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 "block/graph-lock.h"
  31 #include "qemu/main-loop.h"
  32 #include "qemu/atomic.h"
  33 #include "qemu/rcu_queue.h"
  34 #include "block/raw-aio.h"
  35 #include "qemu/coroutine_int.h"
  36 #include "qemu/coroutine-tls.h"
  37 #include "sysemu/cpu-timers.h"
  38 #include "trace.h"
  39
  40 /***********************************************************/
  41 /* bottom halves (can be seen as timers which expire ASAP) */
  42
  43 /* QEMUBH::flags values */
  44 enum {
  45     /* Already enqueued and waiting for aio_bh_poll() */
  46     BH_PENDING   = (1 << 0),
  47
  48     /* Invoke the callback */
  49     BH_SCHEDULED = (1 << 1),
  50
  51     /* Delete without invoking callback */
  52     BH_DELETED   = (1 << 2),
  53
  54     /* Delete after invoking callback */
  55     BH_ONESHOT   = (1 << 3),
  56
  57     /* Schedule periodically when the event loop is idle */
  58     BH_IDLE      = (1 << 4),
  59 };
  60
  61 struct QEMUBH {
  62     AioContext *ctx;
  63     const char *name;
  64     QEMUBHFunc *cb;
  65     void *opaque;
  66     QSLIST_ENTRY(QEMUBH) next;
  67     unsigned flags;
  68 };
  69
  70 /* Called concurrently from any thread */
  71 static void aio_bh_enqueue(QEMUBH *bh, unsigned new_flags)
  72 {
  73     AioContext *ctx = bh->ctx;
  74     unsigned old_flags;
  75
  76     /*
  77      * Synchronizes with atomic_fetch_and() in aio_bh_dequeue(), ensuring that
  78      * insertion starts after BH_PENDING is set.
  79      */
  80     old_flags = qatomic_fetch_or(&bh->flags, BH_PENDING | new_flags);
  81
  82     if (!(old_flags & BH_PENDING)) {
  83         /*
  84          * At this point the bottom half becomes visible to aio_bh_poll().
  85          * This insertion thus synchronizes with QSLIST_MOVE_ATOMIC in
  86          * aio_bh_poll(), ensuring that:
  87          * 1. any writes needed by the callback are visible from the callback
  88          *    after aio_bh_dequeue() returns bh.
  89          * 2. ctx is loaded before the callback has a chance to execute and bh
  90          *    could be freed.
  91          */
  92         QSLIST_INSERT_HEAD_ATOMIC(&ctx->bh_list, bh, next);
  93     }
  94
  95     aio_notify(ctx);
  96     /*
  97      * Workaround for record/replay.
  98      * vCPU execution should be suspended when new BH is set.
  99      * This is needed to avoid guest timeouts caused
 100      * by the long cycles of the execution.
 101      */
 102     icount_notify_exit();
 103 }
 104
 105 /* Only called from aio_bh_poll() and aio_ctx_finalize() */
 106 static QEMUBH *aio_bh_dequeue(BHList *head, unsigned *flags)
 107 {
 108     QEMUBH *bh = QSLIST_FIRST_RCU(head);
 109
 110     if (!bh) {
 111         return NULL;
 112     }
 113
 114     QSLIST_REMOVE_HEAD(head, next);
 115
 116     /*
 117      * Synchronizes with qatomic_fetch_or() in aio_bh_enqueue(), ensuring that
 118      * the removal finishes before BH_PENDING is reset.
