kernel/padata.c

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This source file includes following definitions.
padata_index_to_cpu
padata_cpu_hash
padata_parallel_worker
padata_do_parallel
padata_find_next
padata_reorder
invoke_padata_reorder
padata_serial_worker
padata_do_serial
padata_setup_cpumasks
pd_setup_cpumasks
__padata_list_init
padata_init_squeues
padata_init_pqueues
padata_alloc_pd
padata_free_pd
__padata_start
__padata_stop
padata_replace_one
padata_replace
padata_register_cpumask_notifier
padata_unregister_cpumask_notifier
padata_validate_cpumask
__padata_set_cpumasks
padata_set_cpumask
padata_start
padata_stop
__padata_add_cpu
__padata_remove_cpu
padata_remove_cpu
pinst_has_cpu
padata_cpu_online
padata_cpu_dead
__padata_free
padata_sysfs_release
show_cpumask
store_cpumask
padata_sysfs_show
padata_sysfs_store
padata_alloc
padata_alloc_possible
padata_free
padata_alloc_shell
padata_free_shell
padata_driver_init
padata_driver_exit
   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * padata.c - generic interface to process data streams in parallel
   4  *
   5  * See Documentation/padata.txt for an api documentation.
   6  *
   7  * Copyright (C) 2008, 2009 secunet Security Networks AG
   8  * Copyright (C) 2008, 2009 Steffen Klassert <steffen.klassert@secunet.com>
   9  *
  10  * This program is free software; you can redistribute it and/or modify it
  11  * under the terms and conditions of the GNU General Public License,
  12  * version 2, as published by the Free Software Foundation.
  13  *
  14  * This program is distributed in the hope it will be useful, but WITHOUT
  15  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  16  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  17  * more details.
  18  *
  19  * You should have received a copy of the GNU General Public License along with
  20  * this program; if not, write to the Free Software Foundation, Inc.,
  21  * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
  22  */
  23 
  24 #include <linux/export.h>
  25 #include <linux/cpumask.h>
  26 #include <linux/err.h>
  27 #include <linux/cpu.h>
  28 #include <linux/padata.h>
  29 #include <linux/mutex.h>
  30 #include <linux/sched.h>
  31 #include <linux/slab.h>
  32 #include <linux/sysfs.h>
  33 #include <linux/rcupdate.h>
  34 #include <linux/module.h>
  35 
  36 #define MAX_OBJ_NUM 1000
  37 
  38 static void padata_free_pd(struct parallel_data *pd);
  39 
  40 static int padata_index_to_cpu(struct parallel_data *pd, int cpu_index)
  41 {
  42         int cpu, target_cpu;
  43 
  44         target_cpu = cpumask_first(pd->cpumask.pcpu);
  45         for (cpu = 0; cpu < cpu_index; cpu++)
  46                 target_cpu = cpumask_next(target_cpu, pd->cpumask.pcpu);
  47 
  48         return target_cpu;
  49 }
  50 
  51 static int padata_cpu_hash(struct parallel_data *pd, unsigned int seq_nr)
  52 {
  53         /*
  54          * Hash the sequence numbers to the cpus by taking
  55          * seq_nr mod. number of cpus in use.
  56          */
  57         int cpu_index = seq_nr % cpumask_weight(pd->cpumask.pcpu);
  58 
  59         return padata_index_to_cpu(pd, cpu_index);
  60 }
  61 
  62 static void padata_parallel_worker(struct work_struct *parallel_work)
  63 {
  64         struct padata_parallel_queue *pqueue;
  65         LIST_HEAD(local_list);
  66 
  67         local_bh_disable();
  68         pqueue = container_of(parallel_work,
  69                               struct padata_parallel_queue, work);
  70 
  71         spin_lock(&pqueue->parallel.lock);
  72         list_replace_init(&pqueue->parallel.list, &local_list);
  73         spin_unlock(&pqueue->parallel.lock);
  74 
  75         while (!list_empty(&local_list)) {
  76                 struct padata_priv *padata;
  77 
  78                 padata = list_entry(local_list.next,
  79                                     struct padata_priv, list);
  80 
  81                 list_del_init(&padata->list);
  82 
  83                 padata->parallel(padata);
  84         }
  85 
  86         local_bh_enable();
  87 }
  88 
  89 /**
  90  * padata_do_parallel - padata parallelization function
  91  *
  92  * @ps: padatashell
  93  * @padata: object to be parallelized
  94  * @cb_cpu: pointer to the CPU that the serialization callback function should
  95  *          run on.  If it's not in the serial cpumask of @pinst
  96  *          (i.e. cpumask.cbcpu), this function selects a fallback CPU and if
  97  *          none found, returns -EINVAL.
  98  *
  99  * The parallelization callback function will run with BHs off.
 100  * Note: Every object which is parallelized by padata_do_parallel
 101  * must be seen by padata_do_serial.
