| /* |
| * Data plane event loop |
| * |
| * Copyright (c) 2003-2008 Fabrice Bellard |
| * Copyright (c) 2009-2017 QEMU contributors |
| * |
| * Permission is hereby granted, free of charge, to any person obtaining a copy |
| * of this software and associated documentation files (the "Software"), to deal |
| * in the Software without restriction, including without limitation the rights |
| * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
| * copies of the Software, and to permit persons to whom the Software is |
| * furnished to do so, subject to the following conditions: |
| * |
| * The above copyright notice and this permission notice shall be included in |
| * all copies or substantial portions of the Software. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
| * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
| * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
| * THE SOFTWARE. |
| */ |
| |
| #include "qemu/osdep.h" |
| #include "qapi/error.h" |
| #include "block/aio.h" |
| #include "block/thread-pool.h" |
| #include "qemu/main-loop.h" |
| #include "qemu/atomic.h" |
| #include "qemu/rcu_queue.h" |
| #include "block/raw-aio.h" |
| #include "qemu/coroutine_int.h" |
| #include "trace.h" |
| |
| /***********************************************************/ |
| /* bottom halves (can be seen as timers which expire ASAP) */ |
| |
| /* QEMUBH::flags values */ |
| enum { |
| /* Already enqueued and waiting for aio_bh_poll() */ |
| BH_PENDING = (1 << 0), |
| |
| /* Invoke the callback */ |
| BH_SCHEDULED = (1 << 1), |
| |
| /* Delete without invoking callback */ |
| BH_DELETED = (1 << 2), |
| |
| /* Delete after invoking callback */ |
| BH_ONESHOT = (1 << 3), |
| |
| /* Schedule periodically when the event loop is idle */ |
| BH_IDLE = (1 << 4), |
| }; |
| |
| struct QEMUBH { |
| AioContext *ctx; |
| const char *name; |
| QEMUBHFunc *cb; |
| void *opaque; |
| QSLIST_ENTRY(QEMUBH) next; |
| unsigned flags; |
| }; |
| |
| /* Called concurrently from any thread */ |
| static void aio_bh_enqueue(QEMUBH *bh, unsigned new_flags) |
| { |
| AioContext *ctx = bh->ctx; |
| unsigned old_flags; |
| |
| /* |
| * The memory barrier implicit in qatomic_fetch_or makes sure that: |
| * 1. idle & any writes needed by the callback are done before the |
| * locations are read in the aio_bh_poll. |
| * 2. ctx is loaded before the callback has a chance to execute and bh |
| * could be freed. |
| */ |
| old_flags = qatomic_fetch_or(&bh->flags, BH_PENDING | new_flags); |
| if (!(old_flags & BH_PENDING)) { |
| QSLIST_INSERT_HEAD_ATOMIC(&ctx->bh_list, bh, next); |
| } |
| |
| aio_notify(ctx); |
| } |
| |
| /* Only called from aio_bh_poll() and aio_ctx_finalize() */ |
| static QEMUBH *aio_bh_dequeue(BHList *head, unsigned *flags) |
| { |
| QEMUBH *bh = QSLIST_FIRST_RCU(head); |
| |
| if (!bh) { |
| return NULL; |
| } |
| |
| QSLIST_REMOVE_HEAD(head, next); |
| |
| /* |
