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authorTimos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>2023-10-10 11:40:56 +0000
committerTimos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>2023-10-10 11:40:56 +0000
commite02cda008591317b1625707ff8e115a4841aa889 (patch)
treeaee302e3cf8b59ec2d32ec481be3d1afddfc8968 /include/block/aio.h
parentcc668e6b7e0ffd8c9d130513d12053cf5eda1d3b (diff)
Introduce Virtio-loopback epsilon release:
Epsilon release introduces a new compatibility layer which make virtio-loopback design to work with QEMU and rust-vmm vhost-user backend without require any changes. Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com> Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9
Diffstat (limited to 'include/block/aio.h')
-rw-r--r--include/block/aio.h770
1 files changed, 770 insertions, 0 deletions
diff --git a/include/block/aio.h b/include/block/aio.h
new file mode 100644
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--- /dev/null
+++ b/include/block/aio.h
@@ -0,0 +1,770 @@
+/*
+ * QEMU aio implementation
+ *
+ * Copyright IBM, Corp. 2008
+ *
+ * Authors:
+ * Anthony Liguori <aliguori@us.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2. See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+#ifndef QEMU_AIO_H
+#define QEMU_AIO_H
+
+#ifdef CONFIG_LINUX_IO_URING
+#include <liburing.h>
+#endif
+#include "qemu/coroutine.h"
+#include "qemu/queue.h"
+#include "qemu/event_notifier.h"
+#include "qemu/thread.h"
+#include "qemu/timer.h"
+
+typedef struct BlockAIOCB BlockAIOCB;
+typedef void BlockCompletionFunc(void *opaque, int ret);
+
+typedef struct AIOCBInfo {
+ void (*cancel_async)(BlockAIOCB *acb);
+ AioContext *(*get_aio_context)(BlockAIOCB *acb);
+ size_t aiocb_size;
+} AIOCBInfo;
+
+struct BlockAIOCB {
+ const AIOCBInfo *aiocb_info;
+ BlockDriverState *bs;
+ BlockCompletionFunc *cb;
+ void *opaque;
+ int refcnt;
+};
+
+void *qemu_aio_get(const AIOCBInfo *aiocb_info, BlockDriverState *bs,
+ BlockCompletionFunc *cb, void *opaque);
+void qemu_aio_unref(void *p);
+void qemu_aio_ref(void *p);
+
+typedef struct AioHandler AioHandler;
+typedef QLIST_HEAD(, AioHandler) AioHandlerList;
+typedef void QEMUBHFunc(void *opaque);
+typedef bool AioPollFn(void *opaque);
+typedef void IOHandler(void *opaque);
+
+struct Coroutine;
+struct ThreadPool;
+struct LinuxAioState;
+struct LuringState;
+
+/* Is polling disabled? */
+bool aio_poll_disabled(AioContext *ctx);
+
+/* Callbacks for file descriptor monitoring implementations */
+typedef struct {
+ /*
+ * update:
+ * @ctx: the AioContext
+ * @old_node: the existing handler or NULL if this file descriptor is being
+ * monitored for the first time
+ * @new_node: the new handler or NULL if this file descriptor is being
+ * removed
+ *
+ * Add/remove/modify a monitored file descriptor.
+ *
+ * Called with ctx->list_lock acquired.
+ */
+ void (*update)(AioContext *ctx, AioHandler *old_node, AioHandler *new_node);
+
+ /*
+ * wait:
+ * @ctx: the AioContext
+ * @ready_list: list for handlers that become ready
+ * @timeout: maximum duration to wait, in nanoseconds
+ *
+ * Wait for file descriptors to become ready and place them on ready_list.
+ *
+ * Called with ctx->list_lock incremented but not locked.
+ *
+ * Returns: number of ready file descriptors.
+ */
+ int (*wait)(AioContext *ctx, AioHandlerList *ready_list, int64_t timeout);
+
+ /*
+ * need_wait:
+ * @ctx: the AioContext
+ *
+ * Tell aio_poll() when to stop userspace polling early because ->wait()
+ * has fds ready.
