xref: /openbmc/linux/kernel/padata.c (revision 05bcf503)
1 /*
2  * padata.c - generic interface to process data streams in parallel
3  *
4  * See Documentation/padata.txt for an api documentation.
5  *
6  * Copyright (C) 2008, 2009 secunet Security Networks AG
7  * Copyright (C) 2008, 2009 Steffen Klassert <steffen.klassert@secunet.com>
8  *
9  * This program is free software; you can redistribute it and/or modify it
10  * under the terms and conditions of the GNU General Public License,
11  * version 2, as published by the Free Software Foundation.
12  *
13  * This program is distributed in the hope it will be useful, but WITHOUT
14  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
15  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
16  * more details.
17  *
18  * You should have received a copy of the GNU General Public License along with
19  * this program; if not, write to the Free Software Foundation, Inc.,
20  * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
21  */
22 
23 #include <linux/export.h>
24 #include <linux/cpumask.h>
25 #include <linux/err.h>
26 #include <linux/cpu.h>
27 #include <linux/padata.h>
28 #include <linux/mutex.h>
29 #include <linux/sched.h>
30 #include <linux/slab.h>
31 #include <linux/sysfs.h>
32 #include <linux/rcupdate.h>
33 
34 #define MAX_OBJ_NUM 1000
35 
36 static int padata_index_to_cpu(struct parallel_data *pd, int cpu_index)
37 {
38 	int cpu, target_cpu;
39 
40 	target_cpu = cpumask_first(pd->cpumask.pcpu);
41 	for (cpu = 0; cpu < cpu_index; cpu++)
42 		target_cpu = cpumask_next(target_cpu, pd->cpumask.pcpu);
43 
44 	return target_cpu;
45 }
46 
47 static int padata_cpu_hash(struct parallel_data *pd)
48 {
49 	int cpu_index;
50 
51 	/*
52 	 * Hash the sequence numbers to the cpus by taking
53 	 * seq_nr mod. number of cpus in use.
54 	 */
55 
56 	spin_lock(&pd->seq_lock);
57 	cpu_index =  pd->seq_nr % cpumask_weight(pd->cpumask.pcpu);
58 	pd->seq_nr++;
59 	spin_unlock(&pd->seq_lock);
60 
61 	return padata_index_to_cpu(pd, cpu_index);
62 }
63 
64 static void padata_parallel_worker(struct work_struct *parallel_work)
65 {
66 	struct padata_parallel_queue *pqueue;
67 	struct parallel_data *pd;
68 	struct padata_instance *pinst;
69 	LIST_HEAD(local_list);
70 
71 	local_bh_disable();
72 	pqueue = container_of(parallel_work,
73 			      struct padata_parallel_queue, work);
74 	pd = pqueue->pd;
75 	pinst = pd->pinst;
76 
77 	spin_lock(&pqueue->parallel.lock);
78 	list_replace_init(&pqueue->parallel.list, &local_list);
79 	spin_unlock(&pqueue->parallel.lock);
80 
81 	while (!list_empty(&local_list)) {
82 		struct padata_priv *padata;
83 
84 		padata = list_entry(local_list.next,
85 				    struct padata_priv, list);
86 
87 		list_del_init(&padata->list);
88 
89 		padata->parallel(padata);
90 	}
91 
92 	local_bh_enable();
93 }
94 
95 /**
96  * padata_do_parallel - padata parallelization function
97  *
98  * @pinst: padata instance
99  * @padata: object to be parallelized
100  * @cb_cpu: cpu the serialization callback function will run on,
101  *          must be in the serial cpumask of padata(i.e. cpumask.cbcpu).
102  *
103  * The parallelization callback function will run with BHs off.
104  * Note: Every object which is parallelized by padata_do_parallel
105  * must be seen by padata_do_serial.
106  */
107 int padata_do_parallel(struct padata_instance *pinst,
108 		       struct padata_priv *padata, int cb_cpu)
109 {
110 	int target_cpu, err;
111 	struct padata_parallel_queue *queue;
112 	struct parallel_data *pd;
113 
114 	rcu_read_lock_bh();
115 
116 	pd = rcu_dereference(pinst->pd);
117 
118 	err = -EINVAL;
119 	if (!(pinst->flags & PADATA_INIT) || pinst->flags & PADATA_INVALID)
120 		goto out;
121 
122 	if (!cpumask_test_cpu(cb_cpu, pd->cpumask.cbcpu))
123 		goto out;
124 
125 	err =  -EBUSY;
126 	if ((pinst->flags & PADATA_RESET))
127 		goto out;
128 
129 	if (atomic_read(&pd->refcnt) >= MAX_OBJ_NUM)
130 		goto out;
131 
132 	err = 0;
133 	atomic_inc(&pd->refcnt);
134 	padata->pd = pd;
135 	padata->cb_cpu = cb_cpu;
136 
137 	target_cpu = padata_cpu_hash(pd);
138 	queue = per_cpu_ptr(pd->pqueue, target_cpu);
139 
140 	spin_lock(&queue->parallel.lock);
141 	list_add_tail(&padata->list, &queue->parallel.list);
142 	spin_unlock(&queue->parallel.lock);
143 
144 	queue_work_on(target_cpu, pinst->wq, &queue->work);
145 
146 out:
147 	rcu_read_unlock_bh();
148 
149 	return err;
150 }
151 EXPORT_SYMBOL(padata_do_parallel);
152 
153 /*
154  * padata_get_next - Get the next object that needs serialization.
