Fix loop terminating conditions in fill_sg().

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

2 files changed, 15 insertions, 12 deletions

diff --git a/arch/sparc64/kernel/iommu.c b/arch/sparc64/kernel/iommu.c
index 5d4e96dba41..29af777d7ac 100644
--- a/arch/sparc64/kernel/iommu.c
+++ b/arch/sparc64/kernel/iommu.c
@@ -475,12 +475,11 @@ static void dma_4u_unmap_single(struct device *dev, dma_addr_t bus_addr,
 #define SG_ENT_PHYS_ADDRESS(SG) \
         (__pa(page_address((SG)->page)) + (SG)->offset)
 
-static inline void fill_sg(iopte_t *iopte, struct scatterlist *sg,
-                           int nused, int nelems,
-                           unsigned long iopte_protection)
+static void fill_sg(iopte_t *iopte, struct scatterlist *sg,
+                    int nused, int nelems,
+                    unsigned long iopte_protection)
 {
         struct scatterlist *dma_sg = sg;
-        struct scatterlist *sg_end = sg_last(sg, nelems);
         int i;
 
         for (i = 0; i < nused; i++) {
@@ -516,6 +515,7 @@ static inline void fill_sg(iopte_t *iopte, struct scatterlist *sg,
                                         break;
                                 }
                                 sg = sg_next(sg);
+                                nelems--;
                         }
 
                         pteval = iopte_protection | (pteval & IOPTE_PAGE);
@@ -529,18 +529,20 @@ static inline void fill_sg(iopte_t *iopte, struct scatterlist *sg,
 
                         pteval = (pteval & IOPTE_PAGE) + len;
                         sg = sg_next(sg);
+                        nelems--;
 
                         /* Skip over any tail mappings we've fully mapped,
                          * adjusting pteval along the way.  Stop when we
                          * detect a page crossing event.
                          */
-                        while (sg != sg_end &&
+                        while (nelems &&
                                (pteval << (64 - IO_PAGE_SHIFT)) != 0UL &&
                                (pteval == SG_ENT_PHYS_ADDRESS(sg)) &&
                                ((pteval ^
                                  (SG_ENT_PHYS_ADDRESS(sg) + sg->length - 1UL)) >> IO_PAGE_SHIFT) == 0UL) {
                                 pteval += sg->length;
                                 sg = sg_next(sg);
+                                nelems--;
                         }
                         if ((pteval << (64 - IO_PAGE_SHIFT)) == 0UL)
                                 pteval = ~0UL;
diff --git a/arch/sparc64/kernel/pci_sun4v.c b/arch/sparc64/kernel/pci_sun4v.c
index 119f8efa03d..fe46ace3e59 100644
--- a/arch/sparc64/kernel/pci_sun4v.c
+++ b/arch/sparc64/kernel/pci_sun4v.c
@@ -368,12 +368,11 @@ static void dma_4v_unmap_single(struct device *dev, dma_addr_t bus_addr,
 #define SG_ENT_PHYS_ADDRESS(SG) \
         (__pa(page_address((SG)->page)) + (SG)->offset)
 
-static inline long fill_sg(long entry, struct device *dev,
-                           struct scatterlist *sg,
-                           int nused, int nelems, unsigned long prot)
+static long fill_sg(long entry, struct device *dev,
+                    struct scatterlist *sg,
+                    int nused, int nelems, unsigned long prot)
 {
         struct scatterlist *dma_sg = sg;
-        struct scatterlist *sg_end = sg_last(sg, nelems);
         unsigned long flags;
         int i;
 
@@ -414,6 +413,7 @@ static inline long fill_sg(long entry, struct device *dev,
                                         break;
                                 }
                                 sg = sg_next(sg);
+                                nelems--;
                         }
 
                         pteval = (pteval & IOPTE_PAGE);
@@ -432,19 +432,20 @@ static inline long fill_sg(long entry, struct device *dev,
 
                         pteval = (pteval & IOPTE_PAGE) + len;
                         sg = sg_next(sg);
+                        nelems--;
 
                         /* Skip over any tail mappings we've fully mapped,
                          * adjusting pteval along the way.  Stop when we
                          * detect a page crossing event.
                          */
-                        while ((pteval << (64 - IO_PAGE_SHIFT)) != 0UL &&
+                        while (nelems &&
+                               (pteval << (64 - IO_PAGE_SHIFT)) != 0UL &&
                                (pteval == SG_ENT_PHYS_ADDRESS(sg)) &&
                                ((pteval ^
                                  (SG_ENT_PHYS_ADDRESS(sg) + sg->length - 1UL)) >> IO_PAGE_SHIFT) == 0UL) {
                                 pteval += sg->length;
-                                if (sg == sg_end)
-                                        break;
                                 sg = sg_next(sg);
+                                nelems--;
                         }
                         if ((pteval << (64 - IO_PAGE_SHIFT)) == 0UL)
                                 pteval = ~0UL;