Root/kernel/padata.c

1/*
2 * padata.c - generic interface to process data streams in parallel
3 *
4 * Copyright (C) 2008, 2009 secunet Security Networks AG
5 * Copyright (C) 2008, 2009 Steffen Klassert <steffen.klassert@secunet.com>
6 *
7 * This program is free software; you can redistribute it and/or modify it
8 * under the terms and conditions of the GNU General Public License,
9 * version 2, as published by the Free Software Foundation.
10 *
11 * This program is distributed in the hope it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
14 * more details.
15 *
16 * You should have received a copy of the GNU General Public License along with
17 * this program; if not, write to the Free Software Foundation, Inc.,
18 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
19 */
20
21#include <linux/module.h>
22#include <linux/cpumask.h>
23#include <linux/err.h>
24#include <linux/cpu.h>
25#include <linux/padata.h>
26#include <linux/mutex.h>
27#include <linux/sched.h>
28#include <linux/slab.h>
29#include <linux/sysfs.h>
30#include <linux/rcupdate.h>
31
32#define MAX_SEQ_NR (INT_MAX - NR_CPUS)
33#define MAX_OBJ_NUM 1000
34
35static int padata_index_to_cpu(struct parallel_data *pd, int cpu_index)
36{
37    int cpu, target_cpu;
38
39    target_cpu = cpumask_first(pd->cpumask.pcpu);
40    for (cpu = 0; cpu < cpu_index; cpu++)
41        target_cpu = cpumask_next(target_cpu, pd->cpumask.pcpu);
42
43    return target_cpu;
44}
45
46static int padata_cpu_hash(struct padata_priv *padata)
47{
48    int cpu_index;
49    struct parallel_data *pd;
50
51    pd = padata->pd;
52
53    /*
54     * Hash the sequence numbers to the cpus by taking
55     * seq_nr mod. number of cpus in use.
56     */
57    cpu_index = padata->seq_nr % cpumask_weight(pd->cpumask.pcpu);
58
59    return padata_index_to_cpu(pd, cpu_index);
60}
61
62static void padata_parallel_worker(struct work_struct *parallel_work)
63{
64    struct padata_parallel_queue *pqueue;
65    struct parallel_data *pd;
66    struct padata_instance *pinst;
67    LIST_HEAD(local_list);
68
69    local_bh_disable();
70    pqueue = container_of(parallel_work,
71                  struct padata_parallel_queue, work);
72    pd = pqueue->pd;
73    pinst = pd->pinst;
74
75    spin_lock(&pqueue->parallel.lock);
76    list_replace_init(&pqueue->parallel.list, &local_list);
77    spin_unlock(&pqueue->parallel.lock);
78
79    while (!list_empty(&local_list)) {
80        struct padata_priv *padata;
81
82        padata = list_entry(local_list.next,
83                    struct padata_priv, list);
84
85        list_del_init(&padata->list);
86
87        padata->parallel(padata);
88    }
89
90    local_bh_enable();
91}
92
93/**
94 * padata_do_parallel - padata parallelization function
95 *
96 * @pinst: padata instance
97 * @padata: object to be parallelized
98 * @cb_cpu: cpu the serialization callback function will run on,
99 * must be in the serial cpumask of padata(i.e. cpumask.cbcpu).
100 *
101 * The parallelization callback function will run with BHs off.
102 * Note: Every object which is parallelized by padata_do_parallel
103 * must be seen by padata_do_serial.
104 */
105int padata_do_parallel(struct padata_instance *pinst,
106               struct padata_priv *padata, int cb_cpu)
107{
108    int target_cpu, err;
109    struct padata_parallel_queue *queue;
110    struct parallel_data *pd;
111
112    rcu_read_lock_bh();
113
114    pd = rcu_dereference(pinst->pd);
115
116    err = -EINVAL;
117    if (!(pinst->flags & PADATA_INIT) || pinst->flags & PADATA_INVALID)
118        goto out;
119
120    if (!cpumask_test_cpu(cb_cpu, pd->cpumask.cbcpu))
121        goto out;
122
123    err = -EBUSY;
124    if ((pinst->flags & PADATA_RESET))
125        goto out;
126
127    if (atomic_read(&pd->refcnt) >= MAX_OBJ_NUM)
128        goto out;
129
130    err = 0;
131    atomic_inc(&pd->refcnt);
132    padata->pd = pd;
133    padata->cb_cpu = cb_cpu;
134
135    if (unlikely(atomic_read(&pd->seq_nr) == pd->max_seq_nr))
136        atomic_set(&pd->seq_nr, -1);
137
138    padata->seq_nr = atomic_inc_return(&pd->seq_nr);
139
140    target_cpu = padata_cpu_hash(padata);
141    queue = per_cpu_ptr(pd->pqueue, target_cpu);
142
143    spin_lock(&queue->parallel.lock);
144    list_add_tail(&padata->list, &queue->parallel.list);
145    spin_unlock(&queue->parallel.lock);
146
147    queue_work_on(target_cpu, pinst->wq, &queue->work);
148
149out:
150    rcu_read_unlock_bh();
151
152    return err;
153}
154EXPORT_SYMBOL(padata_do_parallel);
155
156/*
157 * padata_get_next - Get the next object that needs serialization.
