lib/scatterlist: Provide a DMA page iterator

Commit 2db76d7c3c6d ("lib/scatterlist: sg_page_iter: support sg lists w/o
backing pages") introduced the sg_page_iter_dma_address() function without
providing a way to use it in the general case. If the sg_dma_len() is not
equal to the sg length callers cannot safely use the
for_each_sg_page/sg_page_iter_dma_address combination.

Resolve this API mistake by providing a DMA specific iterator,
for_each_sg_dma_page(), that uses the right length so
sg_page_iter_dma_address() works as expected with all sglists.

A new iterator type is introduced to provide compile-time safety against
wrongly mixing accessors and iterators.

Acked-by: Christoph Hellwig <hch@lst.de> (for scatterlist)
Acked-by: Thomas Hellstrom <thellstrom@vmware.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com> (ipu3-cio2)
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/media/pci/intel/ipu3/ipu3-cio2.c b/drivers/media/pci/intel/ipu3/ipu3-cio2.c
index cdb79ae2d8dc..9fbfbda74171 100644
--- a/drivers/media/pci/intel/ipu3/ipu3-cio2.c
+++ b/drivers/media/pci/intel/ipu3/ipu3-cio2.c
@@ -846,7 +846,7 @@ static int cio2_vb2_buf_init(struct vb2_buffer *vb)
         unsigned int pages = DIV_ROUND_UP(vb->planes[0].length, CIO2_PAGE_SIZE);
         unsigned int lops = DIV_ROUND_UP(pages + 1, entries_per_page);
         struct sg_table *sg;
-        struct sg_page_iter sg_iter;
+        struct sg_dma_page_iter sg_iter;
         int i, j;
 
         if (lops <= 0 || lops > CIO2_MAX_LOPS) {
@@ -873,7 +873,7 @@ static int cio2_vb2_buf_init(struct vb2_buffer *vb)
                 b->offset = sg->sgl->offset;
 
         i = j = 0;
-        for_each_sg_page(sg->sgl, &sg_iter, sg->nents, 0) {
+        for_each_sg_dma_page (sg->sgl, &sg_iter, sg->nents, 0) {
                 if (!pages--)
                         break;
                 b->lop[i][j] = sg_page_iter_dma_address(&sg_iter) >> PAGE_SHIFT;