[Bridge] get rid of the address_space override in setsockopt

['Christoph Hellwig']

On Tue, Jul 21, 2020 at 09:38:23AM +0000, David Laight wrote:
> From: Christoph Hellwig
> > Sent: 20 July 2020 13:47
> >
> > setsockopt is the last place in architecture-independ code that still
> > uses set_fs to force the uaccess routines to operate on kernel pointers.
> > 
> > This series adds a new sockptr_t type that can contained either a kernel
> > or user pointer, and which has accessors that do the right thing, and
> > then uses it for setsockopt, starting by refactoring some low-level
> > helpers and moving them over to it before finally doing the main
> > setsockopt method.
> 
> Are you planning to make the equivalent change to getsockopt()?

No.  Only setsockopt can be fed kernel addresses from bpf-cgroup.
There is no point in complicating the read side interface when it
doesn't have that problem.