util/async.c

   1 /*
   2  * Data plane event loop
   3  *
   4  * Copyright (c) 2003-2008 Fabrice Bellard
   5  * Copyright (c) 2009-2017 QEMU contributors
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a copy
   8  * of this software and associated documentation files (the "Software"), to deal
   9  * in the Software without restriction, including without limitation the rights
  10  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  11  * copies of the Software, and to permit persons to whom the Software is
  12  * furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be included in
  15  * all copies or substantial portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  20  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  22  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  23  * THE SOFTWARE.
  24  */
  25
  26 #include "qemu/osdep.h"
  27 #include "qapi/error.h"
  28 #include "block/aio.h"
  29 #include "block/thread-pool.h"
  30 #include "qemu/main-loop.h"
  31 #include "qemu/atomic.h"
  32 #include "qemu/rcu_queue.h"
  33 #include "block/raw-aio.h"
  34 #include "qemu/coroutine_int.h"
  35 #include "qemu/coroutine-tls.h"
  36 #include "sysemu/cpu-timers.h"
  37 #include "trace.h"
  38
  39 /***********************************************************/
  40 /* bottom halves (can be seen as timers which expire ASAP) */
  41
  42 /* QEMUBH::flags values */
  43 enum {
  44     /* Already enqueued and waiting for aio_bh_poll() */
  45     BH_PENDING   = (1 << 0),
  46
  47     /* Invoke the callback */
  48     BH_SCHEDULED = (1 << 1),
  49
  50     /* Delete without invoking callback */
  51     BH_DELETED   = (1 << 2),
  52
  53     /* Delete after invoking callback */
  54     BH_ONESHOT   = (1 << 3),
  55
  56     /* Schedule periodically when the event loop is idle */
  57     BH_IDLE      = (1 << 4),
  58 };
  59
  60 struct QEMUBH {
  61     AioContext *ctx;
  62     const char *name;
  63     QEMUBHFunc *cb;
  64     void *opaque;
  65     QSLIST_ENTRY(QEMUBH) next;
  66     unsigned flags;
  67 };
  68
  69 /* Called concurrently from any thread */
  70 static void aio_bh_enqueue(QEMUBH *bh, unsigned new_flags)
  71 {
  72     AioContext *ctx = bh->ctx;
  73     unsigned old_flags;
  74
  75     /*
  76      * The memory barrier implicit in qatomic_fetch_or makes sure that:
  77      * 1. idle & any writes needed by the callback are done before the
  78      *    locations are read in the aio_bh_poll.
  79      * 2. ctx is loaded before the callback has a chance to execute and bh
  80      *    could be freed.
  81      */
  82     old_flags = qatomic_fetch_or(&bh->flags, BH_PENDING | new_flags);
  83     if (!(old_flags & BH_PENDING)) {
  84         QSLIST_INSERT_HEAD_ATOMIC(&ctx->bh_list, bh, next);
  85     }
  86
  87     aio_notify(ctx);
  88     /*
  89      * Workaround for record/replay.
  90      * vCPU execution should be suspended when new BH is set.
  91      * This is needed to avoid guest timeouts caused
  92      * by the long cycles of the execution.
  93      */
  94     icount_notify_exit();
  95 }
  96
  97 /* Only called from aio_bh_poll() and aio_ctx_finalize() */
  98 static QEMUBH *aio_bh_dequeue(BHList *head, unsigned *flags)
  99 {
 100     QEMUBH *bh = QSLIST_FIRST_RCU(head);
 101
 102     if (!bh) {
 103         return NULL;
 104     }
 105
 106     QSLIST_REMOVE_HEAD(head, next);
 107
 108     /*
 109      * The qatomic_and is paired with aio_bh_enqueue().  The implicit memory
 110      * barrier ensures that the callback sees all writes done by the scheduling
 111      * thread.  It also ensures that the scheduling thread sees the cleared
 112      * flag before bh->cb has run, and thus will call aio_notify again if
 113      * necessary.
