netdev - [BUG] hv_netvsc: Unbind exits before the VFs bound to it are unregistered

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Date:   Thu, 3 Jun 2021 15:34:42 +0300
From:   Leonid Bloch <leonidb@...cscloud.com>
To:     "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>
Cc:     linux-hyperv@...r.kernel.org, netdev@...r.kernel.org
Subject: [BUG] hv_netvsc: Unbind exits before the VFs bound to it are
 unregistered

Hi,

When I try to unbind a network interface from hv_netvsc and bind it to 
uio_hv_generic, once in a while I get the following kernel panic (please 
note the first two lines: it seems as uio_hv_generic is registered 
before the VF bound to hv_netvsc is unregistered):

[Jun 3 09:04] hv_vmbus: registering driver uio_hv_generic
[  +0.002215] hv_netvsc 5e089342-8a78-4b76-9729-25c81bd338fc eth2: VF 
unregistering: eth5
[  +1.088078] BUG: scheduling while atomic: swapper/8/0/0x00010003
[  +0.000001] BUG: scheduling while atomic: swapper/3/0/0x00010003
[  +0.000001] BUG: scheduling while atomic: swapper/6/0/0x00010003
[  +0.000000] BUG: scheduling while atomic: swapper/7/0/0x00010003
[  +0.000005] Modules linked in:
[  +0.000001] Modules linked in:
[  +0.000001]  uio_hv_generic
[  +0.000000] Modules linked in:
[  +0.000000] Modules linked in:
[  +0.000001]  uio_hv_generic uio
[  +0.000001]  uio
[  +0.000000]  uio_hv_generic
[  +0.000000]  uio_hv_generic
...

I run kernel 5.10.27, unmodified, besides RT patch v36, on Azure Stack 
Edge platform, software version 2105 (2.2.1606.3320).

I perform the bind-unbind using the following script (please note the 
comment inline):

net_uuid="f8615163-df3e-46c5-913f-f2d2f965ed0e"
dev_uuid="$(basename "$(readlink "/sys/class/net/eth1/device")")"
modprobe uio_hv_generic
echo "${net_uuid}" > /sys/bus/vmbus/drivers/uio_hv_generic/new_id
printf "%s" "${dev_uuid}" > /sys/bus/vmbus/drivers/hv_netvsc/unbind
### If I insert 'sleep 1' here - all works correctly
printf "%s" "${dev_uuid}" > /sys/bus/vmbus/drivers/uio_hv_generic/bind


Thanks,
Leonid.
___