On Fri, May 27, 2022 at 11:44:09AM +0100, David Howells wrote:
> Add a function, iov_iter_scan(), to iterate over the buffers described by
> an I/O iterator, kmapping and passing each contiguous chunk the supplied
> scanner function in turn, up to the requested amount of data or until the
> scanner function returns an error.
>
> This can be used, for example, to hash all the data in an iterator by
> having the scanner function call the appropriate crypto update function.
> +ssize_t iov_iter_scan(struct iov_iter *i, size_t bytes,
> + ssize_t (*scanner)(struct iov_iter *i, const void *p,
> + size_t len, size_t off, void *priv),
> + void *priv)
> +{
> + ssize_t ret = 0, scanned = 0;
> +
> + if (!bytes)
> + return 0;
> + if (iter_is_iovec(i))
> + might_fault();
> +
> + iterate_and_advance(
> + i, bytes, base, len, off, ({
> + ret = scanner(i, base, len, off, priv);
> + if (ret < 0)
> + break;
> + scanned += ret;
> + }), ({
> + ret = scanner(i, base, len, off, priv);
> + if (ret < 0)
> + break;
> + scanned += ret;
> + })
> + );
> + return ret < 0 ? ret : scanned;
> +}
Have you even tried to run sparse on that? How could that possibly work?
You are feeding the same callback both userland and kernel pointers;
that makes no sense.
NAK.