| * The qatomic_and is paired with aio_bh_enqueue(). The implicit memory |
| * barrier ensures that the callback sees all writes done by the scheduling |
| * thread. It also ensures that the scheduling thread sees the cleared |
| * flag before bh->cb has run, and thus will call aio_notify again if |
| * necessary. |
| */ |
| *flags = qatomic_fetch_and(&bh->flags, |
| ~(BH_PENDING | BH_SCHEDULED | BH_IDLE)); |
| return bh; |
| } |
| |
| void aio_bh_schedule_oneshot_full(AioContext *ctx, QEMUBHFunc *cb, |
| void *opaque, const char *name) |
| { |
| QEMUBH *bh; |
| bh = g_new(QEMUBH, 1); |
| *bh = (QEMUBH){ |
| .ctx = ctx, |
| .cb = cb, |
| .opaque = opaque, |
| .name = name, |
| }; |
| aio_bh_enqueue(bh, BH_SCHEDULED | BH_ONESHOT); |
| } |
| |
| QEMUBH *aio_bh_new_full(AioContext *ctx, QEMUBHFunc *cb, void *opaque, |
| const char *name) |
| { |
| QEMUBH *bh; |
| bh = g_new(QEMUBH, 1); |
| *bh = (QEMUBH){ |
| .ctx = ctx, |
| .cb = cb, |
| .opaque = opaque, |
| .name = name, |
| }; |
| return bh; |
| } |
| |
| void aio_bh_call(QEMUBH *bh) |
| { |
| bh->cb(bh->opaque); |
| } |
| |
| /* Multiple occurrences of aio_bh_poll cannot be called concurrently. */ |
| int aio_bh_poll(AioContext *ctx) |
| { |
| BHListSlice slice; |
| BHListSlice *s; |
| int ret = 0; |
| |
| QSLIST_MOVE_ATOMIC(&slice.bh_list, &ctx->bh_list); |
| QSIMPLEQ_INSERT_TAIL(&ctx->bh_slice_list, &slice, next); |
| |
| while ((s = QSIMPLEQ_FIRST(&ctx->bh_slice_list))) { |
| QEMUBH *bh; |
| unsigned flags; |
| |
| bh = aio_bh_dequeue(&s->bh_list, &flags); |
| if (!bh) { |
| QSIMPLEQ_REMOVE_HEAD(&ctx->bh_slice_list, next); |
| continue; |
| } |
| |
| if ((flags & (BH_SCHEDULED | BH_DELETED)) == BH_SCHEDULED) { |
| /* Idle BHs don't count as progress */ |
| if (!(flags & BH_IDLE)) { |
| ret = 1; |
| } |
| aio_bh_call(bh); |
| } |
| if (flags & (BH_DELETED | BH_ONESHOT)) { |
| g_free(bh); |
| } |
| } |
| |
| return ret; |
| } |
| |
| void qemu_bh_schedule_idle(QEMUBH *bh) |
| { |
| aio_bh_enqueue(bh, BH_SCHEDULED | BH_IDLE); |
| } |
| |
| void qemu_bh_schedule(QEMUBH *bh) |
| { |
| aio_bh_enqueue(bh, BH_SCHEDULED); |
| } |
| |
| /* This func is async. |
| */ |
| void qemu_bh_cancel(QEMUBH *bh) |
| { |
| qatomic_and(&bh->flags, ~BH_SCHEDULED); |
| } |
| |
| /* This func is async.The bottom half will do the delete action at the finial |
| * end. |
| */ |
| void qemu_bh_delete(QEMUBH *bh) |
| { |
| aio_bh_enqueue(bh, BH_DELETED); |
| } |
| |
| static int64_t aio_compute_bh_timeout(BHList *head, int timeout) |
| { |
| QEMUBH *bh; |
| |
| QSLIST_FOREACH_RCU(bh, head, next) { |
| if ((bh->flags & (BH_SCHEDULED | BH_DELETED)) == BH_SCHEDULED) { |
| if (bh->flags & BH_IDLE) { |
| /* idle bottom halves will be polled at least |
| * every 10ms */ |
| timeout = 10000000; |
| } else { |
| /* non-idle bottom halves will be executed |
| * immediately */ |
| return 0; |
| } |
| } |
| } |
| |
| return timeout; |
| } |
| |
| int64_t |
| aio_compute_timeout(AioContext *ctx) |
