util/aio-posix.c

   1 /*
   2  * QEMU aio implementation
   3  *
   4  * Copyright IBM, Corp. 2008
   5  *
   6  * Authors:
   7  *  Anthony Liguori   <aliguori@us.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2.  See
  10  * the COPYING file in the top-level directory.
  11  *
  12  * Contributions after 2012-01-13 are licensed under the terms of the
  13  * GNU GPL, version 2 or (at your option) any later version.
  14  */
  15
  16 #include "qemu/osdep.h"
  17 #include "block/block.h"
  18 #include "qemu/main-loop.h"
  19 #include "qemu/rcu.h"
  20 #include "qemu/rcu_queue.h"
  21 #include "qemu/sockets.h"
  22 #include "qemu/cutils.h"
  23 #include "trace.h"
  24 #include "aio-posix.h"
  25
  26 /* Stop userspace polling on a handler if it isn't active for some time */
  27 #define POLL_IDLE_INTERVAL_NS (7 * NANOSECONDS_PER_SECOND)
  28
  29 bool aio_poll_disabled(AioContext *ctx)
  30 {
  31     return qatomic_read(&ctx->poll_disable_cnt);
  32 }
  33
  34 void aio_add_ready_handler(AioHandlerList *ready_list,
  35                            AioHandler *node,
  36                            int revents)
  37 {
  38     QLIST_SAFE_REMOVE(node, node_ready); /* remove from nested parent's list */
  39     node->pfd.revents = revents;
  40     QLIST_INSERT_HEAD(ready_list, node, node_ready);
  41 }
  42
  43 static AioHandler *find_aio_handler(AioContext *ctx, int fd)
  44 {
  45     AioHandler *node;
  46
  47     QLIST_FOREACH(node, &ctx->aio_handlers, node) {
  48         if (node->pfd.fd == fd) {
  49             if (!QLIST_IS_INSERTED(node, node_deleted)) {
  50                 return node;
  51             }
  52         }
  53     }
  54
  55     return NULL;
  56 }
  57
  58 static bool aio_remove_fd_handler(AioContext *ctx, AioHandler *node)
  59 {
  60     /* If the GSource is in the process of being destroyed then
  61      * g_source_remove_poll() causes an assertion failure.  Skip
  62      * removal in that case, because glib cleans up its state during
  63      * destruction anyway.
  64      */
  65     if (!g_source_is_destroyed(&ctx->source)) {
  66         g_source_remove_poll(&ctx->source, &node->pfd);
  67     }
  68
  69     node->pfd.revents = 0;
  70
  71     /* If the fd monitor has already marked it deleted, leave it alone */
  72     if (QLIST_IS_INSERTED(node, node_deleted)) {
  73         return false;
  74     }
  75
  76     /* If a read is in progress, just mark the node as deleted */
  77     if (qemu_lockcnt_count(&ctx->list_lock)) {
  78         QLIST_INSERT_HEAD_RCU(&ctx->deleted_aio_handlers, node, node_deleted);
  79         return false;
  80     }
  81     /* Otherwise, delete it for real.  We can't just mark it as
  82      * deleted because deleted nodes are only cleaned up while
  83      * no one is walking the handlers list.
  84      */
  85     QLIST_SAFE_REMOVE(node, node_poll);
  86     QLIST_REMOVE(node, node);
  87     return true;
  88 }
  89
  90 void aio_set_fd_handler(AioContext *ctx,
  91                         int fd,
  92                         bool is_external,
  93                         IOHandler *io_read,
  94                         IOHandler *io_write,
  95                         AioPollFn *io_poll,
  96                         void *opaque)
  97 {
  98     AioHandler *node;
  99     AioHandler *new_node = NULL;
 100     bool is_new = false;
 101     bool deleted = false;
 102     int poll_disable_change;
 103
 104     qemu_lockcnt_lock(&ctx->list_lock);
 105
 106     node = find_aio_handler(ctx, fd);
 107
 108     /* Are we deleting the fd handler? */
 109     if (!io_read && !io_write && !io_poll) {
 110         if (node == NULL) {
 111             qemu_lockcnt_unlock(&ctx->list_lock);
 112             return;
 113         }
 114         /* Clean events in order to unregister fd from the ctx epoll. */
 115         node->pfd.events = 0;
 116
 117         poll_disable_change = -!node->io_poll;
 118     } else {
 119         poll_disable_change = !io_poll - (node && !node->io_poll);
 120         if (node == NULL) {
 121             is_new = true;
 122         }
 123         /* Alloc and insert if it's not already there */
 124         new_node = g_new0(AioHandler, 1);
 125
 126         /* Update handler with latest information */
 127         new_node->io_read = io_read;
 128         new_node->io_write = io_write;
 129         new_node->io_poll = io_poll;
 130         new_node->opaque = opaque;
 131         new_node->is_external = is_external;
 132
 133         if (is_new) {
 134             new_node->pfd.fd = fd;
 135         } else {
 136             new_node->pfd = node->pfd;
 137         }
 138         g_source_add_poll(&ctx->source, &new_node->pfd);
 139
 140         new_node->pfd.events = (io_read ? G_IO_IN | G_IO_HUP | G_IO_ERR : 0);
 141         new_node->pfd.events |= (io_write ? G_IO_OUT | G_IO_ERR : 0);
 142
 143         QLIST_INSERT_HEAD_RCU(&ctx->aio_handlers, new_node, node);
 144     }
 145
 146     /* No need to order poll_disable_cnt writes against other updates;
 147      * the counter is only used to avoid wasting time and latency on
 148      * iterated polling when the system call will be ultimately necessary.
