Re: [PATCH tip/core/rcu 9/9] rcu: Provide counterpart to rcu_dereference() for non-RCU situations

[Peter Zijlstra]

On Tue, Oct 28, 2014 at 03:10:02PM -0700, Paul E. McKenney wrote:
> From: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
> 
> Although rcu_dereference() and friends can be used in situations where
> object lifetimes are being managed by something other than RCU, the
> resulting sparse and lockdep-RCU noise can be annoying.  This commit
> therefore supplies a lockless_dereference(), which provides the
> protection for dereferences without the RCU-related debugging noise.
> 
> Reported-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
> ---

> +#define lockless_dereference(p) \
> +({ \
> +	typeof(p) _________p1 = ACCESS_ONCE(p); \
> +	smp_read_barrier_depends(); /* Dependency order vs. p above. */ \
> +	(_________p1); \
> +})

Should we not have at least a single user along with this?
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