 114      */
 115     *flags = qatomic_fetch_and(&bh->flags,
 116                               ~(BH_PENDING | BH_SCHEDULED | BH_IDLE));
 117     return bh;
 118 }
 119
 120 void aio_bh_schedule_oneshot_full(AioContext *ctx, QEMUBHFunc *cb,
 121                                   void *opaque, const char *name)
 122 {
 123     QEMUBH *bh;
 124     bh = g_new(QEMUBH, 1);
 125     *bh = (QEMUBH){
 126         .ctx = ctx,
 127         .cb = cb,
 128         .opaque = opaque,
 129         .name = name,
 130     };
 131     aio_bh_enqueue(bh, BH_SCHEDULED | BH_ONESHOT);
 132 }
 133
 134 QEMUBH *aio_bh_new_full(AioContext *ctx, QEMUBHFunc *cb, void *opaque,
 135                         const char *name)
 136 {
 137     QEMUBH *bh;
 138     bh = g_new(QEMUBH, 1);
 139     *bh = (QEMUBH){
 140         .ctx = ctx,
 141         .cb = cb,
 142         .opaque = opaque,
 143         .name = name,
 144     };
 145     return bh;
 146 }
 147
 148 void aio_bh_call(QEMUBH *bh)
 149 {
 150     bh->cb(bh->opaque);
 151 }
 152
 153 /* Multiple occurrences of aio_bh_poll cannot be called concurrently. */
 154 int aio_bh_poll(AioContext *ctx)
 155 {
 156     BHListSlice slice;
 157     BHListSlice *s;
 158     int ret = 0;
 159
 160     QSLIST_MOVE_ATOMIC(&slice.bh_list, &ctx->bh_list);
 161     QSIMPLEQ_INSERT_TAIL(&ctx->bh_slice_list, &slice, next);
 162
 163     while ((s = QSIMPLEQ_FIRST(&ctx->bh_slice_list))) {
 164         QEMUBH *bh;
 165         unsigned flags;
 166
 167         bh = aio_bh_dequeue(&s->bh_list, &flags);
 168         if (!bh) {
 169             QSIMPLEQ_REMOVE_HEAD(&ctx->bh_slice_list, next);
 170             continue;
 171         }
 172
 173         if ((flags & (BH_SCHEDULED | BH_DELETED)) == BH_SCHEDULED) {
 174             /* Idle BHs don't count as progress */
 175             if (!(flags & BH_IDLE)) {
 176                 ret = 1;
 177             }
 178             aio_bh_call(bh);
 179         }
 180         if (flags & (BH_DELETED | BH_ONESHOT)) {
 181             g_free(bh);
 182         }
 183     }
 184
 185     return ret;
 186 }
 187
 188 void qemu_bh_schedule_idle(QEMUBH *bh)
 189 {
 190     aio_bh_enqueue(bh, BH_SCHEDULED | BH_IDLE);
 191 }
 192
 193 void qemu_bh_schedule(QEMUBH *bh)
 194 {
 195     aio_bh_enqueue(bh, BH_SCHEDULED);
 196 }
 197
 198 /* This func is async.
 199  */
 200 void qemu_bh_cancel(QEMUBH *bh)
 201 {
 202     qatomic_and(&bh->flags, ~BH_SCHEDULED);
 203 }
 204
 205 /* This func is async.The bottom half will do the delete action at the finial
 206  * end.
 207  */
 208 void qemu_bh_delete(QEMUBH *bh)
 209 {
 210     aio_bh_enqueue(bh, BH_DELETED);
 211 }
 212
 213 static int64_t aio_compute_bh_timeout(BHList *head, int timeout)
 214 {
 215     QEMUBH *bh;
 216
 217     QSLIST_FOREACH_RCU(bh, head, next) {
 218         if ((bh->flags & (BH_SCHEDULED | BH_DELETED)) == BH_SCHEDULED) {
 219             if (bh->flags & BH_IDLE) {
 220                 /* idle bottom halves will be polled at least
 221                  * every 10ms */
 222                 timeout = 10000000;
 223             } else {
 224                 /* non-idle bottom halves will be executed
 225                  * immediately */
 226                 return 0;
 227             }
 228         }
 229     }
 230
 231     return timeout;
 232 }
 233
 234 int64_t
 235 aio_compute_timeout(AioContext *ctx)
 236 {
 237     BHListSlice *s;
 238     int64_t deadline;
 239     int timeout = -1;
 240
 241     timeout = aio_compute_bh_timeout(&ctx->bh_list, timeout);
 242     if (timeout == 0) {
 243         return 0;
 244     }
 245
 246     QSIMPLEQ_FOREACH(s, &ctx->bh_slice_list, next) {
 247         timeout = aio_compute_bh_timeout(&s->bh_list, timeout);
 248         if (timeout == 0) {
 249             return 0;
 250         }
 251     }
 252
 253     deadline = timerlistgroup_deadline_ns(&ctx->tlg);
 254     if (deadline == 0) {
 255         return 0;
 256     } else {
 257         return qemu_soonest_timeout(timeout, deadline);
 258     }
 259 }
 260
 261 static gboolean
 262 aio_ctx_prepare(GSource *source, gint    *timeout)
 263 {
 264     AioContext *ctx = (AioContext *) source;
 265
 266     qatomic_set(&ctx->notify_me, qatomic_read(&ctx->notify_me) | 1);
 267
 268     /*
 269      * Write ctx->notify_me before computing the timeout
 270      * (reading bottom half flags, etc.).  Pairs with
 271      * smp_mb in aio_notify().