| { |
| BHListSlice *s; |
| int64_t deadline; |
| int timeout = -1; |
| |
| timeout = aio_compute_bh_timeout(&ctx->bh_list, timeout); |
| if (timeout == 0) { |
| return 0; |
| } |
| |
| QSIMPLEQ_FOREACH(s, &ctx->bh_slice_list, next) { |
| timeout = aio_compute_bh_timeout(&s->bh_list, timeout); |
| if (timeout == 0) { |
| return 0; |
| } |
| } |
| |
| deadline = timerlistgroup_deadline_ns(&ctx->tlg); |
| if (deadline == 0) { |
| return 0; |
| } else { |
| return qemu_soonest_timeout(timeout, deadline); |
| } |
| } |
| |
| static gboolean |
| aio_ctx_prepare(GSource *source, gint *timeout) |
| { |
| AioContext *ctx = (AioContext *) source; |
| |
| qatomic_set(&ctx->notify_me, qatomic_read(&ctx->notify_me) | 1); |
| |
| /* |
| * Write ctx->notify_me before computing the timeout |
| * (reading bottom half flags, etc.). Pairs with |
| * smp_mb in aio_notify(). |
| */ |
| smp_mb(); |
| |
| /* We assume there is no timeout already supplied */ |
| *timeout = qemu_timeout_ns_to_ms(aio_compute_timeout(ctx)); |
| |
| if (aio_prepare(ctx)) { |
| *timeout = 0; |
| } |
| |
| return *timeout == 0; |
| } |
| |
| static gboolean |
| aio_ctx_check(GSource *source) |
| { |
| AioContext *ctx = (AioContext *) source; |
| QEMUBH *bh; |
| BHListSlice *s; |
| |
| /* Finish computing the timeout before clearing the flag. */ |
| qatomic_store_release(&ctx->notify_me, qatomic_read(&ctx->notify_me) & ~1); |
| aio_notify_accept(ctx); |
| |
| QSLIST_FOREACH_RCU(bh, &ctx->bh_list, next) { |
| if ((bh->flags & (BH_SCHEDULED | BH_DELETED)) == BH_SCHEDULED) { |
| return true; |
| } |
| } |
| |
| QSIMPLEQ_FOREACH(s, &ctx->bh_slice_list, next) { |
| QSLIST_FOREACH_RCU(bh, &s->bh_list, next) { |
| if ((bh->flags & (BH_SCHEDULED | BH_DELETED)) == BH_SCHEDULED) { |
| return true; |
| } |
| } |
| } |
| return aio_pending(ctx) || (timerlistgroup_deadline_ns(&ctx->tlg) == 0); |
| } |
| |
| static gboolean |
| aio_ctx_dispatch(GSource *source, |
| GSourceFunc callback, |
| gpointer user_data) |
| { |
| AioContext *ctx = (AioContext *) source; |
| |
| assert(callback == NULL); |
| aio_dispatch(ctx); |
| return true; |
| } |
| |
| static void |
| aio_ctx_finalize(GSource *source) |
| { |
| AioContext *ctx = (AioContext *) source; |
| QEMUBH *bh; |
| unsigned flags; |
| |
| thread_pool_free(ctx->thread_pool); |
| |
| #ifdef CONFIG_LINUX_AIO |
| if (ctx->linux_aio) { |
| laio_detach_aio_context(ctx->linux_aio, ctx); |
| laio_cleanup(ctx->linux_aio); |
| ctx->linux_aio = NULL; |
| } |
| #endif |
| |
| #ifdef CONFIG_LINUX_IO_URING |
| if (ctx->linux_io_uring) { |
| luring_detach_aio_context(ctx->linux_io_uring, ctx); |
| luring_cleanup(ctx->linux_io_uring); |
| ctx->linux_io_uring = NULL; |
| } |
| #endif |
| |
| assert(QSLIST_EMPTY(&ctx->scheduled_coroutines)); |
| qemu_bh_delete(ctx->co_schedule_bh); |
| |
| /* There must be no aio_bh_poll() calls going on */ |
| assert(QSIMPLEQ_EMPTY(&ctx->bh_slice_list)); |
| |
| while ((bh = aio_bh_dequeue(&ctx->bh_list, &flags))) { |
| /* |
| * qemu_bh_delete() must have been called on BHs in this AioContext. In |
| * many cases memory leaks, hangs, or inconsistent state occur when a |
| * BH is leaked because something still expects it to run. |
| * |
| * If you hit this, fix the lifecycle of the BH so that |
| * qemu_bh_delete() and any associated cleanup is called before the |
| * AioContext is finalized. |
| */ |
| if (unlikely(!(flags & BH_DELETED))) { |
| fprintf(stderr, "%s: BH '%s' leaked, aborting...\n", |
| __func__, bh->name); |
| abort(); |
| } |
| |
| g_free(bh); |
| } |
| |
| aio_set_event_notifier(ctx, &ctx->notifier, false, NULL, NULL); |
| event_notifier_cleanup(&ctx->notifier); |
| qemu_rec_mutex_destroy(&ctx->lock); |
| qemu_lockcnt_destroy(&ctx->list_lock); |
| timerlistgroup_deinit(&ctx->tlg); |
| aio_context_destroy(ctx); |
| } |
| |
| static GSourceFuncs aio_source_funcs = { |
| aio_ctx_prepare, |
| aio_ctx_check, |
| aio_ctx_dispatch, |
| aio_ctx_finalize |
| }; |
| |
| GSource *aio_get_g_source(AioContext *ctx) |
| { |
| aio_context_use_g_source(ctx); |
| g_source_ref(&ctx->source); |
| return &ctx->source; |
| } |
| |
| ThreadPool *aio_get_thread_pool(AioContext *ctx) |
| { |
| if (!ctx->thread_pool) { |
| ctx->thread_pool = thread_pool_new(ctx); |
| } |
| return ctx->thread_pool; |
| } |
| |
| #ifdef CONFIG_LINUX_AIO |
| LinuxAioState *aio_setup_linux_aio(AioContext *ctx, Error **errp) |
| { |
| if (!ctx->linux_aio) { |
| ctx->linux_aio = laio_init(errp); |
| if (ctx->linux_aio) { |
| laio_attach_aio_context(ctx->linux_aio, ctx); |
| } |
| } |
| return ctx->linux_aio; |
| } |
| |
| LinuxAioState *aio_get_linux_aio(AioContext *ctx) |
| { |
| assert(ctx->linux_aio); |
| return ctx->linux_aio; |
| } |
| #endif |
| |
| #ifdef CONFIG_LINUX_IO_URING |
| LuringState *aio_setup_linux_io_uring(AioContext *ctx, Error **errp) |
| { |
| if (ctx->linux_io_uring) { |
| return ctx->linux_io_uring; |
| } |
| |
| ctx->linux_io_uring = luring_init(errp); |
| if (!ctx->linux_io_uring) { |
| return NULL; |
| } |
| |
| luring_attach_aio_context(ctx->linux_io_uring, ctx); |
| return ctx->linux_io_uring; |
| } |
| |
| LuringState *aio_get_linux_io_uring(AioContext *ctx) |
| { |
| assert(ctx->linux_io_uring); |
| return ctx->linux_io_uring; |
| } |
| #endif |
| |
| void aio_notify(AioContext *ctx) |
| { |
| /* |
| * Write e.g. bh->flags before writing ctx->notified. Pairs with smp_mb in |
| * aio_notify_accept. |
| */ |
| smp_wmb(); |
| qatomic_set(&ctx->notified, true); |
| |
| /* |
| * Write ctx->notified before reading ctx->notify_me. Pairs |
| * with smp_mb in aio_ctx_prepare or aio_poll. |
| */ |
| smp_mb(); |
| if (qatomic_read(&ctx->notify_me)) { |
| event_notifier_set(&ctx->notifier); |
| } |
| } |
| |
| void aio_notify_accept(AioContext *ctx) |
| { |
| qatomic_set(&ctx->notified, false); |
| |
| /* |
| * Write ctx->notified before reading e.g. bh->flags. Pairs with smp_wmb |