 119      */
 120     *flags = qatomic_fetch_and(&bh->flags,
 121                               ~(BH_PENDING | BH_SCHEDULED | BH_IDLE));
 122     return bh;
 123 }
 124
 125 void aio_bh_schedule_oneshot_full(AioContext *ctx, QEMUBHFunc *cb,
 126                                   void *opaque, const char *name)
 127 {
 128     QEMUBH *bh;
 129     bh = g_new(QEMUBH, 1);
 130     *bh = (QEMUBH){
 131         .ctx = ctx,
 132         .cb = cb,
 133         .opaque = opaque,
 134         .name = name,
 135     };
 136     aio_bh_enqueue(bh, BH_SCHEDULED | BH_ONESHOT);
 137 }
 138
 139 QEMUBH *aio_bh_new_full(AioContext *ctx, QEMUBHFunc *cb, void *opaque,
 140                         const char *name)
 141 {
 142     QEMUBH *bh;
 143     bh = g_new(QEMUBH, 1);
 144     *bh = (QEMUBH){
 145         .ctx = ctx,
 146         .cb = cb,
 147         .opaque = opaque,
 148         .name = name,
 149     };
 150     return bh;
 151 }
 152
 153 void aio_bh_call(QEMUBH *bh)
 154 {
 155     bh->cb(bh->opaque);
 156 }
 157
 158 /* Multiple occurrences of aio_bh_poll cannot be called concurrently. */
 159 int aio_bh_poll(AioContext *ctx)
 160 {
 161     BHListSlice slice;
 162     BHListSlice *s;
 163     int ret = 0;
 164
 165     /* Synchronizes with QSLIST_INSERT_HEAD_ATOMIC in aio_bh_enqueue().  */
 166     QSLIST_MOVE_ATOMIC(&slice.bh_list, &ctx->bh_list);
 167     QSIMPLEQ_INSERT_TAIL(&ctx->bh_slice_list, &slice, next);
 168
 169     while ((s = QSIMPLEQ_FIRST(&ctx->bh_slice_list))) {
 170         QEMUBH *bh;
 171         unsigned flags;
 172
 173         bh = aio_bh_dequeue(&s->bh_list, &flags);
 174         if (!bh) {
 175             QSIMPLEQ_REMOVE_HEAD(&ctx->bh_slice_list, next);
 176             continue;
 177         }
 178
 179         if ((flags & (BH_SCHEDULED | BH_DELETED)) == BH_SCHEDULED) {
 180             /* Idle BHs don't count as progress */
 181             if (!(flags & BH_IDLE)) {
 182                 ret = 1;
 183             }
 184             aio_bh_call(bh);
 185         }
 186         if (flags & (BH_DELETED | BH_ONESHOT)) {
 187             g_free(bh);
 188         }
 189     }
 190
 191     return ret;
 192 }
 193
 194 void qemu_bh_schedule_idle(QEMUBH *bh)
 195 {
 196     aio_bh_enqueue(bh, BH_SCHEDULED | BH_IDLE);
 197 }
 198
 199 void qemu_bh_schedule(QEMUBH *bh)
 200 {
 201     aio_bh_enqueue(bh, BH_SCHEDULED);
 202 }
 203
 204 /* This func is async.
 205  */
 206 void qemu_bh_cancel(QEMUBH *bh)
 207 {
 208     qatomic_and(&bh->flags, ~BH_SCHEDULED);
 209 }
 210
 211 /* This func is async.The bottom half will do the delete action at the finial
 212  * end.
 213  */
 214 void qemu_bh_delete(QEMUBH *bh)
 215 {
 216     aio_bh_enqueue(bh, BH_DELETED);
 217 }
 218
 219 static int64_t aio_compute_bh_timeout(BHList *head, int timeout)
 220 {
 221     QEMUBH *bh;
 222
 223     QSLIST_FOREACH_RCU(bh, head, next) {
 224         if ((bh->flags & (BH_SCHEDULED | BH_DELETED)) == BH_SCHEDULED) {
 225             if (bh->flags & BH_IDLE) {
 226                 /* idle bottom halves will be polled at least
 227                  * every 10ms */
 228                 timeout = 10000000;
 229             } else {
 230                 /* non-idle bottom halves will be executed
 231                  * immediately */
 232                 return 0;
 233             }
 234         }
 235     }
 236
 237     return timeout;
 238 }
 239
 240 int64_t
 241 aio_compute_timeout(AioContext *ctx)
 242 {
 243     BHListSlice *s;
 244     int64_t deadline;
 245     int timeout = -1;
 246
 247     timeout = aio_compute_bh_timeout(&ctx->bh_list, timeout);
 248     if (timeout == 0) {
 249         return 0;
 250     }
 251
 252     QSIMPLEQ_FOREACH(s, &ctx->bh_slice_list, next) {
 253         timeout = aio_compute_bh_timeout(&s->bh_list, timeout);
 254         if (timeout == 0) {
 255             return 0;
 256         }
 257     }
 258
 259     deadline = timerlistgroup_deadline_ns(&ctx->tlg);
 260     if (deadline == 0) {
 261         return 0;
 262     } else {
 263         return qemu_soonest_timeout(timeout, deadline);
 264     }
 265 }
 266
 267 static gboolean
 268 aio_ctx_prepare(GSource *source, gint    *timeout)
 269 {
 270     AioContext *ctx = (AioContext *) source;
 271
 272     qatomic_set(&ctx->notify_me, qatomic_read(&ctx->notify_me) | 1);
 273
 274     /*
 275      * Write ctx->notify_me before computing the timeout
 276      * (reading bottom half flags, etc.).  Pairs with
 277      * smp_mb in aio_notify().