158 *
159 * Return values are:
160 *
161 * A pointer to the control struct of the next object that needs
162 * serialization, if present in one of the percpu reorder queues.
163 *
164 * NULL, if all percpu reorder queues are empty.
165 *
166 * -EINPROGRESS, if the next object that needs serialization will
167 * be parallel processed by another cpu and is not yet present in
168 * the cpu's reorder queue.
169 *
170 * -ENODATA, if this cpu has to do the parallel processing for
171 * the next object.
172 */
173static struct padata_priv *padata_get_next(struct parallel_data *pd)
174{
175    int cpu, num_cpus;
176    int next_nr, next_index;
177    struct padata_parallel_queue *queue, *next_queue;
178    struct padata_priv *padata;
179    struct padata_list *reorder;
180
181    num_cpus = cpumask_weight(pd->cpumask.pcpu);
182
183    /*
184     * Calculate the percpu reorder queue and the sequence
185     * number of the next object.
186     */
187    next_nr = pd->processed;
188    next_index = next_nr % num_cpus;
189    cpu = padata_index_to_cpu(pd, next_index);
190    next_queue = per_cpu_ptr(pd->pqueue, cpu);
191
192    if (unlikely(next_nr > pd->max_seq_nr)) {
193        next_nr = next_nr - pd->max_seq_nr - 1;
194        next_index = next_nr % num_cpus;
195        cpu = padata_index_to_cpu(pd, next_index);
196        next_queue = per_cpu_ptr(pd->pqueue, cpu);
197        pd->processed = 0;
198    }
199
200    padata = NULL;
201
202    reorder = &next_queue->reorder;
203
204    if (!list_empty(&reorder->list)) {
205        padata = list_entry(reorder->list.next,
206                    struct padata_priv, list);
207
208        BUG_ON(next_nr != padata->seq_nr);
209
210        spin_lock(&reorder->lock);
211        list_del_init(&padata->list);
212        atomic_dec(&pd->reorder_objects);
213        spin_unlock(&reorder->lock);
214
215        pd->processed++;
216
217        goto out;
218    }
219
220    queue = per_cpu_ptr(pd->pqueue, smp_processor_id());
221    if (queue->cpu_index == next_queue->cpu_index) {
222        padata = ERR_PTR(-ENODATA);
223        goto out;
224    }
225
226    padata = ERR_PTR(-EINPROGRESS);
227out:
228    return padata;
229}
230
231static void padata_reorder(struct parallel_data *pd)
232{
233    struct padata_priv *padata;
234    struct padata_serial_queue *squeue;
235    struct padata_instance *pinst = pd->pinst;
236
237    /*
238     * We need to ensure that only one cpu can work on dequeueing of
239     * the reorder queue the time. Calculating in which percpu reorder
240     * queue the next object will arrive takes some time. A spinlock
241     * would be highly contended. Also it is not clear in which order
242     * the objects arrive to the reorder queues. So a cpu could wait to
243     * get the lock just to notice that there is nothing to do at the
244     * moment. Therefore we use a trylock and let the holder of the lock
245     * care for all the objects enqueued during the holdtime of the lock.
246     */
247    if (!spin_trylock_bh(&pd->lock))
248        return;
249
250    while (1) {
251        padata = padata_get_next(pd);
252
253        /*
254         * All reorder queues are empty, or the next object that needs
255         * serialization is parallel processed by another cpu and is
256         * still on it's way to the cpu's reorder queue, nothing to
257         * do for now.
258         */
259        if (!padata || PTR_ERR(padata) == -EINPROGRESS)
260            break;
261
262        /*
263         * This cpu has to do the parallel processing of the next
264         * object. It's waiting in the cpu's parallelization queue,
265         * so exit immediately.
266         */
267        if (PTR_ERR(padata) == -ENODATA) {
268            del_timer(&pd->timer);
269            spin_unlock_bh(&pd->lock);
270            return;
271        }
272
273        squeue = per_cpu_ptr(pd->squeue, padata->cb_cpu);
274
275        spin_lock(&squeue->serial.lock);
276        list_add_tail(&padata->list, &squeue->serial.list);
277        spin_unlock(&squeue->serial.lock);
278
279        queue_work_on(padata->cb_cpu, pinst->wq, &squeue->work);
280    }
281
282    spin_unlock_bh(&pd->lock);
283
284    /*
285     * The next object that needs serialization might have arrived to
286     * the reorder queues in the meantime, we will be called again
287     * from the timer function if no one else cares for it.