 272      */
 273     smp_mb();
 274
 275     /* We assume there is no timeout already supplied */
 276     *timeout = qemu_timeout_ns_to_ms(aio_compute_timeout(ctx));
 277
 278     if (aio_prepare(ctx)) {
 279         *timeout = 0;
 280     }
 281
 282     return *timeout == 0;
 283 }
 284
 285 static gboolean
 286 aio_ctx_check(GSource *source)
 287 {
 288     AioContext *ctx = (AioContext *) source;
 289     QEMUBH *bh;
 290     BHListSlice *s;
 291
 292     /* Finish computing the timeout before clearing the flag.  */
 293     qatomic_store_release(&ctx->notify_me, qatomic_read(&ctx->notify_me) & ~1);
 294     aio_notify_accept(ctx);
 295
 296     QSLIST_FOREACH_RCU(bh, &ctx->bh_list, next) {
 297         if ((bh->flags & (BH_SCHEDULED | BH_DELETED)) == BH_SCHEDULED) {
 298             return true;
 299         }
 300     }
 301
 302     QSIMPLEQ_FOREACH(s, &ctx->bh_slice_list, next) {
 303         QSLIST_FOREACH_RCU(bh, &s->bh_list, next) {
 304             if ((bh->flags & (BH_SCHEDULED | BH_DELETED)) == BH_SCHEDULED) {
 305                 return true;
 306             }
 307         }
 308     }
 309     return aio_pending(ctx) || (timerlistgroup_deadline_ns(&ctx->tlg) == 0);
 310 }
 311
 312 static gboolean
 313 aio_ctx_dispatch(GSource     *source,
 314                  GSourceFunc  callback,
 315                  gpointer     user_data)
 316 {
 317     AioContext *ctx = (AioContext *) source;
 318
 319     assert(callback == NULL);
 320     aio_dispatch(ctx);
 321     return true;
 322 }
 323
 324 static void
 325 aio_ctx_finalize(GSource     *source)
 326 {
 327     AioContext *ctx = (AioContext *) source;
 328     QEMUBH *bh;
 329     unsigned flags;
 330
 331     thread_pool_free(ctx->thread_pool);
 332
 333 #ifdef CONFIG_LINUX_AIO
 334     if (ctx->linux_aio) {
 335         laio_detach_aio_context(ctx->linux_aio, ctx);
 336         laio_cleanup(ctx->linux_aio);
 337         ctx->linux_aio = NULL;
 338     }
 339 #endif
 340
 341 #ifdef CONFIG_LINUX_IO_URING
 342     if (ctx->linux_io_uring) {
 343         luring_detach_aio_context(ctx->linux_io_uring, ctx);
 344         luring_cleanup(ctx->linux_io_uring);
 345         ctx->linux_io_uring = NULL;
 346     }
 347 #endif
 348
 349     assert(QSLIST_EMPTY(&ctx->scheduled_coroutines));
 350     qemu_bh_delete(ctx->co_schedule_bh);
 351
 352     /* There must be no aio_bh_poll() calls going on */
 353     assert(QSIMPLEQ_EMPTY(&ctx->bh_slice_list));
 354
 355     while ((bh = aio_bh_dequeue(&ctx->bh_list, &flags))) {
 356         /*
 357          * qemu_bh_delete() must have been called on BHs in this AioContext. In
 358          * many cases memory leaks, hangs, or inconsistent state occur when a
 359          * BH is leaked because something still expects it to run.
 360          *
 361          * If you hit this, fix the lifecycle of the BH so that
 362          * qemu_bh_delete() and any associated cleanup is called before the
 363          * AioContext is finalized.
