>>> On 08.09.12 at 11:58, Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
> When we use this pointer, we cast away the const modifier and modify the
> data. I think it was an accident to declare it as const.
NAK - the const is very valid here, as the v2 interface (as opposed
to the v1 one) does _not_ modify this array (or if it does, it's a
bug). This is a guarantee made to user mode, so it should also be
expressed that way in the interface.
But of course the cast used before this patch isn't right either, as
it indeed inappropriately discards the qualifier. Afaiu this was done
to simplify the internal workings of the code, but I don't think it's
desirable to sacrifice type safety for implementation simplicity.
Jan
> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
>
> diff --git a/include/xen/privcmd.h b/include/xen/privcmd.h
> index a853168..58ed953 100644
> --- a/include/xen/privcmd.h
> +++ b/include/xen/privcmd.h
> @@ -69,7 +69,7 @@ struct privcmd_mmapbatch_v2 {
> unsigned int num; /* number of pages to populate */
> domid_t dom; /* target domain */
> __u64 addr; /* virtual address */
> - const xen_pfn_t __user *arr; /* array of mfns */
> + xen_pfn_t __user *arr; /* array of mfns */
> int __user *err; /* array of error codes */
> };
>
> diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
> index 0ce006a..fceb83e 100644
> --- a/drivers/xen/privcmd.c
> +++ b/drivers/xen/privcmd.c
> @@ -389,7 +389,7 @@ static long privcmd_ioctl_mmap_batch(void __user *udata,
> int version)
>
> if (state.global_error && (version == 1)) {
> /* Write back errors in second pass. */
> - state.user_mfn = (xen_pfn_t *)m.arr;
> + state.user_mfn = m.arr;
> state.err = err_array;
> ret = traverse_pages(m.num, sizeof(xen_pfn_t),
> &pagelist, mmap_return_errors_v1, &state);
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxx
> http://lists.xen.org/xen-devel
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