288     */
289    if (atomic_read(&pd->reorder_objects)
290            && !(pinst->flags & PADATA_RESET))
291        mod_timer(&pd->timer, jiffies + HZ);
292    else
293        del_timer(&pd->timer);
294
295    return;
296}
297
298static void padata_reorder_timer(unsigned long arg)
299{
300    struct parallel_data *pd = (struct parallel_data *)arg;
301
302    padata_reorder(pd);
303}
304
305static void padata_serial_worker(struct work_struct *serial_work)
306{
307    struct padata_serial_queue *squeue;
308    struct parallel_data *pd;
309    LIST_HEAD(local_list);
310
311    local_bh_disable();
312    squeue = container_of(serial_work, struct padata_serial_queue, work);
313    pd = squeue->pd;
314
315    spin_lock(&squeue->serial.lock);
316    list_replace_init(&squeue->serial.list, &local_list);
317    spin_unlock(&squeue->serial.lock);
318
319    while (!list_empty(&local_list)) {
320        struct padata_priv *padata;
321
322        padata = list_entry(local_list.next,
323                    struct padata_priv, list);
324
325        list_del_init(&padata->list);
326
327        padata->serial(padata);
328        atomic_dec(&pd->refcnt);
329    }
330    local_bh_enable();
331}
332
333/**
334 * padata_do_serial - padata serialization function
335 *
336 * @padata: object to be serialized.
337 *
338 * padata_do_serial must be called for every parallelized object.
339 * The serialization callback function will run with BHs off.
340 */
341void padata_do_serial(struct padata_priv *padata)
342{
343    int cpu;
344    struct padata_parallel_queue *pqueue;
345    struct parallel_data *pd;
346
347    pd = padata->pd;
348
349    cpu = get_cpu();
350    pqueue = per_cpu_ptr(pd->pqueue, cpu);
351
352    spin_lock(&pqueue->reorder.lock);
353    atomic_inc(&pd->reorder_objects);
354    list_add_tail(&padata->list, &pqueue->reorder.list);
355    spin_unlock(&pqueue->reorder.lock);
356
357    put_cpu();
358
359    padata_reorder(pd);
360}
361EXPORT_SYMBOL(padata_do_serial);
362
363static int padata_setup_cpumasks(struct parallel_data *pd,
364                 const struct cpumask *pcpumask,
365                 const struct cpumask *cbcpumask)
366{
367    if (!alloc_cpumask_var(&pd->cpumask.pcpu, GFP_KERNEL))
368        return -ENOMEM;
369
370    cpumask_and(pd->cpumask.pcpu, pcpumask, cpu_active_mask);
371    if (!alloc_cpumask_var(&pd->cpumask.cbcpu, GFP_KERNEL)) {
372        free_cpumask_var(pd->cpumask.cbcpu);
373        return -ENOMEM;
374    }
375
376    cpumask_and(pd->cpumask.cbcpu, cbcpumask, cpu_active_mask);
377    return 0;
378}
379
380static void __padata_list_init(struct padata_list *pd_list)
381{
382    INIT_LIST_HEAD(&pd_list->list);
383    spin_lock_init(&pd_list->lock);
384}
385
386/* Initialize all percpu queues used by serial workers */
387static void padata_init_squeues(struct parallel_data *pd)
388{
389    int cpu;
390    struct padata_serial_queue *squeue;
391
392    for_each_cpu(cpu, pd->cpumask.cbcpu) {
393        squeue = per_cpu_ptr(pd->squeue, cpu);
394        squeue->pd = pd;
395        __padata_list_init(&squeue->serial);
396        INIT_WORK(&squeue->work, padata_serial_worker);
397    }
398}
399
400/* Initialize all percpu queues used by parallel workers */
401static void padata_init_pqueues(struct parallel_data *pd)
402{
403    int cpu_index, num_cpus, cpu;
404    struct padata_parallel_queue *pqueue;
405
406    cpu_index = 0;
407    for_each_cpu(cpu, pd->cpumask.pcpu) {
408        pqueue = per_cpu_ptr(pd->pqueue, cpu);
409        pqueue->pd = pd;
410        pqueue->cpu_index = cpu_index;
411        cpu_index++;
412
413        __padata_list_init(&pqueue->reorder);
414        __padata_list_init(&pqueue->parallel);
415        INIT_WORK(&pqueue->work, padata_parallel_worker);
416        atomic_set(&pqueue->num_obj, 0);
417    }
418
419    num_cpus = cpumask_weight(pd->cpumask.pcpu);
420    pd->max_seq_nr = num_cpus ? (MAX_SEQ_NR / num_cpus) * num_cpus - 1 : 0;
421}
422
423/* Allocate and initialize the internal cpumask dependend resources. */
424static struct parallel_data *padata_alloc_pd(struct padata_instance *pinst,
425                         const struct cpumask *pcpumask,