+ *
+ * File descriptor monitoring implementations that cannot poll fd readiness
+ * from userspace should use aio_poll_disabled() here. This ensures that
+ * file descriptors are not starved by handlers that frequently make
+ * progress via userspace polling.
+ *
+ * Returns: true if ->wait() should be called, false otherwise.
+ */
+ bool (*need_wait)(AioContext *ctx);
+} FDMonOps;
+
+/*
+ * Each aio_bh_poll() call carves off a slice of the BH list, so that newly
+ * scheduled BHs are not processed until the next aio_bh_poll() call. All
+ * active aio_bh_poll() calls chain their slices together in a list, so that
+ * nested aio_bh_poll() calls process all scheduled bottom halves.
+ */
+typedef QSLIST_HEAD(, QEMUBH) BHList;
+typedef struct BHListSlice BHListSlice;
+struct BHListSlice {
+ BHList bh_list;
+ QSIMPLEQ_ENTRY(BHListSlice) next;
+};
+
+typedef QSLIST_HEAD(, AioHandler) AioHandlerSList;
+
+struct AioContext {
+ GSource source;
+
+ /* Used by AioContext users to protect from multi-threaded access. */
+ QemuRecMutex lock;
+
+ /* The list of registered AIO handlers. Protected by ctx->list_lock. */
+ AioHandlerList aio_handlers;
+
+ /* The list of AIO handlers to be deleted. Protected by ctx->list_lock. */
+ AioHandlerList deleted_aio_handlers;
+
+ /* Used to avoid unnecessary event_notifier_set calls in aio_notify;
+ * only written from the AioContext home thread, or under the BQL in
+ * the case of the main AioContext. However, it is read from any
+ * thread so it is still accessed with atomic primitives.
+ *
+ * If this field is 0, everything (file descriptors, bottom halves,
+ * timers) will be re-evaluated before the next blocking poll() or
+ * io_uring wait; therefore, the event_notifier_set call can be
+ * skipped. If it is non-zero, you may need to wake up a concurrent
+ * aio_poll or the glib main event loop, making event_notifier_set
+ * necessary.
+ *
+ * Bit 0 is reserved for GSource usage of the AioContext, and is 1
+ * between a call to aio_ctx_prepare and the next call to aio_ctx_check.
+ * Bits 1-31 simply count the number of active calls to aio_poll
+ * that are in the prepare or poll phase.
+ *
+ * The GSource and aio_poll must use a different mechanism because
+ * there is no certainty that a call to GSource's prepare callback
+ * (via g_main_context_prepare) is indeed followed by check and
+ * dispatch. It's not clear whether this would be a bug, but let's
+ * play safe and allow it---it will just cause extra calls to
+ * event_notifier_set until the next call to dispatch.
+ *
+ * Instead, the aio_poll calls include both the prepare and the
+ * dispatch phase, hence a simple counter is enough for them.
+ */
+ uint32_t notify_me;
+
+ /* A lock to protect between QEMUBH and AioHandler adders and deleter,
+ * and to ensure that no callbacks are removed while we're walking and
+ * dispatching them.
+ */
+ QemuLockCnt list_lock;
+
+ /* Bottom Halves pending aio_bh_poll() processing */
+ BHList bh_list;
+
+ /* Chained BH list slices for each nested aio_bh_poll() call */
+ QSIMPLEQ_HEAD(, BHListSlice) bh_slice_list;
+
+ /* Used by aio_notify.
+ *
+ * "notified" is used to avoid expensive event_notifier_test_and_clear
+ * calls. When it is clear, the EventNotifier is clear, or one thread
+ * is going to clear "notified" before processing more events. False
+ * positives are possible, i.e. "notified" could be set even though the
+ * EventNotifier is clear.
+ *
+ * Note that event_notifier_set *cannot* be optimized the same way. For
+ * more information on the problem that would result, see "#ifdef BUG2"
+ * in the docs/aio_notify_accept.promela formal model.
+ */
+ bool notified;
+ EventNotifier notifier;
+
+ QSLIST_HEAD(, Coroutine) scheduled_coroutines;
+ QEMUBH *co_schedule_bh;
+
+ /* Thread pool for performing work and receiving completion callbacks.
+ * Has its own locking.
