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