426                         const struct cpumask *cbcpumask)
427{
428    struct parallel_data *pd;
429
430    pd = kzalloc(sizeof(struct parallel_data), GFP_KERNEL);
431    if (!pd)
432        goto err;
433
434    pd->pqueue = alloc_percpu(struct padata_parallel_queue);
435    if (!pd->pqueue)
436        goto err_free_pd;
437
438    pd->squeue = alloc_percpu(struct padata_serial_queue);
439    if (!pd->squeue)
440        goto err_free_pqueue;
441    if (padata_setup_cpumasks(pd, pcpumask, cbcpumask) < 0)
442        goto err_free_squeue;
443
444    padata_init_pqueues(pd);
445    padata_init_squeues(pd);
446    setup_timer(&pd->timer, padata_reorder_timer, (unsigned long)pd);
447    atomic_set(&pd->seq_nr, -1);
448    atomic_set(&pd->reorder_objects, 0);
449    atomic_set(&pd->refcnt, 0);
450    pd->pinst = pinst;
451    spin_lock_init(&pd->lock);
452
453    return pd;
454
455err_free_squeue:
456    free_percpu(pd->squeue);
457err_free_pqueue:
458    free_percpu(pd->pqueue);
459err_free_pd:
460    kfree(pd);
461err:
462    return NULL;
463}
464
465static void padata_free_pd(struct parallel_data *pd)
466{
467    free_cpumask_var(pd->cpumask.pcpu);
468    free_cpumask_var(pd->cpumask.cbcpu);
469    free_percpu(pd->pqueue);
470    free_percpu(pd->squeue);
471    kfree(pd);
472}
473
474/* Flush all objects out of the padata queues. */
475static void padata_flush_queues(struct parallel_data *pd)
476{
477    int cpu;
478    struct padata_parallel_queue *pqueue;
479    struct padata_serial_queue *squeue;
480
481    for_each_cpu(cpu, pd->cpumask.pcpu) {
482        pqueue = per_cpu_ptr(pd->pqueue, cpu);
483        flush_work(&pqueue->work);
484    }
485
486    del_timer_sync(&pd->timer);
487
488    if (atomic_read(&pd->reorder_objects))
489        padata_reorder(pd);
490
491    for_each_cpu(cpu, pd->cpumask.cbcpu) {
492        squeue = per_cpu_ptr(pd->squeue, cpu);
493        flush_work(&squeue->work);
494    }
495
496    BUG_ON(atomic_read(&pd->refcnt) != 0);
497}
498
499static void __padata_start(struct padata_instance *pinst)
500{
501    pinst->flags |= PADATA_INIT;
502}
503
504static void __padata_stop(struct padata_instance *pinst)
505{
506    if (!(pinst->flags & PADATA_INIT))
507        return;
508
509    pinst->flags &= ~PADATA_INIT;
510
511    synchronize_rcu();
512
513    get_online_cpus();
514    padata_flush_queues(pinst->pd);
515    put_online_cpus();
516}
517
518/* Replace the internal control structure with a new one. */
519static void padata_replace(struct padata_instance *pinst,
520               struct parallel_data *pd_new)
521{
522    struct parallel_data *pd_old = pinst->pd;
523    int notification_mask = 0;
524
525    pinst->flags |= PADATA_RESET;
526
527    rcu_assign_pointer(pinst->pd, pd_new);
528
529    synchronize_rcu();
530
531    if (!cpumask_equal(pd_old->cpumask.pcpu, pd_new->cpumask.pcpu))
532        notification_mask |= PADATA_CPU_PARALLEL;
533    if (!cpumask_equal(pd_old->cpumask.cbcpu, pd_new->cpumask.cbcpu))
534        notification_mask |= PADATA_CPU_SERIAL;
535
536    padata_flush_queues(pd_old);
537    padata_free_pd(pd_old);
538
539    if (notification_mask)
540        blocking_notifier_call_chain(&pinst->cpumask_change_notifier,
541                         notification_mask,
542                         &pd_new->cpumask);
543
544    pinst->flags &= ~PADATA_RESET;
545}
546
547/**
548 * padata_register_cpumask_notifier - Registers a notifier that will be called
549 * if either pcpu or cbcpu or both cpumasks change.
550 *
551 * @pinst: A poineter to padata instance
552 * @nblock: A pointer to notifier block.
553 */
554int padata_register_cpumask_notifier(struct padata_instance *pinst,
555                     struct notifier_block *nblock)
556{
557    return blocking_notifier_chain_register(&pinst->cpumask_change_notifier,
558                        nblock);
559}
560EXPORT_SYMBOL(padata_register_cpumask_notifier);
561
562/**
563 * padata_unregister_cpumask_notifier - Unregisters cpumask notifier
564 * registered earlier using padata_register_cpumask_notifier
565 *
566 * @pinst: A pointer to data instance.
567 * @nlock: A pointer to notifier block.
