[snip]

>> We do have some current code in the network stack that fails miserably
>> when  register_sysctl_table returns NULL, and there are explicit
>> checks for that.
> 
> So that code would be failing today with CONFIG_SYSCTL=n?  Unless the
> failing code is itself under #ifdef CONFIG_SYSCTL, in which case we don't
> need to change anything?

Exactly! If the code checks for the return value it won't work
with CONFIG_SYSCTL=n, if it dies not - it may happily use the
sysctl stub and avoid extra ifdefs.

But this difference looks clumsy :(

Thanks,
Pavel