hw/qdev: introduce qdev_is_realized() helper

Add a helper function to check whether the device is realized without
requiring the Big QEMU Lock. The next patch adds a second caller. The
goal is to avoid spreading DeviceState field accesses throughout the
code.

Suggested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20230516190238.8401-3-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

hw/scsi/scsi-bus.c

@@ -60,8 +60,7 @@ static SCSIDevice *do_scsi_device_find(SCSIBus *bus,
      * the user access the device.
      */
 
-    if (retval && !include_unrealized &&
-        !qatomic_load_acquire(&retval->qdev.realized)) {
+    if (retval && !include_unrealized && !qdev_is_realized(&retval->qdev)) {
         retval = NULL;
     }
 

include/hw/qdev-core.h

@@ -1,6 +1,7 @@
 #ifndef QDEV_CORE_H
 #define QDEV_CORE_H
 
+#include "qemu/atomic.h"
 #include "qemu/queue.h"
 #include "qemu/bitmap.h"
 #include "qemu/rcu.h"
@@ -168,9 +169,6 @@ typedef struct {
 
 /**
  * DeviceState:
- * @realized: Indicates whether the device has been fully constructed.
- *            When accessed outside big qemu lock, must be accessed with
- *            qatomic_load_acquire()
  * @reset: ResettableState for the device; handled by Resettable interface.
  *
  * This structure should not be accessed directly.  We declare it here
@@ -339,6 +337,19 @@ DeviceState *qdev_new(const char *name);
  */
 DeviceState *qdev_try_new(const char *name);
 
+/**
+ * qdev_is_realized:
+ * @dev: The device to check.
+ *
+ * May be called outside big qemu lock.
+ *
+ * Returns: %true% if the device has been fully constructed, %false% otherwise.
+ */
+static inline bool qdev_is_realized(DeviceState *dev)
+{
+    return qatomic_load_acquire(&dev->realized);
+}
+
 /**
  * qdev_realize: Realize @dev.
  * @dev: device to realize