568 */
569int padata_unregister_cpumask_notifier(struct padata_instance *pinst,
570                       struct notifier_block *nblock)
571{
572    return blocking_notifier_chain_unregister(
573        &pinst->cpumask_change_notifier,
574        nblock);
575}
576EXPORT_SYMBOL(padata_unregister_cpumask_notifier);
577
578
579/* If cpumask contains no active cpu, we mark the instance as invalid. */
580static bool padata_validate_cpumask(struct padata_instance *pinst,
581                    const struct cpumask *cpumask)
582{
583    if (!cpumask_intersects(cpumask, cpu_active_mask)) {
584        pinst->flags |= PADATA_INVALID;
585        return false;
586    }
587
588    pinst->flags &= ~PADATA_INVALID;
589    return true;
590}
591
592static int __padata_set_cpumasks(struct padata_instance *pinst,
593                 cpumask_var_t pcpumask,
594                 cpumask_var_t cbcpumask)
595{
596    int valid;
597    struct parallel_data *pd;
598
599    valid = padata_validate_cpumask(pinst, pcpumask);
600    if (!valid) {
601        __padata_stop(pinst);
602        goto out_replace;
603    }
604
605    valid = padata_validate_cpumask(pinst, cbcpumask);
606    if (!valid)
607        __padata_stop(pinst);
608
609out_replace:
610    pd = padata_alloc_pd(pinst, pcpumask, cbcpumask);
611    if (!pd)
612        return -ENOMEM;
613
614    cpumask_copy(pinst->cpumask.pcpu, pcpumask);
615    cpumask_copy(pinst->cpumask.cbcpu, cbcpumask);
616
617    padata_replace(pinst, pd);
618
619    if (valid)
620        __padata_start(pinst);
621
622    return 0;
623}
624
625/**
626 * padata_set_cpumasks - Set both parallel and serial cpumasks. The first
627 * one is used by parallel workers and the second one
628 * by the wokers doing serialization.
629 *
630 * @pinst: padata instance
631 * @pcpumask: the cpumask to use for parallel workers
632 * @cbcpumask: the cpumsak to use for serial workers
633 */
634int padata_set_cpumasks(struct padata_instance *pinst, cpumask_var_t pcpumask,
635            cpumask_var_t cbcpumask)
636{
637    int err;
638
639    mutex_lock(&pinst->lock);
640    get_online_cpus();
641
642    err = __padata_set_cpumasks(pinst, pcpumask, cbcpumask);
643
644    put_online_cpus();
645    mutex_unlock(&pinst->lock);
646
647    return err;
648
649}
650EXPORT_SYMBOL(padata_set_cpumasks);
651
652/**
653 * padata_set_cpumask: Sets specified by @cpumask_type cpumask to the value
654 * equivalent to @cpumask.
655 *
656 * @pinst: padata instance
657 * @cpumask_type: PADATA_CPU_SERIAL or PADATA_CPU_PARALLEL corresponding
658 * to parallel and serial cpumasks respectively.
659 * @cpumask: the cpumask to use
660 */
661int padata_set_cpumask(struct padata_instance *pinst, int cpumask_type,
662               cpumask_var_t cpumask)
663{
664    struct cpumask *serial_mask, *parallel_mask;
665    int err = -EINVAL;
666
667    mutex_lock(&pinst->lock);
668    get_online_cpus();
669
670    switch (cpumask_type) {
671    case PADATA_CPU_PARALLEL:
672        serial_mask = pinst->cpumask.cbcpu;
673        parallel_mask = cpumask;
674        break;
675    case PADATA_CPU_SERIAL:
676        parallel_mask = pinst->cpumask.pcpu;
677        serial_mask = cpumask;
678        break;
679    default:
680         goto out;
681    }
682
683    err = __padata_set_cpumasks(pinst, parallel_mask, serial_mask);
684
685out:
686    put_online_cpus();
687    mutex_unlock(&pinst->lock);
688
689    return err;
690}
691EXPORT_SYMBOL(padata_set_cpumask);
692
693static int __padata_add_cpu(struct padata_instance *pinst, int cpu)
694{
695    struct parallel_data *pd;
696
697    if (cpumask_test_cpu(cpu, cpu_active_mask)) {
698        pd = padata_alloc_pd(pinst, pinst->cpumask.pcpu,
699                     pinst->cpumask.cbcpu);
700        if (!pd)
701            return -ENOMEM;
702
703        padata_replace(pinst, pd);
704
705        if (padata_validate_cpumask(pinst, pinst->cpumask.pcpu) &&
706            padata_validate_cpumask(pinst, pinst->cpumask.cbcpu))
707            __padata_start(pinst);
708    }
709
710    return 0;
711}
712
713 /**
714 * padata_add_cpu - add a cpu to one or both(parallel and serial)
715 * padata cpumasks.
716 *
717 * @pinst: padata instance
718 * @cpu: cpu to add
719 * @mask: bitmask of flags specifying to which cpumask @cpu shuld be added.