+ */
+ struct ThreadPool *thread_pool;
+
+#ifdef CONFIG_LINUX_AIO
+ /*
+ * State for native Linux AIO. Uses aio_context_acquire/release for
+ * locking.
+ */
+ struct LinuxAioState *linux_aio;
+#endif
+#ifdef CONFIG_LINUX_IO_URING
+ /*
+ * State for Linux io_uring. Uses aio_context_acquire/release for
+ * locking.
+ */
+ struct LuringState *linux_io_uring;
+
+ /* State for file descriptor monitoring using Linux io_uring */
+ struct io_uring fdmon_io_uring;
+ AioHandlerSList submit_list;
+#endif
+
+ /* TimerLists for calling timers - one per clock type. Has its own
+ * locking.
+ */
+ QEMUTimerListGroup tlg;
+
+ int external_disable_cnt;
+
+ /* Number of AioHandlers without .io_poll() */
+ int poll_disable_cnt;
+
+ /* Polling mode parameters */
+ int64_t poll_ns; /* current polling time in nanoseconds */
+ int64_t poll_max_ns; /* maximum polling time in nanoseconds */
+ int64_t poll_grow; /* polling time growth factor */
+ int64_t poll_shrink; /* polling time shrink factor */
+
+ /* AIO engine parameters */
+ int64_t aio_max_batch; /* maximum number of requests in a batch */
+
+ /*
+ * List of handlers participating in userspace polling. Protected by
+ * ctx->list_lock. Iterated and modified mostly by the event loop thread
+ * from aio_poll() with ctx->list_lock incremented. aio_set_fd_handler()
+ * only touches the list to delete nodes if ctx->list_lock's count is zero.
+ */
+ AioHandlerList poll_aio_handlers;
+
+ /* Are we in polling mode or monitoring file descriptors? */
+ bool poll_started;
+
+ /* epoll(7) state used when built with CONFIG_EPOLL */
+ int epollfd;
+
+ const FDMonOps *fdmon_ops;
+};
+
+/**
+ * aio_context_new: Allocate a new AioContext.
+ *
+ * AioContext provide a mini event-loop that can be waited on synchronously.
+ * They also provide bottom halves, a service to execute a piece of code
+ * as soon as possible.
+ */
+AioContext *aio_context_new(Error **errp);
+
+/**
+ * aio_context_ref:
+ * @ctx: The AioContext to operate on.
+ *
+ * Add a reference to an AioContext.
+ */
+void aio_context_ref(AioContext *ctx);
+
+/**
+ * aio_context_unref:
+ * @ctx: The AioContext to operate on.
+ *
+ * Drop a reference to an AioContext.
+ */
+void aio_context_unref(AioContext *ctx);
+
+/* Take ownership of the AioContext. If the AioContext will be shared between
+ * threads, and a thread does not want to be interrupted, it will have to
+ * take ownership around calls to aio_poll(). Otherwise, aio_poll()
+ * automatically takes care of calling aio_context_acquire and
+ * aio_context_release.
+ *
+ * Note that this is separate from bdrv_drained_begin/bdrv_drained_end. A
+ * thread still has to call those to avoid being interrupted by the guest.
+ *
+ * Bottom halves, timers and callbacks can be created or removed without
+ * acquiring the AioContext.
+ */
+void aio_context_acquire(AioContext *ctx);
+
+/* Relinquish ownership of the AioContext. */
+void aio_context_release(AioContext *ctx);
+
+/**
+ * aio_bh_schedule_oneshot_full: Allocate a new bottom half structure that will
+ * run only once and as soon as possible.
+ *
+ * @name: A human-readable identifier for debugging purposes.
+ */
+void aio_bh_schedule_oneshot_full(AioContext *ctx, QEMUBHFunc *cb, void *opaque,
+ const char *name);
+
+/**
+ * aio_bh_schedule_oneshot: Allocate a new bottom half structure that will run
+ * only once and as soon as possible.
+ *
+ * A convenience wrapper for aio_bh_schedule_oneshot_full() that uses cb as the
+ * name string.
