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

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