 278      */
 279     smp_mb();
 280
 281     /* We assume there is no timeout already supplied */
 282     *timeout = qemu_timeout_ns_to_ms(aio_compute_timeout(ctx));
 283
 284     if (aio_prepare(ctx)) {
 285         *timeout = 0;
 286     }
 287
 288     return *timeout == 0;
 289 }
 290
 291 static gboolean
 292 aio_ctx_check(GSource *source)
 293 {
 294     AioContext *ctx = (AioContext *) source;
 295     QEMUBH *bh;
 296     BHListSlice *s;
 297
 298     /* Finish computing the timeout before clearing the flag.  */
 299     qatomic_store_release(&ctx->notify_me, qatomic_read(&ctx->notify_me) & ~1);
 300     aio_notify_accept(ctx);
 301
 302     QSLIST_FOREACH_RCU(bh, &ctx->bh_list, next) {
 303         if ((bh->flags & (BH_SCHEDULED | BH_DELETED)) == BH_SCHEDULED) {
 304             return true;
 305         }
 306     }
 307
 308     QSIMPLEQ_FOREACH(s, &ctx->bh_slice_list, next) {
 309         QSLIST_FOREACH_RCU(bh, &s->bh_list, next) {
 310             if ((bh->flags & (BH_SCHEDULED | BH_DELETED)) == BH_SCHEDULED) {
 311                 return true;
 312             }
 313         }
 314     }
 315     return aio_pending(ctx) || (timerlistgroup_deadline_ns(&ctx->tlg) == 0);
 316 }
 317
 318 static gboolean
 319 aio_ctx_dispatch(GSource     *source,
 320                  GSourceFunc  callback,
 321                  gpointer     user_data)
 322 {
 323     AioContext *ctx = (AioContext *) source;
 324
 325     assert(callback == NULL);
 326     aio_dispatch(ctx);
 327     return true;
 328 }
 329
 330 static void
 331 aio_ctx_finalize(GSource     *source)
 332 {
 333     AioContext *ctx = (AioContext *) source;
 334     QEMUBH *bh;
 335     unsigned flags;
 336
 337     thread_pool_free(ctx->thread_pool);
 338
 339 #ifdef CONFIG_LINUX_AIO
 340     if (ctx->linux_aio) {
 341         laio_detach_aio_context(ctx->linux_aio, ctx);
 342         laio_cleanup(ctx->linux_aio);
 343         ctx->linux_aio = NULL;
 344     }
 345 #endif
 346
 347 #ifdef CONFIG_LINUX_IO_URING
 348     if (ctx->linux_io_uring) {
 349         luring_detach_aio_context(ctx->linux_io_uring, ctx);
 350         luring_cleanup(ctx->linux_io_uring);
 351         ctx->linux_io_uring = NULL;
 352     }
 353 #endif
 354
 355     assert(QSLIST_EMPTY(&ctx->scheduled_coroutines));
 356     qemu_bh_delete(ctx->co_schedule_bh);
 357
 358     /* There must be no aio_bh_poll() calls going on */
 359     assert(QSIMPLEQ_EMPTY(&ctx->bh_slice_list));
 360
 361     while ((bh = aio_bh_dequeue(&ctx->bh_list, &flags))) {
 362         /*
 363          * qemu_bh_delete() must have been called on BHs in this AioContext. In
 364          * many cases memory leaks, hangs, or inconsistent state occur when a
 365          * BH is leaked because something still expects it to run.
 366          *
 367          * If you hit this, fix the lifecycle of the BH so that
 368          * qemu_bh_delete() and any associated cleanup is called before the
 369          * AioContext is finalized.
