2 * padata.c - generic interface to process data streams in parallel
4 * Copyright (C) 2008, 2009 secunet Security Networks AG
5 * Copyright (C) 2008, 2009 Steffen Klassert <steffen.klassert@secunet.com>
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.
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
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.
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/rcupdate.h>
31 #define MAX_SEQ_NR INT_MAX - NR_CPUS
32 #define MAX_OBJ_NUM 1000
34 static int padata_index_to_cpu(struct parallel_data *pd, int cpu_index)
38 target_cpu = cpumask_first(pd->cpumask);
39 for (cpu = 0; cpu < cpu_index; cpu++)
40 target_cpu = cpumask_next(target_cpu, pd->cpumask);
45 static int padata_cpu_hash(struct padata_priv *padata)
48 struct parallel_data *pd;
53 * Hash the sequence numbers to the cpus by taking
54 * seq_nr mod. number of cpus in use.
56 cpu_index = padata->seq_nr % cpumask_weight(pd->cpumask);
58 return padata_index_to_cpu(pd, cpu_index);
61 static void padata_parallel_worker(struct work_struct *work)
63 struct padata_queue *queue;
64 struct parallel_data *pd;
65 struct padata_instance *pinst;
66 LIST_HEAD(local_list);
69 queue = container_of(work, struct padata_queue, pwork);
73 spin_lock(&queue->parallel.lock);
74 list_replace_init(&queue->parallel.list, &local_list);
75 spin_unlock(&queue->parallel.lock);
77 while (!list_empty(&local_list)) {
78 struct padata_priv *padata;
80 padata = list_entry(local_list.next,
81 struct padata_priv, list);
83 list_del_init(&padata->list);
85 padata->parallel(padata);
92 * padata_do_parallel - padata parallelization function
94 * @pinst: padata instance
95 * @padata: object to be parallelized
96 * @cb_cpu: cpu the serialization callback function will run on,
97 * must be in the cpumask of padata.
99 * The parallelization callback function will run with BHs off.
100 * Note: Every object which is parallelized by padata_do_parallel
101 * must be seen by padata_do_serial.
103 int padata_do_parallel(struct padata_instance *pinst,
104 struct padata_priv *padata, int cb_cpu)
107 struct padata_queue *queue;
108 struct parallel_data *pd;
112 pd = rcu_dereference(pinst->pd);
115 if (!(pinst->flags & PADATA_INIT))
119 if ((pinst->flags & PADATA_RESET))
122 if (atomic_read(&pd->refcnt) >= MAX_OBJ_NUM)
126 if (!cpumask_test_cpu(cb_cpu, pd->cpumask))
130 atomic_inc(&pd->refcnt);
132 padata->cb_cpu = cb_cpu;
134 if (unlikely(atomic_read(&pd->seq_nr) == pd->max_seq_nr))
135 atomic_set(&pd->seq_nr, -1);
137 padata->seq_nr = atomic_inc_return(&pd->seq_nr);
139 target_cpu = padata_cpu_hash(padata);
140 queue = per_cpu_ptr(pd->queue, target_cpu);
142 spin_lock(&queue->parallel.lock);
143 list_add_tail(&padata->list, &queue->parallel.list);
144 spin_unlock(&queue->parallel.lock);
146 queue_work_on(target_cpu, pinst->wq, &queue->pwork);
149 rcu_read_unlock_bh();
153 EXPORT_SYMBOL(padata_do_parallel);
155 static struct padata_priv *padata_get_next(struct parallel_data *pd)
157 int cpu, num_cpus, empty, calc_seq_nr;
158 int seq_nr, next_nr, overrun, next_overrun;
159 struct padata_queue *queue, *next_queue;
160 struct padata_priv *padata;
161 struct padata_list *reorder;
168 num_cpus = cpumask_weight(pd->cpumask);
170 for_each_cpu(cpu, pd->cpumask) {
171 queue = per_cpu_ptr(pd->queue, cpu);
172 reorder = &queue->reorder;
175 * Calculate the seq_nr of the object that should be
176 * next in this queue.
