kernel/drivers/staging/lustre/lustre/libcfs/workitem.c

   1 /*
   2  * GPL HEADER START
   3  *
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 only,
   8  * as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License version 2 for more details (a copy is included
  14  * in the LICENSE file that accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * version 2 along with this program; If not, see
  18  * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
  19  *
  20  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  21  * CA 95054 USA or visit www.sun.com if you need additional information or
  22  * have any questions.
  23  *
  24  * GPL HEADER END
  25  */
  26 /*
  27  * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
  28  * Use is subject to license terms.
  29  *
  30  * Copyright (c) 2011, 2012, Intel Corporation.
  31  */
  32 /*
  33  * This file is part of Lustre, http://www.lustre.org/
  34  * Lustre is a trademark of Sun Microsystems, Inc.
  35  *
  36  * libcfs/libcfs/workitem.c
  37  *
  38  * Author: Isaac Huang <isaac@clusterfs.com>
  39  *       Liang Zhen  <zhen.liang@sun.com>
  40  */
  41
  42 #define DEBUG_SUBSYSTEM S_LNET
  43
  44 #include "../../include/linux/libcfs/libcfs.h"
  45
  46 #define CFS_WS_NAME_LEN  16
  47
  48 struct cfs_wi_sched {
  49         struct list_head                ws_list;        /* chain on global list */
  50         /** serialised workitems */
  51         spinlock_t              ws_lock;
  52         /** where schedulers sleep */
  53         wait_queue_head_t               ws_waitq;
  54         /** concurrent workitems */
  55         struct list_head                ws_runq;
  56         /** rescheduled running-workitems, a workitem can be rescheduled
  57          * while running in wi_action(), but we don't to execute it again
  58          * unless it returns from wi_action(), so we put it on ws_rerunq
  59          * while rescheduling, and move it to runq after it returns
  60          * from wi_action() */
  61         struct list_head                ws_rerunq;
  62         /** CPT-table for this scheduler */
  63         struct cfs_cpt_table    *ws_cptab;
  64         /** CPT id for affinity */
  65         int                     ws_cpt;
  66         /** number of scheduled workitems */
  67         int                     ws_nscheduled;
  68         /** started scheduler thread, protected by cfs_wi_data::wi_glock */
  69         unsigned int            ws_nthreads:30;
  70         /** shutting down, protected by cfs_wi_data::wi_glock */
  71         unsigned int            ws_stopping:1;
  72         /** serialize starting thread, protected by cfs_wi_data::wi_glock */
  73         unsigned int            ws_starting:1;
  74         /** scheduler name */
  75         char                    ws_name[CFS_WS_NAME_LEN];
  76 };
  77
  78 static struct cfs_workitem_data {
  79         /** serialize */
  80         spinlock_t              wi_glock;
  81         /** list of all schedulers */
  82         struct list_head                wi_scheds;
  83         /** WI module is initialized */
  84         int                     wi_init;
  85         /** shutting down the whole WI module */
  86         int                     wi_stopping;
  87 } cfs_wi_data;
  88
  89 static inline void
  90 cfs_wi_sched_lock(struct cfs_wi_sched *sched)
  91 {
  92         spin_lock(&sched->ws_lock);
  93 }
  94
  95 static inline void
  96 cfs_wi_sched_unlock(struct cfs_wi_sched *sched)
  97 {
  98         spin_unlock(&sched->ws_lock);
  99 }
 100
 101 static inline int
 102 cfs_wi_sched_cansleep(struct cfs_wi_sched *sched)
 103 {
 104         cfs_wi_sched_lock(sched);
 105         if (sched->ws_stopping) {
 106                 cfs_wi_sched_unlock(sched);
 107                 return 0;
 108         }
 109
 110         if (!list_empty(&sched->ws_runq)) {
 111                 cfs_wi_sched_unlock(sched);
 112                 return 0;
 113         }
 114         cfs_wi_sched_unlock(sched);
 115         return 1;
 116 }
 117
 118 /* XXX:
 119  * 0. it only works when called from wi->wi_action.
 120  * 1. when it returns no one shall try to schedule the workitem.
 121  */
 122 void
 123 cfs_wi_exit(struct cfs_wi_sched *sched, cfs_workitem_t *wi)
 124 {
 125         LASSERT(!in_interrupt()); /* because we use plain spinlock */
 126         LASSERT(!sched->ws_stopping);
 127
 128         cfs_wi_sched_lock(sched);
 129
 130         LASSERT(wi->wi_running);
 131         if (wi->wi_scheduled) { /* cancel pending schedules */
 132                 LASSERT(!list_empty(&wi->wi_list));
 133                 list_del_init(&wi->wi_list);
 134
 135                 LASSERT(sched->ws_nscheduled > 0);
 136                 sched->ws_nscheduled--;
 137         }
 138
 139         LASSERT(list_empty(&wi->wi_list));
 140
 141         wi->wi_scheduled = 1; /* LBUG future schedule attempts */
 142         cfs_wi_sched_unlock(sched);
 143
 144         return;
 145 }
 146 EXPORT_SYMBOL(cfs_wi_exit);
 147
 148 /**
 149  * cancel schedule request of workitem \a wi
 150  */
 151 int
 152 cfs_wi_deschedule(struct cfs_wi_sched *sched, cfs_workitem_t *wi)
 153 {
 154         int     rc;
 155
 156         LASSERT(!in_interrupt()); /* because we use plain spinlock */
 157         LASSERT(!sched->ws_stopping);
 158
 159         /*
 160          * return 0 if it's running already, otherwise return 1, which
 161          * means the workitem will not be scheduled and will not have
 162          * any race with wi_action.
 163          */
 164         cfs_wi_sched_lock(sched);
 165
 166         rc = !(wi->wi_running);
 167
 168         if (wi->wi_scheduled) { /* cancel pending schedules */
 169                 LASSERT(!list_empty(&wi->wi_list));
 170                 list_del_init(&wi->wi_list);
 171
 172                 LASSERT(sched->ws_nscheduled > 0);
 173                 sched->ws_nscheduled--;
 174
 175                 wi->wi_scheduled = 0;
 176         }
 177
 178         LASSERT (list_empty(&wi->wi_list));
 179
 180         cfs_wi_sched_unlock(sched);
 181         return rc;
 182 }
 183 EXPORT_SYMBOL(cfs_wi_deschedule);
 184
 185 /*
 186  * Workitem scheduled with (serial == 1) is strictly serialised not only with
 187  * itself, but also with others scheduled this way.
 188  *
 189  * Now there's only one static serialised queue, but in the future more might
 190  * be added, and even dynamic creation of serialised queues might be supported.
 191  */
 192 void
 193 cfs_wi_schedule(struct cfs_wi_sched *sched, cfs_workitem_t *wi)
 194 {
 195         LASSERT(!in_interrupt()); /* because we use plain spinlock */
 196         LASSERT(!sched->ws_stopping);
 197
 198         cfs_wi_sched_lock(sched);
 199
 200         if (!wi->wi_scheduled) {
 201                 LASSERT (list_empty(&wi->wi_list));
 202
 203                 wi->wi_scheduled = 1;
 204                 sched->ws_nscheduled++;
 205                 if (!wi->wi_running) {
 206                         list_add_tail(&wi->wi_list, &sched->ws_runq);
 207                         wake_up(&sched->ws_waitq);
 208                 } else {
 209                         list_add(&wi->wi_list, &sched->ws_rerunq);
 210                 }
 211         }
 212
 213         LASSERT (!list_empty(&wi->wi_list));
 214         cfs_wi_sched_unlock(sched);
 215         return;
 216 }
 217 EXPORT_SYMBOL(cfs_wi_schedule);
 218
 219 static int
 220 cfs_wi_scheduler (void *arg)
 221 {
 222         struct cfs_wi_sched     *sched = (struct cfs_wi_sched *)arg;
 223
 224         cfs_block_allsigs();
 225
 226         /* CPT affinity scheduler? */
 227         if (sched->ws_cptab != NULL)
 228                 cfs_cpt_bind(sched->ws_cptab, sched->ws_cpt);
 229
 230         spin_lock(&cfs_wi_data.wi_glock);
 231
 232         LASSERT(sched->ws_starting == 1);
 233         sched->ws_starting--;
 234         sched->ws_nthreads++;
 235
 236         spin_unlock(&cfs_wi_data.wi_glock);
 237
 238         cfs_wi_sched_lock(sched);
 239
 240         while (!sched->ws_stopping) {
 241                 int          nloops = 0;
 242                 int          rc;
 243                 cfs_workitem_t *wi;
 244
 245                 while (!list_empty(&sched->ws_runq) &&
 246                        nloops < CFS_WI_RESCHED) {
 247                         wi = list_entry(sched->ws_runq.next,
 248                                             cfs_workitem_t, wi_list);