720 * The @mask may be any combination of the following flags:
721 * PADATA_CPU_SERIAL - serial cpumask
722 * PADATA_CPU_PARALLEL - parallel cpumask
723 */
724
725int padata_add_cpu(struct padata_instance *pinst, int cpu, int mask)
726{
727    int err;
728
729    if (!(mask & (PADATA_CPU_SERIAL | PADATA_CPU_PARALLEL)))
730        return -EINVAL;
731
732    mutex_lock(&pinst->lock);
733
734    get_online_cpus();
735    if (mask & PADATA_CPU_SERIAL)
736        cpumask_set_cpu(cpu, pinst->cpumask.cbcpu);
737    if (mask & PADATA_CPU_PARALLEL)
738        cpumask_set_cpu(cpu, pinst->cpumask.pcpu);
739
740    err = __padata_add_cpu(pinst, cpu);
741    put_online_cpus();
742
743    mutex_unlock(&pinst->lock);
744
745    return err;
746}
747EXPORT_SYMBOL(padata_add_cpu);
748
749static int __padata_remove_cpu(struct padata_instance *pinst, int cpu)
750{
751    struct parallel_data *pd = NULL;
752
753    if (cpumask_test_cpu(cpu, cpu_online_mask)) {
754
755        if (!padata_validate_cpumask(pinst, pinst->cpumask.pcpu) ||
756            !padata_validate_cpumask(pinst, pinst->cpumask.cbcpu))
757            __padata_stop(pinst);
758
759        pd = padata_alloc_pd(pinst, pinst->cpumask.pcpu,
760                     pinst->cpumask.cbcpu);
761        if (!pd)
762            return -ENOMEM;
763
764        padata_replace(pinst, pd);
765    }
766
767    return 0;
768}
769
770 /**
771 * padata_remove_cpu - remove a cpu from the one or both(serial and parallel)
772 * padata cpumasks.
773 *
774 * @pinst: padata instance
775 * @cpu: cpu to remove
776 * @mask: bitmask specifying from which cpumask @cpu should be removed
777 * The @mask may be any combination of the following flags:
778 * PADATA_CPU_SERIAL - serial cpumask
779 * PADATA_CPU_PARALLEL - parallel cpumask
780 */
781int padata_remove_cpu(struct padata_instance *pinst, int cpu, int mask)
782{
783    int err;
784
785    if (!(mask & (PADATA_CPU_SERIAL | PADATA_CPU_PARALLEL)))
786        return -EINVAL;
787
788    mutex_lock(&pinst->lock);
789
790    get_online_cpus();
791    if (mask & PADATA_CPU_SERIAL)
792        cpumask_clear_cpu(cpu, pinst->cpumask.cbcpu);
793    if (mask & PADATA_CPU_PARALLEL)
794        cpumask_clear_cpu(cpu, pinst->cpumask.pcpu);
795
796    err = __padata_remove_cpu(pinst, cpu);
797    put_online_cpus();
798
799    mutex_unlock(&pinst->lock);
800
801    return err;
802}
803EXPORT_SYMBOL(padata_remove_cpu);
804
805/**
806 * padata_start - start the parallel processing
807 *
808 * @pinst: padata instance to start
809 */
810int padata_start(struct padata_instance *pinst)
811{
812    int err = 0;
813
814    mutex_lock(&pinst->lock);
815
816    if (pinst->flags & PADATA_INVALID)
817        err =-EINVAL;
818
819     __padata_start(pinst);
820
821    mutex_unlock(&pinst->lock);
822
823    return err;
824}
825EXPORT_SYMBOL(padata_start);
826
827/**
828 * padata_stop - stop the parallel processing
829 *
830 * @pinst: padata instance to stop
831 */
832void padata_stop(struct padata_instance *pinst)
833{
834    mutex_lock(&pinst->lock);
835    __padata_stop(pinst);
836    mutex_unlock(&pinst->lock);
837}
838EXPORT_SYMBOL(padata_stop);
839
840#ifdef CONFIG_HOTPLUG_CPU
841
842static inline int pinst_has_cpu(struct padata_instance *pinst, int cpu)
843{
844    return cpumask_test_cpu(cpu, pinst->cpumask.pcpu) ||
845        cpumask_test_cpu(cpu, pinst->cpumask.cbcpu);
846}
847
848
849static int padata_cpu_callback(struct notifier_block *nfb,
850                   unsigned long action, void *hcpu)
851{
852    int err;
