anyway,
119          * since the device can't have more than that in flight. If we're
120          * scaling down, then keep a setting of 1/1/1.
121          */
122         if (rqd->queue_depth == 1) {
123                 if (rqd->scale_step > 0)
124                         rqd->max_depth = 1;
125                 else {
126                         rqd->max_depth = 2;
127                         ret = true;
128                 }
129         } else {
130                 /*
131                  * scale_step == 0 is our default state. If we have suffered
132                  * latency spikes, step will be > 0, and we shrink the
133                  * allowed write depths. If step is < 0, we're only doing
134                  * writes, and we allow a temporarily higher depth to
135                  * increase performance.
136                  */
137                 depth = min_t(unsigned int, rqd->default_depth,
138                               rqd->queue_depth);
139                 if (rqd->scale_step > 0)
140                         depth = 1 + ((depth - 1) >> min(31, rqd->scale_step));
141                 else if (rqd->scale_step < 0) {
142                         unsigned int maxd = 3 * rqd->queue_depth / 4;
143
144                         depth = 1 + ((depth - 1) << -rqd->scale_step);
145                         if (depth > maxd) {
146                                 depth = maxd;
147                                 ret = true;
148                         }
149                 }
150
151                 rqd->max_depth = depth;
152         }
153
154         return ret;
155 }
156
157 /* Returns true on success and false if scaling up wasn't possible */
158 bool rq_depth_scale_up(struct rq_depth *rqd)
159 {
160         /*
161          * Hit max in previous round, stop here
162          */
163         if (rqd->scaled_max)
164                 return false;
165
166         rqd->scale_step--;
167
168         rqd->scaled_max = rq_depth_calc_max_depth(rqd);
169         return true;
170 }
171
172 /*
173  * Scale rwb down. If 'hard_throttle' is set, do it quicker, since we
174  * had a latency violation. Returns true on success and returns false if
175  * scaling down wasn't possible.
176  */
177 bool rq_depth_scale_down(struct rq_depth *rqd, bool hard_throttle)
178 {
179         /*
180          * Stop scaling down when we've hit the limit. This also prevents
181          * ->scale_step from going to crazy values, if the device can't
182          * keep up.
183          */
184         if (rqd->max_depth == 1)
185                 return false;
186
187         if (rqd->scale_step < 0 && hard_throttle)
188                 rqd->scale_step = 0;
189         else
190                 rqd->scale_step++;
191
192         rqd->scaled_max = false;
193         rq_depth_calc_max_depth(rqd);
194         return true;
195 }
196
197 struct rq_qos_wait_data {
198         struct wait_queue_entry wq;
199         struct task_struct *task;
200         struct rq_wait *rqw;
201         acquire_inflight_cb_t *cb;
202         void *private_data;
203         bool got_token;
204 };
205
206 static int rq_qos_wake_function(struct wait_queue_entry *curr,
207                                 unsigned int mode, int wake_flags, void *key)
208 {
209         struct rq_qos_wait_data *data = container_of(curr,
210                                                      struct rq_qos_wait_data,
211                                                      wq);
212
213         /*
214          * If we fail to get a budget, return -1 to interrupt the wake up loop
215          * in __wake_up_common.
216          */
217         if (!data->cb(data->rqw, data->private_data))
218                 return -1;
219
220         data->got_token = true;
221         smp_wmb();
222         list_del_init(&curr->entry);
223         wake_up_process(data->task);
224         return 1;
225 }
226
227 /**
228  * rq_qos_wait - throttle on a rqw if we need to
229  * @rqw: rqw to throttle on
230  * @private_data: caller provided specific data
231  * @acquire_inflight_cb: inc the rqw->inflight counter if we can
232  * @cleanup_cb: the callback to cleanup in case we race with a waker
233  *
234  * This provides a uniform place for the rq_qos users to do their throttling.
235  * Since you can end up with a lot of things sleeping at once, this manages the
236  * waking up based on the resources available.  The acquire_inflight_cb should
237  * inc the rqw->inflight if we have the ability to do so, or return false if not
238  * and then we will sleep until the room becomes available.
