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From: Heinz Graalfs <graalfs@linux.vnet.ibm.com>
Date: Tue,  1 Apr 2014 15:55:37 +0200
Message-Id: <1396360537-12520-1-git-send-email-graalfs@linux.vnet.ibm.com>
Subject: [Qemu-devel] drive_del vs. device_del: what should come first?
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To: kwolf@redhat.com
Cc: qemu-devel@nongnu.org, stefanha@redhat.com

Hi Kevin,

doing a 

     virsh detach-device ...

ends up in the following QEMU monitor commands:

1. device_del ... 
2. drive_del ...

qmp_device_del() performs the device unplug path.
In case of a block device do_drive_del() tries to 
prevent further IO against the host device.

However, bdrv_find() during drive_del() results in 
an error, because the device is already gone. Due to
this error all the bdrv_xxx calls to quiesce the block
driver as well as all other processing is skipped.

Is the sequence that libvirt triggers OK?
Shouldn't drive_del be executed first?

Thanks,
Heinz