+ */
+#define aio_bh_schedule_oneshot(ctx, cb, opaque) \
+ aio_bh_schedule_oneshot_full((ctx), (cb), (opaque), (stringify(cb)))
+
+/**
+ * aio_bh_new_full: Allocate a new bottom half structure.
+ *
+ * Bottom halves are lightweight callbacks whose invocation is guaranteed
+ * to be wait-free, thread-safe and signal-safe. The #QEMUBH structure
+ * is opaque and must be allocated prior to its use.
+ *
+ * @name: A human-readable identifier for debugging purposes.
+ */
+QEMUBH *aio_bh_new_full(AioContext *ctx, QEMUBHFunc *cb, void *opaque,
+ const char *name);
+
+/**
+ * aio_bh_new: Allocate a new bottom half structure
+ *
+ * A convenience wrapper for aio_bh_new_full() that uses the cb as the name
+ * string.
+ */
+#define aio_bh_new(ctx, cb, opaque) \
+ aio_bh_new_full((ctx), (cb), (opaque), (stringify(cb)))
+
+/**
+ * aio_notify: Force processing of pending events.
+ *
+ * Similar to signaling a condition variable, aio_notify forces
+ * aio_poll to exit, so that the next call will re-examine pending events.
+ * The caller of aio_notify will usually call aio_poll again very soon,
+ * or go through another iteration of the GLib main loop. Hence, aio_notify
+ * also has the side effect of recalculating the sets of file descriptors
+ * that the main loop waits for.
+ *
+ * Calling aio_notify is rarely necessary, because for example scheduling
+ * a bottom half calls it already.
+ */
+void aio_notify(AioContext *ctx);
+
+/**
+ * aio_notify_accept: Acknowledge receiving an aio_notify.
+ *
+ * aio_notify() uses an EventNotifier in order to wake up a sleeping
+ * aio_poll() or g_main_context_iteration(). Calls to aio_notify() are
+ * usually rare, but the AioContext has to clear the EventNotifier on
+ * every aio_poll() or g_main_context_iteration() in order to avoid
+ * busy waiting. This event_notifier_test_and_clear() cannot be done
+ * using the usual aio_context_set_event_notifier(), because it must
+ * be done before processing all events (file descriptors, bottom halves,
+ * timers).
+ *
+ * aio_notify_accept() is an optimized event_notifier_test_and_clear()
+ * that is specific to an AioContext's notifier; it is used internally
+ * to clear the EventNotifier only if aio_notify() had been called.
+ */
+void aio_notify_accept(AioContext *ctx);
+
+/**
+ * aio_bh_call: Executes callback function of the specified BH.
+ */
+void aio_bh_call(QEMUBH *bh);
+
+/**
+ * aio_bh_poll: Poll bottom halves for an AioContext.
+ *
+ * These are internal functions used by the QEMU main loop.
+ * And notice that multiple occurrences of aio_bh_poll cannot
+ * be called concurrently
+ */
+int aio_bh_poll(AioContext *ctx);
+
+/**
+ * qemu_bh_schedule: Schedule a bottom half.
+ *
+ * Scheduling a bottom half interrupts the main loop and causes the
+ * execution of the callback that was passed to qemu_bh_new.
+ *
+ * Bottom halves that are scheduled from a bottom half handler are instantly
+ * invoked. This can create an infinite loop if a bottom half handler
+ * schedules itself.
+ *
+ * @bh: The bottom half to be scheduled.
+ */
+void qemu_bh_schedule(QEMUBH *bh);
+
+/**
+ * qemu_bh_cancel: Cancel execution of a bottom half.
+ *
+ * Canceling execution of a bottom half undoes the effect of calls to
+ * qemu_bh_schedule without freeing its resources yet. While cancellation
+ * itself is also wait-free and thread-safe, it can of course race with the
+ * loop that executes bottom halves unless you are holding the iothread
+ * mutex. This makes it mostly useless if you are not holding the mutex.
+ *
+ * @bh: The bottom half to be canceled.
+ */
+void qemu_bh_cancel(QEMUBH *bh);
+
+/**
+ *qemu_bh_delete: Cancel execution of a bottom half and free its resources.
+ *
+ * Deleting a bottom half frees the memory that was allocated for it by
+ * qemu_bh_new. It also implies canceling the bottom half if it was
+ * scheduled.