155  *
156  * Return values are:
157  *
158  * A pointer to the control struct of the next object that needs
159  * serialization, if present in one of the percpu reorder queues.
160  *
161  * NULL, if all percpu reorder queues are empty.
162  *
163  * -EINPROGRESS, if the next object that needs serialization will
164  *  be parallel processed by another cpu and is not yet present in
165  *  the cpu's reorder queue.
166  *
167  * -ENODATA, if this cpu has to do the parallel processing for
168  *  the next object.
169  */
170 static struct padata_priv *padata_get_next(struct parallel_data *pd)
171 {
172 	int cpu, num_cpus;
173 	unsigned int next_nr, next_index;
174 	struct padata_parallel_queue *queue, *next_queue;
175 	struct padata_priv *padata;
176 	struct padata_list *reorder;
177 
178 	num_cpus = cpumask_weight(pd->cpumask.pcpu);
179 
180 	/*
181 	 * Calculate the percpu reorder queue and the sequence
182 	 * number of the next object.
183 	 */
184 	next_nr = pd->processed;
185 	next_index = next_nr % num_cpus;
186 	cpu = padata_index_to_cpu(pd, next_index);
187 	next_queue = per_cpu_ptr(pd->pqueue, cpu);
188 
189 	padata = NULL;
190 
191 	reorder = &next_queue->reorder;
192 
193 	if (!list_empty(&reorder->list)) {
194 		padata = list_entry(reorder->list.next,
195 				    struct padata_priv, list);
196 
197 		spin_lock(&reorder->lock);
198 		list_del_init(&padata->list);
199 		atomic_dec(&pd->reorder_objects);
200 		spin_unlock(&reorder->lock);
201 
202 		pd->processed++;
203 
204 		goto out;
205 	}
206 
207 	queue = per_cpu_ptr(pd->pqueue, smp_processor_id());
208 	if (queue->cpu_index == next_queue->cpu_index) {
209 		padata = ERR_PTR(-ENODATA);
210 		goto out;
211 	}
212 
213 	padata = ERR_PTR(-EINPROGRESS);
214 out:
215 	return padata;
216 }
217 
218 static void padata_reorder(struct parallel_data *pd)
219 {
220 	int cb_cpu;
221 	struct padata_priv *padata;
222 	struct padata_serial_queue *squeue;
223 	struct padata_instance *pinst = pd->pinst;
224 
225 	/*
226 	 * We need to ensure that only one cpu can work on dequeueing of
227 	 * the reorder queue the time. Calculating in which percpu reorder
228 	 * queue the next object will arrive takes some time. A spinlock
229 	 * would be highly contended. Also it is not clear in which order
230 	 * the objects arrive to the reorder queues. So a cpu could wait to
231 	 * get the lock just to notice that there is nothing to do at the
232 	 * moment. Therefore we use a trylock and let the holder of the lock
233 	 * care for all the objects enqueued during the holdtime of the lock.
234 	 */
235 	if (!spin_trylock_bh(&pd->lock))
236 		return;
237 
238 	while (1) {
239 		padata = padata_get_next(pd);
240 
241 		/*
242 		 * All reorder queues are empty, or the next object that needs
243 		 * serialization is parallel processed by another cpu and is
244 		 * still on it's way to the cpu's reorder queue, nothing to
245 		 * do for now.
246 		 */
247 		if (!padata || PTR_ERR(padata) == -EINPROGRESS)
248 			break;
249 
250 		/*
251 		 * This cpu has to do the parallel processing of the next
252 		 * object. It's waiting in the cpu's parallelization queue,
253 		 * so exit immediately.
254 		 */
255 		if (PTR_ERR(padata) == -ENODATA) {
256 			del_timer(&pd->timer);
257 			spin_unlock_bh(&pd->lock);
258 			return;
259 		}
260 
261 		cb_cpu = padata->cb_cpu;
262 		squeue = per_cpu_ptr(pd->squeue, cb_cpu);
263 
264 		spin_lock(&squeue->serial.lock);
265 		list_add_tail(&padata->list, &squeue->serial.list);
266 		spin_unlock(&squeue->serial.lock);
267 
268 		queue_work_on(cb_cpu, pinst->wq, &squeue->work);
269 	}
270 
271 	spin_unlock_bh(&pd->lock);
272 
273 	/*
274 	 * The next object that needs serialization might have arrived to
275 	 * the reorder queues in the meantime, we will be called again
276 	 * from the timer function if no one else cares for it.
