Re: [Xen-devel] [PATCH] io/ring.h: drop unused and broken *_RING_ATTACH() macros

[Keir Fraser <keir.xen@xxxxxxxxx>]

On 11/06/2013 09:47, "Jan Beulich" <JBeulich@xxxxxxxx> wrote:

> Initializing r*_prod_pvt and r*_cons from independent shared ring
> fields is broken, as other macros in this header rely on them being
> coupled. Furthermore using the backend variant would also imply a
> security vulnerability.
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Acked-by: Keir Fraser <keir@xxxxxxx>

> --- a/xen/include/public/io/ring.h
> +++ b/xen/include/public/io/ring.h
> @@ -174,21 +174,6 @@ typedef struct __name##_back_ring __name
>      (_r)->sring = (_s);                                                 \
>  } while (0)
>  
> -/* Initialize to existing shared indexes -- for recovery */
> -#define FRONT_RING_ATTACH(_r, _s, __size) do {                          \
> -    (_r)->sring = (_s);                                                 \
> -    (_r)->req_prod_pvt = (_s)->req_prod;                                \
> -    (_r)->rsp_cons = (_s)->rsp_prod;                                    \
> -    (_r)->nr_ents = __RING_SIZE(_s, __size);                            \
> -} while (0)
> -
> -#define BACK_RING_ATTACH(_r, _s, __size) do {                           \
> -    (_r)->sring = (_s);                                                 \
> -    (_r)->rsp_prod_pvt = (_s)->rsp_prod;                                \
> -    (_r)->req_cons = (_s)->req_prod;                                    \
> -    (_r)->nr_ents = __RING_SIZE(_s, __size);                            \
> -} while (0)
> -
>  /* How big is this ring? */
>  #define RING_SIZE(_r)                                                   \
>      ((_r)->nr_ents)
> 
> 
> 
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