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Commit 8f5ba10e authored by Bart Van Assche's avatar Bart Van Assche Committed by Doug Ledford
Browse files

IB core: Fix ib_sg_to_pages() 



On 12/03/2015 01:18 AM, Christoph Hellwig wrote:
> The patch looks good to me, but while we touch this area, how about
> throwing in a few cosmetic fixes as well?

How about the patch below ? In that version of the ib_sg_to_pages() fix
these concerns have been addressed and additionally to more bugs have been fixed.

------------

[PATCH] IB core: Fix ib_sg_to_pages()

Fix the code for detecting gaps. A gap occurs not only if the
second or later scatterlist element is not aligned but also if
any scatterlist element other than the last does not end at a
page boundary.

In the code for coalescing contiguous elements, ensure that
mr->length is correct and that last_page_addr is up-to-date.

Ensure that this function returns a negative
error code instead of zero if the first set_page() call fails.

Fixes: commit 4c67e2bf ("IB/core: Introduce new fast registration API")
Reported-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarSagi Grimberg <sagig@mellanox.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>

Signed-off-by: default avatarDoug Ledford <dledford@redhat.com>
parent 57b0be9c

drivers/infiniband/core/verbs.c

+22 −21
Original line number Diff line number Diff line
@@ -1516,7 +1516,7 @@ EXPORT_SYMBOL(ib_map_mr_sg); 
 * @sg_nents:      number of entries in sg

 * @set_page:      driver page assignment function pointer

 *

 * Core service helper for drivers to covert the largest

 * Core service helper for drivers to convert the largest

 * prefix of given sg list to a page vector. The sg list

 * prefix converted is the prefix that meet the requirements

 * of ib_map_mr_sg.
@@ -1533,7 +1533,7 @@ int ib_sg_to_pages(struct ib_mr *mr, 
	u64 last_end_dma_addr = 0, last_page_addr = 0;

	unsigned int last_page_off = 0;

	u64 page_mask = ~((u64)mr->page_size - 1);

	int i;

	int i, ret;



	mr->iova = sg_dma_address(&sgl[0]);

	mr->length = 0;
@@ -1544,27 +1544,29 @@ int ib_sg_to_pages(struct ib_mr *mr, 
		u64 end_dma_addr = dma_addr + dma_len;

		u64 page_addr = dma_addr & page_mask;



		if (i && page_addr != dma_addr) {

			if (last_end_dma_addr != dma_addr) {

				/* gap */

				goto done;

		/*

		 * For the second and later elements, check whether either the

		 * end of element i-1 or the start of element i is not aligned

		 * on a page boundary.

		 */

		if (i && (last_page_off != 0 || page_addr != dma_addr)) {

			/* Stop mapping if there is a gap. */

			if (last_end_dma_addr != dma_addr)

				break;



			} else if (last_page_off + dma_len <= mr->page_size) {

				/* chunk this fragment with the last */

				mr->length += dma_len;

				last_end_dma_addr += dma_len;

				last_page_off += dma_len;

				continue;

			} else {

				/* map starting from the next page */

				page_addr = last_page_addr + mr->page_size;

				dma_len -= mr->page_size - last_page_off;

			}

			/*

			 * Coalesce this element with the last. If it is small

			 * enough just update mr->length. Otherwise start

			 * mapping from the next page.

			 */

			goto next_page;

		}



		do {

			if (unlikely(set_page(mr, page_addr)))

				goto done;

			ret = set_page(mr, page_addr);

			if (unlikely(ret < 0))

				return i ? : ret;

next_page:

			page_addr += mr->page_size;

		} while (page_addr < end_dma_addr);
@@ -1574,7 +1576,6 @@ int ib_sg_to_pages(struct ib_mr *mr, 
		last_page_off = end_dma_addr & ~page_mask;

	}



done:

	return i;

}

EXPORT_SYMBOL(ib_sg_to_pages);