 249                         LASSERT(wi->wi_scheduled && !wi->wi_running);
 250
 251                         list_del_init(&wi->wi_list);
 252
 253                         LASSERT(sched->ws_nscheduled > 0);
 254                         sched->ws_nscheduled--;
 255
 256                         wi->wi_running   = 1;
 257                         wi->wi_scheduled = 0;
 258
 259                         cfs_wi_sched_unlock(sched);
 260                         nloops++;
 261
 262                         rc = (*wi->wi_action) (wi);
 263
 264                         cfs_wi_sched_lock(sched);
 265                         if (rc != 0) /* WI should be dead, even be freed! */
 266                                 continue;
 267
 268                         wi->wi_running = 0;
 269                         if (list_empty(&wi->wi_list))
 270                                 continue;
 271
 272                         LASSERT(wi->wi_scheduled);
 273                         /* wi is rescheduled, should be on rerunq now, we
 274                          * move it to runq so it can run action now */
 275                         list_move_tail(&wi->wi_list, &sched->ws_runq);
 276                 }
 277
 278                 if (!list_empty(&sched->ws_runq)) {
 279                         cfs_wi_sched_unlock(sched);
 280                         /* don't sleep because some workitems still
 281                          * expect me to come back soon */
 282                         cond_resched();
 283                         cfs_wi_sched_lock(sched);
 284                         continue;
 285                 }
 286
 287                 cfs_wi_sched_unlock(sched);
 288                 rc = wait_event_interruptible_exclusive(sched->ws_waitq,
 289                                                 !cfs_wi_sched_cansleep(sched));
 290                 cfs_wi_sched_lock(sched);
 291         }
 292
 293         cfs_wi_sched_unlock(sched);
 294
 295         spin_lock(&cfs_wi_data.wi_glock);
 296         sched->ws_nthreads--;
 297         spin_unlock(&cfs_wi_data.wi_glock);
 298
 299         return 0;
 300 }
 301
 302 void
 303 cfs_wi_sched_destroy(struct cfs_wi_sched *sched)
 304 {
 305         int     i;
 306
 307         LASSERT(cfs_wi_data.wi_init);
 308         LASSERT(!cfs_wi_data.wi_stopping);
 309
 310         spin_lock(&cfs_wi_data.wi_glock);
 311         if (sched->ws_stopping) {
 312                 CDEBUG(D_INFO, "%s is in progress of stopping\n",
 313                        sched->ws_name);
 314                 spin_unlock(&cfs_wi_data.wi_glock);
 315                 return;
 316         }
 317
 318         LASSERT(!list_empty(&sched->ws_list));
 319         sched->ws_stopping = 1;
 320
 321         spin_unlock(&cfs_wi_data.wi_glock);
 322
 323         i = 2;
 324         wake_up_all(&sched->ws_waitq);
 325
 326         spin_lock(&cfs_wi_data.wi_glock);
 327         while (sched->ws_nthreads > 0) {
 328                 CDEBUG(IS_PO2(++i) ? D_WARNING : D_NET,
 329                        "waiting for %d threads of WI sched[%s] to terminate\n",
 330                        sched->ws_nthreads, sched->ws_name);
 331
 332                 spin_unlock(&cfs_wi_data.wi_glock);
 333                 set_current_state(TASK_UNINTERRUPTIBLE);
 334                 schedule_timeout(cfs_time_seconds(1) / 20);
 335                 spin_lock(&cfs_wi_data.wi_glock);
 336         }
 337
 338         list_del(&sched->ws_list);
 339
 340         spin_unlock(&cfs_wi_data.wi_glock);
 341         LASSERT(sched->ws_nscheduled == 0);
 342
 343         LIBCFS_FREE(sched, sizeof(*sched));
 344 }
 345 EXPORT_SYMBOL(cfs_wi_sched_destroy);
 346
 347 int
 348 cfs_wi_sched_create(char *name, struct cfs_cpt_table *cptab,
 349                     int cpt, int nthrs, struct cfs_wi_sched **sched_pp)
 350 {
 351         struct cfs_wi_sched     *sched;
 352         int                     rc;
 353
 354         LASSERT(cfs_wi_data.wi_init);
 355         LASSERT(!cfs_wi_data.wi_stopping);
 356         LASSERT(cptab == NULL || cpt == CFS_CPT_ANY ||
 357                 (cpt >= 0 && cpt < cfs_cpt_number(cptab)));
 358
 359         LIBCFS_ALLOC(sched, sizeof(*sched));
 360         if (sched == NULL)
 361                 return -ENOMEM;
 362
