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Bug 1256619 - qemu quit with "qemu_chr_fe_claim_no_fail: error chardev "charnet0" already used"
Summary: qemu quit with "qemu_chr_fe_claim_no_fail: error chardev "charnet0" already u...
Keywords:
Status: CLOSED DUPLICATE of bug 1256618
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: qemu-kvm-rhev
Version: 7.2
Hardware: x86_64
OS: Unspecified
medium
medium
Target Milestone: rc
: ---
Assignee: Marc-Andre Lureau
QA Contact: xiywang
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2015-08-25 06:51 UTC by Qian Guo
Modified: 2017-10-19 02:34 UTC (History)
6 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2017-10-09 01:14:26 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)

Description Qian Guo 2015-08-25 06:51:40 UTC 
Description of problem:
Hot remove virtio-net-pci and  vhost-user netdev, but with the chardev left in the qemu.

Then try to hot plug the vhost-user, qemu will quit with 
"qemu_chr_fe_claim_no_fail: error chardev "charnet0" already used
"

I think it should not quit directly due to if the guest is running some important work, it should warning and refuse to hot plug the vhost-user.

Version-Release number of selected component (if applicable):
qemu-kvm-rhev-2.3.0-18.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
1.Boot guest with chardev and vhost-user that user the chardev.
...
-chardev socket,id=charnet0,path=/var/run/openvswitch/vhost-user1 \
-netdev type=vhost-user,id=hostnet0,chardev=charnet0 \
-device virtio-net-pci,netdev=hostnet0,mrg_rxbuf=off,id=net0,mac=52:54:00:01:0b:11,bus=pci.0,addr=0x9
...

2.Hot remove net0 and netdev_del hostnet0

3.Try to hot plug a new netdev that connect to the chardev.
(qemu) netdev_add vhost-user,id=hostnet0,chardev=charnet0



Actual results:
QEMU quit with following infos:
(qemu) netdev_add vhost-user,id=hostnet0,chardev=charnet0
qemu_chr_fe_claim_no_fail: error chardev "charnet0" already used


Expected results:
1. if the chardev is in use, should refuse to use it, but not quit the qemu.

Additional info:
Comment 2 Marc-Andre Lureau 2015-09-03 13:26:48 UTC 
I am not sure this is a bug, you must also remove/recreate a chardev to establish a new connection anyway... It could perhaps destroy the chardev for you though when removing the netdev.
Comment 3 Marc-Andre Lureau 2015-09-03 14:22:11 UTC 
sent a RFC to qemu-devel "vhost-user: release chardev on cleanup"
Comment 6 Marc-Andre Lureau 2016-08-11 09:17:39 UTC 
patches are not even reviewed upstream, low-prio, moving to 7.4
Comment 7 Marc-Andre Lureau 2016-12-27 17:52:06 UTC 
patches are not even reviewed upstream, low-prio, moving to 7.5

will resend for 2.9
Comment 8 Marc-Andre Lureau 2017-01-24 18:57:51 UTC 
likely fixed in v2.7.0 with:

commit 25f0d2aa5e3d21caa1bc622b21368cc2e383f02c
Author: Paolo Bonzini <pbonzini>
Date:   Wed Jun 29 15:15:33 2016 +0200

    vhost-user: disable chardev handlers on close

I will check
Comment 9 Marc-Andre Lureau 2017-10-06 11:15:03 UTC 
I suggest we close as duplicate of bug 1256618, now that the behaviour is fixed to remove the chardev.
Comment 10 xiywang 2017-10-09 01:14:26 UTC 
I checked bug 1256618, we can close as duplicate.
Thanks Marc-Andre.

*** This bug has been marked as a duplicate of bug 1256618 ***
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