If we want to wake up a coroutine from a worker thread, aio_co_wake() currently does not work. In that scenario, aio_co_wake() calls aio_co_enter(), but there is no current AioContext and therefore qemu_get_current_aio_context() returns the main thread. aio_co_wake() then attempts to call aio_context_acquire() instead of going through aio_co_schedule(). The default case of qemu_get_current_aio_context() was added to cover synchronous I/O started from the vCPU thread, but the main and vCPU threads are quite different. The main thread is an I/O thread itself, only running a more complicated event loop; the vCPU thread instead is essentially a worker thread that occasionally calls qemu_mutex_lock_iothread(). It is only in those critical sections that it acts as if it were the home thread of the main AioContext. Therefore, this patch detaches qemu_get_current_aio_context() from iothreads, which is a useless complication. The AioContext pointer is stored directly in the thread-local variable, including for the main loop. Worker threads (including vCPU threads) optionally behave as temporary home threads if they have taken the big QEMU lock, but if that is not the case they will always schedule coroutines on remote threads via aio_co_schedule(). With this change, the stub qemu_mutex_iothread_locked() must be changed from true to false. The previous value of true was needed because the main thread did not have an AioContext in the thread-local variable, but now it does have one. Reported-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20210609122234.544153-1-pbonzini@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Tested-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> [eblake: tweak commit message per Vladimir's review] Signed-off-by: Eric Blake <eblake@redhat.com>
672 lines
17 KiB
C
672 lines
17 KiB
C
/*
|
|
* 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;
|
|
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(AioContext *ctx, QEMUBHFunc *cb, void *opaque)
|
|
{
|
|
QEMUBH *bh;
|
|
bh = g_new(QEMUBH, 1);
|
|
*bh = (QEMUBH){
|
|
.ctx = ctx,
|
|
.cb = cb,
|
|
.opaque = opaque,
|
|
};
|
|
aio_bh_enqueue(bh, BH_SCHEDULED | BH_ONESHOT);
|
|
}
|
|
|
|
QEMUBH *aio_bh_new(AioContext *ctx, QEMUBHFunc *cb, void *opaque)
|
|
{
|
|
QEMUBH *bh;
|
|
bh = g_new(QEMUBH, 1);
|
|
*bh = (QEMUBH){
|
|
.ctx = ctx,
|
|
.cb = cb,
|
|
.opaque = opaque,
|
|
};
|
|
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 */
|
|
assert(flags & BH_DELETED);
|
|
|
|
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;
|
|
}
|