 149      * Changing handlers is a rare event, and a little wasted polling until
 150      * the aio_notify below is not an issue.
 151      */
 152     qatomic_set(&ctx->poll_disable_cnt,
 153                qatomic_read(&ctx->poll_disable_cnt) + poll_disable_change);
 154
 155     ctx->fdmon_ops->update(ctx, node, new_node);
 156     if (node) {
 157         deleted = aio_remove_fd_handler(ctx, node);
 158     }
 159     qemu_lockcnt_unlock(&ctx->list_lock);
 160     aio_notify(ctx);
 161
 162     if (deleted) {
 163         g_free(node);
 164     }
 165 }
 166
 167 void aio_set_fd_poll(AioContext *ctx, int fd,
 168                      IOHandler *io_poll_begin,
 169                      IOHandler *io_poll_end)
 170 {
 171     AioHandler *node = find_aio_handler(ctx, fd);
 172
 173     if (!node) {
 174         return;
 175     }
 176
 177     node->io_poll_begin = io_poll_begin;
 178     node->io_poll_end = io_poll_end;
 179 }
 180
 181 void aio_set_event_notifier(AioContext *ctx,
 182                             EventNotifier *notifier,
 183                             bool is_external,
 184                             EventNotifierHandler *io_read,
 185                             AioPollFn *io_poll)
 186 {
 187     aio_set_fd_handler(ctx, event_notifier_get_fd(notifier), is_external,
 188                        (IOHandler *)io_read, NULL, io_poll, notifier);
 189 }
 190
 191 void aio_set_event_notifier_poll(AioContext *ctx,
 192                                  EventNotifier *notifier,
 193                                  EventNotifierHandler *io_poll_begin,
 194                                  EventNotifierHandler *io_poll_end)
 195 {
 196     aio_set_fd_poll(ctx, event_notifier_get_fd(notifier),
 197                     (IOHandler *)io_poll_begin,
 198                     (IOHandler *)io_poll_end);
 199 }
 200
 201 static bool poll_set_started(AioContext *ctx, bool started)
 202 {
 203     AioHandler *node;
 204     bool progress = false;
 205
 206     if (started == ctx->poll_started) {
 207         return false;
 208     }
 209
 210     ctx->poll_started = started;
 211
 212     qemu_lockcnt_inc(&ctx->list_lock);
 213     QLIST_FOREACH(node, &ctx->poll_aio_handlers, node_poll) {
 214         IOHandler *fn;
 215
 216         if (QLIST_IS_INSERTED(node, node_deleted)) {
 217             continue;
 218         }
 219
 220         if (started) {
 221             fn = node->io_poll_begin;
 222         } else {
 223             fn = node->io_poll_end;
 224         }
 225
 226         if (fn) {
 227             fn(node->opaque);
 228         }
 229
 230         /* Poll one last time in case ->io_poll_end() raced with the event */
 231         if (!started) {
 232             progress = node->io_poll(node->opaque) || progress;
 233         }
 234     }
 235     qemu_lockcnt_dec(&ctx->list_lock);
 236
 237     return progress;
 238 }
 239
 240
 241 bool aio_prepare(AioContext *ctx)
 242 {
 243     /* Poll mode cannot be used with glib's event loop, disable it. */
 244     poll_set_started(ctx, false);
 245
 246     return false;
 247 }
 248
 249 bool aio_pending(AioContext *ctx)
 250 {
 251     AioHandler *node;
 252     bool result = false;
 253
 254     /*
 255      * We have to walk very carefully in case aio_set_fd_handler is
 256      * called while we're walking.
