Re: [Qemu-devel] [Xen-devel] [PATCH] xen: fix qdisk BLKIF_OP_DISCARD for 32/64 word size mix

[Jan Beulich]

>>> On 16.06.16 at 12:02, <address@hidden> wrote:
> In case the word size of the domU and qemu running the qdisk backend
> differ BLKIF_OP_DISCARD will not work reliably, as the request
> structure in the ring have different layouts for different word size.
> 
> Correct this by copying the request structure in case of different
> word size element by element in the BLKIF_OP_DISCARD case, too.
> 
> Signed-off-by: Juergen Gross <address@hidden>

With the indentation (tabs vs blanks) fixed
Reviewed-by: Jan Beulich <address@hidden>

And maybe ...

> @@ -82,7 +98,7 @@ static inline void blkif_get_x86_32_req(blkif_request_t 
> *dst, blkif_x86_32_reque
>       /* Prevent the compiler from using src->... instead. */
>       barrier();
>       if (dst->operation == BLKIF_OP_DISCARD) {
> -             struct blkif_request_discard *s = (void *)src;
> +                struct blkif_x86_32_request_discard *s = (void *)src;

... it would also be worth adding const here and ...

> @@ -105,7 +121,7 @@ static inline void blkif_get_x86_64_req(blkif_request_t 
> *dst, blkif_x86_64_reque
>       /* Prevent the compiler from using src->... instead. */
>       barrier();
>       if (dst->operation == BLKIF_OP_DISCARD) {
> -             struct blkif_request_discard *s = (void *)src;
> +                struct blkif_x86_64_request_discard *s = (void *)src;

... here.

Jan