| * in aio_notify. |
| */ |
| smp_mb(); |
| } |
| |
| static void aio_timerlist_notify(void *opaque, QEMUClockType type) |
| { |
| aio_notify(opaque); |
| } |
| |
| static void aio_context_notifier_cb(EventNotifier *e) |
| { |
| AioContext *ctx = container_of(e, AioContext, notifier); |
| |
| event_notifier_test_and_clear(&ctx->notifier); |
| } |
| |
| /* Returns true if aio_notify() was called (e.g. a BH was scheduled) */ |
| static bool aio_context_notifier_poll(void *opaque) |
| { |
| EventNotifier *e = opaque; |
| AioContext *ctx = container_of(e, AioContext, notifier); |
| |
| return qatomic_read(&ctx->notified); |
| } |
| |
| static void co_schedule_bh_cb(void *opaque) |
| { |
| AioContext *ctx = opaque; |
| QSLIST_HEAD(, Coroutine) straight, reversed; |
| |
| QSLIST_MOVE_ATOMIC(&reversed, &ctx->scheduled_coroutines); |
| QSLIST_INIT(&straight); |
| |
| while (!QSLIST_EMPTY(&reversed)) { |
| Coroutine *co = QSLIST_FIRST(&reversed); |
| QSLIST_REMOVE_HEAD(&reversed, co_scheduled_next); |
| QSLIST_INSERT_HEAD(&straight, co, co_scheduled_next); |
| } |
| |
| while (!QSLIST_EMPTY(&straight)) { |
| Coroutine *co = QSLIST_FIRST(&straight); |
| QSLIST_REMOVE_HEAD(&straight, co_scheduled_next); |
| trace_aio_co_schedule_bh_cb(ctx, co); |
| aio_context_acquire(ctx); |
| |
| /* Protected by write barrier in qemu_aio_coroutine_enter */ |
| qatomic_set(&co->scheduled, NULL); |
| qemu_aio_coroutine_enter(ctx, co); |
| aio_context_release(ctx); |
| } |
| } |
| |
| AioContext *aio_context_new(Error **errp) |
| { |
| int ret; |
| AioContext *ctx; |
| |
| ctx = (AioContext *) g_source_new(&aio_source_funcs, sizeof(AioContext)); |
| QSLIST_INIT(&ctx->bh_list); |
| QSIMPLEQ_INIT(&ctx->bh_slice_list); |
| aio_context_setup(ctx); |
| |
| ret = event_notifier_init(&ctx->notifier, false); |
| if (ret < 0) { |
| error_setg_errno(errp, -ret, "Failed to initialize event notifier"); |
| goto fail; |
| } |
| g_source_set_can_recurse(&ctx->source, true); |
| qemu_lockcnt_init(&ctx->list_lock); |
| |
| ctx->co_schedule_bh = aio_bh_new(ctx, co_schedule_bh_cb, ctx); |
| QSLIST_INIT(&ctx->scheduled_coroutines); |
| |
| aio_set_event_notifier(ctx, &ctx->notifier, |
| false, |
| aio_context_notifier_cb, |
| aio_context_notifier_poll); |
| #ifdef CONFIG_LINUX_AIO |
| ctx->linux_aio = NULL; |
| #endif |
| |
| #ifdef CONFIG_LINUX_IO_URING |
| ctx->linux_io_uring = NULL; |
| #endif |
| |
| ctx->thread_pool = NULL; |
| qemu_rec_mutex_init(&ctx->lock); |
| timerlistgroup_init(&ctx->tlg, aio_timerlist_notify, ctx); |
| |
| ctx->poll_ns = 0; |
| ctx->poll_max_ns = 0; |
| ctx->poll_grow = 0; |
| ctx->poll_shrink = 0; |
| |
| return ctx; |
| fail: |
| g_source_destroy(&ctx->source); |
| return NULL; |
| } |
| |
| void aio_co_schedule(AioContext *ctx, Coroutine *co) |
| { |
| trace_aio_co_schedule(ctx, co); |
| const char *scheduled = qatomic_cmpxchg(&co->scheduled, NULL, |
| __func__); |