 257      */
 258     qemu_lockcnt_inc(&ctx->list_lock);
 259
 260     QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) {
 261         int revents;
 262
 263         revents = node->pfd.revents & node->pfd.events;
 264         if (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR) && node->io_read &&
 265             aio_node_check(ctx, node->is_external)) {
 266             result = true;
 267             break;
 268         }
 269         if (revents & (G_IO_OUT | G_IO_ERR) && node->io_write &&
 270             aio_node_check(ctx, node->is_external)) {
 271             result = true;
 272             break;
 273         }
 274     }
 275     qemu_lockcnt_dec(&ctx->list_lock);
 276
 277     return result;
 278 }
 279
 280 static void aio_free_deleted_handlers(AioContext *ctx)
 281 {
 282     AioHandler *node;
 283
 284     if (QLIST_EMPTY_RCU(&ctx->deleted_aio_handlers)) {
 285         return;
 286     }
 287     if (!qemu_lockcnt_dec_if_lock(&ctx->list_lock)) {
 288         return; /* we are nested, let the parent do the freeing */
 289     }
 290
 291     while ((node = QLIST_FIRST_RCU(&ctx->deleted_aio_handlers))) {
 292         QLIST_REMOVE(node, node);
 293         QLIST_REMOVE(node, node_deleted);
 294         QLIST_SAFE_REMOVE(node, node_poll);
 295         g_free(node);
 296     }
 297
 298     qemu_lockcnt_inc_and_unlock(&ctx->list_lock);
 299 }
 300
 301 static bool aio_dispatch_handler(AioContext *ctx, AioHandler *node)
 302 {
 303     bool progress = false;
 304     int revents;
 305
 306     revents = node->pfd.revents & node->pfd.events;
 307     node->pfd.revents = 0;
 308
 309     /*
 310      * Start polling AioHandlers when they become ready because activity is
 311      * likely to continue.  Note that starvation is theoretically possible when
 312      * fdmon_supports_polling(), but only until the fd fires for the first
 313      * time.
 314      */
 315     if (!QLIST_IS_INSERTED(node, node_deleted) &&
 316         !QLIST_IS_INSERTED(node, node_poll) &&
 317         node->io_poll) {
 318         trace_poll_add(ctx, node, node->pfd.fd, revents);
 319         if (ctx->poll_started && node->io_poll_begin) {
 320             node->io_poll_begin(node->opaque);
 321         }
 322         QLIST_INSERT_HEAD(&ctx->poll_aio_handlers, node, node_poll);
 323     }
 324
 325     if (!QLIST_IS_INSERTED(node, node_deleted) &&
 326         (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR)) &&
 327         aio_node_check(ctx, node->is_external) &&
 328         node->io_read) {
 329         node->io_read(node->opaque);
 330
 331         /* aio_notify() does not count as progress */
 332         if (node->opaque != &ctx->notifier) {
 333             progress = true;
 334         }
 335     }
 336     if (!QLIST_IS_INSERTED(node, node_deleted) &&
 337         (revents & (G_IO_OUT | G_IO_ERR)) &&
 338         aio_node_check(ctx, node->is_external) &&
 339         node->io_write) {
 340         node->io_write(node->opaque);
 341         progress = true;
 342     }
 343
 344     return progress;
 345 }
 346
 347 /*
 348  * If we have a list of ready handlers then this is more efficient than
 349  * scanning all handlers with aio_dispatch_handlers().