277 	 */
278 	if (atomic_read(&pd->reorder_objects)
279 			&& !(pinst->flags & PADATA_RESET))
280 		mod_timer(&pd->timer, jiffies + HZ);
281 	else
282 		del_timer(&pd->timer);
283 
284 	return;
285 }
286 
287 static void padata_reorder_timer(unsigned long arg)
288 {
289 	struct parallel_data *pd = (struct parallel_data *)arg;
290 
291 	padata_reorder(pd);
292 }
293 
294 static void padata_serial_worker(struct work_struct *serial_work)
295 {
296 	struct padata_serial_queue *squeue;
297 	struct parallel_data *pd;
298 	LIST_HEAD(local_list);
299 
300 	local_bh_disable();
301 	squeue = container_of(serial_work, struct padata_serial_queue, work);
302 	pd = squeue->pd;
303 
304 	spin_lock(&squeue->serial.lock);
305 	list_replace_init(&squeue->serial.list, &local_list);
306 	spin_unlock(&squeue->serial.lock);
307 
308 	while (!list_empty(&local_list)) {
309 		struct padata_priv *padata;
310 
311 		padata = list_entry(local_list.next,
312 				    struct padata_priv, list);
313 
314 		list_del_init(&padata->list);
315 
316 		padata->serial(padata);
317 		atomic_dec(&pd->refcnt);
318 	}
319 	local_bh_enable();
320 }
321 
322 /**
323  * padata_do_serial - padata serialization function
324  *
325  * @padata: object to be serialized.
326  *
327  * padata_do_serial must be called for every parallelized object.
328  * The serialization callback function will run with BHs off.
329  */
330 void padata_do_serial(struct padata_priv *padata)
331 {
332 	int cpu;
333 	struct padata_parallel_queue *pqueue;
334 	struct parallel_data *pd;
335 
336 	pd = padata->pd;
337 
338 	cpu = get_cpu();
339 	pqueue = per_cpu_ptr(pd->pqueue, cpu);
340 
341 	spin_lock(&pqueue->reorder.lock);
342 	atomic_inc(&pd->reorder_objects);
343 	list_add_tail(&padata->list, &pqueue->reorder.list);
344 	spin_unlock(&pqueue->reorder.lock);
345 
346 	put_cpu();
347 
348 	padata_reorder(pd);
349 }
350 EXPORT_SYMBOL(padata_do_serial);
351 
352 static int padata_setup_cpumasks(struct parallel_data *pd,
353 				 const struct cpumask *pcpumask,
354 				 const struct cpumask *cbcpumask)
355 {
356 	if (!alloc_cpumask_var(&pd->cpumask.pcpu, GFP_KERNEL))
357 		return -ENOMEM;
358 
359 	cpumask_and(pd->cpumask.pcpu, pcpumask, cpu_online_mask);
360 	if (!alloc_cpumask_var(&pd->cpumask.cbcpu, GFP_KERNEL)) {
361 		free_cpumask_var(pd->cpumask.cbcpu);
362 		return -ENOMEM;
363 	}
364 
365 	cpumask_and(pd->cpumask.cbcpu, cbcpumask, cpu_online_mask);
366 	return 0;
367 }
368 
369 static void __padata_list_init(struct padata_list *pd_list)
370 {
371 	INIT_LIST_HEAD(&pd_list->list);
372 	spin_lock_init(&pd_list->lock);
373 }
374 
375 /* Initialize all percpu queues used by serial workers */
376 static void padata_init_squeues(struct parallel_data *pd)
377 {
378 	int cpu;
379 	struct padata_serial_queue *squeue;
380 
381 	for_each_cpu(cpu, pd->cpumask.cbcpu) {
382 		squeue = per_cpu_ptr(pd->squeue, cpu);
383 		squeue->pd = pd;
384 		__padata_list_init(&squeue->serial);
385 		INIT_WORK(&squeue->work, padata_serial_worker);
386 	}
387 }
388 
389 /* Initialize all percpu queues used by parallel workers */
390 static void padata_init_pqueues(struct parallel_data *pd)
391 {
392 	int cpu_index, cpu;
393 	struct padata_parallel_queue *pqueue;
394 
395 	cpu_index = 0;
396 	for_each_cpu(cpu, pd->cpumask.pcpu) {
397 		pqueue = per_cpu_ptr(pd->pqueue, cpu);
398 		pqueue->pd = pd;
399 		pqueue->cpu_index = cpu_index;
400 		cpu_index++;
401 
402 		__padata_list_init(&pqueue->reorder);
403 		__padata_list_init(&pqueue->parallel);
404 		INIT_WORK(&pqueue->work, padata_parallel_worker);
405 		atomic_set(&pqueue->num_obj, 0);
406 	}
407 }
408 
409 /* Allocate and initialize the internal cpumask dependend resources. */
410 static struct parallel_data *padata_alloc_pd(struct padata_instance *pinst,
411 					     const struct cpumask *pcpumask,
412 					     const struct cpumask *cbcpumask)
413 {
414 	struct parallel_data *pd;