+ * This func is async. The bottom half will do the delete action at the finial
+ * end.
+ *
+ * @bh: The bottom half to be deleted.
+ */
+void qemu_bh_delete(QEMUBH *bh);
+
+/* Return whether there are any pending callbacks from the GSource
+ * attached to the AioContext, before g_poll is invoked.
+ *
+ * This is used internally in the implementation of the GSource.
+ */
+bool aio_prepare(AioContext *ctx);
+
+/* Return whether there are any pending callbacks from the GSource
+ * attached to the AioContext, after g_poll is invoked.
+ *
+ * This is used internally in the implementation of the GSource.
+ */
+bool aio_pending(AioContext *ctx);
+
+/* Dispatch any pending callbacks from the GSource attached to the AioContext.
+ *
+ * This is used internally in the implementation of the GSource.
+ */
+void aio_dispatch(AioContext *ctx);
+
+/* Progress in completing AIO work to occur. This can issue new pending
+ * aio as a result of executing I/O completion or bh callbacks.
+ *
+ * Return whether any progress was made by executing AIO or bottom half
+ * handlers. If @blocking == true, this should always be true except
+ * if someone called aio_notify.
+ *
+ * If there are no pending bottom halves, but there are pending AIO
+ * operations, it may not be possible to make any progress without
+ * blocking. If @blocking is true, this function will wait until one
+ * or more AIO events have completed, to ensure something has moved
+ * before returning.
+ */
+bool aio_poll(AioContext *ctx, bool blocking);
+
+/* Register a file descriptor and associated callbacks. Behaves very similarly
+ * to qemu_set_fd_handler. Unlike qemu_set_fd_handler, these callbacks will
+ * be invoked when using aio_poll().
+ *
+ * Code that invokes AIO completion functions should rely on this function
+ * instead of qemu_set_fd_handler[2].
+ */
+void aio_set_fd_handler(AioContext *ctx,
+ int fd,
+ bool is_external,
+ IOHandler *io_read,
+ IOHandler *io_write,
+ AioPollFn *io_poll,
+ void *opaque);
+
+/* Set polling begin/end callbacks for a file descriptor that has already been
+ * registered with aio_set_fd_handler. Do nothing if the file descriptor is
+ * not registered.
+ */
+void aio_set_fd_poll(AioContext *ctx, int fd,
+ IOHandler *io_poll_begin,
+ IOHandler *io_poll_end);
+
+/* Register an event notifier and associated callbacks. Behaves very similarly
+ * to event_notifier_set_handler. Unlike event_notifier_set_handler, these callbacks
+ * will be invoked when using aio_poll().
+ *
+ * Code that invokes AIO completion functions should rely on this function
+ * instead of event_notifier_set_handler.
+ */
+void aio_set_event_notifier(AioContext *ctx,
+ EventNotifier *notifier,
+ bool is_external,
+ EventNotifierHandler *io_read,
+ AioPollFn *io_poll);
+
+/* Set polling begin/end callbacks for an event notifier that has already been
+ * registered with aio_set_event_notifier. Do nothing if the event notifier is
+ * not registered.
+ */
+void aio_set_event_notifier_poll(AioContext *ctx,
+ EventNotifier *notifier,
+ EventNotifierHandler *io_poll_begin,
+ EventNotifierHandler *io_poll_end);
+
+/* Return a GSource that lets the main loop poll the file descriptors attached
+ * to this AioContext.
+ */
+GSource *aio_get_g_source(AioContext *ctx);
+
+/* Return the ThreadPool bound to this AioContext */
+struct ThreadPool *aio_get_thread_pool(AioContext *ctx);
+
+/* Setup the LinuxAioState bound to this AioContext */
+struct LinuxAioState *aio_setup_linux_aio(AioContext *ctx, Error **errp);
+
+/* Return the LinuxAioState bound to this AioContext */
+struct LinuxAioState *aio_get_linux_aio(AioContext *ctx);
+
+/* Setup the LuringState bound to this AioContext */
+struct LuringState *aio_setup_linux_io_uring(AioContext *ctx, Error **errp);
+
+/* Return the LuringState bound to this AioContext */
+struct LuringState *aio_get_linux_io_uring(AioContext *ctx);
+/**
+ * aio_timer_new_with_attrs:
+ * @ctx: the aio context
+ * @type: the clock type
+ * @scale: the scale
+ * @attributes: 0, or one to multiple OR'ed QEMU_TIMER_ATTR_<id> values
+ * to assign
+ * @cb: the callback to call on timer expiry
+ * @opaque: the opaque pointer to pass to the callback
+ *
+ * Allocate a new timer (with attributes) attached to the context @ctx.