 350  */
 351 static bool aio_dispatch_ready_handlers(AioContext *ctx,
 352                                         AioHandlerList *ready_list)
 353 {
 354     bool progress = false;
 355     AioHandler *node;
 356
 357     while ((node = QLIST_FIRST(ready_list))) {
 358         QLIST_REMOVE(node, node_ready);
 359         progress = aio_dispatch_handler(ctx, node) || progress;
 360     }
 361
 362     return progress;
 363 }
 364
 365 /* Slower than aio_dispatch_ready_handlers() but only used via glib */
 366 static bool aio_dispatch_handlers(AioContext *ctx)
 367 {
 368     AioHandler *node, *tmp;
 369     bool progress = false;
 370
 371     QLIST_FOREACH_SAFE_RCU(node, &ctx->aio_handlers, node, tmp) {
 372         progress = aio_dispatch_handler(ctx, node) || progress;
 373     }
 374
 375     return progress;
 376 }
 377
 378 void aio_dispatch(AioContext *ctx)
 379 {
 380     qemu_lockcnt_inc(&ctx->list_lock);
 381     aio_bh_poll(ctx);
 382     aio_dispatch_handlers(ctx);
 383     aio_free_deleted_handlers(ctx);
 384     qemu_lockcnt_dec(&ctx->list_lock);
 385
 386     timerlistgroup_run_timers(&ctx->tlg);
 387 }
 388
 389 static bool run_poll_handlers_once(AioContext *ctx,
 390                                    int64_t now,
 391                                    int64_t *timeout)
 392 {
 393     bool progress = false;
 394     AioHandler *node;
 395     AioHandler *tmp;
 396
 397     QLIST_FOREACH_SAFE(node, &ctx->poll_aio_handlers, node_poll, tmp) {
 398         if (aio_node_check(ctx, node->is_external) &&
 399             node->io_poll(node->opaque)) {
 400             node->poll_idle_timeout = now + POLL_IDLE_INTERVAL_NS;
 401
 402             /*
 403              * Polling was successful, exit try_poll_mode immediately
 404              * to adjust the next polling time.
 405              */
 406             *timeout = 0;
 407             if (node->opaque != &ctx->notifier) {
 408                 progress = true;
 409             }
 410         }
 411
 412         /* Caller handles freeing deleted nodes.  Don't do it here. */
 413     }
 414
 415     return progress;
 416 }
 417
 418 static bool fdmon_supports_polling(AioContext *ctx)
 419 {
 420     return ctx->fdmon_ops->need_wait != aio_poll_disabled;
 421 }
 422
 423 static bool remove_idle_poll_handlers(AioContext *ctx, int64_t now)
 424 {
 425     AioHandler *node;
 426     AioHandler *tmp;
 427     bool progress = false;
 428
 429     /*
 430      * File descriptor monitoring implementations without userspace polling
 431      * support suffer from starvation when a subset of handlers is polled
 432      * because fds will not be processed in a timely fashion.  Don't remove
 433      * idle poll handlers.
 434      */
 435     if (!fdmon_supports_polling(ctx)) {
 436         return false;
 437     }
 438
 439     QLIST_FOREACH_SAFE(node, &ctx->poll_aio_handlers, node_poll, tmp) {
 440         if (node->poll_idle_timeout == 0LL) {
 441             node->poll_idle_timeout = now + POLL_IDLE_INTERVAL_NS;
 442         } else if (now >= node->poll_idle_timeout) {
 443             trace_poll_remove(ctx, node, node->pfd.fd);
 444             node->poll_idle_timeout = 0LL;
 445             QLIST_SAFE_REMOVE(node, node_poll);
 446             if (ctx->poll_started && node->io_poll_end) {
 447                 node->io_poll_end(node->opaque);
 448
 449                 /*
 450                  * Final poll in case ->io_poll_end() races with an event.
 451                  * Nevermind about re-adding the handler in the rare case where
 452                  * this causes progress.
 453                  */
 454                 progress = node->io_poll(node->opaque) || progress;
 455             }
 456         }
 457     }
 458
 459     return progress;
 460 }
 461
 462 /* run_poll_handlers:
 463  * @ctx: the AioContext
 464  * @max_ns: maximum time to poll for, in nanoseconds
 465  *
 466  * Polls for a given time.
 467  *
 468  * Note that the caller must have incremented ctx->list_lock.
 469  *
 470  * Returns: true if progress was made, false otherwise
 471  */
 472 static bool run_poll_handlers(AioContext *ctx, int64_t max_ns, int64_t *timeout)
 473 {
 474     bool progress;
 475     int64_t start_time, elapsed_time;
 476
 477     assert(qemu_lockcnt_count(&ctx->list_lock) > 0);
 478
 479     trace_run_poll_handlers_begin(ctx, max_ns, *timeout);
 480
 481     /*
 482      * Optimization: ->io_poll() handlers often contain RCU read critical
 483      * sections and we therefore see many rcu_read_lock() -> rcu_read_unlock()
 484      * -> rcu_read_lock() -> ... sequences with expensive memory
 485      * synchronization primitives.  Make the entire polling loop an RCU
 486      * critical section because nested rcu_read_lock()/rcu_read_unlock() calls
 487      * are cheap.