 364          */
 365         if (unlikely(!(flags & BH_DELETED))) {
 366             fprintf(stderr, "%s: BH '%s' leaked, aborting...\n",
 367                     __func__, bh->name);
 368             abort();
 369         }
 370
 371         g_free(bh);
 372     }
 373
 374     aio_set_event_notifier(ctx, &ctx->notifier, false, NULL, NULL, NULL);
 375     event_notifier_cleanup(&ctx->notifier);
 376     qemu_rec_mutex_destroy(&ctx->lock);
 377     qemu_lockcnt_destroy(&ctx->list_lock);
 378     timerlistgroup_deinit(&ctx->tlg);
 379     aio_context_destroy(ctx);
 380 }
 381
 382 static GSourceFuncs aio_source_funcs = {
 383     aio_ctx_prepare,
 384     aio_ctx_check,
 385     aio_ctx_dispatch,
 386     aio_ctx_finalize
 387 };
 388
 389 GSource *aio_get_g_source(AioContext *ctx)
 390 {
 391     aio_context_use_g_source(ctx);
 392     g_source_ref(&ctx->source);
 393     return &ctx->source;
 394 }
 395
 396 ThreadPool *aio_get_thread_pool(AioContext *ctx)
 397 {
 398     if (!ctx->thread_pool) {
 399         ctx->thread_pool = thread_pool_new(ctx);
 400     }
 401     return ctx->thread_pool;
 402 }
 403
 404 #ifdef CONFIG_LINUX_AIO
 405 LinuxAioState *aio_setup_linux_aio(AioContext *ctx, Error **errp)
 406 {
 407     if (!ctx->linux_aio) {
 408         ctx->linux_aio = laio_init(errp);
 409         if (ctx->linux_aio) {
 410             laio_attach_aio_context(ctx->linux_aio, ctx);
 411         }
 412     }
 413     return ctx->linux_aio;
 414 }
 415
 416 LinuxAioState *aio_get_linux_aio(AioContext *ctx)
 417 {
 418     assert(ctx->linux_aio);
 419     return ctx->linux_aio;
 420 }
 421 #endif
 422
 423 #ifdef CONFIG_LINUX_IO_URING
 424 LuringState *aio_setup_linux_io_uring(AioContext *ctx, Error **errp)
 425 {
 426     if (ctx->linux_io_uring) {
 427         return ctx->linux_io_uring;
 428     }
 429
 430     ctx->linux_io_uring = luring_init(errp);
 431     if (!ctx->linux_io_uring) {
 432         return NULL;
 433     }
 434
 435     luring_attach_aio_context(ctx->linux_io_uring, ctx);
 436     return ctx->linux_io_uring;
 437 }
 438
 439 LuringState *aio_get_linux_io_uring(AioContext *ctx)
 440 {
 441     assert(ctx->linux_io_uring);
 442     return ctx->linux_io_uring;
 443 }
 444 #endif
 445
 446 void aio_notify(AioContext *ctx)
 447 {
 448     /*
 449      * Write e.g. bh->flags before writing ctx->notified.  Pairs with smp_mb in
 450      * aio_notify_accept.
 451      */
 452     smp_wmb();
 453     qatomic_set(&ctx->notified, true);
 454
 455     /*
 456      * Write ctx->notified before reading ctx->notify_me.  Pairs
 457      * with smp_mb in aio_ctx_prepare or aio_poll.
 458      */
 459     smp_mb();
 460     if (qatomic_read(&ctx->notify_me)) {
 461         event_notifier_set(&ctx->notifier);
 462     }
 463 }
 464
 465 void aio_notify_accept(AioContext *ctx)
 466 {
 467     qatomic_set(&ctx->notified, false);
 468
 469     /*
 470      * Write ctx->notified before reading e.g. bh->flags.  Pairs with smp_wmb
 471      * in aio_notify.
