coroutines: Locks

Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 124 insertions, 0 deletions

diff --git a/qemu-coroutine-lock.c b/qemu-coroutine-lock.c
new file mode 100644
index 0000000000..abaa1f7967
--- /dev/null
+++ b/qemu-coroutine-lock.c
@@ -0,0 +1,124 @@
+/*
+ * 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 "qemu-coroutine.h"
+#include "qemu-coroutine-int.h"
+#include "qemu-queue.h"
+#include "trace.h"
+
+static QTAILQ_HEAD(, Coroutine) unlock_bh_queue =
+    QTAILQ_HEAD_INITIALIZER(unlock_bh_queue);
+
+struct unlock_bh {
+    QEMUBH *bh;
+};
+
+static void qemu_co_queue_next_bh(void *opaque)
+{
+    struct unlock_bh *unlock_bh = 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);
+    }
+
+    qemu_bh_delete(unlock_bh->bh);
+    qemu_free(unlock_bh);
+}
+
+void qemu_co_queue_init(CoQueue *queue)
+{
+    QTAILQ_INIT(&queue->entries);
+}
+
+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());
+}
+
+bool qemu_co_queue_next(CoQueue *queue)
+{
+    struct unlock_bh *unlock_bh;
+    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);
+
+        unlock_bh = qemu_malloc(sizeof(*unlock_bh));
+        unlock_bh->bh = qemu_bh_new(qemu_co_queue_next_bh, unlock_bh);
+        qemu_bh_schedule(unlock_bh->bh);
+    }
+
+    return (next != NULL);
+}
+
+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);
+}