415 
416 	pd = kzalloc(sizeof(struct parallel_data), GFP_KERNEL);
417 	if (!pd)
418 		goto err;
419 
420 	pd->pqueue = alloc_percpu(struct padata_parallel_queue);
421 	if (!pd->pqueue)
422 		goto err_free_pd;
423 
424 	pd->squeue = alloc_percpu(struct padata_serial_queue);
425 	if (!pd->squeue)
426 		goto err_free_pqueue;
427 	if (padata_setup_cpumasks(pd, pcpumask, cbcpumask) < 0)
428 		goto err_free_squeue;
429 
430 	padata_init_pqueues(pd);
431 	padata_init_squeues(pd);
432 	setup_timer(&pd->timer, padata_reorder_timer, (unsigned long)pd);
433 	pd->seq_nr = 0;
434 	atomic_set(&pd->reorder_objects, 0);
435 	atomic_set(&pd->refcnt, 0);
436 	pd->pinst = pinst;
437 	spin_lock_init(&pd->lock);
438 
439 	return pd;
440 
441 err_free_squeue:
442 	free_percpu(pd->squeue);
443 err_free_pqueue:
444 	free_percpu(pd->pqueue);
445 err_free_pd:
446 	kfree(pd);
447 err:
448 	return NULL;
449 }
450 
451 static void padata_free_pd(struct parallel_data *pd)
452 {
453 	free_cpumask_var(pd->cpumask.pcpu);
454 	free_cpumask_var(pd->cpumask.cbcpu);
455 	free_percpu(pd->pqueue);
456 	free_percpu(pd->squeue);
457 	kfree(pd);
458 }
459 
460 /* Flush all objects out of the padata queues. */
461 static void padata_flush_queues(struct parallel_data *pd)
462 {
463 	int cpu;
464 	struct padata_parallel_queue *pqueue;
465 	struct padata_serial_queue *squeue;
466 
467 	for_each_cpu(cpu, pd->cpumask.pcpu) {
468 		pqueue = per_cpu_ptr(pd->pqueue, cpu);
469 		flush_work(&pqueue->work);
470 	}
471 
472 	del_timer_sync(&pd->timer);
473 
474 	if (atomic_read(&pd->reorder_objects))
475 		padata_reorder(pd);
476 
477 	for_each_cpu(cpu, pd->cpumask.cbcpu) {
478 		squeue = per_cpu_ptr(pd->squeue, cpu);
479 		flush_work(&squeue->work);
480 	}
481 
482 	BUG_ON(atomic_read(&pd->refcnt) != 0);
483 }
484 
485 static void __padata_start(struct padata_instance *pinst)
486 {
487 	pinst->flags |= PADATA_INIT;
488 }
489 
490 static void __padata_stop(struct padata_instance *pinst)
491 {
492 	if (!(pinst->flags & PADATA_INIT))
493 		return;
494 
495 	pinst->flags &= ~PADATA_INIT;
496 
497 	synchronize_rcu();
498 
499 	get_online_cpus();
500 	padata_flush_queues(pinst->pd);
501 	put_online_cpus();
502 }
503 
504 /* Replace the internal control structure with a new one. */
505 static void padata_replace(struct padata_instance *pinst,
506 			   struct parallel_data *pd_new)
507 {
508 	struct parallel_data *pd_old = pinst->pd;
509 	int notification_mask = 0;
510 
511 	pinst->flags |= PADATA_RESET;
512 
513 	rcu_assign_pointer(pinst->pd, pd_new);
514 
515 	synchronize_rcu();
516 
517 	if (!cpumask_equal(pd_old->cpumask.pcpu, pd_new->cpumask.pcpu))
518 		notification_mask |= PADATA_CPU_PARALLEL;
519 	if (!cpumask_equal(pd_old->cpumask.cbcpu, pd_new->cpumask.cbcpu))
520 		notification_mask |= PADATA_CPU_SERIAL;
521 
522 	padata_flush_queues(pd_old);
523 	padata_free_pd(pd_old);
524 
525 	if (notification_mask)
526 		blocking_notifier_call_chain(&pinst->cpumask_change_notifier,
527 					     notification_mask,
528 					     &pd_new->cpumask);
529 
530 	pinst->flags &= ~PADATA_RESET;
531 }
532 
533 /**
534  * padata_register_cpumask_notifier - Registers a notifier that will be called
535  *                             if either pcpu or cbcpu or both cpumasks change.
536  *
537  * @pinst: A poineter to padata instance
538  * @nblock: A pointer to notifier block.
539  */
540 int padata_register_cpumask_notifier(struct padata_instance *pinst,
541 				     struct notifier_block *nblock)
542 {
543 	return blocking_notifier_chain_register(&pinst->cpumask_change_notifier,
544 						nblock);
545 }
546 EXPORT_SYMBOL(padata_register_cpumask_notifier);
547 
548 /**
549  * padata_unregister_cpumask_notifier - Unregisters cpumask notifier
550  *        registered earlier  using padata_register_cpumask_notifier
551  *
552  * @pinst: A pointer to data instance.
553  * @nlock: A pointer to notifier block.
