On Tue, Apr 02, 2019 at 12:56:27PM -0500, Shiraz Saleem wrote:
> +/* ib_umem_add_sg_table - Add N contiguous pages to scatter table
> + *
> + * sg: current scatterlist entry
> + * page_list: array of npage struct page pointers
> + * npages: number of pages in page_list
> + * max_seg_size: maximum segment size in bytes
max_seg_sz
> + * nents: [out] number of entries in the scatterlist
> + *
> + * Return new end of scatterlist
> + */
> +static struct scatterlist *ib_umem_add_sg_table(struct scatterlist *sg,
> + struct page **page_list,
> + unsigned long npages,
> + unsigned int max_seg_sz,
> + int *nents)
> +{
> + unsigned long first_pfn;
> + unsigned long i = 0;
> + bool update_cur_sg = false;
> + bool first = !sg_page(sg);
> +
> + /* Check if new page_list is contiguous with end of previous page_list.
> + * sg->length here is a multiple of PAGE_SIZE and sg->offset is 0.
> + */
> + if (!first && (page_to_pfn(sg_page(sg)) + (sg->length >> PAGE_SHIFT) ==
> + page_to_pfn(page_list[0])))
> + update_cur_sg = true;
> +
> + while (i != npages) {
> + unsigned long len;
> + struct page *first_page = page_list[i];
> +
> + first_pfn = page_to_pfn(first_page);
> +
> + /* Compute the number of contiguous pages we have starting
> + * at i
> + */
> + for (len = 0; i != npages &&
> + first_pfn + len == page_to_pfn(page_list[i]);
> + len++)
> + i++;
> +
> + /* Squash N contiguous pages from page_list into current sge */
> + if (update_cur_sg &&
> + ((sg->length + (len << PAGE_SHIFT)) < max_seg_sz))
> {
This add can still overflow.. should be something like
(max_seg_sz - sg->length) <= (len << PAGE_SHIFT)
> diff --git a/include/rdma/ib_umem.h b/include/rdma/ib_umem.h
> index 73af05d..ccc44c0 100644
> +++ b/include/rdma/ib_umem.h
> @@ -53,7 +53,7 @@ struct ib_umem {
> struct work_struct work;
> struct sg_table sg_head;
> int nmap;
> - int npages;
> + int sg_nents;
This probably should be unsigned int
Otherwise this seems fine - what HW were you able to test it on?
Jason
