Description of problem:
passthrough input device disappeared in the namespace when trying to attach the device to the guest twice

Version-Release number of selected component (if applicable):
libvirt-5.10.0-1.el8.x86_64

How reproducible:
100%

Steps to Reproduce:
1.Prepare the passthrough input device xml:
#cat input.xml
<input type='passthrough' bus='virtio'>
    <source evdev='/dev/input/event1'/>
</input>

2.Attach the input device to a guest:
# virsh attach-device vm2 input.xml 
Device attached successfully

3.Check the input device in the qemu namespace:
# nsenter -t `pidof qemu-kvm` -m ls -l /dev/input
total 0
crw-rw----. 1 qemu qemu 13, 65 Dec  6 03:20 event1

4.Attach the input device to the same guest again:
#virsh attach-device vm2 input.xml
error: Failed to attach device from dev.xml
error: internal error: unable to execute QEMU command 'device_add': /dev/input/event1: failed to get exclusive access: Device or resource bus

5.Check the input device in the qemu namespace:
# nsenter -t `pidof qemu-kvm` -m ls -l /dev/input
total 0

Actual results:
passthrough input device disappeared in the namespace when trying to attach the device to the guest twice

Expected results:
passthrough input device should not disappeare in the namespace when trying to attach the device to the guest twice

Additional info: