gpu: nvgpu: mm: fix MISRA 4.7 violations in vm.c

This fixes MISRA rule 4.7 violations in the function nvgpu_vm_map(). The
violations were caused by trying to use ERR_PTR() to return error
information. Rather than try to return errors in a pointer, just change
the API to return an int and pass the pointer the arguments.

JIRA NVGPU-3332

Change-Id: I2852a6de808d9203b8c7826e2b8211bab97ccd16
Signed-off-by: Philip Elcan <pelcan@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/2114027
GVS: Gerrit_Virtual_Submit
Reviewed-by: Vinod Gopalakrishnakurup <vinodg@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

drivers/gpu/nvgpu/common/mm/vm.c

@@ -866,18 +866,19 @@ void nvgpu_vm_put_buffers(struct vm_gk20a *vm,
 	nvgpu_big_free(vm->mm->g, mapped_buffers);
 }
 
-struct nvgpu_mapped_buf *nvgpu_vm_map(struct vm_gk20a *vm,
-				      struct nvgpu_os_buffer *os_buf,
-				      struct nvgpu_sgt *sgt,
-				      u64 map_addr,
-				      u64 map_size,
-				      u64 phys_offset,
-				      enum gk20a_mem_rw_flag rw,
-				      u32 flags,
-				      s16 compr_kind,
-				      s16 incompr_kind,
-				      struct vm_gk20a_mapping_batch *batch,
-				      enum nvgpu_aperture aperture)
+int nvgpu_vm_map(struct vm_gk20a *vm,
+		 struct nvgpu_os_buffer *os_buf,
+		 struct nvgpu_sgt *sgt,
+		 u64 map_addr,
+		 u64 map_size,
+		 u64 phys_offset,
+		 enum gk20a_mem_rw_flag rw,
+		 u32 flags,
+		 s16 compr_kind,
+		 s16 incompr_kind,
+		 struct vm_gk20a_mapping_batch *batch,
+		 enum nvgpu_aperture aperture,
+		 struct nvgpu_mapped_buf **mapped_buffer_arg)
 {
 	struct gk20a *g = gk20a_from_vm(vm);
 	struct nvgpu_mapped_buf *mapped_buffer = NULL;
@@ -901,12 +902,14 @@ struct nvgpu_mapped_buf *nvgpu_vm_map(struct vm_gk20a *vm,
 	 */
 	u8 pte_kind;
 
+	*mapped_buffer_arg = NULL;
+
 	if (vm->userspace_managed &&
 	    (flags & NVGPU_VM_MAP_FIXED_OFFSET) == 0U) {
 		nvgpu_err(g,
 			  "non-fixed-offset mapping not available on "
 			  "userspace managed address spaces");
-		return ERR_PTR(-EINVAL);
+		return -EINVAL;
 	}
 
 	binfo.flags = flags;
@@ -936,7 +939,8 @@ struct nvgpu_mapped_buf *nvgpu_vm_map(struct vm_gk20a *vm,
 		if (mapped_buffer != NULL) {
 			nvgpu_ref_get(&mapped_buffer->ref);
 			nvgpu_mutex_release(&vm->update_gmmu_lock);
-			return mapped_buffer;
+			*mapped_buffer_arg = mapped_buffer;
+			return 0;
 		}
 		nvgpu_mutex_release(&vm->update_gmmu_lock);
 	}
@@ -947,8 +951,9 @@ struct nvgpu_mapped_buf *nvgpu_vm_map(struct vm_gk20a *vm,
 	mapped_buffer = nvgpu_kzalloc(g, sizeof(*mapped_buffer));
 	if (mapped_buffer == NULL) {
 		nvgpu_warn(g, "oom allocating tracking buffer");
-		return ERR_PTR(-ENOMEM);
+		return -ENOMEM;
 	}
+	*mapped_buffer_arg = mapped_buffer;
 
 	align = nvgpu_sgt_alignment(g, sgt);
 	if (g->mm.disable_bigpage) {
@@ -1151,7 +1156,7 @@ struct nvgpu_mapped_buf *nvgpu_vm_map(struct vm_gk20a *vm,
 
 	nvgpu_mutex_release(&vm->update_gmmu_lock);
 