 102  */
 103 int padata_do_parallel(struct padata_shell *ps,
 104                        struct padata_priv *padata, int *cb_cpu)
 105 {
 106         struct padata_instance *pinst = ps->pinst;
 107         int i, cpu, cpu_index, target_cpu, err;
 108         struct padata_parallel_queue *queue;
 109         struct parallel_data *pd;
 110 
 111         rcu_read_lock_bh();
 112 
 113         pd = rcu_dereference_bh(ps->pd);
 114 
 115         err = -EINVAL;
 116         if (!(pinst->flags & PADATA_INIT) || pinst->flags & PADATA_INVALID)
 117                 goto out;
 118 
 119         if (!cpumask_test_cpu(*cb_cpu, pd->cpumask.cbcpu)) {
 120                 if (!cpumask_weight(pd->cpumask.cbcpu))
 121                         goto out;
 122 
 123                 /* Select an alternate fallback CPU and notify the caller. */
 124                 cpu_index = *cb_cpu % cpumask_weight(pd->cpumask.cbcpu);
 125 
 126                 cpu = cpumask_first(pd->cpumask.cbcpu);
 127                 for (i = 0; i < cpu_index; i++)
 128                         cpu = cpumask_next(cpu, pd->cpumask.cbcpu);
 129 
 130                 *cb_cpu = cpu;
 131         }
 132 
 133         err =  -EBUSY;
 134         if ((pinst->flags & PADATA_RESET))
 135                 goto out;
 136 
 137         if (atomic_read(&pd->refcnt) >= MAX_OBJ_NUM)
 138                 goto out;
 139 
 140         err = 0;
 141         atomic_inc(&pd->refcnt);
 142         padata->pd = pd;
 143         padata->cb_cpu = *cb_cpu;
 144 
 145         padata->seq_nr = atomic_inc_return(&pd->seq_nr);
 146         target_cpu = padata_cpu_hash(pd, padata->seq_nr);
 147         padata->cpu = target_cpu;
 148         queue = per_cpu_ptr(pd->pqueue, target_cpu);
 149 
 150         spin_lock(&queue->parallel.lock);
 151         list_add_tail(&padata->list, &queue->parallel.list);
 152         spin_unlock(&queue->parallel.lock);
 153 
 154         queue_work(pinst->parallel_wq, &queue->work);
 155 
 156 out:
 157         rcu_read_unlock_bh();
 158 
 159         return err;
 160 }
 161 EXPORT_SYMBOL(padata_do_parallel);
 162 
 163 /*
 164  * padata_find_next - Find the next object that needs serialization.
 165  *
 166  * Return values are:
 167  *
 168  * A pointer to the control struct of the next object that needs
 169  * serialization, if present in one of the percpu reorder queues.
 170  *
 171  * NULL, if the next object that needs serialization will
 172  *  be parallel processed by another cpu and is not yet present in
 173  *  the cpu's reorder queue.
 174  */
 175 static struct padata_priv *padata_find_next(struct parallel_data *pd,
 176                                             bool remove_object)
 177 {
 178         struct padata_parallel_queue *next_queue;
 179         struct padata_priv *padata;
 180         struct padata_list *reorder;
 181         int cpu = pd->cpu;
 182 
 183         next_queue = per_cpu_ptr(pd->pqueue, cpu);
 184         reorder = &next_queue->reorder;
 185 
 186         spin_lock(&reorder->lock);
 187         if (list_empty(&reorder->list)) {
 188                 spin_unlock(&reorder->lock);
 189                 return NULL;
 190         }
 191 
 192         padata = list_entry(reorder->list.next, struct padata_priv, list);
 193 
 194         /*
 195          * Checks the rare case where two or more parallel jobs have hashed to
 196          * the same CPU and one of the later ones finishes first.
 197          */
 198         if (padata->seq_nr != pd->processed) {
 199                 spin_unlock(&reorder->lock);
 200                 return NULL;
 201         }
 202 
 203         if (remove_object) {
 204                 list_del_init(&padata->list);
 205                 atomic_dec(&pd->reorder_objects);
 206                 ++pd->processed;
 207                 pd->cpu = cpumask_next_wrap(cpu, pd->cpumask.pcpu, -1, false);
 208         }
 209 
 210         spin_unlock(&reorder->lock);
 211         return padata;
 212 }
 213 
 214 static void padata_reorder(struct parallel_data *pd)
 215 {
 216         struct padata_instance *pinst = pd->ps->pinst;
 217         int cb_cpu;
 218         struct padata_priv *padata;
 219         struct padata_serial_queue *squeue;
 220         struct padata_parallel_queue *next_queue;
 221 
 222         /*
 223          * We need to ensure that only one cpu can work on dequeueing of
 224          * the reorder queue the time. Calculating in which percpu reorder
 225          * queue the next object will arrive takes some time. A spinlock
 226          * would be highly contended. Also it is not clear in which order
 227          * the objects arrive to the reorder queues. So a cpu could wait to
 228          * get the lock just to notice that there is nothing to do at the
 229          * moment. Therefore we use a trylock and let the holder of the lock
 230          * care for all the objects enqueued during the holdtime of the lock.
 231          */
 232         if (!spin_trylock_bh(&pd->lock))
 233                 return;
 234 
 235         while (1) {
 236                 padata = padata_find_next(pd, true);
 237 
 238                 /*
 239                  * If the next object that needs serialization is parallel
 240                  * processed by another cpu and is still on it's way to the
 241                  * cpu's reorder queue, nothing to do for now.
 242                  */
 243                 if (!padata)
 244                         break;
 245 
 246                 cb_cpu = padata->cb_cpu;
 247                 squeue = per_cpu_ptr(pd->squeue, cb_cpu);
 248 
 249                 spin_lock(&squeue->serial.lock);
 250                 list_add_tail(&padata->list, &squeue->serial.list);
 251                 spin_unlock(&squeue->serial.lock);
 252 
 253                 queue_work_on(cb_cpu, pinst->serial_wq, &squeue->work);
 254         }
 255 
 256         spin_unlock_bh(&pd->lock);
 257 
 258         /*
 259          * The next object that needs serialization might have arrived to
 260          * the reorder queues in the meantime.
 261          *
 262          * Ensure reorder queue is read after pd->lock is dropped so we see
 263          * new objects from another task in padata_do_serial.  Pairs with
 264          * smp_mb__after_atomic in padata_do_serial.
