iommu sg merging: parisc: make iommu respect the segment size limits

This patch makes iommu respect segment size limits when merging sg
lists.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Jeff Garzik <jeff@garzik.org>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Acked-by: Grant Grundler <grundler@parisc-linux.org>
Cc: Matthew Wilcox <willy@debian.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 1 deletions

diff --git a/drivers/parisc/iommu-helpers.h b/drivers/parisc/iommu-helpers.h
index 0a1f99a2e93e..97ba8286c596 100644
--- a/drivers/parisc/iommu-helpers.h
+++ b/drivers/parisc/iommu-helpers.h
@@ -95,12 +95,14 @@ iommu_fill_pdir(struct ioc *ioc, struct scatterlist *startsg, int nents,
 */
 
 static inline unsigned int
-iommu_coalesce_chunks(struct ioc *ioc, struct scatterlist *startsg, int nents,
+iommu_coalesce_chunks(struct ioc *ioc, struct device *dev,
+                      struct scatterlist *startsg, int nents,
                       int (*iommu_alloc_range)(struct ioc *, size_t))
 {
         struct scatterlist *contig_sg;     /* contig chunk head */
         unsigned long dma_offset, dma_len; /* start/len of DMA stream */
         unsigned int n_mappings = 0;
+        unsigned int max_seg_size = dma_get_max_seg_size(dev);
 
         while (nents > 0) {
 
@@ -142,6 +144,9 @@ iommu_coalesce_chunks(struct ioc *ioc, struct scatterlist *startsg, int nents,
                                             IOVP_SIZE) > DMA_CHUNK_SIZE))
                                 break;
 
+                        if (startsg->length + dma_len > max_seg_size)
+                                break;
+
                         /*
                         ** Next see if we can append the next chunk (i.e.
                         ** it must end on one page and begin on another