[Qemu-devel] [PATCH 01/16] introduce a new API to enable/disable attach device model

[Wen Congyang <wency@cn.fujitsu.com>]

Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
---
 block/block-backend.c          | 24 ++++++++++++++++++++++++
 include/sysemu/block-backend.h |  2 ++
 2 files changed, 26 insertions(+)

diff --git a/block/block-backend.c b/block/block-backend.c
index aee8a12..72d8b2c 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -344,6 +344,30 @@ void *blk_get_attached_dev(BlockBackend *blk)
 }
 
 /*
+ * Disable to attach a device mode to @blk.
+ * Return 0 on success, -EBUSY when a device model is attached already.
+ */
+int blk_disable_attach_dev(BlockBackend *blk)
+{
+    if (blk->dev) {
+        return blk->dev == (void *)-1 ? 0 : -EBUSY;
+    }
+
+    blk->dev = (void *)-1;
+    return 0;
+}
+
+/*
+ * Enable to attach a device mode to @blk.
+ */
+void blk_enable_attach_dev(BlockBackend *blk)
+{
+    if (blk->dev == (void *)-1) {
+        blk->dev = NULL;
+    }
+}
+
+/*
  * Set @blk's device model callbacks to @ops.
  * @opaque is the opaque argument to pass to the callbacks.
  * This is for use by device models.
diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
index 8fc960f..7619a9f 100644
--- a/include/sysemu/block-backend.h
+++ b/include/sysemu/block-backend.h
@@ -80,6 +80,8 @@ int blk_attach_dev(BlockBackend *blk, void *dev);
 void blk_attach_dev_nofail(BlockBackend *blk, void *dev);
 void blk_detach_dev(BlockBackend *blk, void *dev);
 void *blk_get_attached_dev(BlockBackend *blk);
+int blk_disable_attach_dev(BlockBackend *blk);
+void blk_enable_attach_dev(BlockBackend *blk);
 void blk_set_dev_ops(BlockBackend *blk, const BlockDevOps *ops, void *opaque);
 int blk_read(BlockBackend *blk, int64_t sector_num, uint8_t *buf,
              int nb_sectors);
-- 
2.4.3