 363         strncpy(sched->ws_name, name, CFS_WS_NAME_LEN);
 364         sched->ws_name[CFS_WS_NAME_LEN - 1] = '\0';
 365         sched->ws_cptab = cptab;
 366         sched->ws_cpt = cpt;
 367
 368         spin_lock_init(&sched->ws_lock);
 369         init_waitqueue_head(&sched->ws_waitq);
 370         INIT_LIST_HEAD(&sched->ws_runq);
 371         INIT_LIST_HEAD(&sched->ws_rerunq);
 372         INIT_LIST_HEAD(&sched->ws_list);
 373
 374         rc = 0;
 375         while (nthrs > 0)  {
 376                 char    name[16];
 377                 struct task_struct *task;
 378
 379                 spin_lock(&cfs_wi_data.wi_glock);
 380                 while (sched->ws_starting > 0) {
 381                         spin_unlock(&cfs_wi_data.wi_glock);
 382                         schedule();
 383                         spin_lock(&cfs_wi_data.wi_glock);
 384                 }
 385
 386                 sched->ws_starting++;
 387                 spin_unlock(&cfs_wi_data.wi_glock);
 388
 389                 if (sched->ws_cptab != NULL && sched->ws_cpt >= 0) {
 390                         snprintf(name, sizeof(name), "%s_%02d_%02u",
 391                                  sched->ws_name, sched->ws_cpt,
 392                                  sched->ws_nthreads);
 393                 } else {
 394                         snprintf(name, sizeof(name), "%s_%02u",
 395                                  sched->ws_name, sched->ws_nthreads);
 396                 }
 397
 398                 task = kthread_run(cfs_wi_scheduler, sched, "%s", name);
 399                 if (!IS_ERR(task)) {
 400                         nthrs--;
 401                         continue;
 402                 }
 403                 rc = PTR_ERR(task);
 404
 405                 CERROR("Failed to create thread for WI scheduler %s: %d\n",
 406                        name, rc);
 407
 408                 spin_lock(&cfs_wi_data.wi_glock);
 409
 410                 /* make up for cfs_wi_sched_destroy */
 411                 list_add(&sched->ws_list, &cfs_wi_data.wi_scheds);
 412                 sched->ws_starting--;
 413
 414                 spin_unlock(&cfs_wi_data.wi_glock);
 415
 416                 cfs_wi_sched_destroy(sched);
 417                 return rc;
 418         }
 419         spin_lock(&cfs_wi_data.wi_glock);
 420         list_add(&sched->ws_list, &cfs_wi_data.wi_scheds);
 421         spin_unlock(&cfs_wi_data.wi_glock);
 422
 423         *sched_pp = sched;
 424         return 0;
 425 }
 426 EXPORT_SYMBOL(cfs_wi_sched_create);
 427
 428 int
 429 cfs_wi_startup(void)
 430 {
 431         memset(&cfs_wi_data, 0, sizeof(cfs_wi_data));
 432
 433         spin_lock_init(&cfs_wi_data.wi_glock);
 434         INIT_LIST_HEAD(&cfs_wi_data.wi_scheds);
 435         cfs_wi_data.wi_init = 1;
 436
 437         return 0;
 438 }
 439
 440 void
 441 cfs_wi_shutdown(void)
 442 {
 443         struct cfs_wi_sched     *sched;
 444
 445         spin_lock(&cfs_wi_data.wi_glock);
 446         cfs_wi_data.wi_stopping = 1;
 447         spin_unlock(&cfs_wi_data.wi_glock);
 448
 449         /* nobody should contend on this list */
 450         list_for_each_entry(sched, &cfs_wi_data.wi_scheds, ws_list) {
 451                 sched->ws_stopping = 1;
 452                 wake_up_all(&sched->ws_waitq);
 453         }
 454
 455         list_for_each_entry(sched, &cfs_wi_data.wi_scheds, ws_list) {
 456                 spin_lock(&cfs_wi_data.wi_glock);
 457
 458                 while (sched->ws_nthreads != 0) {
 459                         spin_unlock(&cfs_wi_data.wi_glock);
 460                         set_current_state(TASK_UNINTERRUPTIBLE);
 461                         schedule_timeout(cfs_time_seconds(1) / 20);
 462                         spin_lock(&cfs_wi_data.wi_glock);
 463                 }
 464                 spin_unlock(&cfs_wi_data.wi_glock);
 465         }
 466         while (!list_empty(&cfs_wi_data.wi_scheds)) {
 467                 sched = list_entry(cfs_wi_data.wi_scheds.next,
 468                                        struct cfs_wi_sched, ws_list);
 469                 list_del(&sched->ws_list);
 470                 LIBCFS_FREE(sched, sizeof(*sched));
 471         }
 472
 473         cfs_wi_data.wi_stopping = 0;
 474         cfs_wi_data.wi_init = 0;
 475 }