 265          */
 266         smp_mb();
 267 
 268         next_queue = per_cpu_ptr(pd->pqueue, pd->cpu);
 269         if (!list_empty(&next_queue->reorder.list) &&
 270             padata_find_next(pd, false))
 271                 queue_work(pinst->serial_wq, &pd->reorder_work);
 272 }
 273 
 274 static void invoke_padata_reorder(struct work_struct *work)
 275 {
 276         struct parallel_data *pd;
 277 
 278         local_bh_disable();
 279         pd = container_of(work, struct parallel_data, reorder_work);
 280         padata_reorder(pd);
 281         local_bh_enable();
 282 }
 283 
 284 static void padata_serial_worker(struct work_struct *serial_work)
 285 {
 286         struct padata_serial_queue *squeue;
 287         struct parallel_data *pd;
 288         LIST_HEAD(local_list);
 289         int cnt;
 290 
 291         local_bh_disable();
 292         squeue = container_of(serial_work, struct padata_serial_queue, work);
 293         pd = squeue->pd;
 294 
 295         spin_lock(&squeue->serial.lock);
 296         list_replace_init(&squeue->serial.list, &local_list);
 297         spin_unlock(&squeue->serial.lock);
 298 
 299         cnt = 0;
 300 
 301         while (!list_empty(&local_list)) {
 302                 struct padata_priv *padata;
 303 
 304                 padata = list_entry(local_list.next,
 305                                     struct padata_priv, list);
 306 
 307                 list_del_init(&padata->list);
 308 
 309                 padata->serial(padata);
 310                 cnt++;
 311         }
 312         local_bh_enable();
 313 
 314         if (atomic_sub_and_test(cnt, &pd->refcnt))
 315                 padata_free_pd(pd);
 316 }
 317 
 318 /**
 319  * padata_do_serial - padata serialization function
 320  *
 321  * @padata: object to be serialized.
 322  *
 323  * padata_do_serial must be called for every parallelized object.
 324  * The serialization callback function will run with BHs off.
 325  */
 326 void padata_do_serial(struct padata_priv *padata)
 327 {
 328         struct parallel_data *pd = padata->pd;
 329         struct padata_parallel_queue *pqueue = per_cpu_ptr(pd->pqueue,
 330                                                            padata->cpu);
 331         struct padata_priv *cur;
 332 
 333         spin_lock(&pqueue->reorder.lock);
 334         /* Sort in ascending order of sequence number. */
 335         list_for_each_entry_reverse(cur, &pqueue->reorder.list, list)
 336                 if (cur->seq_nr < padata->seq_nr)
 337                         break;
 338         list_add(&padata->list, &cur->list);
 339         atomic_inc(&pd->reorder_objects);
 340         spin_unlock(&pqueue->reorder.lock);
 341 
 342         /*
 343          * Ensure the addition to the reorder list is ordered correctly
 344          * with the trylock of pd->lock in padata_reorder.  Pairs with smp_mb
 345          * in padata_reorder.
 346          */
 347         smp_mb__after_atomic();
 348 
 349         padata_reorder(pd);
 350 }
 351 EXPORT_SYMBOL(padata_do_serial);
 352 
 353 static int padata_setup_cpumasks(struct padata_instance *pinst)
 354 {
 355         struct workqueue_attrs *attrs;
 356         int err;
 357 
 358         attrs = alloc_workqueue_attrs();
 359         if (!attrs)
 360                 return -ENOMEM;
 361 
 362         /* Restrict parallel_wq workers to pd->cpumask.pcpu. */
 363         cpumask_copy(attrs->cpumask, pinst->cpumask.pcpu);
 364         err = apply_workqueue_attrs(pinst->parallel_wq, attrs);
 365         free_workqueue_attrs(attrs);
 366 
 367         return err;
 368 }
 369 
 370 static int pd_setup_cpumasks(struct parallel_data *pd,
 371                              const struct cpumask *pcpumask,
 372                              const struct cpumask *cbcpumask)
 373 {
 374         int err = -ENOMEM;
 375 
 376         if (!alloc_cpumask_var(&pd->cpumask.pcpu, GFP_KERNEL))
 377                 goto out;
 378         if (!alloc_cpumask_var(&pd->cpumask.cbcpu, GFP_KERNEL))
 379                 goto free_pcpu_mask;
 380 
 381         cpumask_copy(pd->cpumask.pcpu, pcpumask);
 382         cpumask_copy(pd->cpumask.cbcpu, cbcpumask);
 383 
 384         return 0;
 385 
 386 free_pcpu_mask:
 387         free_cpumask_var(pd->cpumask.pcpu);
 388 out:
 389         return err;
 390 }
 391 
 392 static void __padata_list_init(struct padata_list *pd_list)
 393 {
 394         INIT_LIST_HEAD(&pd_list->list);
 395         spin_lock_init(&pd_list->lock);
 396 }
 397 
 398 /* Initialize all percpu queues used by serial workers */
 399 static void padata_init_squeues(struct parallel_data *pd)
 400 {
 401         int cpu;
 402         struct padata_serial_queue *squeue;
 403 
 404         for_each_cpu(cpu, pd->cpumask.cbcpu) {
 405                 squeue = per_cpu_ptr(pd->squeue, cpu);
 406                 squeue->pd = pd;
 407                 __padata_list_init(&squeue->serial);
 408                 INIT_WORK(&squeue->work, padata_serial_worker);
 409         }
 410 }
 411 
 412 /* Initialize all percpu queues used by parallel workers */
 413 static void padata_init_pqueues(struct parallel_data *pd)
 414 {
 415         int cpu;
 416         struct padata_parallel_queue *pqueue;
 417 