+ * The function is responsible for memory allocation.
+ *
+ * The preferred interface is aio_timer_init or aio_timer_init_with_attrs.
+ * Use that unless you really need dynamic memory allocation.
+ *
+ * Returns: a pointer to the new timer
+ */
+static inline QEMUTimer *aio_timer_new_with_attrs(AioContext *ctx,
+ QEMUClockType type,
+ int scale, int attributes,
+ QEMUTimerCB *cb, void *opaque)
+{
+ return timer_new_full(&ctx->tlg, type, scale, attributes, cb, opaque);
+}
+
+/**
+ * aio_timer_new:
+ * @ctx: the aio context
+ * @type: the clock type
+ * @scale: the scale
+ * @cb: the callback to call on timer expiry
+ * @opaque: the opaque pointer to pass to the callback
+ *
+ * Allocate a new timer attached to the context @ctx.
+ * See aio_timer_new_with_attrs for details.
+ *
+ * Returns: a pointer to the new timer
+ */
+static inline QEMUTimer *aio_timer_new(AioContext *ctx, QEMUClockType type,
+ int scale,
+ QEMUTimerCB *cb, void *opaque)
+{
+ return timer_new_full(&ctx->tlg, type, scale, 0, cb, opaque);
+}
+
+/**
+ * aio_timer_init_with_attrs:
+ * @ctx: the aio context
+ * @ts: the timer
+ * @type: the clock type
+ * @scale: the scale
+ * @attributes: 0, or one to multiple OR'ed QEMU_TIMER_ATTR_<id> values
+ * to assign
+ * @cb: the callback to call on timer expiry
+ * @opaque: the opaque pointer to pass to the callback
+ *
+ * Initialise a new timer (with attributes) attached to the context @ctx.
+ * The caller is responsible for memory allocation.
+ */
+static inline void aio_timer_init_with_attrs(AioContext *ctx,
+ QEMUTimer *ts, QEMUClockType type,
+ int scale, int attributes,
+ QEMUTimerCB *cb, void *opaque)
+{
+ timer_init_full(ts, &ctx->tlg, type, scale, attributes, cb, opaque);
+}
+
+/**
+ * aio_timer_init:
+ * @ctx: the aio context
+ * @ts: the timer
+ * @type: the clock type
+ * @scale: the scale
+ * @cb: the callback to call on timer expiry
+ * @opaque: the opaque pointer to pass to the callback
+ *
+ * Initialise a new timer attached to the context @ctx.
+ * See aio_timer_init_with_attrs for details.
+ */
+static inline void aio_timer_init(AioContext *ctx,
+ QEMUTimer *ts, QEMUClockType type,
+ int scale,
+ QEMUTimerCB *cb, void *opaque)
+{
+ timer_init_full(ts, &ctx->tlg, type, scale, 0, cb, opaque);
+}
+
+/**
+ * aio_compute_timeout:
+ * @ctx: the aio context
+ *
+ * Compute the timeout that a blocking aio_poll should use.
+ */
+int64_t aio_compute_timeout(AioContext *ctx);
+
+/**
+ * aio_disable_external:
+ * @ctx: the aio context
+ *
+ * Disable the further processing of external clients.
+ */
+static inline void aio_disable_external(AioContext *ctx)
+{
+ qatomic_inc(&ctx->external_disable_cnt);
+}
+
+/**
+ * aio_enable_external:
+ * @ctx: the aio context
+ *
+ * Enable the processing of external clients.
