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