Re: [PATCH] iov_iter: Fix build error without CONFIG_CRYPTO

[Al Viro <viro@zeniv.linux.org.uk>]

On Wed, Apr 03, 2019 at 05:50:31PM +0800, Yue Haibing wrote:
> From: YueHaibing <yuehaibing@huawei.com>
> 
> If CONFIG_CRYPTO is not set or set to m,
> gcc building warn this:
> 
> lib/iov_iter.o: In function `hash_and_copy_to_iter':
> iov_iter.c:(.text+0x9129): undefined reference to `crypto_stats_get'
> iov_iter.c:(.text+0x9152): undefined reference to `crypto_stats_ahash_update'
> 
> Reported-by: Hulk Robot <hulkci@huawei.com>
> Fixes: d05f443554b3 ("iov_iter: introduce hash_and_copy_to_iter helper")
> Signed-off-by: YueHaibing <yuehaibing@huawei.com>

I'm not sure it's the right fix; might be better to have something like

size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,
                struct iov_iter *i)
{
#ifdef CONFIG_CRYPTO
        struct ahash_request *hash = hashp;
        struct scatterlist sg;
        size_t copied;

        copied = copy_to_iter(addr, bytes, i);
        sg_init_one(&sg, addr, copied);
        ahash_request_set_crypt(hash, &sg, NULL, copied);
        crypto_ahash_update(hash);
        return copied;
#else
	return 0;
#endif
}
EXPORT_SYMBOL(hash_and_copy_to_iter);

instead.  Objections?