/* * coroutine queues and locks * * Copyright (c) 2011 Kevin Wolf <kwolf@redhat.com> * * 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-common.h" #include "block/coroutine.h" #include "block/coroutine_int.h" #include "qemu/queue.h" #include "block/aio.h" #include "trace.h" static QTAILQ_HEAD(, Coroutine) unlock_bh_queue = QTAILQ_HEAD_INITIALIZER(unlock_bh_queue); static QEMUBH* unlock_bh; static void qemu_co_queue_next_bh(void *opaque) { Coroutine *next; trace_qemu_co_queue_next_bh(); while ((next = QTAILQ_FIRST(&unlock_bh_queue))) { QTAILQ_REMOVE(&unlock_bh_queue, next, co_queue_next); qemu_coroutine_enter(next, NULL); } } void qemu_co_queue_init(CoQueue *queue) { QTAILQ_INIT(&queue->entries); if (!unlock_bh) { unlock_bh = qemu_bh_new(qemu_co_queue_next_bh, NULL); } } void coroutine_fn qemu_co_queue_wait(CoQueue *queue) { Coroutine *self = qemu_coroutine_self(); QTAILQ_INSERT_TAIL(&queue->entries, self, co_queue_next); qemu_coroutine_yield(); assert(qemu_in_coroutine()); } void coroutine_fn qemu_co_queue_wait_insert_head(CoQueue *queue) { Coroutine *self = qemu_coroutine_self(); QTAILQ_INSERT_HEAD(&queue->entries, self, co_queue_next); qemu_coroutine_yield(); assert(qemu_in_coroutine()); } bool qemu_co_queue_next(CoQueue *queue) { Coroutine *next; next = QTAILQ_FIRST(&queue->entries); if (next) { QTAILQ_REMOVE(&queue->entries, next, co_queue_next); QTAILQ_INSERT_TAIL(&unlock_bh_queue, next, co_queue_next); trace_qemu_co_queue_next(next); qemu_bh_schedule(unlock_bh); } return (next != NULL); } void qemu_co_queue_restart_all(CoQueue *queue) { while (qemu_co_queue_next(queue)) { /* Do nothing */ } } bool qemu_co_queue_empty(CoQueue *queue) { return (QTAILQ_FIRST(&queue->entries) == NULL); } void qemu_co_mutex_init(CoMutex *mutex) { memset(mutex, 0, sizeof(*mutex)); qemu_co_queue_init(&mutex->queue); } void coroutine_fn qemu_co_mutex_lock(CoMutex *mutex) { Coroutine *self = qemu_coroutine_self(); trace_qemu_co_mutex_lock_entry(mutex, self); while (mutex->locked) { qemu_co_queue_wait(&mutex->queue); } mutex->locked = true; trace_qemu_co_mutex_lock_return(mutex, self); } void coroutine_fn qemu_co_mutex_unlock(CoMutex *mutex) { Coroutine *self = qemu_coroutine_self(); trace_qemu_co_mutex_unlock_entry(mutex, self); assert(mutex->locked == true); assert(qemu_in_coroutine()); mutex->locked = false; qemu_co_queue_next(&mutex->queue); trace_qemu_co_mutex_unlock_return(mutex, self); } void qemu_co_rwlock_init(CoRwlock *lock) { memset(lock, 0, sizeof(*lock)); qemu_co_queue_init(&lock->queue); } void qemu_co_rwlock_rdlock(CoRwlock *lock) { while (lock->writer) { qemu_co_queue_wait(&lock->queue); } lock->reader++; } void qemu_co_rwlock_unlock(CoRwlock *lock) { assert(qemu_in_coroutine()); if (lock->writer) { lock->writer = false; qemu_co_queue_restart_all(&lock->queue); } else { lock->reader--; assert(lock->reader >= 0); /* Wakeup only one waiting writer */ if (!lock->reader) { qemu_co_queue_next(&lock->queue); } } } void qemu_co_rwlock_wrlock(CoRwlock *lock) { while (lock->writer || lock->reader) { qemu_co_queue_wait(&lock->queue); } lock->writer = true; }