Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to refcount_t

[Eric Dumazet]

On Tue, 2017-03-21 at 16:51 -0700, Kees Cook wrote:

> Am I understanding you correctly that you'd want something like:
> 
> refcount.h:
> #ifdef UNPROTECTED_REFCOUNT
> #define refcount_inc(x)   atomic_inc(x)
> ...
> #else
> void refcount_inc(...
> ...
> #endif
> 
> some/net.c:
> #define UNPROTECTED_REFCOUNT
> #include <refcount.h>
> 
> or similar?

At first, it could be something simple like that yes.

Note that we might define two refcount_inc()  : One that does whole
tests, and refcount_inc_relaxed() that might translate to atomic_inc()
on non debug kernels.

Then later, maybe provide a dynamic infrastructure so that we can
dynamically force the full checks even for refcount_inc_relaxed() on say
1% of the hosts, to get better debug coverage ?