Re: [PATCH net-next 05/12] ptr_ring: disallow lockless __ptr_ring_full

[Jason Wang]

On 2018å01æ26æ 10:46, Michael S. Tsirkin wrote:
> > On 2018å01æ26æ 07:36, Michael S. Tsirkin wrote:
> > > Similar to bcecb4bbf88a ("net: ptr_ring: otherwise safe empty checks can
> > > overrun array bounds") a lockless use of __ptr_ring_full might
> > > cause an out of bounds access.
> > >
> > > We can fix this, but it's easier to just disallow lockless
> > > __ptr_ring_full for now.
> > It looks to me that just fix this is better than disallow through doc (which
> > is easily to be ignored ...).
> >
> > Thanks
> lockless is tricky, and I'd rather not sprinkle READ/WRITE_ONCE where
> they aren't necessary.

The problem is then API looks a little bit strange. Lockless were only 
allowed to be done at __ptr_ring_empty() but not __ptr_ring_full().

Thanks