Revert "pc: Kill the "use flash device for BIOS unless KVM" misfeature"

[qemu.git] / qemu-coroutine-lock.c

diff --git a/qemu-coroutine-lock.c b/qemu-coroutine-lock.c
index a80f437c595b7132544323fa8f664d648d54981e..86efe1f86a486da60ae03148dc521223703d7b49 100644 (file)
--- a/qemu-coroutine-lock.c
+++ b/qemu-coroutine-lock.c
@@ -23,33 +23,42 @@
  */
 
 #include "qemu-common.h"
-#include "qemu-coroutine.h"
-#include "qemu-coroutine-int.h"
-#include "qemu-queue.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;
+/* Coroutines are awoken from a BH to allow the current coroutine to complete
+ * its flow of execution.  The BH may run after the CoQueue has been destroyed,
+ * so keep BH data in a separate heap-allocated struct.
+ */
+typedef struct {
+    QEMUBH *bh;
+    QTAILQ_HEAD(, Coroutine) entries;
+} CoQueueNextData;
 
 static void qemu_co_queue_next_bh(void *opaque)
 {
+    CoQueueNextData *data = 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);
+    while ((next = QTAILQ_FIRST(&data->entries))) {
+        QTAILQ_REMOVE(&data->entries, next, co_queue_next);
         qemu_coroutine_enter(next, NULL);
     }
+
+    qemu_bh_delete(data->bh);
+    g_slice_free(CoQueueNextData, data);
 }
 
 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);
-    }
+    /* This will be exposed to callers once there are multiple AioContexts */
+    queue->ctx = qemu_get_aio_context();
 }
 
 void coroutine_fn qemu_co_queue_wait(CoQueue *queue)
@@ -60,19 +69,47 @@ void coroutine_fn qemu_co_queue_wait(CoQueue *queue)
     assert(qemu_in_coroutine());
 }
 
-bool qemu_co_queue_next(CoQueue *queue)
+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());
+}
+
+static bool qemu_co_queue_do_restart(CoQueue *queue, bool single)
 {
     Coroutine *next;
+    CoQueueNextData *data;
+
+    if (QTAILQ_EMPTY(&queue->entries)) {
+        return false;
+    }
 
-    next = QTAILQ_FIRST(&queue->entries);
-    if (next) {
+    data = g_slice_new(CoQueueNextData);
+    data->bh = aio_bh_new(queue->ctx, qemu_co_queue_next_bh, data);
+    QTAILQ_INIT(&data->entries);
+    qemu_bh_schedule(data->bh);
+
+    while ((next = QTAILQ_FIRST(&queue->entries)) != NULL) {
         QTAILQ_REMOVE(&queue->entries, next, co_queue_next);
-        QTAILQ_INSERT_TAIL(&unlock_bh_queue, next, co_queue_next);
+        QTAILQ_INSERT_TAIL(&data->entries, next, co_queue_next);
         trace_qemu_co_queue_next(next);
-        qemu_bh_schedule(unlock_bh);
+        if (single) {
+            break;
+        }
     }
+    return true;
+}
 
-    return (next != NULL);
+bool qemu_co_queue_next(CoQueue *queue)
+{
+    return qemu_co_queue_do_restart(queue, true);
+}
+
+void qemu_co_queue_restart_all(CoQueue *queue)
+{
+    qemu_co_queue_do_restart(queue, false);
 }
 
 bool qemu_co_queue_empty(CoQueue *queue)
@@ -115,3 +152,41 @@ void coroutine_fn qemu_co_mutex_unlock(CoMutex *mutex)
 
     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;
+}