179 calc_seq_nr = (atomic_read(&queue->num_obj) * num_cpus)
182 if (unlikely(calc_seq_nr > pd->max_seq_nr)) {
183 calc_seq_nr = calc_seq_nr - pd->max_seq_nr - 1;
187 if (!list_empty(&reorder->list)) {
188 padata = list_entry(reorder->list.next,
189 struct padata_priv, list);
191 seq_nr = padata->seq_nr;
192 BUG_ON(calc_seq_nr != seq_nr);
194 seq_nr = calc_seq_nr;
198 if (next_nr < 0 || seq_nr < next_nr
199 || (next_overrun && !overrun)) {
201 next_overrun = overrun;
208 if (empty == num_cpus)
211 reorder = &next_queue->reorder;
213 if (!list_empty(&reorder->list)) {
214 padata = list_entry(reorder->list.next,
215 struct padata_priv, list);
217 if (unlikely(next_overrun)) {
218 for_each_cpu(cpu, pd->cpumask) {
219 queue = per_cpu_ptr(pd->queue, cpu);
220 atomic_set(&queue->num_obj, 0);
224 spin_lock(&reorder->lock);
225 list_del_init(&padata->list);
226 atomic_dec(&pd->reorder_objects);
227 spin_unlock(&reorder->lock);
229 atomic_inc(&next_queue->num_obj);
234 queue = per_cpu_ptr(pd->queue, smp_processor_id());
235 if (queue->cpu_index == next_queue->cpu_index) {
236 padata = ERR_PTR(-ENODATA);
240 padata = ERR_PTR(-EINPROGRESS);
245 static void padata_reorder(struct parallel_data *pd)
247 struct padata_priv *padata;
248 struct padata_queue *queue;
249 struct padata_instance *pinst = pd->pinst;
251 if (!spin_trylock_bh(&pd->lock))
255 padata = padata_get_next(pd);
257 if (!padata || PTR_ERR(padata) == -EINPROGRESS)
260 if (PTR_ERR(padata) == -ENODATA) {
261 del_timer(&pd->timer);
262 spin_unlock_bh(&pd->lock);
266 queue = per_cpu_ptr(pd->queue, padata->cb_cpu);
268 spin_lock(&queue->serial.lock);
269 list_add_tail(&padata->list, &queue->serial.list);
270 spin_unlock(&queue->serial.lock);
272 queue_work_on(padata->cb_cpu, pinst->wq, &queue->swork);
275 spin_unlock_bh(&pd->lock);
277 if (atomic_read(&pd->reorder_objects)
278 && !(pinst->flags & PADATA_RESET))
279 mod_timer(&pd->timer, jiffies + HZ);
281 del_timer(&pd->timer);
286 static void padata_reorder_timer(unsigned long arg)
288 struct parallel_data *pd = (struct parallel_data *)arg;
293 static void padata_serial_worker(struct work_struct *work)
295 struct padata_queue *queue;
296 struct parallel_data *pd;
297 LIST_HEAD(local_list);
300 queue = container_of(work, struct padata_queue, swork);
303 spin_lock(&queue->serial.lock);
304 list_replace_init(&queue->serial.list, &local_list);
305 spin_unlock(&queue->serial.lock);
307 while (!list_empty(&local_list)) {
308 struct padata_priv *padata;
310 padata = list_entry(local_list.next,
311 struct padata_priv, list);
313 list_del_init(&padata->list);
315 padata->serial(padata);
316 atomic_dec(&pd->refcnt);
322 * padata_do_serial - padata serialization function
324 * @padata: object to be serialized.
326 * padata_do_serial must be called for every parallelized object.
327 * The serialization callback function will run with BHs off.
