Root/kernel/padata.c

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
36static 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
47static 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
64static 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 */
107int 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
146out:
147    rcu_read_unlock_bh();
148
149    return err;
150}
151EXPORT_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 */
170static 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);
214out:
215    return padata;
216}
217
218static 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
287static void padata_reorder_timer(unsigned long arg)
288{
289    struct parallel_data *pd = (struct parallel_data *)arg;
290
291    padata_reorder(pd);
292}
293
294static 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 */
330void 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}
350EXPORT_SYMBOL(padata_do_serial);
351
352static 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
369static 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 */
376static 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 */
390static 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. */
410static 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
441err_free_squeue:
442    free_percpu(pd->squeue);
443err_free_pqueue:
444    free_percpu(pd->pqueue);
445err_free_pd:
446    kfree(pd);
447err:
448    return NULL;
449}
450
451static 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. */
461static 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
485static void __padata_start(struct padata_instance *pinst)
486{
487    pinst->flags |= PADATA_INIT;
488}
489
490static 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. */
505static 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 */
540int 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}
546EXPORT_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 */
555int 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}
562EXPORT_SYMBOL(padata_unregister_cpumask_notifier);
563
564
565/* If cpumask contains no active cpu, we mark the instance as invalid. */
566static 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
578static 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
595out_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 */
620int 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}
636EXPORT_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 */
647int 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
671out:
672    put_online_cpus();
673    mutex_unlock(&pinst->lock);
674
675    return err;
676}
677EXPORT_SYMBOL(padata_set_cpumask);
678
679static 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
711int 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}
733EXPORT_SYMBOL(padata_add_cpu);
734
735static 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 */
770int 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}
792EXPORT_SYMBOL(padata_remove_cpu);
793
794/**
795 * padata_start - start the parallel processing
796 *
797 * @pinst: padata instance to start
798 */
799int 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}
814EXPORT_SYMBOL(padata_start);
815
816/**
817 * padata_stop - stop the parallel processing
818 *
819 * @pinst: padata instance to stop
820 */
821void padata_stop(struct padata_instance *pinst)
822{
823    mutex_lock(&pinst->lock);
824    __padata_stop(pinst);
825    mutex_unlock(&pinst->lock);
826}
827EXPORT_SYMBOL(padata_stop);
828
829#ifdef CONFIG_HOTPLUG_CPU
830
831static 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
838static 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
891static 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
909static void padata_sysfs_release(struct kobject *kobj)
910{
911    struct padata_instance *pinst = kobj2pinst(kobj);
912    __padata_free(pinst);
913}
914
915struct 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
922static 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
945static 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
967out:
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
979PADATA_ATTR_RW(serial_cpumask, show_cpumask, store_cpumask);
980PADATA_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 */
987static struct attribute *padata_default_attrs[] = {
988    &serial_cpumask_attr.attr,
989    &parallel_cpumask_attr.attr,
990    NULL,
991};
992
993static 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
1008static 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
1023static const struct sysfs_ops padata_sysfs_ops = {
1024    .show = padata_sysfs_show,
1025    .store = padata_sysfs_store,
1026};
1027
1028static 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 */
1041struct padata_instance *padata_alloc_possible(struct workqueue_struct *wq)
1042{
1043    return padata_alloc(wq, cpu_possible_mask, cpu_possible_mask);
1044}
1045EXPORT_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 */
1055struct 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
1104err_free_masks:
1105    free_cpumask_var(pinst->cpumask.pcpu);
1106    free_cpumask_var(pinst->cpumask.cbcpu);
1107err_free_inst:
1108    kfree(pinst);
1109    put_online_cpus();
1110err:
1111    return NULL;
1112}
1113EXPORT_SYMBOL(padata_alloc);
1114
1115/**
1116 * padata_free - free a padata instance
1117 *
1118 * @padata_inst: padata instance to free
1119 */
1120void padata_free(struct padata_instance *pinst)
1121{
1122    kobject_put(&pinst->kobj);
1123}
1124EXPORT_SYMBOL(padata_free);
1125

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