239  *
240  * cleanup_cb is in case that we race with a waker and need to cleanup the
241  * inflight count accordingly.
242  */
243 void rq_qos_wait(struct rq_wait *rqw, void *private_data,
244                  acquire_inflight_cb_t *acquire_inflight_cb,
245                  cleanup_cb_t *cleanup_cb)
246 {
247         struct rq_qos_wait_data data = {
248                 .wq = {
249                         .func   = rq_qos_wake_function,
250                         .entry  = LIST_HEAD_INIT(data.wq.entry),
251                 },
252                 .task = current,
253                 .rqw = rqw,
254                 .cb = acquire_inflight_cb,
255                 .private_data = private_data,
256         };
257         bool has_sleeper;
258
259         has_sleeper = wq_has_sleeper(&rqw->wait);
260         if (!has_sleeper && acquire_inflight_cb(rqw, private_data))
261                 return;
262
263         has_sleeper = !prepare_to_wait_exclusive(&rqw->wait, &data.wq,
264                                                  TASK_UNINTERRUPTIBLE);
265         do {
266                 /* The memory barrier in set_task_state saves us here. */
267                 if (data.got_token)
268                         break;
269                 if (!has_sleeper && acquire_inflight_cb(rqw, private_data)) {
270                         finish_wait(&rqw->wait, &data.wq);
271
272                         /*
273                          * We raced with rq_qos_wake_function() getting a token,
274                          * which means we now have two. Put our local token
275                          * and wake anyone else potentially waiting for one.
276                          */
277                         smp_rmb();
278                         if (data.got_token)
279                                 cleanup_cb(rqw, private_data);
280                         break;
281                 }
282                 io_schedule();
283                 has_sleeper = true;
284                 set_current_state(TASK_UNINTERRUPTIBLE);
285         } while (1);
286         finish_wait(&rqw->wait, &data.wq);
287 }
288
289 void rq_qos_exit(struct request_queue *q)
290 {
291         mutex_lock(&q->rq_qos_mutex);
292         while (q->rq_qos) {
293                 struct rq_qos *rqos = q->rq_qos;
294                 q->rq_qos = rqos->next;
295                 rqos->ops->exit(rqos);
296         }
297         mutex_unlock(&q->rq_qos_mutex);
298 }
299
300 int rq_qos_add(struct rq_qos *rqos, struct gendisk *disk, enum rq_qos_id id,
301                 const struct rq_qos_ops *ops)
302 {
303         struct request_queue *q = disk->queue;
304
305         lockdep_assert_held(&q->rq_qos_mutex);
306
307         rqos->disk = disk;
308         rqos->id = id;
309         rqos->ops = ops;
310
311         /*
312          * No IO can be in-flight when adding rqos, so freeze queue, which
313          * is fine since we only support rq_qos for blk-mq queue.
314          */
315         blk_mq_freeze_queue(q);
316
317         if (rq_qos_id(q, rqos->id))
318                 goto ebusy;
319         rqos->next = q->rq_qos;
320         q->rq_qos = rqos;
321
322         blk_mq_unfreeze_queue(q);
323
324         if (rqos->ops->debugfs_attrs) {
325                 mutex_lock(&q->debugfs_mutex);
326                 blk_mq_debugfs_register_rqos(rqos);
327                 mutex_unlock(&q->debugfs_mutex);
328         }
329
330         return 0;
331 ebusy:
332         blk_mq_unfreeze_queue(q);
333         return -EBUSY;
334 }
335
336 void rq_qos_del(struct rq_qos *rqos)
337 {
338         struct request_queue *q = rqos->disk->queue;
339         struct rq_qos **cur;
340
341         lockdep_assert_held(&q->rq_qos_mutex);
342
343         blk_mq_freeze_queue(q);
344         for (cur = &q->rq_qos; *cur; cur = &(*cur)->next) {
345                 if (*cur == rqos) {
346                         *cur = rqos->next;
347                         break;
348                 }
349         }
350         blk_mq_unfreeze_queue(q);
351
352         mutex_lock(&q->debugfs_mutex);
353         blk_mq_debugfs_unregister_rqos(rqos);
354         mutex_unlock(&q->debugfs_mutex);
355 }