Re: [PATCH 1/3] ipc: convert ipc_namespace.count from atomic_t to refcount_t

[Andrew Morton]

On Sun, 09 Jul 2017 16:59:55 -0500 ebiederm@xxxxxxxxxxxx (Eric W. Biederman) wrote:

> Elena Reshetova <elena.reshetova@xxxxxxxxx> writes:
> 
> > refcount_t type and corresponding API should be
> > used instead of atomic_t when the variable is used as
> > a reference counter. This allows to avoid accidental
> > refcounter overflows that might lead to use-after-free
> > situations.
> 
> In this patch you can see all of the uses of the count.
> What accidental refcount overflows are possible?

I do rather dislike these conversions from the point of view of
performance overhead and general code bloat.  But I seem to have lost
that struggle and I don't think any of these are fastpath(?).