853    struct padata_instance *pinst;
854    int cpu = (unsigned long)hcpu;
855
856    pinst = container_of(nfb, struct padata_instance, cpu_notifier);
857
858    switch (action) {
859    case CPU_ONLINE:
860    case CPU_ONLINE_FROZEN:
861        if (!pinst_has_cpu(pinst, cpu))
862            break;
863        mutex_lock(&pinst->lock);
864        err = __padata_add_cpu(pinst, cpu);
865        mutex_unlock(&pinst->lock);
866        if (err)
867            return notifier_from_errno(err);
868        break;
869
870    case CPU_DOWN_PREPARE:
871    case CPU_DOWN_PREPARE_FROZEN:
872        if (!pinst_has_cpu(pinst, cpu))
873            break;
874        mutex_lock(&pinst->lock);
875        err = __padata_remove_cpu(pinst, cpu);
876        mutex_unlock(&pinst->lock);
877        if (err)
878            return notifier_from_errno(err);
879        break;
880
881    case CPU_UP_CANCELED:
882    case CPU_UP_CANCELED_FROZEN:
883        if (!pinst_has_cpu(pinst, cpu))
884            break;
885        mutex_lock(&pinst->lock);
886        __padata_remove_cpu(pinst, cpu);
887        mutex_unlock(&pinst->lock);
888
889    case CPU_DOWN_FAILED:
890    case CPU_DOWN_FAILED_FROZEN:
891        if (!pinst_has_cpu(pinst, cpu))
892            break;
893        mutex_lock(&pinst->lock);
894        __padata_add_cpu(pinst, cpu);
895        mutex_unlock(&pinst->lock);
896    }
897
898    return NOTIFY_OK;
899}
900#endif
901
902static void __padata_free(struct padata_instance *pinst)
903{
904#ifdef CONFIG_HOTPLUG_CPU
905    unregister_hotcpu_notifier(&pinst->cpu_notifier);
906#endif
907
908    padata_stop(pinst);
909    padata_free_pd(pinst->pd);
910    free_cpumask_var(pinst->cpumask.pcpu);
911    free_cpumask_var(pinst->cpumask.cbcpu);
912    kfree(pinst);
913}
914
915#define kobj2pinst(_kobj) \
916    container_of(_kobj, struct padata_instance, kobj)
917#define attr2pentry(_attr) \
918    container_of(_attr, struct padata_sysfs_entry, attr)
919
920static void padata_sysfs_release(struct kobject *kobj)
921{
922    struct padata_instance *pinst = kobj2pinst(kobj);
923    __padata_free(pinst);
924}
925
926struct padata_sysfs_entry {
927    struct attribute attr;
928    ssize_t (*show)(struct padata_instance *, struct attribute *, char *);
929    ssize_t (*store)(struct padata_instance *, struct attribute *,
930             const char *, size_t);
931};
932
933static ssize_t show_cpumask(struct padata_instance *pinst,
934                struct attribute *attr, char *buf)
935{
936    struct cpumask *cpumask;
937    ssize_t len;
938
939    mutex_lock(&pinst->lock);
940    if (!strcmp(attr->name, "serial_cpumask"))
941        cpumask = pinst->cpumask.cbcpu;
942    else
943        cpumask = pinst->cpumask.pcpu;
944
945    len = bitmap_scnprintf(buf, PAGE_SIZE, cpumask_bits(cpumask),
946                   nr_cpu_ids);
947    if (PAGE_SIZE - len < 2)
948        len = -EINVAL;
949    else
950        len += sprintf(buf + len, "\n");
951
952    mutex_unlock(&pinst->lock);
953    return len;
954}
955
956static ssize_t store_cpumask(struct padata_instance *pinst,
957                 struct attribute *attr,
958                 const char *buf, size_t count)
959{
960    cpumask_var_t new_cpumask;
961    ssize_t ret;
962    int mask_type;
963
964    if (!alloc_cpumask_var(&new_cpumask, GFP_KERNEL))
965        return -ENOMEM;
966
967    ret = bitmap_parse(buf, count, cpumask_bits(new_cpumask),
968               nr_cpumask_bits);
969    if (ret < 0)
970        goto out;
971
972    mask_type = !strcmp(attr->name, "serial_cpumask") ?