554  */
555 int padata_unregister_cpumask_notifier(struct padata_instance *pinst,
556 				       struct notifier_block *nblock)
557 {
558 	return blocking_notifier_chain_unregister(
559 		&pinst->cpumask_change_notifier,
560 		nblock);
561 }
562 EXPORT_SYMBOL(padata_unregister_cpumask_notifier);
563 
564 
565 /* If cpumask contains no active cpu, we mark the instance as invalid. */
566 static bool padata_validate_cpumask(struct padata_instance *pinst,
567 				    const struct cpumask *cpumask)
568 {
569 	if (!cpumask_intersects(cpumask, cpu_online_mask)) {
570 		pinst->flags |= PADATA_INVALID;
571 		return false;
572 	}
573 
574 	pinst->flags &= ~PADATA_INVALID;
575 	return true;
576 }
577 
578 static int __padata_set_cpumasks(struct padata_instance *pinst,
579 				 cpumask_var_t pcpumask,
580 				 cpumask_var_t cbcpumask)
581 {
582 	int valid;
583 	struct parallel_data *pd;
584 
585 	valid = padata_validate_cpumask(pinst, pcpumask);
586 	if (!valid) {
587 		__padata_stop(pinst);
588 		goto out_replace;
589 	}
590 
591 	valid = padata_validate_cpumask(pinst, cbcpumask);
592 	if (!valid)
593 		__padata_stop(pinst);
594 
595 out_replace:
596 	pd = padata_alloc_pd(pinst, pcpumask, cbcpumask);
597 	if (!pd)
598 		return -ENOMEM;
599 
600 	cpumask_copy(pinst->cpumask.pcpu, pcpumask);
601 	cpumask_copy(pinst->cpumask.cbcpu, cbcpumask);
602 
603 	padata_replace(pinst, pd);
604 
605 	if (valid)
606 		__padata_start(pinst);
607 
608 	return 0;
609 }
610 
611 /**
612  * padata_set_cpumasks - Set both parallel and serial cpumasks. The first
613  *                       one is used by parallel workers and the second one
614  *                       by the wokers doing serialization.
615  *
616  * @pinst: padata instance
617  * @pcpumask: the cpumask to use for parallel workers
618  * @cbcpumask: the cpumsak to use for serial workers
619  */
620 int padata_set_cpumasks(struct padata_instance *pinst, cpumask_var_t pcpumask,
621 			cpumask_var_t cbcpumask)
622 {
623 	int err;
624 
625 	mutex_lock(&pinst->lock);
626 	get_online_cpus();
627 
628 	err = __padata_set_cpumasks(pinst, pcpumask, cbcpumask);
629 
630 	put_online_cpus();
631 	mutex_unlock(&pinst->lock);
632 
633 	return err;
634 
635 }
636 EXPORT_SYMBOL(padata_set_cpumasks);
637 
638 /**
639  * padata_set_cpumask: Sets specified by @cpumask_type cpumask to the value
640  *                     equivalent to @cpumask.
641  *
642  * @pinst: padata instance
643  * @cpumask_type: PADATA_CPU_SERIAL or PADATA_CPU_PARALLEL corresponding
644  *                to parallel and serial cpumasks respectively.
645  * @cpumask: the cpumask to use
646  */
647 int padata_set_cpumask(struct padata_instance *pinst, int cpumask_type,
648 		       cpumask_var_t cpumask)
649 {
650 	struct cpumask *serial_mask, *parallel_mask;
651 	int err = -EINVAL;
652 
653 	mutex_lock(&pinst->lock);
654 	get_online_cpus();
655 
656 	switch (cpumask_type) {
657 	case PADATA_CPU_PARALLEL:
658 		serial_mask = pinst->cpumask.cbcpu;
659 		parallel_mask = cpumask;
660 		break;
661 	case PADATA_CPU_SERIAL:
662 		parallel_mask = pinst->cpumask.pcpu;
663 		serial_mask = cpumask;
664 		break;
665 	default:
666 		 goto out;
667 	}
668 
669 	err =  __padata_set_cpumasks(pinst, parallel_mask, serial_mask);
670 
671 out:
672 	put_online_cpus();
673 	mutex_unlock(&pinst->lock);
674 
675 	return err;
676 }
677 EXPORT_SYMBOL(padata_set_cpumask);
678 
679 static int __padata_add_cpu(struct padata_instance *pinst, int cpu)
680 {
681 	struct parallel_data *pd;
682 
683 	if (cpumask_test_cpu(cpu, cpu_online_mask)) {
684 		pd = padata_alloc_pd(pinst, pinst->cpumask.pcpu,
685 				     pinst->cpumask.cbcpu);
686 		if (!pd)
687 			return -ENOMEM;
688 
689 		padata_replace(pinst, pd);
690 
691 		if (padata_validate_cpumask(pinst, pinst->cpumask.pcpu) &&
692 		    padata_validate_cpumask(pinst, pinst->cpumask.cbcpu))
693 			__padata_start(pinst);
694 	}
695 
696 	return 0;
697 }
698 
699  /**
700  * padata_add_cpu - add a cpu to one or both(parallel and serial)
701  *                  padata cpumasks.
702  *
703  * @pinst: padata instance
704  * @cpu: cpu to add
705  * @mask: bitmask of flags specifying to which cpumask @cpu shuld be added.
