Re: [PATCH] virtio-net: failover: add missing remove_migration_state_change_notifier()

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Laurent Vivier (lvivier@redhat.com) wrote:
> In the failover case configuration, virtio_net_device_realize() uses an
> add_migration_state_change_notifier() to add a state notifier, but this
> notifier is not removed by the unrealize function when the virtio-net
> card is unplugged.
> 
> If the card is unplugged and a migration is started, the notifier is
> called and as it is not valid anymore QEMU crashes.
> 
> This patch fixes the problem by adding the
> remove_migration_state_change_notifier() in virtio_net_device_unrealize().
> 
> The problem can be reproduced with:
> 
>   $ qemu-system-x86_64 -enable-kvm -m 1g -M q35 \
>     -device pcie-root-port,slot=4,id=root1 \
>     -device pcie-root-port,slot=5,id=root2 \
>     -device virtio-net-pci,id=net1,mac=52:54:00:6f:55:cc,failover=on,bus=root1 \
>     -monitor stdio disk.qcow2
>   (qemu) device_del net1
>   (qemu) migrate "exec:gzip -c > STATEFILE.gz"
> 
>   Thread 1 "qemu-system-x86" received signal SIGSEGV, Segmentation fault.
>   0x0000000000000000 in ?? ()
>   (gdb) bt
>   #0  0x0000000000000000 in  ()
>   #1  0x0000555555d726d7 in notifier_list_notify (...)
>       at .../util/notify.c:39
>   #2  0x0000555555842c1a in migrate_fd_connect (...)
>       at .../migration/migration.c:3975
>   #3  0x0000555555950f7d in migration_channel_connect (...)
>       error@entry=0x0) at .../migration/channel.c:107
>   #4  0x0000555555910922 in exec_start_outgoing_migration (...)
>       at .../migration/exec.c:42
> 
> Reported-by: Igor Mammedov <imammedo@redhat.com>
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>

Yep, I think that's OK.


Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> ---
>  hw/net/virtio-net.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index 66b9ff451185..914051feb75b 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -3373,6 +3373,7 @@ static void virtio_net_device_unrealize(DeviceState *dev)
>  
>      if (n->failover) {
>          device_listener_unregister(&n->primary_listener);
> +        remove_migration_state_change_notifier(&n->migration_state);
>      }
>  
>      max_queues = n->multiqueue ? n->max_queues : 1;
> -- 
> 2.30.2
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK