Re: [PATCH net-next] devlink: Require devlink lock during device reload

Jiri Pirko
2021-11-11T12:05:19Z

Tue, Nov 09, 2021 at 07:24:27PM CET, jgg@nvidia.com wrote:
>On Tue, Nov 09, 2021 at 08:20:42AM -0800, Jakub Kicinski wrote:
>> On Tue, 9 Nov 2021 11:33:35 -0400 Jason Gunthorpe wrote:
>> > > > I once sketched out fixing this by removing the need to hold the
>> > > > per_net_rwsem just for list iteration, which in turn avoids holding it
>> > > > over the devlink reload paths. It seemed like a reasonable step toward
>> > > > finer grained locking.
>> > >
>> > > Seems to me the locking is just a symptom.
>> >
>> > My fear is this reload during net ns destruction is devlink uAPI now
>> > and, yes it may be only a symptom, but the root cause may be unfixable
>> > uAPI constraints.
>>
>> If I'm reading this right it locks up 100% of the time, what is a uAPI
>> for? DoS? ;)
>>
>> Hence my questions about the actual use cases.
>
>Removing namespace support from devlink would solve the crasher. I
>certainly didn't feel bold enough to suggest such a thing :)
>
>If no other devlink driver cares about this it is probably the best
>idea.

Devlink namespace support is not generic, not related to any driver.

>
>Jason