*/
#include "qemu/osdep.h"
-#include "qemu/coroutine.h"
#include "qemu/coroutine_int.h"
#include "qemu/processor.h"
#include "qemu/queue.h"
QSIMPLEQ_INIT(&queue->entries);
}
-void coroutine_fn qemu_co_queue_wait_impl(CoQueue *queue, QemuLockable *lock)
+void coroutine_fn qemu_co_queue_wait_impl(CoQueue *queue, QemuLockable *lock,
+ CoQueueWaitFlags flags)
{
Coroutine *self = qemu_coroutine_self();
- QSIMPLEQ_INSERT_TAIL(&queue->entries, self, co_queue_next);
+ if (flags & CO_QUEUE_WAIT_FRONT) {
+ QSIMPLEQ_INSERT_HEAD(&queue->entries, self, co_queue_next);
+ } else {
+ QSIMPLEQ_INSERT_TAIL(&queue->entries, self, co_queue_next);
+ }
if (lock) {
qemu_lockable_unlock(lock);
trace_qemu_co_mutex_lock_entry(mutex, self);
push_waiter(mutex, &w);
+ /*
+ * Add waiter before reading mutex->handoff. Pairs with qatomic_set_mb
+ * in qemu_co_mutex_unlock.
+ */
+ smp_mb__after_rmw();
+
/* This is the "Responsibility Hand-Off" protocol; a lock() picks from
* a concurrent unlock() the responsibility of waking somebody up.
*/
- old_handoff = qatomic_mb_read(&mutex->handoff);
+ old_handoff = qatomic_read(&mutex->handoff);
if (old_handoff &&
has_waiters(mutex) &&
qatomic_cmpxchg(&mutex->handoff, old_handoff, 0) == old_handoff) {
}
our_handoff = mutex->sequence;
- qatomic_mb_set(&mutex->handoff, our_handoff);
+ /* Set handoff before checking for waiters. */
+ qatomic_set_mb(&mutex->handoff, our_handoff);
if (!has_waiters(mutex)) {
/* The concurrent lock has not added itself yet, so it
* will be able to pick our handoff.