 488      */
 489     RCU_READ_LOCK_GUARD();
 490
 491     start_time = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
 492     do {
 493         progress = run_poll_handlers_once(ctx, start_time, timeout);
 494         elapsed_time = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - start_time;
 495         max_ns = qemu_soonest_timeout(*timeout, max_ns);
 496         assert(!(max_ns && progress));
 497     } while (elapsed_time < max_ns && !ctx->fdmon_ops->need_wait(ctx));
 498
 499     if (remove_idle_poll_handlers(ctx, start_time + elapsed_time)) {
 500         *timeout = 0;
 501         progress = true;
 502     }
 503
 504     /* If time has passed with no successful polling, adjust *timeout to
 505      * keep the same ending time.
 506      */
 507     if (*timeout != -1) {
 508         *timeout -= MIN(*timeout, elapsed_time);
 509     }
 510
 511     trace_run_poll_handlers_end(ctx, progress, *timeout);
 512     return progress;
 513 }
 514
 515 /* try_poll_mode:
 516  * @ctx: the AioContext
 517  * @timeout: timeout for blocking wait, computed by the caller and updated if
 518  *    polling succeeds.
 519  *
 520  * Note that the caller must have incremented ctx->list_lock.
 521  *
 522  * Returns: true if progress was made, false otherwise
 523  */
 524 static bool try_poll_mode(AioContext *ctx, int64_t *timeout)
 525 {
 526     int64_t max_ns;
 527
 528     if (QLIST_EMPTY_RCU(&ctx->poll_aio_handlers)) {
 529         return false;
 530     }
 531
 532     max_ns = qemu_soonest_timeout(*timeout, ctx->poll_ns);
 533     if (max_ns && !ctx->fdmon_ops->need_wait(ctx)) {
 534         poll_set_started(ctx, true);
 535
 536         if (run_poll_handlers(ctx, max_ns, timeout)) {
 537             return true;
 538         }
 539     }
 540
 541     if (poll_set_started(ctx, false)) {
 542         *timeout = 0;
 543         return true;
 544     }
 545
 546     return false;
 547 }
 548
 549 bool aio_poll(AioContext *ctx, bool blocking)
 550 {
 551     AioHandlerList ready_list = QLIST_HEAD_INITIALIZER(ready_list);
 552     int ret = 0;
 553     bool progress;
 554     bool use_notify_me;
 555     int64_t timeout;
 556     int64_t start = 0;
 557
 558     /*
 559      * There cannot be two concurrent aio_poll calls for the same AioContext (or
 560      * an aio_poll concurrent with a GSource prepare/check/dispatch callback).
 561      * We rely on this below to avoid slow locked accesses to ctx->notify_me.
 562      *
 563      * aio_poll() may only be called in the AioContext's thread. iohandler_ctx
 564      * is special in that it runs in the main thread, but that thread's context
 565      * is qemu_aio_context.
 566      */
 567     assert(in_aio_context_home_thread(ctx == iohandler_get_aio_context() ?
 568                                       qemu_get_aio_context() : ctx));
 569
 570     qemu_lockcnt_inc(&ctx->list_lock);
 571
 572     if (ctx->poll_max_ns) {
 573         start = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
 574     }
 575
 576     timeout = blocking ? aio_compute_timeout(ctx) : 0;
 577     progress = try_poll_mode(ctx, &timeout);
 578     assert(!(timeout && progress));
 579
 580     /*
 581      * aio_notify can avoid the expensive event_notifier_set if
 582      * everything (file descriptors, bottom halves, timers) will
 583      * be re-evaluated before the next blocking poll().  This is
 584      * already true when aio_poll is called with blocking == false;
 585      * if blocking == true, it is only true after poll() returns,
 586      * so disable the optimization now.
 587      */
 588     use_notify_me = timeout != 0;
 589     if (use_notify_me) {
 590         qatomic_set(&ctx->notify_me, qatomic_read(&ctx->notify_me) + 2);
 591         /*
 592          * Write ctx->notify_me before reading ctx->notified.  Pairs with
 593          * smp_mb in aio_notify().