 418         for_each_cpu(cpu, pd->cpumask.pcpu) {
 419                 pqueue = per_cpu_ptr(pd->pqueue, cpu);
 420 
 421                 __padata_list_init(&pqueue->reorder);
 422                 __padata_list_init(&pqueue->parallel);
 423                 INIT_WORK(&pqueue->work, padata_parallel_worker);
 424                 atomic_set(&pqueue->num_obj, 0);
 425         }
 426 }
 427 
 428 /* Allocate and initialize the internal cpumask dependend resources. */
 429 static struct parallel_data *padata_alloc_pd(struct padata_shell *ps)
 430 {
 431         struct padata_instance *pinst = ps->pinst;
 432         const struct cpumask *cbcpumask;
 433         const struct cpumask *pcpumask;
 434         struct parallel_data *pd;
 435 
 436         cbcpumask = pinst->rcpumask.cbcpu;
 437         pcpumask = pinst->rcpumask.pcpu;
 438 
 439         pd = kzalloc(sizeof(struct parallel_data), GFP_KERNEL);
 440         if (!pd)
 441                 goto err;
 442 
 443         pd->pqueue = alloc_percpu(struct padata_parallel_queue);
 444         if (!pd->pqueue)
 445                 goto err_free_pd;
 446 
 447         pd->squeue = alloc_percpu(struct padata_serial_queue);
 448         if (!pd->squeue)
 449                 goto err_free_pqueue;
 450 
 451         pd->ps = ps;
 452         if (pd_setup_cpumasks(pd, pcpumask, cbcpumask))
 453                 goto err_free_squeue;
 454 
 455         padata_init_pqueues(pd);
 456         padata_init_squeues(pd);
 457         atomic_set(&pd->seq_nr, -1);
 458         atomic_set(&pd->reorder_objects, 0);
 459         atomic_set(&pd->refcnt, 1);
 460         spin_lock_init(&pd->lock);
 461         pd->cpu = cpumask_first(pd->cpumask.pcpu);
 462         INIT_WORK(&pd->reorder_work, invoke_padata_reorder);
 463 
 464         return pd;
 465 
 466 err_free_squeue:
 467         free_percpu(pd->squeue);
 468 err_free_pqueue:
 469         free_percpu(pd->pqueue);
 470 err_free_pd:
 471         kfree(pd);
 472 err:
 473         return NULL;
 474 }
 475 
 476 static void padata_free_pd(struct parallel_data *pd)
 477 {
 478         free_cpumask_var(pd->cpumask.pcpu);
 479         free_cpumask_var(pd->cpumask.cbcpu);
 480         free_percpu(pd->pqueue);
 481         free_percpu(pd->squeue);
 482         kfree(pd);
 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 
 500 /* Replace the internal control structure with a new one. */
 501 static int padata_replace_one(struct padata_shell *ps)
 502 {
 503         struct parallel_data *pd_new;
 504 
 505         pd_new = padata_alloc_pd(ps);
 506         if (!pd_new)
 507                 return -ENOMEM;
 508 
 509         ps->opd = rcu_dereference_protected(ps->pd, 1);
 510         rcu_assign_pointer(ps->pd, pd_new);
 511 
 512         return 0;
 513 }
 514 
 515 static int padata_replace(struct padata_instance *pinst)
 516 {
 517         int notification_mask = 0;
 518         struct padata_shell *ps;
 519         int err = 0;
 520 
 521         pinst->flags |= PADATA_RESET;
 522 
 523         cpumask_copy(pinst->omask, pinst->rcpumask.pcpu);
 524         cpumask_and(pinst->rcpumask.pcpu, pinst->cpumask.pcpu,
 525                     cpu_online_mask);
 526         if (!cpumask_equal(pinst->omask, pinst->rcpumask.pcpu))
 527                 notification_mask |= PADATA_CPU_PARALLEL;
 528 
 529         cpumask_copy(pinst->omask, pinst->rcpumask.cbcpu);
 530         cpumask_and(pinst->rcpumask.cbcpu, pinst->cpumask.cbcpu,
 531                     cpu_online_mask);
 532         if (!cpumask_equal(pinst->omask, pinst->rcpumask.cbcpu))
 533                 notification_mask |= PADATA_CPU_SERIAL;
 534 
 535         list_for_each_entry(ps, &pinst->pslist, list) {
 536                 err = padata_replace_one(ps);
 537                 if (err)
 538                         break;
 539         }
 540 
 541         synchronize_rcu();
 542 
 543         list_for_each_entry_continue_reverse(ps, &pinst->pslist, list)
 544                 if (atomic_dec_and_test(&ps->opd->refcnt))
 545                         padata_free_pd(ps->opd);
 546 
 547         if (notification_mask)
 548                 blocking_notifier_call_chain(&pinst->cpumask_change_notifier,
 549                                              notification_mask,
 550                                              &pinst->cpumask);
 551 
 552         pinst->flags &= ~PADATA_RESET;
 553 
 554         return err;
 555 }
 556 
 557 /**
 558  * padata_register_cpumask_notifier - Registers a notifier that will be called
 559  *                             if either pcpu or cbcpu or both cpumasks change.
 560  *
 561  * @pinst: A poineter to padata instance
 562  * @nblock: A pointer to notifier block.
 563  */
 564 int padata_register_cpumask_notifier(struct padata_instance *pinst,
 565                                      struct notifier_block *nblock)
 566 {
 567         return blocking_notifier_chain_register(&pinst->cpumask_change_notifier,
 568                                                 nblock);
 569 }
 570 EXPORT_SYMBOL(padata_register_cpumask_notifier);
 571 
 572 /**
 573  * padata_unregister_cpumask_notifier - Unregisters cpumask notifier
 574  *        registered earlier  using padata_register_cpumask_notifier
 575  *
 576  * @pinst: A pointer to data instance.