 472      */
 473     smp_mb();
 474 }
 475
 476 static void aio_timerlist_notify(void *opaque, QEMUClockType type)
 477 {
 478     aio_notify(opaque);
 479 }
 480
 481 static void aio_context_notifier_cb(EventNotifier *e)
 482 {
 483     AioContext *ctx = container_of(e, AioContext, notifier);
 484
 485     event_notifier_test_and_clear(&ctx->notifier);
 486 }
 487
 488 /* Returns true if aio_notify() was called (e.g. a BH was scheduled) */
 489 static bool aio_context_notifier_poll(void *opaque)
 490 {
 491     EventNotifier *e = opaque;
 492     AioContext *ctx = container_of(e, AioContext, notifier);
 493
 494     return qatomic_read(&ctx->notified);
 495 }
 496
 497 static void aio_context_notifier_poll_ready(EventNotifier *e)
 498 {
 499     /* Do nothing, we just wanted to kick the event loop */
 500 }
 501
 502 static void co_schedule_bh_cb(void *opaque)
 503 {
 504     AioContext *ctx = opaque;
 505     QSLIST_HEAD(, Coroutine) straight, reversed;
 506
 507     QSLIST_MOVE_ATOMIC(&reversed, &ctx->scheduled_coroutines);
 508     QSLIST_INIT(&straight);
 509
 510     while (!QSLIST_EMPTY(&reversed)) {
 511         Coroutine *co = QSLIST_FIRST(&reversed);
 512         QSLIST_REMOVE_HEAD(&reversed, co_scheduled_next);
 513         QSLIST_INSERT_HEAD(&straight, co, co_scheduled_next);
 514     }
 515
 516     while (!QSLIST_EMPTY(&straight)) {
 517         Coroutine *co = QSLIST_FIRST(&straight);
 518         QSLIST_REMOVE_HEAD(&straight, co_scheduled_next);
 519         trace_aio_co_schedule_bh_cb(ctx, co);
 520         aio_context_acquire(ctx);
 521
 522         /* Protected by write barrier in qemu_aio_coroutine_enter */
 523         qatomic_set(&co->scheduled, NULL);
 524         qemu_aio_coroutine_enter(ctx, co);
 525         aio_context_release(ctx);
 526     }
 527 }
 528
 529 AioContext *aio_context_new(Error **errp)
 530 {
 531     int ret;
 532     AioContext *ctx;
 533
 534     ctx = (AioContext *) g_source_new(&aio_source_funcs, sizeof(AioContext));
 535     QSLIST_INIT(&ctx->bh_list);
 536     QSIMPLEQ_INIT(&ctx->bh_slice_list);
 537     aio_context_setup(ctx);
 538
 539     ret = event_notifier_init(&ctx->notifier, false);
 540     if (ret < 0) {
 541         error_setg_errno(errp, -ret, "Failed to initialize event notifier");
 542         goto fail;
 543     }
 544     g_source_set_can_recurse(&ctx->source, true);
 545     qemu_lockcnt_init(&ctx->list_lock);
 546
 547     ctx->co_schedule_bh = aio_bh_new(ctx, co_schedule_bh_cb, ctx);
 548     QSLIST_INIT(&ctx->scheduled_coroutines);
 549
 550     aio_set_event_notifier(ctx, &ctx->notifier,
 551                            false,
 552                            aio_context_notifier_cb,
 553                            aio_context_notifier_poll,
 554                            aio_context_notifier_poll_ready);
 555 #ifdef CONFIG_LINUX_AIO
 556     ctx->linux_aio = NULL;
 557 #endif
 558
 559 #ifdef CONFIG_LINUX_IO_URING
 560     ctx->linux_io_uring = NULL;
 561 #endif
 562
 563     ctx->thread_pool = NULL;
 564     qemu_rec_mutex_init(&ctx->lock);
 565     timerlistgroup_init(&ctx->tlg, aio_timerlist_notify, ctx);
 566
 567     ctx->poll_ns = 0;
 568     ctx->poll_max_ns = 0;
 569     ctx->poll_grow = 0;
 570     ctx->poll_shrink = 0;
 571
 572     ctx->aio_max_batch = 0;
 573
 574     ctx->thread_pool_min = 0;
 575     ctx->thread_pool_max = THREAD_POOL_MAX_THREADS_DEFAULT;
 576
 577     return ctx;
 578 fail:
 579     g_source_destroy(&ctx->source);
 580     return NULL;
 581 }
 582
 583 void aio_co_schedule(AioContext *ctx, Coroutine *co)
 584 {
 585     trace_aio_co_schedule(ctx, co);
 586     const char *scheduled = qatomic_cmpxchg(&co->scheduled, NULL,
 587                                            __func__);
 588
 589     if (scheduled) {
 590         fprintf(stderr,
 591                 "%s: Co-routine was already scheduled in '%s'\n",
 592                 __func__, scheduled);
 593         abort();
 594     }
 595
 596     /* The coroutine might run and release the last ctx reference before we
 597      * invoke qemu_bh_schedule().  Take a reference to keep ctx alive until
 598      * we're done.