 370          */
 371         if (unlikely(!(flags & BH_DELETED))) {
 372             fprintf(stderr, "%s: BH '%s' leaked, aborting...\n",
 373                     __func__, bh->name);
 374             abort();
 375         }
 376
 377         g_free(bh);
 378     }
 379
 380     aio_set_event_notifier(ctx, &ctx->notifier, false, NULL, NULL, NULL);
 381     event_notifier_cleanup(&ctx->notifier);
 382     qemu_rec_mutex_destroy(&ctx->lock);
 383     qemu_lockcnt_destroy(&ctx->list_lock);
 384     timerlistgroup_deinit(&ctx->tlg);
 385     unregister_aiocontext(ctx);
 386     aio_context_destroy(ctx);
 387 }
 388
 389 static GSourceFuncs aio_source_funcs = {
 390     aio_ctx_prepare,
 391     aio_ctx_check,
 392     aio_ctx_dispatch,
 393     aio_ctx_finalize
 394 };
 395
 396 GSource *aio_get_g_source(AioContext *ctx)
 397 {
 398     aio_context_use_g_source(ctx);
 399     g_source_ref(&ctx->source);
 400     return &ctx->source;
 401 }
 402
 403 ThreadPool *aio_get_thread_pool(AioContext *ctx)
 404 {
 405     if (!ctx->thread_pool) {
 406         ctx->thread_pool = thread_pool_new(ctx);
 407     }
 408     return ctx->thread_pool;
 409 }
 410
 411 #ifdef CONFIG_LINUX_AIO
 412 LinuxAioState *aio_setup_linux_aio(AioContext *ctx, Error **errp)
 413 {
 414     if (!ctx->linux_aio) {
 415         ctx->linux_aio = laio_init(errp);
 416         if (ctx->linux_aio) {
 417             laio_attach_aio_context(ctx->linux_aio, ctx);
 418         }
 419     }
 420     return ctx->linux_aio;
 421 }
 422
 423 LinuxAioState *aio_get_linux_aio(AioContext *ctx)
 424 {
 425     assert(ctx->linux_aio);
 426     return ctx->linux_aio;
 427 }
 428 #endif
 429
 430 #ifdef CONFIG_LINUX_IO_URING
 431 LuringState *aio_setup_linux_io_uring(AioContext *ctx, Error **errp)
 432 {
 433     if (ctx->linux_io_uring) {
 434         return ctx->linux_io_uring;
 435     }
 436
 437     ctx->linux_io_uring = luring_init(errp);
 438     if (!ctx->linux_io_uring) {
 439         return NULL;
 440     }
 441
 442     luring_attach_aio_context(ctx->linux_io_uring, ctx);
 443     return ctx->linux_io_uring;
 444 }
 445
 446 LuringState *aio_get_linux_io_uring(AioContext *ctx)
 447 {
 448     assert(ctx->linux_io_uring);
 449     return ctx->linux_io_uring;
 450 }
 451 #endif
 452
 453 void aio_notify(AioContext *ctx)
 454 {
 455     /*
 456      * Write e.g. ctx->bh_list before writing ctx->notified.  Pairs with
 457      * smp_mb() in aio_notify_accept().
 458      */
 459     smp_wmb();
 460     qatomic_set(&ctx->notified, true);
 461
 462     /*
 463      * Write ctx->notified (and also ctx->bh_list) before reading ctx->notify_me.
 464      * Pairs with smp_mb() in aio_ctx_prepare or aio_poll.
 465      */
 466     smp_mb();
 467     if (qatomic_read(&ctx->notify_me)) {
 468         event_notifier_set(&ctx->notifier);
 469     }
 470 }
 471
 472 void aio_notify_accept(AioContext *ctx)
 473 {
 474     qatomic_set(&ctx->notified, false);
 475
 476     /*
 477      * Order reads of ctx->notified (in aio_context_notifier_poll()) and the
 478      * above clearing of ctx->notified before reads of e.g. bh->flags.  Pairs
 479      * with smp_wmb() in aio_notify.
 480      */
 481     smp_mb();
 482 }
 483
 484 static void aio_timerlist_notify(void *opaque, QEMUClockType type)
 485 {
 486     aio_notify(opaque);
 487 }
 488
 489 static void aio_context_notifier_cb(EventNotifier *e)
 490 {
 491     AioContext *ctx = container_of(e, AioContext, notifier);
 492
 493     event_notifier_test_and_clear(&ctx->notifier);
 494 }
 495
 496 /* Returns true if aio_notify() was called (e.g. a BH was scheduled) */
 497 static bool aio_context_notifier_poll(void *opaque)
 498 {
 499     EventNotifier *e = opaque;
 500     AioContext *ctx = container_of(e, AioContext, notifier);
 501
 502     /*
 503      * No need for load-acquire because we just want to kick the
 504      * event loop.  aio_notify_accept() takes care of synchronizing
 505      * the event loop with the producers.
