coroutine-lock: introduce qemu_co_queue_enter_all

Because qemu_co_queue_restart_all does not release the lock, it should
be used only in coroutine context.  Introduce a new function that,
like qemu_co_enter_next, does release the lock, and use it whenever
qemu_co_queue_restart_all was used outside coroutine context.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20220427130830.150180-3-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

include/qemu/coroutine.h

@@ -234,6 +234,19 @@ void qemu_co_queue_restart_all(CoQueue *queue);
     qemu_co_enter_next_impl(queue, QEMU_MAKE_LOCKABLE(lock))
 bool qemu_co_enter_next_impl(CoQueue *queue, QemuLockable *lock);
 
+/**
+ * Empties the CoQueue, waking the waiting coroutine one at a time.  Unlike
+ * qemu_co_queue_all, this function releases the lock during aio_co_wake
+ * because it is meant to be used outside coroutine context; in that case, the
+ * coroutine is entered immediately, before qemu_co_enter_all returns.
+ *
+ * If used in coroutine context, qemu_co_enter_all is equivalent to
+ * qemu_co_queue_all.
+ */
+#define qemu_co_enter_all(queue, lock) \
+    qemu_co_enter_all_impl(queue, QEMU_MAKE_LOCKABLE(lock))
+void qemu_co_enter_all_impl(CoQueue *queue, QemuLockable *lock);
+
 /**
  * Checks if the CoQueue is empty.
  */

ui/console.c

@@ -221,7 +221,7 @@ static void gui_setup_refresh(DisplayState *ds)
 void graphic_hw_update_done(QemuConsole *con)
 {
     if (con) {
-        qemu_co_queue_restart_all(&con->dump_queue);
+        qemu_co_enter_all(&con->dump_queue, NULL);
     }
 }
 

util/qemu-coroutine-lock.c

@@ -108,6 +108,13 @@ bool coroutine_fn qemu_co_queue_next(CoQueue *queue)
     return qemu_co_enter_next_impl(queue, NULL);
 }
 
+void qemu_co_enter_all_impl(CoQueue *queue, QemuLockable *lock)
+{
+    while (qemu_co_enter_next_impl(queue, lock)) {
+        /* just loop */
+    }
+}
+
 bool qemu_co_queue_empty(CoQueue *queue)
 {
     return QSIMPLEQ_FIRST(&queue->entries) == NULL;