[PATCH 06/16] drivers, net, mlx5: convert mlx5_cq.refcount from atomic_t to refcount_t

Reshetova, Elena elena.reshetova at intel.com
Tue Mar 28 07:00:01 PDT 2017

> From: Elena Reshetova
> > Sent: 28 March 2017 09:57
> >
> > 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.
> I can't help feeling that you ought to find a scheme
> that will detect extra decrements and extra increments
> before the counter wraps 32 bits.
> If an extra reference is requested every 100us it takes 4.8 days
> for the counter to increment back to zero.
> Simple tests aren't doing to find that - but it can easily happen
> on a system that is running for several years.

So, you are proposing to try detecting this case instead of preventing overflows?
Not sure how this would look like in a generic form...

> 	David

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