 577  * @nlock: A pointer to notifier block.
 578  */
 579 int padata_unregister_cpumask_notifier(struct padata_instance *pinst,
 580                                        struct notifier_block *nblock)
 581 {
 582         return blocking_notifier_chain_unregister(
 583                 &pinst->cpumask_change_notifier,
 584                 nblock);
 585 }
 586 EXPORT_SYMBOL(padata_unregister_cpumask_notifier);
 587 
 588 
 589 /* If cpumask contains no active cpu, we mark the instance as invalid. */
 590 static bool padata_validate_cpumask(struct padata_instance *pinst,
 591                                     const struct cpumask *cpumask)
 592 {
 593         if (!cpumask_intersects(cpumask, cpu_online_mask)) {
 594                 pinst->flags |= PADATA_INVALID;
 595                 return false;
 596         }
 597 
 598         pinst->flags &= ~PADATA_INVALID;
 599         return true;
 600 }
 601 
 602 static int __padata_set_cpumasks(struct padata_instance *pinst,
 603                                  cpumask_var_t pcpumask,
 604                                  cpumask_var_t cbcpumask)
 605 {
 606         int valid;
 607         int err;
 608 
 609         valid = padata_validate_cpumask(pinst, pcpumask);
 610         if (!valid) {
 611                 __padata_stop(pinst);
 612                 goto out_replace;
 613         }
 614 
 615         valid = padata_validate_cpumask(pinst, cbcpumask);
 616         if (!valid)
 617                 __padata_stop(pinst);
 618 
 619 out_replace:
 620         cpumask_copy(pinst->cpumask.pcpu, pcpumask);
 621         cpumask_copy(pinst->cpumask.cbcpu, cbcpumask);
 622 
 623         err = padata_setup_cpumasks(pinst) ?: padata_replace(pinst);
 624 
 625         if (valid)
 626                 __padata_start(pinst);
 627 
 628         return err;
 629 }
 630 
 631 /**
 632  * padata_set_cpumask: Sets specified by @cpumask_type cpumask to the value
 633  *                     equivalent to @cpumask.
 634  *
 635  * @pinst: padata instance
 636  * @cpumask_type: PADATA_CPU_SERIAL or PADATA_CPU_PARALLEL corresponding
 637  *                to parallel and serial cpumasks respectively.
 638  * @cpumask: the cpumask to use
 639  */
 640 int padata_set_cpumask(struct padata_instance *pinst, int cpumask_type,
 641                        cpumask_var_t cpumask)
 642 {
 643         struct cpumask *serial_mask, *parallel_mask;
 644         int err = -EINVAL;
 645 
 646         get_online_cpus();
 647         mutex_lock(&pinst->lock);
 648 
 649         switch (cpumask_type) {
 650         case PADATA_CPU_PARALLEL:
 651                 serial_mask = pinst->cpumask.cbcpu;
 652                 parallel_mask = cpumask;
 653                 break;
 654         case PADATA_CPU_SERIAL:
 655                 parallel_mask = pinst->cpumask.pcpu;
 656                 serial_mask = cpumask;
 657                 break;
 658         default:
 659                  goto out;
 660         }
 661 
 662         err =  __padata_set_cpumasks(pinst, parallel_mask, serial_mask);
 663 
 664 out:
 665         mutex_unlock(&pinst->lock);
 666         put_online_cpus();
 667 
 668         return err;
 669 }
 670 EXPORT_SYMBOL(padata_set_cpumask);
 671 
 672 /**
 673  * padata_start - start the parallel processing
 674  *
 675  * @pinst: padata instance to start
 676  */
 677 int padata_start(struct padata_instance *pinst)
 678 {
 679         int err = 0;
 680 
 681         mutex_lock(&pinst->lock);
 682 
 683         if (pinst->flags & PADATA_INVALID)
 684                 err = -EINVAL;
 685 
 686         __padata_start(pinst);
 687 
 688         mutex_unlock(&pinst->lock);
 689 
 690         return err;
 691 }
 692 EXPORT_SYMBOL(padata_start);
 693 
 694 /**
 695  * padata_stop - stop the parallel processing
 696  *
 697  * @pinst: padata instance to stop
 698  */
 699 void padata_stop(struct padata_instance *pinst)
 700 {
 701         mutex_lock(&pinst->lock);
 702         __padata_stop(pinst);
 703         mutex_unlock(&pinst->lock);
 704 }
 705 EXPORT_SYMBOL(padata_stop);
 706 
 707 #ifdef CONFIG_HOTPLUG_CPU
 708 
 709 static int __padata_add_cpu(struct padata_instance *pinst, int cpu)
 710 {
 711         int err = 0;
 712 
 713         if (cpumask_test_cpu(cpu, cpu_online_mask)) {
 714                 err = padata_replace(pinst);
 715 
 716                 if (padata_validate_cpumask(pinst, pinst->cpumask.pcpu) &&
 717                     padata_validate_cpumask(pinst, pinst->cpumask.cbcpu))
 718                         __padata_start(pinst);
 719         }
 720 
 721         return err;
 722 }
 723 
 724 static int __padata_remove_cpu(struct padata_instance *pinst, int cpu)
 725 {
 726         int err = 0;
 727 
 728         if (!cpumask_test_cpu(cpu, cpu_online_mask)) {
 729                 if (!padata_validate_cpumask(pinst, pinst->cpumask.pcpu) ||
 730                     !padata_validate_cpumask(pinst, pinst->cpumask.cbcpu))
 731                         __padata_stop(pinst);
 732 
 733                 err = padata_replace(pinst);
 734         }
 735 
 736         return err;
 737 }
 738 
 739  /**
 740  * padata_remove_cpu - remove a cpu from the one or both(serial and parallel)
 741  *                     padata cpumasks.
 742  *
 743  * @pinst: padata instance
 744  * @cpu: cpu to remove
 745  * @mask: bitmask specifying from which cpumask @cpu should be removed
 746  *        The @mask may be any combination of the following flags:
 747  *          PADATA_CPU_SERIAL   - serial cpumask
 748  *          PADATA_CPU_PARALLEL - parallel cpumask
 749  */
 750 int padata_remove_cpu(struct padata_instance *pinst, int cpu, int mask)
 751 {
 752         int err;
 753 
 754         if (!(mask & (PADATA_CPU_SERIAL | PADATA_CPU_PARALLEL)))
 755                 return -EINVAL;
 756 
 757         mutex_lock(&pinst->lock);
 758 
 759         get_online_cpus();
 760         if (mask & PADATA_CPU_SERIAL)
 761                 cpumask_clear_cpu(cpu, pinst->cpumask.cbcpu);
 762         if (mask & PADATA_CPU_PARALLEL)
 763                 cpumask_clear_cpu(cpu, pinst->cpumask.pcpu);
 764 
 765         err = __padata_remove_cpu(pinst, cpu);
 766         put_online_cpus();
 767 
 768         mutex_unlock(&pinst->lock);
 769 
 770         return err;
 771 }
 772 EXPORT_SYMBOL(padata_remove_cpu);
 773 
 774 static inline int pinst_has_cpu(struct padata_instance *pinst, int cpu)
 775 {
 776         return cpumask_test_cpu(cpu, pinst->cpumask.pcpu) ||
 777                 cpumask_test_cpu(cpu, pinst->cpumask.cbcpu);
 778 }
 779 
 780 static int padata_cpu_online(unsigned int cpu, struct hlist_node *node)
 781 {
 782         struct padata_instance *pinst;
 783         int ret;
 784 
 785         pinst = hlist_entry_safe(node, struct padata_instance, cpu_online_node);
 786         if (!pinst_has_cpu(pinst, cpu))
 787                 return 0;
 788 
 789         mutex_lock(&pinst->lock);
 790         ret = __padata_add_cpu(pinst, cpu);
 791         mutex_unlock(&pinst->lock);
 792         return ret;
 793 }
 794 
 795 static int padata_cpu_dead(unsigned int cpu, struct hlist_node *node)
 796 {
 797         struct padata_instance *pinst;
 798         int ret;
 799 
 800         pinst = hlist_entry_safe(node, struct padata_instance, cpu_dead_node);
 801         if (!pinst_has_cpu(pinst, cpu))
 802                 return 0;
 803 
 804         mutex_lock(&pinst->lock);
 805         ret = __padata_remove_cpu(pinst, cpu);
 806         mutex_unlock(&pinst->lock);
 807         return ret;
 808 }
 809 
 810 static enum cpuhp_state hp_online;
 811 #endif
 812 
 813 static void __padata_free(struct padata_instance *pinst)
 814 {
 815 #ifdef CONFIG_HOTPLUG_CPU
 816         cpuhp_state_remove_instance_nocalls(CPUHP_PADATA_DEAD,
 817                                             &pinst->cpu_dead_node);
 818         cpuhp_state_remove_instance_nocalls(hp_online, &pinst->cpu_online_node);
 819 #endif
 820 
 821         WARN_ON(!list_empty(&pinst->pslist));
 822 
 823         padata_stop(pinst);
 824         free_cpumask_var(pinst->omask);
 825         free_cpumask_var(pinst->rcpumask.cbcpu);
 826         free_cpumask_var(pinst->rcpumask.pcpu);
 827         free_cpumask_var(pinst->cpumask.pcpu);
 828         free_cpumask_var(pinst->cpumask.cbcpu);
 829         destroy_workqueue(pinst->serial_wq);
 830         destroy_workqueue(pinst->parallel_wq);
 831         kfree(pinst);
 832 }
 833 
 834 #define kobj2pinst(_kobj)                                       \
 835         container_of(_kobj, struct padata_instance, kobj)
 836 #define attr2pentry(_attr)                                      \
 837         container_of(_attr, struct padata_sysfs_entry, attr)
 838 
 839 static void padata_sysfs_release(struct kobject *kobj)
 840 {
 841         struct padata_instance *pinst = kobj2pinst(kobj);
 842         __padata_free(pinst);
 843 }
 844 
 845 struct padata_sysfs_entry {
 846         struct attribute attr;
 847         ssize_t (*show)(struct padata_instance *, struct attribute *, char *);
 848         ssize_t (*store)(struct padata_instance *, struct attribute *,
 849                          const char *, size_t);
 850 };
 851 
 852 static ssize_t show_cpumask(struct padata_instance *pinst,
 853                             struct attribute *attr,  char *buf)
 854 {
 855         struct cpumask *cpumask;
 856         ssize_t len;
 857 
 858         mutex_lock(&pinst->lock);
 859         if (!strcmp(attr->name, "serial_cpumask"))
 860                 cpumask = pinst->cpumask.cbcpu;
 861         else
 862                 cpumask = pinst->cpumask.pcpu;
 863 
 864         len = snprintf(buf, PAGE_SIZE, "%*pb\n",
 865                        nr_cpu_ids, cpumask_bits(cpumask));
 866         mutex_unlock(&pinst->lock);
 867         return len < PAGE_SIZE ? len : -EINVAL;
 868 }
 869 
 870 static ssize_t store_cpumask(struct padata_instance *pinst,
 871                              struct attribute *attr,
 872                              const char *buf, size_t count)
 873 {
 874         cpumask_var_t new_cpumask;
 875         ssize_t ret;
 876         int mask_type;
 877 
 878         if (!alloc_cpumask_var(&new_cpumask, GFP_KERNEL))
 879                 return -ENOMEM;
 880 
 881         ret = bitmap_parse(buf, count, cpumask_bits(new_cpumask),
 882                            nr_cpumask_bits);
 883         if (ret < 0)
 884                 goto out;
 885 
 886         mask_type = !strcmp(attr->name, "serial_cpumask") ?