 506      */
 507     return qatomic_read(&ctx->notified);
 508 }
 509
 510 static void aio_context_notifier_poll_ready(EventNotifier *e)
 511 {
 512     /* Do nothing, we just wanted to kick the event loop */
 513 }
 514
 515 static void co_schedule_bh_cb(void *opaque)
 516 {
 517     AioContext *ctx = opaque;
 518     QSLIST_HEAD(, Coroutine) straight, reversed;
 519
 520     QSLIST_MOVE_ATOMIC(&reversed, &ctx->scheduled_coroutines);
 521     QSLIST_INIT(&straight);
 522
 523     while (!QSLIST_EMPTY(&reversed)) {
 524         Coroutine *co = QSLIST_FIRST(&reversed);
 525         QSLIST_REMOVE_HEAD(&reversed, co_scheduled_next);
 526         QSLIST_INSERT_HEAD(&straight, co, co_scheduled_next);
 527     }
 528
 529     while (!QSLIST_EMPTY(&straight)) {
 530         Coroutine *co = QSLIST_FIRST(&straight);
 531         QSLIST_REMOVE_HEAD(&straight, co_scheduled_next);
 532         trace_aio_co_schedule_bh_cb(ctx, co);
 533         aio_context_acquire(ctx);
 534
 535         /* Protected by write barrier in qemu_aio_coroutine_enter */
 536         qatomic_set(&co->scheduled, NULL);
 537         qemu_aio_coroutine_enter(ctx, co);
 538         aio_context_release(ctx);
 539     }
 540 }
 541
 542 AioContext *aio_context_new(Error **errp)
 543 {
 544     int ret;
 545     AioContext *ctx;
 546
 547     ctx = (AioContext *) g_source_new(&aio_source_funcs, sizeof(AioContext));
 548     QSLIST_INIT(&ctx->bh_list);
 549     QSIMPLEQ_INIT(&ctx->bh_slice_list);
 550     aio_context_setup(ctx);
 551
 552     ret = event_notifier_init(&ctx->notifier, false);
 553     if (ret < 0) {
 554         error_setg_errno(errp, -ret, "Failed to initialize event notifier");
 555         goto fail;
 556     }
 557     g_source_set_can_recurse(&ctx->source, true);
 558     qemu_lockcnt_init(&ctx->list_lock);
 559
 560     ctx->co_schedule_bh = aio_bh_new(ctx, co_schedule_bh_cb, ctx);
 561     QSLIST_INIT(&ctx->scheduled_coroutines);
 562
 563     aio_set_event_notifier(ctx, &ctx->notifier,
 564                            false,
 565                            aio_context_notifier_cb,
 566                            aio_context_notifier_poll,
 567                            aio_context_notifier_poll_ready);
 568 #ifdef CONFIG_LINUX_AIO
 569     ctx->linux_aio = NULL;
 570 #endif
 571
 572 #ifdef CONFIG_LINUX_IO_URING
 573     ctx->linux_io_uring = NULL;
 574 #endif
 575
 576     ctx->thread_pool = NULL;
 577     qemu_rec_mutex_init(&ctx->lock);
 578     timerlistgroup_init(&ctx->tlg, aio_timerlist_notify, ctx);
 579
 580     ctx->poll_ns = 0;
 581     ctx->poll_max_ns = 0;
 582     ctx->poll_grow = 0;
 583     ctx->poll_shrink = 0;
 584
 585     ctx->aio_max_batch = 0;
 586
 587     ctx->thread_pool_min = 0;
 588     ctx->thread_pool_max = THREAD_POOL_MAX_THREADS_DEFAULT;
 589
 590     register_aiocontext(ctx);
 591
 592     return ctx;
 593 fail:
 594     g_source_destroy(&ctx->source);
 595     return NULL;
 596 }
 597
 598 void aio_co_schedule(AioContext *ctx, Coroutine *co)
 599 {
 600     trace_aio_co_schedule(ctx, co);
 601     const char *scheduled = qatomic_cmpxchg(&co->scheduled, NULL,
 602                                            __func__);
 603
 604     if (scheduled) {
 605         fprintf(stderr,
 606                 "%s: Co-routine was already scheduled in '%s'\n",
 607                 __func__, scheduled);
 608         abort();
 609     }
 610
 611     /* The coroutine might run and release the last ctx reference before we
 612      * invoke qemu_bh_schedule().  Take a reference to keep ctx alive until
 613      * we're done.