 594          */
 595         smp_mb();
 596
 597         /* Don't block if aio_notify() was called */
 598         if (qatomic_read(&ctx->notified)) {
 599             timeout = 0;
 600         }
 601     }
 602
 603     /* If polling is allowed, non-blocking aio_poll does not need the
 604      * system call---a single round of run_poll_handlers_once suffices.
 605      */
 606     if (timeout || ctx->fdmon_ops->need_wait(ctx)) {
 607         ret = ctx->fdmon_ops->wait(ctx, &ready_list, timeout);
 608     }
 609
 610     if (use_notify_me) {
 611         /* Finish the poll before clearing the flag.  */
 612         qatomic_store_release(&ctx->notify_me,
 613                              qatomic_read(&ctx->notify_me) - 2);
 614     }
 615
 616     aio_notify_accept(ctx);
 617
 618     /* Adjust polling time */
 619     if (ctx->poll_max_ns) {
 620         int64_t block_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - start;
 621
 622         if (block_ns <= ctx->poll_ns) {
 623             /* This is the sweet spot, no adjustment needed */
 624         } else if (block_ns > ctx->poll_max_ns) {
 625             /* We'd have to poll for too long, poll less */
 626             int64_t old = ctx->poll_ns;
 627
 628             if (ctx->poll_shrink) {
 629                 ctx->poll_ns /= ctx->poll_shrink;
 630             } else {
 631                 ctx->poll_ns = 0;
 632             }
 633
 634             trace_poll_shrink(ctx, old, ctx->poll_ns);
 635         } else if (ctx->poll_ns < ctx->poll_max_ns &&
 636                    block_ns < ctx->poll_max_ns) {
 637             /* There is room to grow, poll longer */
 638             int64_t old = ctx->poll_ns;
 639             int64_t grow = ctx->poll_grow;
 640
 641             if (grow == 0) {
 642                 grow = 2;
 643             }
 644
 645             if (ctx->poll_ns) {
 646                 ctx->poll_ns *= grow;
 647             } else {
 648                 ctx->poll_ns = 4000; /* start polling at 4 microseconds */
 649             }
 650
 651             if (ctx->poll_ns > ctx->poll_max_ns) {
 652                 ctx->poll_ns = ctx->poll_max_ns;
 653             }
 654
 655             trace_poll_grow(ctx, old, ctx->poll_ns);
 656         }
 657     }
 658
 659     progress |= aio_bh_poll(ctx);
 660
 661     if (ret > 0) {
 662         progress |= aio_dispatch_ready_handlers(ctx, &ready_list);
 663     }
 664
 665     aio_free_deleted_handlers(ctx);
 666
 667     qemu_lockcnt_dec(&ctx->list_lock);
 668
 669     progress |= timerlistgroup_run_timers(&ctx->tlg);
 670
 671     return progress;
 672 }
 673
 674 void aio_context_setup(AioContext *ctx)
 675 {
 676     ctx->fdmon_ops = &fdmon_poll_ops;
 677     ctx->epollfd = -1;
 678
 679     /* Use the fastest fd monitoring implementation if available */
 680     if (fdmon_io_uring_setup(ctx)) {
 681         return;
 682     }
 683
 684     fdmon_epoll_setup(ctx);
 685 }
 686
 687 void aio_context_destroy(AioContext *ctx)
 688 {
 689     fdmon_io_uring_destroy(ctx);
 690     fdmon_epoll_disable(ctx);
 691     aio_free_deleted_handlers(ctx);
 692 }
 693
 694 void aio_context_use_g_source(AioContext *ctx)
 695 {
 696     /*
 697      * Disable io_uring when the glib main loop is used because it doesn't
 698      * support mixed glib/aio_poll() usage. It relies on aio_poll() being
 699      * called regularly so that changes to the monitored file descriptors are
 700      * submitted, otherwise a list of pending fd handlers builds up.
 701      */
 702     fdmon_io_uring_destroy(ctx);
 703     aio_free_deleted_handlers(ctx);
 704 }
 705
 706 void aio_context_set_poll_params(AioContext *ctx, int64_t max_ns,
 707                                  int64_t grow, int64_t shrink, Error **errp)
 708 {
 709     /* No thread synchronization here, it doesn't matter if an incorrect value
 710      * is used once.
 711      */
 712     ctx->poll_max_ns = max_ns;
 713     ctx->poll_ns = 0;
 714     ctx->poll_grow = grow;
 715     ctx->poll_shrink = shrink;
 716
 717     aio_notify(ctx);
 718 }