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