 614      */
 615     aio_context_ref(ctx);
 616
 617     QSLIST_INSERT_HEAD_ATOMIC(&ctx->scheduled_coroutines,
 618                               co, co_scheduled_next);
 619     qemu_bh_schedule(ctx->co_schedule_bh);
 620
 621     aio_context_unref(ctx);
 622 }
 623
 624 typedef struct AioCoRescheduleSelf {
 625     Coroutine *co;
 626     AioContext *new_ctx;
 627 } AioCoRescheduleSelf;
 628
 629 static void aio_co_reschedule_self_bh(void *opaque)
 630 {
 631     AioCoRescheduleSelf *data = opaque;
 632     aio_co_schedule(data->new_ctx, data->co);
 633 }
 634
 635 void coroutine_fn aio_co_reschedule_self(AioContext *new_ctx)
 636 {
 637     AioContext *old_ctx = qemu_get_current_aio_context();
 638
 639     if (old_ctx != new_ctx) {
 640         AioCoRescheduleSelf data = {
 641             .co = qemu_coroutine_self(),
 642             .new_ctx = new_ctx,
 643         };
 644         /*
 645          * We can't directly schedule the coroutine in the target context
 646          * because this would be racy: The other thread could try to enter the
 647          * coroutine before it has yielded in this one.
 648          */
 649         aio_bh_schedule_oneshot(old_ctx, aio_co_reschedule_self_bh, &data);
 650         qemu_coroutine_yield();
 651     }
 652 }
 653
 654 void aio_co_wake(Coroutine *co)
 655 {
 656     AioContext *ctx;
 657
 658     /* Read coroutine before co->ctx.  Matches smp_wmb in
 659      * qemu_coroutine_enter.
 660      */
 661     smp_read_barrier_depends();
 662     ctx = qatomic_read(&co->ctx);
 663
 664     aio_co_enter(ctx, co);
 665 }
 666
 667 void aio_co_enter(AioContext *ctx, Coroutine *co)
 668 {
 669     if (ctx != qemu_get_current_aio_context()) {
 670         aio_co_schedule(ctx, co);
 671         return;
 672     }
 673
 674     if (qemu_in_coroutine()) {
 675         Coroutine *self = qemu_coroutine_self();
 676         assert(self != co);
 677         QSIMPLEQ_INSERT_TAIL(&self->co_queue_wakeup, co, co_queue_next);
 678     } else {
 679         aio_context_acquire(ctx);
 680         qemu_aio_coroutine_enter(ctx, co);
 681         aio_context_release(ctx);
 682     }
 683 }
 684
 685 void aio_context_ref(AioContext *ctx)
 686 {
 687     g_source_ref(&ctx->source);
 688 }
 689
 690 void aio_context_unref(AioContext *ctx)
 691 {
 692     g_source_unref(&ctx->source);
 693 }
 694
 695 void aio_context_acquire(AioContext *ctx)
 696 {
 697     qemu_rec_mutex_lock(&ctx->lock);
 698 }
 699
 700 void aio_context_release(AioContext *ctx)
 701 {
 702     qemu_rec_mutex_unlock(&ctx->lock);
 703 }
 704
 705 QEMU_DEFINE_STATIC_CO_TLS(AioContext *, my_aiocontext)
 706
 707 AioContext *qemu_get_current_aio_context(void)
 708 {
 709     AioContext *ctx = get_my_aiocontext();
 710     if (ctx) {
 711         return ctx;
 712     }
 713     if (qemu_mutex_iothread_locked()) {
 714         /* Possibly in a vCPU thread.  */
 715         return qemu_get_aio_context();
 716     }
 717     return NULL;
 718 }
 719
 720 void qemu_set_current_aio_context(AioContext *ctx)
 721 {
 722     assert(!get_my_aiocontext());
 723     set_my_aiocontext(ctx);
 724 }
 725
 726 void aio_context_set_thread_pool_params(AioContext *ctx, int64_t min,
 727                                         int64_t max, Error **errp)
 728 {
 729
 730     if (min > max || !max || min > INT_MAX || max > INT_MAX) {
 731         error_setg(errp, "bad thread-pool-min/thread-pool-max values");
 732         return;
 733     }
 734
 735     ctx->thread_pool_min = min;
 736     ctx->thread_pool_max = max;
 737
 738     if (ctx->thread_pool) {
 739         thread_pool_update_params(ctx->thread_pool, ctx);
 740     }
 741 }