+ */
+static inline void aio_enable_external(AioContext *ctx)
+{
+ int old;
+
+ old = qatomic_fetch_dec(&ctx->external_disable_cnt);
+ assert(old > 0);
+ if (old == 1) {
+ /* Kick event loop so it re-arms file descriptors */
+ aio_notify(ctx);
+ }
+}
+
+/**
+ * aio_external_disabled:
+ * @ctx: the aio context
+ *
+ * Return true if the external clients are disabled.
+ */
+static inline bool aio_external_disabled(AioContext *ctx)
+{
+ return qatomic_read(&ctx->external_disable_cnt);
+}
+
+/**
+ * aio_node_check:
+ * @ctx: the aio context
+ * @is_external: Whether or not the checked node is an external event source.
+ *
+ * Check if the node's is_external flag is okay to be polled by the ctx at this
+ * moment. True means green light.
+ */
+static inline bool aio_node_check(AioContext *ctx, bool is_external)
+{
+ return !is_external || !qatomic_read(&ctx->external_disable_cnt);
+}
+
+/**
+ * aio_co_schedule:
+ * @ctx: the aio context
+ * @co: the coroutine
+ *
+ * Start a coroutine on a remote AioContext.
+ *
+ * The coroutine must not be entered by anyone else while aio_co_schedule()
+ * is active. In addition the coroutine must have yielded unless ctx
+ * is the context in which the coroutine is running (i.e. the value of
+ * qemu_get_current_aio_context() from the coroutine itself).
+ */
+void aio_co_schedule(AioContext *ctx, struct Coroutine *co);
+
+/**
+ * aio_co_reschedule_self:
+ * @new_ctx: the new context
+ *
+ * Move the currently running coroutine to new_ctx. If the coroutine is already
+ * running in new_ctx, do nothing.
+ */
+void coroutine_fn aio_co_reschedule_self(AioContext *new_ctx);
+
+/**
+ * aio_co_wake:
+ * @co: the coroutine
+ *
+ * Restart a coroutine on the AioContext where it was running last, thus
+ * preventing coroutines from jumping from one context to another when they
+ * go to sleep.
+ *
+ * aio_co_wake may be executed either in coroutine or non-coroutine
+ * context. The coroutine must not be entered by anyone else while
+ * aio_co_wake() is active.
+ */
+void aio_co_wake(struct Coroutine *co);
+
+/**
+ * aio_co_enter:
+ * @ctx: the context to run the coroutine
+ * @co: the coroutine to run
+ *
+ * Enter a coroutine in the specified AioContext.
+ */
+void aio_co_enter(AioContext *ctx, struct Coroutine *co);
+
+/**
+ * Return the AioContext whose event loop runs in the current thread.
+ *
+ * If called from an IOThread this will be the IOThread's AioContext. If
+ * called from the main thread or with the "big QEMU lock" taken it
+ * will be the main loop AioContext.
+ */
+AioContext *qemu_get_current_aio_context(void);
+
+void qemu_set_current_aio_context(AioContext *ctx);
+
+/**
+ * aio_context_setup:
+ * @ctx: the aio context
+ *
+ * Initialize the aio context.
+ */
+void aio_context_setup(AioContext *ctx);
+
+/**
+ * aio_context_destroy:
+ * @ctx: the aio context
+ *
+ * Destroy the aio context.
+ */
+void aio_context_destroy(AioContext *ctx);
+
+/* Used internally, do not call outside AioContext code */
+void aio_context_use_g_source(AioContext *ctx);
+
+/**
+ * aio_context_set_poll_params:
+ * @ctx: the aio context
+ * @max_ns: how long to busy poll for, in nanoseconds
+ * @grow: polling time growth factor
+ * @shrink: polling time shrink factor
+ *
+ * Poll mode can be disabled by setting poll_max_ns to 0.
+ */
+void aio_context_set_poll_params(AioContext *ctx, int64_t max_ns,
+ int64_t grow, int64_t shrink,
+ Error **errp);
+
+/**
+ * aio_context_set_aio_params:
+ * @ctx: the aio context
+ * @max_batch: maximum number of requests in a batch, 0 means that the
+ * engine will use its default
+ */
+void aio_context_set_aio_params(AioContext *ctx, int64_t max_batch,
+ Error **errp);
+
+#endif