-	return mapped_buffer;
+	return 0;
 
 clean_up:
 	if (mapped_buffer->addr != 0ULL) {
@@ -1169,7 +1174,7 @@ clean_up:
 clean_up_nolock:
 	nvgpu_kfree(g, mapped_buffer);
 
-	return ERR_PTR(err);
+	return err;
 }
 
 /*

drivers/gpu/nvgpu/include/nvgpu/vm.h

@@ -255,18 +255,19 @@ struct nvgpu_mapped_buf *nvgpu_vm_find_mapping(struct vm_gk20a *vm,
 					       u32 flags,
 					       int kind);
 
-struct nvgpu_mapped_buf *nvgpu_vm_map(struct vm_gk20a *vm,
-				      struct nvgpu_os_buffer *os_buf,
-				      struct nvgpu_sgt *sgt,
-				      u64 map_addr,
-				      u64 map_size,
-				      u64 phys_offset,
-				      enum gk20a_mem_rw_flag rw,
-				      u32 flags,
-				      s16 compr_kind,
-				      s16 incompr_kind,
-				      struct vm_gk20a_mapping_batch *batch,
-				      enum nvgpu_aperture aperture);
+int nvgpu_vm_map(struct vm_gk20a *vm,
+		 struct nvgpu_os_buffer *os_buf,
+		 struct nvgpu_sgt *sgt,
+		 u64 map_addr,
+		 u64 map_size,
+		 u64 phys_offset,
+		 enum gk20a_mem_rw_flag rw,
+		 u32 flags,
+		 s16 compr_kind,
+		 s16 incompr_kind,
+		 struct vm_gk20a_mapping_batch *batch,
+		 enum nvgpu_aperture aperture,
+		 struct nvgpu_mapped_buf **mapped_buffer_arg);
 
 void nvgpu_vm_unmap(struct vm_gk20a *vm, u64 offset,
 		    struct vm_gk20a_mapping_batch *batch);

drivers/gpu/nvgpu/os/linux/vm.c

@@ -219,23 +219,23 @@ int nvgpu_vm_map_linux(struct vm_gk20a *vm,
 		goto clean_up;
 	}
 
-	mapped_buffer = nvgpu_vm_map(vm,
-				     &os_buf,
-				     nvgpu_sgt,
-				     map_addr,
-				     mapping_size,
-				     buffer_offset,
-				     rw_flag,
-				     flags,
-				     compr_kind,
-				     incompr_kind,
-				     batch,
-				     gk20a_dmabuf_aperture(g, dmabuf));
+	err = nvgpu_vm_map(vm,
+			   &os_buf,
+			   nvgpu_sgt,
+			   map_addr,
+			   mapping_size,
+			   buffer_offset,
+			   rw_flag,
+			   flags,
+			   compr_kind,
+			   incompr_kind,
+			   batch,
+			   gk20a_dmabuf_aperture(g, dmabuf),
+			   &mapped_buffer);
 
 	nvgpu_sgt_free(g, nvgpu_sgt);
 
-	if (IS_ERR(mapped_buffer)) {
-		err = PTR_ERR(mapped_buffer);
+	if (err != 0) {
 		goto clean_up;
 	}
 

userspace/units/mm/vm/vm.c

@@ -227,19 +227,20 @@ static int map_buffer(struct unit_module *m,
 		}
 	}
 
-	mapped_buf = nvgpu_vm_map(vm,
-				  &os_buf,
-				  sgt,
-				  gpu_va,
-				  buf_size,
-				  0,
-				  gk20a_mem_flag_none,
-				  NVGPU_VM_MAP_CACHEABLE,
-				  0,
-				  0,
-				  NULL,
-				  APERTURE_SYSMEM);
-	if (mapped_buf == NULL) {
+	ret = nvgpu_vm_map(vm,
+			   &os_buf,
+			   sgt,
+			   gpu_va,
+			   buf_size,
+			   0,
+			   gk20a_mem_flag_none,
+			   NVGPU_VM_MAP_CACHEABLE,
+			   0,
+			   0,
+			   NULL,
+			   APERTURE_SYSMEM,
+			   &mapped_buf);
+	if (ret != 0) {
 		unit_err(m, "Failed to map buffer into the GPU virtual address"
 			    " space\n");
 		ret = UNIT_FAIL;