On Sun, 2 Apr 2006 21:57:43 +0200 (CEST) Guennadi Liakhovetski wrote:
> Hello all,
>
> This time I really mean it:-)
Hi Guennadi,
James pointed me at this patch since I have aha152x also having
problems with using page_address() while trying to do PIO.
I see a NULL pointer during a data-out phase. I'll attempt
to use the kmap_atomic() support that you have added in the
aha152x driver.
I have a few small patch comments below.
> diff -u a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> --- a/drivers/scsi/scsi_lib.c 30 Mar 2006 19:19:08 -0000
> +++ b/drivers/scsi/scsi_lib.c 2 Apr 2006 19:13:12 -0000
> @@ -2307,3 +2307,60 @@
> return 1;
> }
> EXPORT_SYMBOL_GPL(scsi_execute_in_process_context);
> +
> +/**
> + * scsi_kmap_atomic_sg - find and atomically map an sg-elemnt
s/elemnt/element/
> + * @sg: scatter-gather list
> + * @sg_count: number of segments in sg
> + * @offset: offset in bytes into sg, on return offset into the mapped area
> + * @len: bytes to map, on return number of bytes mapped
> + *
> + * Returns virtual address of the start of the mapped page
> + */
> +void *scsi_kmap_atomic_sg(struct scatterlist *sg, int sg_count,
> + size_t *offset, size_t *len)
> +{
> + int i;
> + size_t sg_len = 0, len_complete = 0;
> + struct page *page;
> +
> + for (i = 0; i < sg_count; i++) {
> + len_complete = sg_len; /* Complete sg-entries */
> + sg_len += sg[i].length;
> + if (sg_len > *offset)
> + break;
> + }
> +
> + if (i == sg_count) {
> + printk(KERN_ERR "%s: Bytes in sg: %u, requested offset %u, elements %d\n",
> + __FUNCTION__, sg_len, *offset, sg_count);
> + WARN_ON(1);
> + return NULL;
> + }
> +
> + /* Offset starting from the beginning of first page in this sg-entry */
> + *offset = *offset - len_complete + sg[i].offset;
> +
> + /* Assumption: contiguous pages can be accessed as "page + i" */
> + page = nth_page(sg[i].page, (*offset >> PAGE_SHIFT));
> + *offset &= ~PAGE_MASK;
> +
> + /* Bytes in this sg-entry from *offset to the end of the page */
> + sg_len = PAGE_SIZE - *offset;
> + if (*len > sg_len)
> + *len = sg_len;
> +
> + return kmap_atomic(page, KM_BIO_SRC_IRQ);
> +}
> +EXPORT_SYMBOL(scsi_kmap_atomic_sg);
> +
> +/**
> + * scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously
> + * mapped with scsi_kmap_atomic_sg
First line of function kernel-doc must be just one line long. Sorry. :(
You can add more descriptive text after the parameter(s) plus one
blank line if you want to do it that way.
> + * @virt: virtual address to be unmapped
> + */
> +void scsi_kunmap_atomic_sg(void *virt)
> +{
> + kunmap_atomic(virt, KM_BIO_SRC_IRQ);
> +}
> +EXPORT_SYMBOL(scsi_kunmap_atomic_sg);
Thanks,
---
~Randy
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