Re: [PATCH net v2] net: avoid registering new queue objects after device unregistration

On Mon, 22 Nov 2021 17:56:06 +0100 Antoine Tenart wrote:

Quoting Jakub Kicinski (2021-11-22 17:31:44)

quoted

On Mon, 22 Nov 2021 17:20:07 +0100 Antoine Tenart wrote:  

quoted

   veth_set_channels+0x1c3/0x550
   ethnl_set_channels+0x524/0x610  

The patch looks fine, but ethtool calls should not happen after
unregister IMHO. Too many drivers would be surprised. 

Maybe we should catch unregistered devices in ethnl_ops_begin()?  

That might be good to have indeed, I'll have a look. I'm not sure about
other paths that could do the same: if there are, we might want to keep
the check in this patch as well. Or WARN to catch future misuses?

My knee jerk reaction was to add a WARN() just because I can't think
why changing queue count after unregister would be needed. But it's not
really illegal and we do support it before register, so why not after
unregister..

We can venture a warning with a comment saying that this is just for
catching bad uses and see if any driver hits it on a normal path?