Re: [PATCH] dc395x: Fix support for highmem

[Jens Axboe <axboe@suse.de>]

On Thu, Apr 21 2005, Guennadi Liakhovetski wrote:
> +static void *dc390_kmap_atomic_sg(struct scatterlist *sg, int sg_count, size_t offset, size_t *len)
> +{
> +	int i;
> +	size_t sg_len = 0;
> +
> +	for (i = 0; i < sg_count; i++) {
> +		sg_len += sg[i].length;
> +		if (sg_len > offset)
> +			break;
> +	}
> +
> +	BUG_ON(i == sg_count);
> +
> +	*len = sg_len - offset;
> +
> +	return kmap_atomic(sg[i].page, KM_BIO_SRC_IRQ) + sg[i].offset + sg[i].length - *len;
> +}
> +
> +static void dc390_kunmap_atomic_sg(void *virt)
> +{
> +	kunmap_atomic(virt_to_page(virt), KM_BIO_SRC_IRQ);
> +}

Please remember to test this with highmem debug. The above is buggy,
kunmap_atomic() takes the mapped pointer, not the page structure.

-- 
Jens Axboe