 599      */
 600     aio_context_ref(ctx);
 601
 602     QSLIST_INSERT_HEAD_ATOMIC(&ctx->scheduled_coroutines,
 603                               co, co_scheduled_next);
 604     qemu_bh_schedule(ctx->co_schedule_bh);
 605
 606     aio_context_unref(ctx);
 607 }
 608
 609 typedef struct AioCoRescheduleSelf {
 610     Coroutine *co;
 611     AioContext *new_ctx;
 612 } AioCoRescheduleSelf;
 613
 614 static void aio_co_reschedule_self_bh(void *opaque)
 615 {
 616     AioCoRescheduleSelf *data = opaque;
 617     aio_co_schedule(data->new_ctx, data->co);
 618 }
 619
 620 void coroutine_fn aio_co_reschedule_self(AioContext *new_ctx)
 621 {
 622     AioContext *old_ctx = qemu_get_current_aio_context();
 623
 624     if (old_ctx != new_ctx) {
 625         AioCoRescheduleSelf data = {
 626             .co = qemu_coroutine_self(),
 627             .new_ctx = new_ctx,
 628         };
 629         /*
 630          * We can't directly schedule the coroutine in the target context
 631          * because this would be racy: The other thread could try to enter the
 632          * coroutine before it has yielded in this one.
 633          */
 634         aio_bh_schedule_oneshot(old_ctx, aio_co_reschedule_self_bh, &data);
 635         qemu_coroutine_yield();
 636     }
 637 }
 638
 639 void aio_co_wake(struct Coroutine *co)
 640 {
 641     AioContext *ctx;
 642
 643     /* Read coroutine before co->ctx.  Matches smp_wmb in
 644      * qemu_coroutine_enter.
 645      */
 646     smp_read_barrier_depends();
 647     ctx = qatomic_read(&co->ctx);
 648
 649     aio_co_enter(ctx, co);
 650 }
 651
 652 void aio_co_enter(AioContext *ctx, struct Coroutine *co)
 653 {
 654     if (ctx != qemu_get_current_aio_context()) {
 655         aio_co_schedule(ctx, co);
 656         return;
 657     }
 658
 659     if (qemu_in_coroutine()) {
 660         Coroutine *self = qemu_coroutine_self();
 661         assert(self != co);
 662         QSIMPLEQ_INSERT_TAIL(&self->co_queue_wakeup, co, co_queue_next);
 663     } else {
 664         aio_context_acquire(ctx);
 665         qemu_aio_coroutine_enter(ctx, co);
 666         aio_context_release(ctx);
 667     }
 668 }
 669
 670 void aio_context_ref(AioContext *ctx)
 671 {
 672     g_source_ref(&ctx->source);
 673 }
 674
 675 void aio_context_unref(AioContext *ctx)
 676 {
 677     g_source_unref(&ctx->source);
 678 }
 679
 680 void aio_context_acquire(AioContext *ctx)
 681 {
 682     qemu_rec_mutex_lock(&ctx->lock);
 683 }
 684
 685 void aio_context_release(AioContext *ctx)
 686 {
 687     qemu_rec_mutex_unlock(&ctx->lock);
 688 }
 689
 690 QEMU_DEFINE_STATIC_CO_TLS(AioContext *, my_aiocontext)
 691
 692 AioContext *qemu_get_current_aio_context(void)
 693 {
 694     AioContext *ctx = get_my_aiocontext();
 695     if (ctx) {
 696         return ctx;
 697     }
 698     if (qemu_mutex_iothread_locked()) {
 699         /* Possibly in a vCPU thread.  */
 700         return qemu_get_aio_context();
 701     }
 702     return NULL;
 703 }
 704
 705 void qemu_set_current_aio_context(AioContext *ctx)
 706 {
 707     assert(!get_my_aiocontext());
 708     set_my_aiocontext(ctx);
 709 }
 710
 711 void aio_context_set_thread_pool_params(AioContext *ctx, int64_t min,
 712                                         int64_t max, Error **errp)
 713 {
 714
 715     if (min > max || !max || min > INT_MAX || max > INT_MAX) {
 716         error_setg(errp, "bad thread-pool-min/thread-pool-max values");
 717         return;
 718     }
 719
 720     ctx->thread_pool_min = min;
 721     ctx->thread_pool_max = max;
 722
 723     if (ctx->thread_pool) {
 724         thread_pool_update_params(ctx->thread_pool, ctx);
 725     }
 726 }