Re: [PATCH tip/core/urgent 1/4] rcu: add rcu_access_pointer andrcu_dereference_protected

From: Paul E. McKenney
Date: Fri Apr 09 2010 - 12:57:46 EST


On Fri, Apr 09, 2010 at 11:24:18AM +0200, Eric Dumazet wrote:
> Le vendredi 09 avril 2010 à 10:10 +0100, David Howells a écrit :
> > Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> wrote:
> >
> > > +#define rcu_access_pointer(p) ((void *)ACCESS_ONCE(p))
> > > ...
> > > +#define rcu_access_pointer(p) ((void *)ACCESS_ONCE(p))
> >
> > There's no difference between your two versions of rcu_access_pointer(), so
> > you could move that whole construct outside of the #ifdef'ed section.
> >
> > Other than that:
> >
> > Acked-by: David Howells <dhowells@xxxxxxxxxx>
>
> I also prefer to keep type checking if possible
>
> #define rcu_access_pointer(p) (ACCESS_ONCE(p))

Yikes! I was obsessing on preventing people from dereferencing the
pointer, but you are quite right, they might be comparing it to a
constant pointer to check for array bounds or for use of a statically
allocated emergency-pool item.

I will fix and resubmit.

> Other than that:
>
> Acked-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>

Thanx, Paul
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