| |
| if (scheduled) { |
| fprintf(stderr, |
| "%s: Co-routine was already scheduled in '%s'\n", |
| __func__, scheduled); |
| abort(); |
| } |
| |
| /* The coroutine might run and release the last ctx reference before we |
| * invoke qemu_bh_schedule(). Take a reference to keep ctx alive until |
| * we're done. |
| */ |
| aio_context_ref(ctx); |
| |
| QSLIST_INSERT_HEAD_ATOMIC(&ctx->scheduled_coroutines, |
| co, co_scheduled_next); |
| qemu_bh_schedule(ctx->co_schedule_bh); |
| |
| aio_context_unref(ctx); |
| } |
| |
| typedef struct AioCoRescheduleSelf { |
| Coroutine *co; |
| AioContext *new_ctx; |
| } AioCoRescheduleSelf; |
| |
| static void aio_co_reschedule_self_bh(void *opaque) |
| { |
| AioCoRescheduleSelf *data = opaque; |
| aio_co_schedule(data->new_ctx, data->co); |
| } |
| |
| void coroutine_fn aio_co_reschedule_self(AioContext *new_ctx) |
| { |
| AioContext *old_ctx = qemu_get_current_aio_context(); |
| |
| if (old_ctx != new_ctx) { |
| AioCoRescheduleSelf data = { |
| .co = qemu_coroutine_self(), |
| .new_ctx = new_ctx, |
| }; |
| /* |
| * We can't directly schedule the coroutine in the target context |
| * because this would be racy: The other thread could try to enter the |
| * coroutine before it has yielded in this one. |
| */ |
| aio_bh_schedule_oneshot(old_ctx, aio_co_reschedule_self_bh, &data); |
| qemu_coroutine_yield(); |
| } |
| } |
| |
| void aio_co_wake(struct Coroutine *co) |
| { |
| AioContext *ctx; |
| |
| /* Read coroutine before co->ctx. Matches smp_wmb in |
| * qemu_coroutine_enter. |
| */ |
| smp_read_barrier_depends(); |
| ctx = qatomic_read(&co->ctx); |
| |
| aio_co_enter(ctx, co); |
| } |
| |
| void aio_co_enter(AioContext *ctx, struct Coroutine *co) |
| { |
| if (ctx != qemu_get_current_aio_context()) { |
| aio_co_schedule(ctx, co); |
| return; |
| } |
| |
| if (qemu_in_coroutine()) { |
| Coroutine *self = qemu_coroutine_self(); |
| assert(self != co); |
| QSIMPLEQ_INSERT_TAIL(&self->co_queue_wakeup, co, co_queue_next); |
| } else { |
| aio_context_acquire(ctx); |
| qemu_aio_coroutine_enter(ctx, co); |
| aio_context_release(ctx); |
| } |
| } |
| |
| void aio_context_ref(AioContext *ctx) |
| { |
| g_source_ref(&ctx->source); |
| } |
| |
| void aio_context_unref(AioContext *ctx) |
| { |
| g_source_unref(&ctx->source); |
| } |
| |
| void aio_context_acquire(AioContext *ctx) |
| { |
| qemu_rec_mutex_lock(&ctx->lock); |
| } |
| |
| void aio_context_release(AioContext *ctx) |
| { |
| qemu_rec_mutex_unlock(&ctx->lock); |
| } |
| |
| static __thread AioContext *my_aiocontext; |
| |
| AioContext *qemu_get_current_aio_context(void) |
| { |
| if (my_aiocontext) { |
| return my_aiocontext; |
| } |
| if (qemu_mutex_iothread_locked()) { |
| /* Possibly in a vCPU thread. */ |
| return qemu_get_aio_context(); |
| } |
| return NULL; |
| } |
| |
| void qemu_set_current_aio_context(AioContext *ctx) |
| { |
| assert(!my_aiocontext); |
| my_aiocontext = ctx; |
| } |