gpu: nvgpu: Add for_each construct for nvgpu_sgts

Add a macro to iterate across nvgpu_sgts. This makes it easier on
developers who may accidentally forget to move to the next SGL.

JIRA NVGPU-243

Change-Id: I90154a5d23f0014cb79bbcd5b6e8d8dbda303820
Signed-off-by: Alex Waterman <alexw@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1566627
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

3 files changed, 14 insertions, 10 deletions

diff --git a/drivers/gpu/nvgpu/common/mm/gmmu.c b/drivers/gpu/nvgpu/common/mm/gmmu.c
index ab9d0d41..cad53fa1 100644
--- a/drivers/gpu/nvgpu/common/mm/gmmu.c
+++ b/drivers/gpu/nvgpu/common/mm/gmmu.c
@@ -497,8 +497,7 @@ static int __nvgpu_gmmu_update_page_table_vidmem(struct vm_gk20a *vm,
          * Otherwise iterate across all the chunks in this allocation and
          * map them.
          */
-        sgl = sgt->sgl;
-        while (sgl) {
+        nvgpu_sgt_for_each_sgl(sgl, sgt) {
                 if (space_to_skip &&
                     space_to_skip >= nvgpu_sgt_get_length(sgt, sgl)) {
                         space_to_skip -= nvgpu_sgt_get_length(sgt, sgl);
@@ -526,7 +525,6 @@ static int __nvgpu_gmmu_update_page_table_vidmem(struct vm_gk20a *vm,
                  */
                 virt_addr += chunk_length;
                 length    -= chunk_length;
-                sgl = nvgpu_sgt_get_next(sgt, sgl);
 
                 if (length == 0)
                         break;
@@ -544,7 +542,7 @@ static int __nvgpu_gmmu_update_page_table_sysmem(struct vm_gk20a *vm,
 {
         struct gk20a *g = gk20a_from_vm(vm);
         void *sgl;
-        int err;
+        int err = 0;
 
         if (!sgt) {
                 /*
@@ -567,10 +565,8 @@ static int __nvgpu_gmmu_update_page_table_sysmem(struct vm_gk20a *vm,
          * mapping is simple since the "physical" address is actually a virtual
          * IO address and will be contiguous.
          */
-        sgl = sgt->sgl;
-
         if (!g->mm.bypass_smmu) {
-                u64 io_addr = nvgpu_sgt_get_gpu_addr(sgt, g, sgl, attrs);
+                u64 io_addr = nvgpu_sgt_get_gpu_addr(sgt, g, sgt->sgl, attrs);
 
                 io_addr += space_to_skip;
 
@@ -588,7 +584,7 @@ static int __nvgpu_gmmu_update_page_table_sysmem(struct vm_gk20a *vm,
          * Finally: last possible case: do the no-IOMMU mapping. In this case we
          * really are mapping physical pages directly.
          */
-        while (sgl) {
+        nvgpu_sgt_for_each_sgl(sgl, sgt) {
                 u64 phys_addr;
                 u64 chunk_length;
 
@@ -616,7 +612,6 @@ static int __nvgpu_gmmu_update_page_table_sysmem(struct vm_gk20a *vm,
                 space_to_skip = 0;
                 virt_addr += chunk_length;
                 length    -= chunk_length;
-                sgl        = nvgpu_sgt_get_next(sgt, sgl);
 
                 if (length == 0)
                         break;
diff --git a/drivers/gpu/nvgpu/common/pramin.c b/drivers/gpu/nvgpu/common/pramin.c
index 9d59f61d..4f7d6248 100644
--- a/drivers/gpu/nvgpu/common/pramin.c
+++ b/drivers/gpu/nvgpu/common/pramin.c
@@ -105,7 +105,8 @@ void nvgpu_pramin_access_batched(struct gk20a *g, struct nvgpu_mem *mem,
 
         alloc = get_vidmem_page_alloc(mem->priv.sgt->sgl);
         sgt = &alloc->sgt;
-        for (sgl = sgt->sgl; sgl; sgl = nvgpu_sgt_get_next(sgt, sgl)) {
+
+        nvgpu_sgt_for_each_sgl(sgl, sgt) {
                 if (offset >= nvgpu_sgt_get_length(sgt, sgl))
                         offset -= nvgpu_sgt_get_length(sgt, sgl);
                 else
diff --git a/drivers/gpu/nvgpu/include/nvgpu/nvgpu_mem.h b/drivers/gpu/nvgpu/include/nvgpu/nvgpu_mem.h
index c2f0e37b..23a1bad7 100644
--- a/drivers/gpu/nvgpu/include/nvgpu/nvgpu_mem.h
+++ b/drivers/gpu/nvgpu/include/nvgpu/nvgpu_mem.h
@@ -104,6 +104,14 @@ struct nvgpu_mem_sgl {
         u64                      length;
 };
 
+/*
+ * Iterate over the SGL entries in an SGT.
+ */
+#define nvgpu_sgt_for_each_sgl(__sgl__, __sgt__)                \
+        for ((__sgl__) = (__sgt__)->sgl;                        \
+             (__sgl__) != NULL;                                 \
+             (__sgl__) = nvgpu_sgt_get_next(__sgt__, __sgl__))
+
 struct nvgpu_mem {
         /*
          * Populated for all nvgpu_mem structs - vidmem or system.