329 void padata_do_serial(struct padata_priv *padata)
332 struct padata_queue *queue;
333 struct parallel_data *pd;
338 queue = per_cpu_ptr(pd->queue, cpu);
340 spin_lock(&queue->reorder.lock);
341 atomic_inc(&pd->reorder_objects);
342 list_add_tail(&padata->list, &queue->reorder.list);
343 spin_unlock(&queue->reorder.lock);
349 EXPORT_SYMBOL(padata_do_serial);
351 static struct parallel_data *padata_alloc_pd(struct padata_instance *pinst,
352 const struct cpumask *cpumask)
354 int cpu, cpu_index, num_cpus;
355 struct padata_queue *queue;
356 struct parallel_data *pd;
360 pd = kzalloc(sizeof(struct parallel_data), GFP_KERNEL);
364 pd->queue = alloc_percpu(struct padata_queue);
368 if (!alloc_cpumask_var(&pd->cpumask, GFP_KERNEL))
371 cpumask_and(pd->cpumask, cpumask, cpu_active_mask);
373 for_each_cpu(cpu, pd->cpumask) {
374 queue = per_cpu_ptr(pd->queue, cpu);
378 queue->cpu_index = cpu_index;
381 INIT_LIST_HEAD(&queue->reorder.list);
382 INIT_LIST_HEAD(&queue->parallel.list);
383 INIT_LIST_HEAD(&queue->serial.list);
384 spin_lock_init(&queue->reorder.lock);
385 spin_lock_init(&queue->parallel.lock);
386 spin_lock_init(&queue->serial.lock);
388 INIT_WORK(&queue->pwork, padata_parallel_worker);
389 INIT_WORK(&queue->swork, padata_serial_worker);
390 atomic_set(&queue->num_obj, 0);
393 num_cpus = cpumask_weight(pd->cpumask);
394 pd->max_seq_nr = (MAX_SEQ_NR / num_cpus) * num_cpus - 1;
396 setup_timer(&pd->timer, padata_reorder_timer, (unsigned long)pd);
397 atomic_set(&pd->seq_nr, -1);
398 atomic_set(&pd->reorder_objects, 0);
399 atomic_set(&pd->refcnt, 0);
401 spin_lock_init(&pd->lock);
406 free_percpu(pd->queue);
413 static void padata_free_pd(struct parallel_data *pd)
415 free_cpumask_var(pd->cpumask);
416 free_percpu(pd->queue);
420 static void padata_replace(struct padata_instance *pinst,
421 struct parallel_data *pd_new)
423 struct parallel_data *pd_old = pinst->pd;
425 pinst->flags |= PADATA_RESET;
427 rcu_assign_pointer(pinst->pd, pd_new);
431 while (atomic_read(&pd_old->refcnt) != 0)
434 flush_workqueue(pinst->wq);
436 padata_free_pd(pd_old);
438 pinst->flags &= ~PADATA_RESET;
442 * padata_set_cpumask - set the cpumask that padata should use
444 * @pinst: padata instance
445 * @cpumask: the cpumask to use
447 int padata_set_cpumask(struct padata_instance *pinst,
448 cpumask_var_t cpumask)
450 struct parallel_data *pd;
453 mutex_lock(&pinst->lock);
457 pd = padata_alloc_pd(pinst, cpumask);
463 cpumask_copy(pinst->cpumask, cpumask);
465 padata_replace(pinst, pd);
470 mutex_unlock(&pinst->lock);
474 EXPORT_SYMBOL(padata_set_cpumask);
476 static int __padata_add_cpu(struct padata_instance *pinst, int cpu)
478 struct parallel_data *pd;
480 if (cpumask_test_cpu(cpu, cpu_active_mask)) {
481 pd = padata_alloc_pd(pinst, pinst->cpumask);
485 padata_replace(pinst, pd);
492 * padata_add_cpu - add a cpu to the padata cpumask
494 * @pinst: padata instance
497 int padata_add_cpu(struct padata_instance *pinst, int cpu)
501 mutex_lock(&pinst->lock);
504 cpumask_set_cpu(cpu, pinst->cpumask);
505 err = __padata_add_cpu(pinst, cpu);
508 mutex_unlock(&pinst->lock);
512 EXPORT_SYMBOL(padata_add_cpu);
514 static int __padata_remove_cpu(struct padata_instance *pinst, int cpu)
516 struct parallel_data *pd;
518 if (cpumask_test_cpu(cpu, cpu_online_mask)) {
