Subject: Re: [PATCH v4] net: ip, diag -- Add diag interface for raw sockets

From: Cyrill Gorcunov <[email-masked]>
Date: Tue, 27 Sep 2016 18:45:40 +0300

On Tue, Sep 27, 2016 at 08:39:59AM -0700, Eric Dumazet wrote:
...
> > +	}
> > +	if (sk && !atomic_inc_not_zero(&sk->sk_refcnt))
> > +		sk = NULL;
> 
> Minor detail, but note that raw sockets do not use rcu (yet)
> 
> Since you have read_lock(&hashinfo->lock), no writer can suddenly change
> sk->sk_refcnt to a zero value.
> 
> Therefore, a mere "sock_hold(sk)" should be enough to get a reference on
> the socket.
> 
> Using atomic_inc_not_zero() also works, but might distract/confuse the
> next guy trying to understand this code ;)

Oh, I see. Thanks Eric! I'll update the patch (hopefully tonight)
and send it out (need to finish urgent task atm).