706  *        The @mask may be any combination of the following flags:
707  *          PADATA_CPU_SERIAL   - serial cpumask
708  *          PADATA_CPU_PARALLEL - parallel cpumask
709  */
710 
711 int padata_add_cpu(struct padata_instance *pinst, int cpu, int mask)
712 {
713 	int err;
714 
715 	if (!(mask & (PADATA_CPU_SERIAL | PADATA_CPU_PARALLEL)))
716 		return -EINVAL;
717 
718 	mutex_lock(&pinst->lock);
719 
720 	get_online_cpus();
721 	if (mask & PADATA_CPU_SERIAL)
722 		cpumask_set_cpu(cpu, pinst->cpumask.cbcpu);
723 	if (mask & PADATA_CPU_PARALLEL)
724 		cpumask_set_cpu(cpu, pinst->cpumask.pcpu);
725 
726 	err = __padata_add_cpu(pinst, cpu);
727 	put_online_cpus();
728 
729 	mutex_unlock(&pinst->lock);
730 
731 	return err;
732 }
733 EXPORT_SYMBOL(padata_add_cpu);
734 
735 static int __padata_remove_cpu(struct padata_instance *pinst, int cpu)
736 {
737 	struct parallel_data *pd = NULL;
738 
739 	if (cpumask_test_cpu(cpu, cpu_online_mask)) {
740 
741 		if (!padata_validate_cpumask(pinst, pinst->cpumask.pcpu) ||
742 		    !padata_validate_cpumask(pinst, pinst->cpumask.cbcpu))
743 			__padata_stop(pinst);
744 
745 		pd = padata_alloc_pd(pinst, pinst->cpumask.pcpu,
746 				     pinst->cpumask.cbcpu);
747 		if (!pd)
748 			return -ENOMEM;
749 
750 		padata_replace(pinst, pd);
751 
752 		cpumask_clear_cpu(cpu, pd->cpumask.cbcpu);
753 		cpumask_clear_cpu(cpu, pd->cpumask.pcpu);
754 	}
755 
756 	return 0;
757 }
758 
759  /**
760  * padata_remove_cpu - remove a cpu from the one or both(serial and parallel)
761  *                     padata cpumasks.
762  *
763  * @pinst: padata instance
764  * @cpu: cpu to remove
765  * @mask: bitmask specifying from which cpumask @cpu should be removed
766  *        The @mask may be any combination of the following flags:
767  *          PADATA_CPU_SERIAL   - serial cpumask
768  *          PADATA_CPU_PARALLEL - parallel cpumask
769  */
770 int padata_remove_cpu(struct padata_instance *pinst, int cpu, int mask)
771 {
772 	int err;
773 
774 	if (!(mask & (PADATA_CPU_SERIAL | PADATA_CPU_PARALLEL)))
775 		return -EINVAL;
776 
777 	mutex_lock(&pinst->lock);
778 
779 	get_online_cpus();
780 	if (mask & PADATA_CPU_SERIAL)
781 		cpumask_clear_cpu(cpu, pinst->cpumask.cbcpu);
782 	if (mask & PADATA_CPU_PARALLEL)
783 		cpumask_clear_cpu(cpu, pinst->cpumask.pcpu);
784 
785 	err = __padata_remove_cpu(pinst, cpu);
786 	put_online_cpus();
787 
788 	mutex_unlock(&pinst->lock);
789 
790 	return err;
791 }
792 EXPORT_SYMBOL(padata_remove_cpu);
793 
794 /**
795  * padata_start - start the parallel processing
796  *
797  * @pinst: padata instance to start
798  */
799 int padata_start(struct padata_instance *pinst)
800 {
801 	int err = 0;
802 
803 	mutex_lock(&pinst->lock);
804 
805 	if (pinst->flags & PADATA_INVALID)
806 		err =-EINVAL;
807 
808 	 __padata_start(pinst);
809 
810 	mutex_unlock(&pinst->lock);
811 
812 	return err;
813 }
814 EXPORT_SYMBOL(padata_start);
815 
816 /**
817  * padata_stop - stop the parallel processing
818  *
819  * @pinst: padata instance to stop
820  */
821 void padata_stop(struct padata_instance *pinst)
822 {
823 	mutex_lock(&pinst->lock);
824 	__padata_stop(pinst);
825 	mutex_unlock(&pinst->lock);
826 }
827 EXPORT_SYMBOL(padata_stop);
828 
829 #ifdef CONFIG_HOTPLUG_CPU
830 
831 static inline int pinst_has_cpu(struct padata_instance *pinst, int cpu)
832 {
833 	return cpumask_test_cpu(cpu, pinst->cpumask.pcpu) ||
834 		cpumask_test_cpu(cpu, pinst->cpumask.cbcpu);
835 }
836 
837 
838 static int padata_cpu_callback(struct notifier_block *nfb,
839 			       unsigned long action, void *hcpu)
840 {
841 	int err;
842 	struct padata_instance *pinst;
843 	int cpu = (unsigned long)hcpu;
844 
845 	pinst = container_of(nfb, struct padata_instance, cpu_notifier);
846 
847 	switch (action) {
848 	case CPU_ONLINE:
849 	case CPU_ONLINE_FROZEN:
850 		if (!pinst_has_cpu(pinst, cpu))
851 			break;
852 		mutex_lock(&pinst->lock);
853 		err = __padata_add_cpu(pinst, cpu);
854 		mutex_unlock(&pinst->lock);
855 		if (err)
856 			return notifier_from_errno(err);
857 		break;
858 
859 	case CPU_DOWN_PREPARE:
860 	case CPU_DOWN_PREPARE_FROZEN:
861 		if (!pinst_has_cpu(pinst, cpu))
862 			break;
863 		mutex_lock(&pinst->lock);
864 		err = __padata_remove_cpu(pinst, cpu);
865 		mutex_unlock(&pinst->lock);
866 		if (err)
867 			return notifier_from_errno(err);
868 		break;
869 
870 	case CPU_UP_CANCELED:
871 	case CPU_UP_CANCELED_FROZEN:
872 		if (!pinst_has_cpu(pinst, cpu))
873 			break;
874 		mutex_lock(&pinst->lock);
875 		__padata_remove_cpu(pinst, cpu);
876 		mutex_unlock(&pinst->lock);
877 
878 	case CPU_DOWN_FAILED:
879 	case CPU_DOWN_FAILED_FROZEN:
880 		if (!pinst_has_cpu(pinst, cpu))
881 			break;
882 		mutex_lock(&pinst->lock);
883 		__padata_add_cpu(pinst, cpu);
884 		mutex_unlock(&pinst->lock);
885 	}
886 
887 	return NOTIFY_OK;
888 }
889 #endif
890 
891 static void __padata_free(struct padata_instance *pinst)
892 {
893 #ifdef CONFIG_HOTPLUG_CPU
894 	unregister_hotcpu_notifier(&pinst->cpu_notifier);
895 #endif
896 
897 	padata_stop(pinst);
898 	padata_free_pd(pinst->pd);
899 	free_cpumask_var(pinst->cpumask.pcpu);
900 	free_cpumask_var(pinst->cpumask.cbcpu);
901 	kfree(pinst);
902 }
903 
904 #define kobj2pinst(_kobj)					\
905 	container_of(_kobj, struct padata_instance, kobj)
906 #define attr2pentry(_attr)					\
907 	container_of(_attr, struct padata_sysfs_entry, attr)
908 
909 static void padata_sysfs_release(struct kobject *kobj)
910 {
911 	struct padata_instance *pinst = kobj2pinst(kobj);
912 	__padata_free(pinst);
913 }
914 
915 struct padata_sysfs_entry {
916 	struct attribute attr;
917 	ssize_t (*show)(struct padata_instance *, struct attribute *, char *);
918 	ssize_t (*store)(struct padata_instance *, struct attribute *,
919 			 const char *, size_t);
920 };
921 
922 static ssize_t show_cpumask(struct padata_instance *pinst,
923 			    struct attribute *attr,  char *buf)
924 {
925 	struct cpumask *cpumask;
926 	ssize_t len;
927 
928 	mutex_lock(&pinst->lock);
929 	if (!strcmp(attr->name, "serial_cpumask"))
930 		cpumask = pinst->cpumask.cbcpu;
931 	else
932 		cpumask = pinst->cpumask.pcpu;
933 
934 	len = bitmap_scnprintf(buf, PAGE_SIZE, cpumask_bits(cpumask),
935 			       nr_cpu_ids);
936 	if (PAGE_SIZE - len < 2)
937 		len = -EINVAL;
938 	else
939 		len += sprintf(buf + len, "\n");
940 
941 	mutex_unlock(&pinst->lock);
942 	return len;
943 }
944 
945 static ssize_t store_cpumask(struct padata_instance *pinst,
946 			     struct attribute *attr,
947 			     const char *buf, size_t count)
948 {
949 	cpumask_var_t new_cpumask;
950 	ssize_t ret;
951 	int mask_type;
952 
953 	if (!alloc_cpumask_var(&new_cpumask, GFP_KERNEL))
954 		return -ENOMEM;
955 
956 	ret = bitmap_parse(buf, count, cpumask_bits(new_cpumask),
957 			   nr_cpumask_bits);
958 	if (ret < 0)
959 		goto out;
960 
961 	mask_type = !strcmp(attr->name, "serial_cpumask") ?
