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[Qemu-block] [PATCH 2/4] coroutine-lock: convert CoQueue to use QemuLock
From: |
Paolo Bonzini |
Subject: |
[Qemu-block] [PATCH 2/4] coroutine-lock: convert CoQueue to use QemuLockable |
Date: |
Mon, 15 Jan 2018 23:08:20 +0100 |
There are cases in which a queued coroutine must be restarted from
non-coroutine context (with qemu_co_enter_next). In this cases,
qemu_co_enter_next also needs to be thread-safe, but it cannot use
a CoMutex and so cannot qemu_co_queue_wait. Use QemuLockable so
that the CoQueue can interchangeably use CoMutex or QemuMutex.
Signed-off-by: Paolo Bonzini <address@hidden>
---
include/qemu/coroutine.h | 6 +++++-
util/qemu-coroutine-lock.c | 12 +++++++-----
2 files changed, 12 insertions(+), 6 deletions(-)
diff --git a/include/qemu/coroutine.h b/include/qemu/coroutine.h
index 8a5129741c..1e5f0957e6 100644
--- a/include/qemu/coroutine.h
+++ b/include/qemu/coroutine.h
@@ -183,7 +183,9 @@ void qemu_co_queue_init(CoQueue *queue);
* caller of the coroutine. The mutex is unlocked during the wait and
* locked again afterwards.
*/
-void coroutine_fn qemu_co_queue_wait(CoQueue *queue, CoMutex *mutex);
+#define qemu_co_queue_wait(queue, lock) \
+ qemu_co_queue_wait_impl(queue, QEMU_MAKE_LOCKABLE(lock))
+void coroutine_fn qemu_co_queue_wait_impl(CoQueue *queue, QemuLockable *lock);
/**
* Restarts the next coroutine in the CoQueue and removes it from the queue.
@@ -271,4 +273,6 @@ void coroutine_fn qemu_co_sleep_ns(QEMUClockType type,
int64_t ns);
*/
void coroutine_fn yield_until_fd_readable(int fd);
+#include "qemu/lockable.h"
+
#endif /* QEMU_COROUTINE_H */
diff --git a/util/qemu-coroutine-lock.c b/util/qemu-coroutine-lock.c
index 846ff9167f..2a66fc1467 100644
--- a/util/qemu-coroutine-lock.c
+++ b/util/qemu-coroutine-lock.c
@@ -40,13 +40,13 @@ void qemu_co_queue_init(CoQueue *queue)
QSIMPLEQ_INIT(&queue->entries);
}
-void coroutine_fn qemu_co_queue_wait(CoQueue *queue, CoMutex *mutex)
+void coroutine_fn qemu_co_queue_wait_impl(CoQueue *queue, QemuLockable *lock)
{
Coroutine *self = qemu_coroutine_self();
QSIMPLEQ_INSERT_TAIL(&queue->entries, self, co_queue_next);
- if (mutex) {
- qemu_co_mutex_unlock(mutex);
+ if (lock) {
+ qemu_lockable_unlock(lock);
}
/* There is no race condition here. Other threads will call
@@ -60,9 +60,11 @@ void coroutine_fn qemu_co_queue_wait(CoQueue *queue, CoMutex
*mutex)
/* TODO: OSv implements wait morphing here, where the wakeup
* primitive automatically places the woken coroutine on the
* mutex's queue. This avoids the thundering herd effect.
+ * This could be implemented for CoMutexes, but not really for
+ * other cases of QemuLockable.
*/
- if (mutex) {
- qemu_co_mutex_lock(mutex);
+ if (lock) {
+ qemu_lockable_lock(lock);
}
}
--
2.14.3