[Bridge] [PATCH net 2/2] net: bridge: fix lockdep multicast_lock false positive splat

[Taehee Yoo]

On 4/26/21 10:15 PM, Nikolay Aleksandrov wrote:
 > On 26/04/2021 15:48, Herbert Xu wrote:

Hi Nikolay and Herbert,
Thank you for the reviews!

 >> On Sun, Apr 25, 2021 at 07:45:27PM +0300, Nikolay Aleksandrov wrote:
 >>>
 >>> Ugh.. that's just very ugly. :) The setup you've described above is 
by all means invalid, but
 >>> possible unfortunately. The bridge already checks if it's being 
added as a port to another
 >>> bridge, but not through multiple levels of indirection. These locks 
are completely unrelated
 >>> as they're in very different contexts (different devices).
 >>
 >> Surely we should forbid this? Otherwise what's to stop someone
 >> from creating a loop?
 >>
 >> Cheers,
 >>
 >
 > Indeed that would be best, it's very easy to loop them.
 >

We can make very various interface graphs with master/slave interface types.
So, if we need something to forbid it, I think it should be generic 
code, not only for the bridge module.