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0a6f0c76a0
Allow using QemuCoSleep to sleep forever until woken by qemu_co_sleep_wake. This makes the logic of qemu_co_sleep_ns_wakeable easy to understand. In the future we will introduce an API that can work even if the sleep and wake happen from different threads. For now, initializing w->to_wake after timer_mod is fine because the timer can only fire in the same AioContext. Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-id: 20210517100548.28806-7-pbonzini@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
81 lines
2.1 KiB
C
81 lines
2.1 KiB
C
/*
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* QEMU coroutine sleep
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*
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* Copyright IBM, Corp. 2011
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*
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* Authors:
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* Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
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*
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* This work is licensed under the terms of the GNU LGPL, version 2 or later.
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* See the COPYING.LIB file in the top-level directory.
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*
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*/
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#include "qemu/osdep.h"
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#include "qemu/coroutine.h"
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#include "qemu/coroutine_int.h"
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#include "qemu/timer.h"
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#include "block/aio.h"
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static const char *qemu_co_sleep_ns__scheduled = "qemu_co_sleep_ns";
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void qemu_co_sleep_wake(QemuCoSleep *w)
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{
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Coroutine *co;
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co = w->to_wake;
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w->to_wake = NULL;
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if (co) {
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/* Write of schedule protected by barrier write in aio_co_schedule */
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const char *scheduled = qatomic_cmpxchg(&co->scheduled,
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qemu_co_sleep_ns__scheduled, NULL);
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assert(scheduled == qemu_co_sleep_ns__scheduled);
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aio_co_wake(co);
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}
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}
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static void co_sleep_cb(void *opaque)
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{
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QemuCoSleep *w = opaque;
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qemu_co_sleep_wake(w);
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}
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void coroutine_fn qemu_co_sleep(QemuCoSleep *w)
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{
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Coroutine *co = qemu_coroutine_self();
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const char *scheduled = qatomic_cmpxchg(&co->scheduled, NULL,
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qemu_co_sleep_ns__scheduled);
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if (scheduled) {
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fprintf(stderr,
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"%s: Co-routine was already scheduled in '%s'\n",
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__func__, scheduled);
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abort();
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}
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w->to_wake = co;
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qemu_coroutine_yield();
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/* w->to_wake is cleared before resuming this coroutine. */
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assert(w->to_wake == NULL);
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}
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void coroutine_fn qemu_co_sleep_ns_wakeable(QemuCoSleep *w,
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QEMUClockType type, int64_t ns)
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{
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AioContext *ctx = qemu_get_current_aio_context();
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QEMUTimer ts;
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aio_timer_init(ctx, &ts, type, SCALE_NS, co_sleep_cb, w);
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timer_mod(&ts, qemu_clock_get_ns(type) + ns);
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/*
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* The timer will fire in the current AiOContext, so the callback
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* must happen after qemu_co_sleep yields and there is no race
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* between timer_mod and qemu_co_sleep.
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*/
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qemu_co_sleep(w);
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timer_del(&ts);
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}
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