962 		PADATA_CPU_SERIAL : PADATA_CPU_PARALLEL;
963 	ret = padata_set_cpumask(pinst, mask_type, new_cpumask);
964 	if (!ret)
965 		ret = count;
966 
967 out:
968 	free_cpumask_var(new_cpumask);
969 	return ret;
970 }
971 
972 #define PADATA_ATTR_RW(_name, _show_name, _store_name)		\
973 	static struct padata_sysfs_entry _name##_attr =		\
974 		__ATTR(_name, 0644, _show_name, _store_name)
975 #define PADATA_ATTR_RO(_name, _show_name)		\
976 	static struct padata_sysfs_entry _name##_attr = \
977 		__ATTR(_name, 0400, _show_name, NULL)
978 
979 PADATA_ATTR_RW(serial_cpumask, show_cpumask, store_cpumask);
980 PADATA_ATTR_RW(parallel_cpumask, show_cpumask, store_cpumask);
981 
982 /*
983  * Padata sysfs provides the following objects:
984  * serial_cpumask   [RW] - cpumask for serial workers
985  * parallel_cpumask [RW] - cpumask for parallel workers
986  */
987 static struct attribute *padata_default_attrs[] = {
988 	&serial_cpumask_attr.attr,
989 	&parallel_cpumask_attr.attr,
990 	NULL,
991 };
992 
993 static ssize_t padata_sysfs_show(struct kobject *kobj,
994 				 struct attribute *attr, char *buf)
995 {
996 	struct padata_instance *pinst;
997 	struct padata_sysfs_entry *pentry;
998 	ssize_t ret = -EIO;
999 
1000 	pinst = kobj2pinst(kobj);
1001 	pentry = attr2pentry(attr);
1002 	if (pentry->show)
1003 		ret = pentry->show(pinst, attr, buf);
1004 
1005 	return ret;
1006 }
1007 
1008 static ssize_t padata_sysfs_store(struct kobject *kobj, struct attribute *attr,
1009 				  const char *buf, size_t count)
1010 {
1011 	struct padata_instance *pinst;
1012 	struct padata_sysfs_entry *pentry;
1013 	ssize_t ret = -EIO;
1014 
1015 	pinst = kobj2pinst(kobj);
1016 	pentry = attr2pentry(attr);
1017 	if (pentry->show)
1018 		ret = pentry->store(pinst, attr, buf, count);
1019 
1020 	return ret;
1021 }
1022 
1023 static const struct sysfs_ops padata_sysfs_ops = {
1024 	.show = padata_sysfs_show,
1025 	.store = padata_sysfs_store,
1026 };
1027 
1028 static struct kobj_type padata_attr_type = {
1029 	.sysfs_ops = &padata_sysfs_ops,
1030 	.default_attrs = padata_default_attrs,
1031 	.release = padata_sysfs_release,
1032 };
1033 
1034 /**
1035  * padata_alloc_possible - Allocate and initialize padata instance.
1036  *                         Use the cpu_possible_mask for serial and
1037  *                         parallel workers.
1038  *
1039  * @wq: workqueue to use for the allocated padata instance
1040  */
1041 struct padata_instance *padata_alloc_possible(struct workqueue_struct *wq)
1042 {
1043 	return padata_alloc(wq, cpu_possible_mask, cpu_possible_mask);
1044 }
1045 EXPORT_SYMBOL(padata_alloc_possible);
1046 
1047 /**
1048  * padata_alloc - allocate and initialize a padata instance and specify
1049  *                cpumasks for serial and parallel workers.
1050  *
1051  * @wq: workqueue to use for the allocated padata instance
1052  * @pcpumask: cpumask that will be used for padata parallelization
1053  * @cbcpumask: cpumask that will be used for padata serialization
1054  */
1055 struct padata_instance *padata_alloc(struct workqueue_struct *wq,
1056 				     const struct cpumask *pcpumask,
1057 				     const struct cpumask *cbcpumask)
1058 {
1059 	struct padata_instance *pinst;
1060 	struct parallel_data *pd = NULL;
1061 
1062 	pinst = kzalloc(sizeof(struct padata_instance), GFP_KERNEL);
1063 	if (!pinst)
1064 		goto err;
1065 
1066 	get_online_cpus();
1067 	if (!alloc_cpumask_var(&pinst->cpumask.pcpu, GFP_KERNEL))
1068 		goto err_free_inst;
1069 	if (!alloc_cpumask_var(&pinst->cpumask.cbcpu, GFP_KERNEL)) {
1070 		free_cpumask_var(pinst->cpumask.pcpu);
1071 		goto err_free_inst;
1072 	}
1073 	if (!padata_validate_cpumask(pinst, pcpumask) ||
1074 	    !padata_validate_cpumask(pinst, cbcpumask))
1075 		goto err_free_masks;
1076 
1077 	pd = padata_alloc_pd(pinst, pcpumask, cbcpumask);
1078 	if (!pd)
1079 		goto err_free_masks;
1080 
1081 	rcu_assign_pointer(pinst->pd, pd);
1082 
1083 	pinst->wq = wq;
1084 
1085 	cpumask_copy(pinst->cpumask.pcpu, pcpumask);
1086 	cpumask_copy(pinst->cpumask.cbcpu, cbcpumask);
1087 
1088 	pinst->flags = 0;
1089 
1090 #ifdef CONFIG_HOTPLUG_CPU
1091 	pinst->cpu_notifier.notifier_call = padata_cpu_callback;
1092 	pinst->cpu_notifier.priority = 0;
1093 	register_hotcpu_notifier(&pinst->cpu_notifier);
1094 #endif
1095 
1096 	put_online_cpus();
1097 
1098 	BLOCKING_INIT_NOTIFIER_HEAD(&pinst->cpumask_change_notifier);
1099 	kobject_init(&pinst->kobj, &padata_attr_type);
1100 	mutex_init(&pinst->lock);
1101 
1102 	return pinst;
1103 
1104 err_free_masks:
1105 	free_cpumask_var(pinst->cpumask.pcpu);
1106 	free_cpumask_var(pinst->cpumask.cbcpu);
1107 err_free_inst:
1108 	kfree(pinst);
1109 	put_online_cpus();
1110 err:
1111 	return NULL;
1112 }
1113 EXPORT_SYMBOL(padata_alloc);
1114 
1115 /**
1116  * padata_free - free a padata instance
1117  *
1118  * @padata_inst: padata instance to free
1119  */
1120 void padata_free(struct padata_instance *pinst)
1121 {
1122 	kobject_put(&pinst->kobj);
1123 }
1124 EXPORT_SYMBOL(padata_free);
1125