Linux Virtualization - Mar 2019 - [RFC PATCH net-next] failover: allow name change on IFF_UP slave interfaces

> On 6 Mar 2019, at 23:42, si-wei liu <si-wei.liu at oracle.com> wrote:
> 
> 
> 
> On 3/6/2019 1:36 PM, Samudrala, Sridhar wrote:
>> 
>> On 3/6/2019 1:26 PM, si-wei liu wrote:
>>> 
>>> 
>>> On 3/6/2019 4:04 AM, Jiri Pirko wrote:
>>>>> --- a/net/core/failover.c
>>>>> +++ b/net/core/failover.c
>>>>> @@ -16,6 +16,11 @@
>>>>> 
>>>>> static LIST_HEAD(failover_list);
>>>>> static DEFINE_SPINLOCK(failover_lock);
>>>>> +static bool slave_rename_ok = true;
>>>>> +
>>>>> +module_param(slave_rename_ok, bool, (S_IRUGO | S_IWUSR));
>>>>> +MODULE_PARM_DESC(slave_rename_ok,
>>>>> +		 "If set allow renaming the slave when failover
master is up");
>>>>> 
>>>> No module parameters please. If you need to set something do it
using
>>>> rtnl_link_ops. Thanks.
>>>> 
>>>> 
>>> I understand what you ask for, but without module parameters
userspace don't work. During boot (dracut) the virtio netdev gets enslaved
earlier than when userspace comes up, so failover has to determine the setting
during initialization/creation. This config is not dynamic, at least for the
life cycle of a particular failover link it shouldn't be changed. Without
module parameter, how does the userspace specify this value during kernel
initialization?
>>> 
>> Can we enable this by default and not make it configurable via module
parameter?
>> Is there any  usecase where someone expects rename to fail with
failover slaves?
> Probably just cater for those application that assumes fixed name on UP
interface?
> 
> It's already the default for the configurable. I myself don't think
that's a big problem for failover users. So far there's not even QEMU
support I think everything can be changed. I don't feel strong to just fix
it without introducing configurable. But maybe Michael or others think it
differently...
> 
> If no one objects, I don't feel strong to make it fixed behavior.
> 
> -Siwei
> 
I agree we should just remove the module parameter.

-Liran