 887                 PADATA_CPU_SERIAL : PADATA_CPU_PARALLEL;
 888         ret = padata_set_cpumask(pinst, mask_type, new_cpumask);
 889         if (!ret)
 890                 ret = count;
 891 
 892 out:
 893         free_cpumask_var(new_cpumask);
 894         return ret;
 895 }
 896 
 897 #define PADATA_ATTR_RW(_name, _show_name, _store_name)          \
 898         static struct padata_sysfs_entry _name##_attr =         \
 899                 __ATTR(_name, 0644, _show_name, _store_name)
 900 #define PADATA_ATTR_RO(_name, _show_name)               \
 901         static struct padata_sysfs_entry _name##_attr = \
 902                 __ATTR(_name, 0400, _show_name, NULL)
 903 
 904 PADATA_ATTR_RW(serial_cpumask, show_cpumask, store_cpumask);
 905 PADATA_ATTR_RW(parallel_cpumask, show_cpumask, store_cpumask);
 906 
 907 /*
 908  * Padata sysfs provides the following objects:
 909  * serial_cpumask   [RW] - cpumask for serial workers
 910  * parallel_cpumask [RW] - cpumask for parallel workers
 911  */
 912 static struct attribute *padata_default_attrs[] = {
 913         &serial_cpumask_attr.attr,
 914         &parallel_cpumask_attr.attr,
 915         NULL,
 916 };
 917 ATTRIBUTE_GROUPS(padata_default);
 918 
 919 static ssize_t padata_sysfs_show(struct kobject *kobj,
 920                                  struct attribute *attr, char *buf)
 921 {
 922         struct padata_instance *pinst;
 923         struct padata_sysfs_entry *pentry;
 924         ssize_t ret = -EIO;
 925 
 926         pinst = kobj2pinst(kobj);
 927         pentry = attr2pentry(attr);
 928         if (pentry->show)
 929                 ret = pentry->show(pinst, attr, buf);
 930 
 931         return ret;
 932 }
 933 
 934 static ssize_t padata_sysfs_store(struct kobject *kobj, struct attribute *attr,
 935                                   const char *buf, size_t count)
 936 {
 937         struct padata_instance *pinst;
 938         struct padata_sysfs_entry *pentry;
 939         ssize_t ret = -EIO;
 940 
 941         pinst = kobj2pinst(kobj);
 942         pentry = attr2pentry(attr);
 943         if (pentry->show)
 944                 ret = pentry->store(pinst, attr, buf, count);
 945 
 946         return ret;
 947 }
 948 
 949 static const struct sysfs_ops padata_sysfs_ops = {
 950         .show = padata_sysfs_show,
 951         .store = padata_sysfs_store,
 952 };
 953 
 954 static struct kobj_type padata_attr_type = {
 955         .sysfs_ops = &padata_sysfs_ops,
 956         .default_groups = padata_default_groups,
 957         .release = padata_sysfs_release,
 958 };
 959 
 960 /**
 961  * padata_alloc - allocate and initialize a padata instance and specify
 962  *                cpumasks for serial and parallel workers.
 963  *
 964  * @name: used to identify the instance
 965  * @pcpumask: cpumask that will be used for padata parallelization
 966  * @cbcpumask: cpumask that will be used for padata serialization
 967  */
 968 static struct padata_instance *padata_alloc(const char *name,
 969                                             const struct cpumask *pcpumask,
 970                                             const struct cpumask *cbcpumask)
 971 {
 972         struct padata_instance *pinst;
 973 
 974         pinst = kzalloc(sizeof(struct padata_instance), GFP_KERNEL);
 975         if (!pinst)
 976                 goto err;
 977 
 978         pinst->parallel_wq = alloc_workqueue("%s_parallel", WQ_UNBOUND, 0,
 979                                              name);
 980         if (!pinst->parallel_wq)
 981                 goto err_free_inst;
 982 
 983         get_online_cpus();
 984 
 985         pinst->serial_wq = alloc_workqueue("%s_serial", WQ_MEM_RECLAIM |
 986                                            WQ_CPU_INTENSIVE, 1, name);
 987         if (!pinst->serial_wq)
 988                 goto err_put_cpus;
 989 
 990         if (!alloc_cpumask_var(&pinst->cpumask.pcpu, GFP_KERNEL))
 991                 goto err_free_serial_wq;
 992         if (!alloc_cpumask_var(&pinst->cpumask.cbcpu, GFP_KERNEL)) {
 993                 free_cpumask_var(pinst->cpumask.pcpu);
 994                 goto err_free_serial_wq;
 995         }
 996         if (!padata_validate_cpumask(pinst, pcpumask) ||
 997             !padata_validate_cpumask(pinst, cbcpumask))
 998                 goto err_free_masks;
 999 
1000         if (!alloc_cpumask_var(&pinst->rcpumask.pcpu, GFP_KERNEL))
1001                 goto err_free_masks;
1002         if (!alloc_cpumask_var(&pinst->rcpumask.cbcpu, GFP_KERNEL))
1003                 goto err_free_rcpumask_pcpu;
1004         if (!alloc_cpumask_var(&pinst->omask, GFP_KERNEL))
1005                 goto err_free_rcpumask_cbcpu;
1006 
1007         INIT_LIST_HEAD(&pinst->pslist);
1008 
1009         cpumask_copy(pinst->cpumask.pcpu, pcpumask);
1010         cpumask_copy(pinst->cpumask.cbcpu, cbcpumask);
1011         cpumask_and(pinst->rcpumask.pcpu, pcpumask, cpu_online_mask);
1012         cpumask_and(pinst->rcpumask.cbcpu, cbcpumask, cpu_online_mask);
1013 
1014         if (padata_setup_cpumasks(pinst))
1015                 goto err_free_omask;
1016 
1017         pinst->flags = 0;
1018 
1019         BLOCKING_INIT_NOTIFIER_HEAD(&pinst->cpumask_change_notifier);
1020         kobject_init(&pinst->kobj, &padata_attr_type);
1021         mutex_init(&pinst->lock);
1022 
1023 #ifdef CONFIG_HOTPLUG_CPU
1024         cpuhp_state_add_instance_nocalls_cpuslocked(hp_online,
1025                                                     &pinst->cpu_online_node);
1026         cpuhp_state_add_instance_nocalls_cpuslocked(CPUHP_PADATA_DEAD,
1027                                                     &pinst->cpu_dead_node);
1028 #endif
1029 
1030         put_online_cpus();
1031 
1032         return pinst;
1033 
1034 err_free_omask:
1035         free_cpumask_var(pinst->omask);
1036 err_free_rcpumask_cbcpu:
1037         free_cpumask_var(pinst->rcpumask.cbcpu);
1038 err_free_rcpumask_pcpu:
1039         free_cpumask_var(pinst->rcpumask.pcpu);
1040 err_free_masks:
1041         free_cpumask_var(pinst->cpumask.pcpu);
1042         free_cpumask_var(pinst->cpumask.cbcpu);
1043 err_free_serial_wq:
1044         destroy_workqueue(pinst->serial_wq);
1045 err_put_cpus:
1046         put_online_cpus();
1047         destroy_workqueue(pinst->parallel_wq);
1048 err_free_inst:
1049         kfree(pinst);
1050 err:
1051         return NULL;
1052 }
1053 
1054 /**
1055  * padata_alloc_possible - Allocate and initialize padata instance.
1056  *                         Use the cpu_possible_mask for serial and
1057  *                         parallel workers.
1058  *
1059  * @name: used to identify the instance
1060  */
1061 struct padata_instance *padata_alloc_possible(const char *name)
1062 {
1063         return padata_alloc(name, cpu_possible_mask, cpu_possible_mask);
1064 }
1065 EXPORT_SYMBOL(padata_alloc_possible);
1066 
1067 /**
1068  * padata_free - free a padata instance
1069  *
1070  * @padata_inst: padata instance to free
1071  */
1072 void padata_free(struct padata_instance *pinst)
1073 {
1074         kobject_put(&pinst->kobj);
1075 }
1076 EXPORT_SYMBOL(padata_free);
1077 
1078 /**
1079  * padata_alloc_shell - Allocate and initialize padata shell.
1080  *
1081  * @pinst: Parent padata_instance object.
1082  */
1083 struct padata_shell *padata_alloc_shell(struct padata_instance *pinst)
1084 {
1085         struct parallel_data *pd;
1086         struct padata_shell *ps;
1087 
1088         ps = kzalloc(sizeof(*ps), GFP_KERNEL);
1089         if (!ps)
1090                 goto out;
1091 
1092         ps->pinst = pinst;
1093 
1094         get_online_cpus();
1095         pd = padata_alloc_pd(ps);
1096         put_online_cpus();
1097 
1098         if (!pd)
1099                 goto out_free_ps;
1100 
1101         mutex_lock(&pinst->lock);
1102         RCU_INIT_POINTER(ps->pd, pd);
1103         list_add(&ps->list, &pinst->pslist);
1104         mutex_unlock(&pinst->lock);
1105 
1106         return ps;
1107 
1108 out_free_ps:
1109         kfree(ps);
1110 out:
1111         return NULL;
1112 }
1113 EXPORT_SYMBOL(padata_alloc_shell);
1114 
1115 /**
1116  * padata_free_shell - free a padata shell
1117  *
1118  * @ps: padata shell to free
1119  */
1120 void padata_free_shell(struct padata_shell *ps)
1121 {
1122         struct padata_instance *pinst = ps->pinst;
1123 
1124         mutex_lock(&pinst->lock);
1125         list_del(&ps->list);
1126         padata_free_pd(rcu_dereference_protected(ps->pd, 1));
1127         mutex_unlock(&pinst->lock);
1128 
1129         kfree(ps);
1130 }
1131 EXPORT_SYMBOL(padata_free_shell);
1132 
1133 #ifdef CONFIG_HOTPLUG_CPU
1134 
1135 static __init int padata_driver_init(void)
1136 {
1137         int ret;
1138 
1139         ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN, "padata:online",
1140                                       padata_cpu_online, NULL);
1141         if (ret < 0)
1142                 return ret;
1143         hp_online = ret;
1144 
1145         ret = cpuhp_setup_state_multi(CPUHP_PADATA_DEAD, "padata:dead",
1146                                       NULL, padata_cpu_dead);
1147         if (ret < 0) {
1148                 cpuhp_remove_multi_state(hp_online);
1149                 return ret;
1150         }
1151         return 0;
1152 }
1153 module_init(padata_driver_init);
1154 
1155 static __exit void padata_driver_exit(void)
1156 {
1157         cpuhp_remove_multi_state(CPUHP_PADATA_DEAD);
1158         cpuhp_remove_multi_state(hp_online);
1159 }
1160 module_exit(padata_driver_exit);
1161 #endif
/* [<][>][^][v][top][bottom][index][help] */
root/kernel/padata.c

DEFINITIONS
