Re: [RFC][PATCH 2/7] kref: Add kref_read()

[Greg KH]

On Wed, Nov 16, 2016 at 11:10:42AM +0100, Peter Zijlstra wrote:
> On Wed, Nov 16, 2016 at 09:21:51AM +0100, Greg KH wrote:
> > > What should we do about things like this (bpf_prog_put() and callbacks
> > > from kernel/bpf/syscall.c):
> > > 
> > > 
> > > static void bpf_prog_uncharge_memlock(struct bpf_prog *prog)
> > > {
> > >         struct user_struct *user = prog->aux->user;
> > > 
> > >         atomic_long_sub(prog->pages, &user->locked_vm);
> > 
> > Oh that's scary.  Let's just make one reference count rely on another
> > one and not check things...
> 
> Its not a reference count, its a resource limit thingy. Also, isn't
> stacking, or in general building an object graph, the entire point of
> reference counts?

Ah, that wasn't obvious, but yes, you are correct here, sorry for the
noise.

greg k-h