973        PADATA_CPU_SERIAL : PADATA_CPU_PARALLEL;
974    ret = padata_set_cpumask(pinst, mask_type, new_cpumask);
975    if (!ret)
976        ret = count;
977
978out:
979    free_cpumask_var(new_cpumask);
980    return ret;
981}
982
983#define PADATA_ATTR_RW(_name, _show_name, _store_name) \
984    static struct padata_sysfs_entry _name##_attr = \
985        __ATTR(_name, 0644, _show_name, _store_name)
986#define PADATA_ATTR_RO(_name, _show_name) \
987    static struct padata_sysfs_entry _name##_attr = \
988        __ATTR(_name, 0400, _show_name, NULL)
989
990PADATA_ATTR_RW(serial_cpumask, show_cpumask, store_cpumask);
991PADATA_ATTR_RW(parallel_cpumask, show_cpumask, store_cpumask);
992
993/*
994 * Padata sysfs provides the following objects:
995 * serial_cpumask [RW] - cpumask for serial workers
996 * parallel_cpumask [RW] - cpumask for parallel workers
997 */
998static struct attribute *padata_default_attrs[] = {
999    &serial_cpumask_attr.attr,
1000    &parallel_cpumask_attr.attr,
1001    NULL,
1002};
1003
1004static ssize_t padata_sysfs_show(struct kobject *kobj,
1005                 struct attribute *attr, char *buf)
1006{
1007    struct padata_instance *pinst;
1008    struct padata_sysfs_entry *pentry;
1009    ssize_t ret = -EIO;
1010
1011    pinst = kobj2pinst(kobj);
1012    pentry = attr2pentry(attr);
1013    if (pentry->show)
1014        ret = pentry->show(pinst, attr, buf);
1015
1016    return ret;
1017}
1018
1019static ssize_t padata_sysfs_store(struct kobject *kobj, struct attribute *attr,
1020                  const char *buf, size_t count)
1021{
1022    struct padata_instance *pinst;
1023    struct padata_sysfs_entry *pentry;
1024    ssize_t ret = -EIO;
1025
1026    pinst = kobj2pinst(kobj);
1027    pentry = attr2pentry(attr);
1028    if (pentry->show)
1029        ret = pentry->store(pinst, attr, buf, count);
1030
1031    return ret;
1032}
1033
1034static const struct sysfs_ops padata_sysfs_ops = {
1035    .show = padata_sysfs_show,
1036    .store = padata_sysfs_store,
1037};
1038
1039static struct kobj_type padata_attr_type = {
1040    .sysfs_ops = &padata_sysfs_ops,
1041    .default_attrs = padata_default_attrs,
1042    .release = padata_sysfs_release,
1043};
1044
1045/**
1046 * padata_alloc_possible - Allocate and initialize padata instance.
1047 * Use the cpu_possible_mask for serial and
1048 * parallel workers.
1049 *
1050 * @wq: workqueue to use for the allocated padata instance
1051 */
1052struct padata_instance *padata_alloc_possible(struct workqueue_struct *wq)
1053{
1054    return padata_alloc(wq, cpu_possible_mask, cpu_possible_mask);
1055}
1056EXPORT_SYMBOL(padata_alloc_possible);
1057
1058/**
1059 * padata_alloc - allocate and initialize a padata instance and specify
1060 * cpumasks for serial and parallel workers.
1061 *
1062 * @wq: workqueue to use for the allocated padata instance
1063 * @pcpumask: cpumask that will be used for padata parallelization
1064 * @cbcpumask: cpumask that will be used for padata serialization
1065 */
1066struct padata_instance *padata_alloc(struct workqueue_struct *wq,
1067                     const struct cpumask *pcpumask,
1068                     const struct cpumask *cbcpumask)
1069{
1070    struct padata_instance *pinst;
1071    struct parallel_data *pd = NULL;
1072
1073    pinst = kzalloc(sizeof(struct padata_instance), GFP_KERNEL);
1074    if (!pinst)
1075        goto err;
1076
1077    get_online_cpus();
1078    if (!alloc_cpumask_var(&pinst->cpumask.pcpu, GFP_KERNEL))
1079        goto err_free_inst;
1080    if (!alloc_cpumask_var(&pinst->cpumask.cbcpu, GFP_KERNEL)) {
1081        free_cpumask_var(pinst->cpumask.pcpu);
1082        goto err_free_inst;
1083    }
1084    if (!padata_validate_cpumask(pinst, pcpumask) ||
1085        !padata_validate_cpumask(pinst, cbcpumask))
1086        goto err_free_masks;
1087
1088    pd = padata_alloc_pd(pinst, pcpumask, cbcpumask);
1089    if (!pd)
1090        goto err_free_masks;
1091
1092    rcu_assign_pointer(pinst->pd, pd);
1093
1094    pinst->wq = wq;
1095
1096    cpumask_copy(pinst->cpumask.pcpu, pcpumask);
1097    cpumask_copy(pinst->cpumask.cbcpu, cbcpumask);
1098
1099    pinst->flags = 0;
1100
1101#ifdef CONFIG_HOTPLUG_CPU
1102    pinst->cpu_notifier.notifier_call = padata_cpu_callback;
1103    pinst->cpu_notifier.priority = 0;
1104    register_hotcpu_notifier(&pinst->cpu_notifier);
1105#endif
1106
1107    put_online_cpus();
1108
1109    BLOCKING_INIT_NOTIFIER_HEAD(&pinst->cpumask_change_notifier);
1110    kobject_init(&pinst->kobj, &padata_attr_type);
1111    mutex_init(&pinst->lock);
1112
1113    return pinst;
1114
1115err_free_masks:
1116    free_cpumask_var(pinst->cpumask.pcpu);
1117    free_cpumask_var(pinst->cpumask.cbcpu);
1118err_free_inst:
1119    kfree(pinst);
1120    put_online_cpus();
1121err:
1122    return NULL;
1123}
1124EXPORT_SYMBOL(padata_alloc);
1125
1126/**
1127 * padata_free - free a padata instance
1128 *
1129 * @padata_inst: padata instance to free
1130 */
1131void padata_free(struct padata_instance *pinst)
1132{
1133    kobject_put(&pinst->kobj);
1134}
1135EXPORT_SYMBOL(padata_free);
1136

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