519 pd = padata_alloc_pd(pinst, pinst->cpumask);
523 padata_replace(pinst, pd);
530 * padata_remove_cpu - remove a cpu from the padata cpumask
532 * @pinst: padata instance
533 * @cpu: cpu to remove
535 int padata_remove_cpu(struct padata_instance *pinst, int cpu)
539 mutex_lock(&pinst->lock);
542 cpumask_clear_cpu(cpu, pinst->cpumask);
543 err = __padata_remove_cpu(pinst, cpu);
546 mutex_unlock(&pinst->lock);
550 EXPORT_SYMBOL(padata_remove_cpu);
553 * padata_start - start the parallel processing
555 * @pinst: padata instance to start
557 void padata_start(struct padata_instance *pinst)
559 mutex_lock(&pinst->lock);
560 pinst->flags |= PADATA_INIT;
561 mutex_unlock(&pinst->lock);
563 EXPORT_SYMBOL(padata_start);
566 * padata_stop - stop the parallel processing
568 * @pinst: padata instance to stop
570 void padata_stop(struct padata_instance *pinst)
572 mutex_lock(&pinst->lock);
573 pinst->flags &= ~PADATA_INIT;
574 mutex_unlock(&pinst->lock);
576 EXPORT_SYMBOL(padata_stop);
578 #ifdef CONFIG_HOTPLUG_CPU
579 static int padata_cpu_callback(struct notifier_block *nfb,
580 unsigned long action, void *hcpu)
583 struct padata_instance *pinst;
584 int cpu = (unsigned long)hcpu;
586 pinst = container_of(nfb, struct padata_instance, cpu_notifier);
590 case CPU_ONLINE_FROZEN:
591 if (!cpumask_test_cpu(cpu, pinst->cpumask))
593 mutex_lock(&pinst->lock);
594 err = __padata_add_cpu(pinst, cpu);
595 mutex_unlock(&pinst->lock);
600 case CPU_DOWN_PREPARE:
601 case CPU_DOWN_PREPARE_FROZEN:
602 if (!cpumask_test_cpu(cpu, pinst->cpumask))
604 mutex_lock(&pinst->lock);
605 err = __padata_remove_cpu(pinst, cpu);
606 mutex_unlock(&pinst->lock);
611 case CPU_UP_CANCELED:
612 case CPU_UP_CANCELED_FROZEN:
613 if (!cpumask_test_cpu(cpu, pinst->cpumask))
615 mutex_lock(&pinst->lock);
616 __padata_remove_cpu(pinst, cpu);
617 mutex_unlock(&pinst->lock);
619 case CPU_DOWN_FAILED:
620 case CPU_DOWN_FAILED_FROZEN:
621 if (!cpumask_test_cpu(cpu, pinst->cpumask))
623 mutex_lock(&pinst->lock);
624 __padata_add_cpu(pinst, cpu);
625 mutex_unlock(&pinst->lock);
633 * padata_alloc - allocate and initialize a padata instance
635 * @cpumask: cpumask that padata uses for parallelization
636 * @wq: workqueue to use for the allocated padata instance
638 struct padata_instance *padata_alloc(const struct cpumask *cpumask,
639 struct workqueue_struct *wq)
641 struct padata_instance *pinst;
642 struct parallel_data *pd;
644 pinst = kzalloc(sizeof(struct padata_instance), GFP_KERNEL);
650 pd = padata_alloc_pd(pinst, cpumask);
654 if (!alloc_cpumask_var(&pinst->cpumask, GFP_KERNEL))
657 rcu_assign_pointer(pinst->pd, pd);
661 cpumask_copy(pinst->cpumask, cpumask);
665 #ifdef CONFIG_HOTPLUG_CPU
666 pinst->cpu_notifier.notifier_call = padata_cpu_callback;
667 pinst->cpu_notifier.priority = 0;
668 register_hotcpu_notifier(&pinst->cpu_notifier);
673 mutex_init(&pinst->lock);
685 EXPORT_SYMBOL(padata_alloc);
688 * padata_free - free a padata instance
690 * @ padata_inst: padata instance to free
692 void padata_free(struct padata_instance *pinst)
698 while (atomic_read(&pinst->pd->refcnt) != 0)
701 #ifdef CONFIG_HOTPLUG_CPU
702 unregister_hotcpu_notifier(&pinst->cpu_notifier);
704 padata_free_pd(pinst->pd);
705 free_cpumask_var(pinst->cpumask);
708 EXPORT_SYMBOL(padata_free);