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TOMOYO Linux Cross Reference
Linux/kernel/padata.c

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

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