Re: [PATCH v3 05/19] drm/xe/vma: Modify new_vma to accept struct xe_vma_mem_attr as parameter

[Dan Carpenter <dan.carpenter@linaro.org>]

Hi Himal,

kernel test robot noticed the following build warnings:

https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Himal-Prasad-Ghimiray/Introduce-drm_gpuvm_sm_map_ops_flags-enums-for-sm_map_ops/20250528-041919
base:   https://gitlab.freedesktop.org/drm/xe/kernel.git drm-xe-next
patch link:    https://lore.kernel.org/r/20250527164003.1068118-6-himal.prasad.ghimiray%40intel.com
patch subject: [PATCH v3 05/19] drm/xe/vma: Modify new_vma to accept struct xe_vma_mem_attr as parameter
config: loongarch-randconfig-r073-20250529 (https://download.01.org/0day-ci/archive/20250530/202505300251.vkfxetWu-lkp@intel.com/config)
compiler: loongarch64-linux-gcc (GCC) 15.1.0

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
| Closes: https://lore.kernel.org/r/202505300251.vkfxetWu-lkp@intel.com/

New smatch warnings:
drivers/gpu/drm/xe/xe_vm.c:2492 new_vma() error: 'vma' dereferencing possible ERR_PTR()

vim +/vma +2492 drivers/gpu/drm/xe/xe_vm.c

b06d47be7c83165 Matthew Brost         2023-07-07  2444  static struct xe_vma *new_vma(struct xe_vm *vm, struct drm_gpuva_op_map *op,
341ac2942dd2087 Himal Prasad Ghimiray 2025-05-27  2445  			      struct xe_vma_mem_attr attr, unsigned int flags)
b06d47be7c83165 Matthew Brost         2023-07-07  2446  {
b06d47be7c83165 Matthew Brost         2023-07-07  2447  	struct xe_bo *bo = op->gem.obj ? gem_to_xe_bo(op->gem.obj) : NULL;
24f947d58fe554c Thomas Hellström      2023-12-12  2448  	struct drm_exec exec;
b06d47be7c83165 Matthew Brost         2023-07-07  2449  	struct xe_vma *vma;
33991ae8f40a824 Matthew Brost         2024-06-17  2450  	int err = 0;
b06d47be7c83165 Matthew Brost         2023-07-07  2451  
b06d47be7c83165 Matthew Brost         2023-07-07  2452  	lockdep_assert_held_write(&vm->lock);
b06d47be7c83165 Matthew Brost         2023-07-07  2453  
b06d47be7c83165 Matthew Brost         2023-07-07  2454  	if (bo) {
d2197029026021e Dave Airlie           2023-12-22  2455  		drm_exec_init(&exec, DRM_EXEC_INTERRUPTIBLE_WAIT, 0);
24f947d58fe554c Thomas Hellström      2023-12-12  2456  		drm_exec_until_all_locked(&exec) {
24f947d58fe554c Thomas Hellström      2023-12-12  2457  			err = 0;
24f947d58fe554c Thomas Hellström      2023-12-12  2458  			if (!bo->vm) {
24f947d58fe554c Thomas Hellström      2023-12-12  2459  				err = drm_exec_lock_obj(&exec, xe_vm_obj(vm));
24f947d58fe554c Thomas Hellström      2023-12-12  2460  				drm_exec_retry_on_contention(&exec);
24f947d58fe554c Thomas Hellström      2023-12-12  2461  			}
24f947d58fe554c Thomas Hellström      2023-12-12  2462  			if (!err) {
24f947d58fe554c Thomas Hellström      2023-12-12  2463  				err = drm_exec_lock_obj(&exec, &bo->ttm.base);
24f947d58fe554c Thomas Hellström      2023-12-12  2464  				drm_exec_retry_on_contention(&exec);
24f947d58fe554c Thomas Hellström      2023-12-12  2465  			}
24f947d58fe554c Thomas Hellström      2023-12-12  2466  			if (err) {
24f947d58fe554c Thomas Hellström      2023-12-12  2467  				drm_exec_fini(&exec);
b06d47be7c83165 Matthew Brost         2023-07-07  2468  				return ERR_PTR(err);
dd08ebf6c3525a7 Matthew Brost         2023-03-30  2469  			}
24f947d58fe554c Thomas Hellström      2023-12-12  2470  		}
24f947d58fe554c Thomas Hellström      2023-12-12  2471  	}
b06d47be7c83165 Matthew Brost         2023-07-07  2472  	vma = xe_vma_create(vm, bo, op->gem.offset,
b06d47be7c83165 Matthew Brost         2023-07-07  2473  			    op->va.addr, op->va.addr +
341ac2942dd2087 Himal Prasad Ghimiray 2025-05-27  2474  			    op->va.range - 1, attr.pat_index, flags);
33991ae8f40a824 Matthew Brost         2024-06-17  2475  	if (IS_ERR(vma))
33991ae8f40a824 Matthew Brost         2024-06-17  2476  		goto err_unlock;

Missing "err = PTR_ERR(vma);"

dd08ebf6c3525a7 Matthew Brost         2023-03-30  2477  
33991ae8f40a824 Matthew Brost         2024-06-17  2478  	if (xe_vma_is_userptr(vma))
5bd24e78829ad56 Thomas Hellström      2024-01-31  2479  		err = xe_vma_userptr_pin_pages(to_userptr_vma(vma));
33991ae8f40a824 Matthew Brost         2024-06-17  2480  	else if (!xe_vma_has_no_bo(vma) && !bo->vm)
b06d47be7c83165 Matthew Brost         2023-07-07  2481  		err = add_preempt_fences(vm, bo);
33991ae8f40a824 Matthew Brost         2024-06-17  2482  
33991ae8f40a824 Matthew Brost         2024-06-17  2483  err_unlock:
33991ae8f40a824 Matthew Brost         2024-06-17  2484  	if (bo)
33991ae8f40a824 Matthew Brost         2024-06-17  2485  		drm_exec_fini(&exec);
33991ae8f40a824 Matthew Brost         2024-06-17  2486  
b06d47be7c83165 Matthew Brost         2023-07-07  2487  	if (err) {
b06d47be7c83165 Matthew Brost         2023-07-07  2488  		prep_vma_destroy(vm, vma, false);
b06d47be7c83165 Matthew Brost         2023-07-07  2489  		xe_vma_destroy_unlocked(vma);
33991ae8f40a824 Matthew Brost         2024-06-17  2490  		vma = ERR_PTR(err);
341ac2942dd2087 Himal Prasad Ghimiray 2025-05-27  2491  	} else {
341ac2942dd2087 Himal Prasad Ghimiray 2025-05-27 @2492  		cp_vma_mem_attr(&vma->attr, &attr);
                                                                                        ^^^^
leads to error pointer dereference.

dd08ebf6c3525a7 Matthew Brost         2023-03-30  2493  	}
dd08ebf6c3525a7 Matthew Brost         2023-03-30  2494  
b06d47be7c83165 Matthew Brost         2023-07-07  2495  	return vma;

I was wondering why Smatch doesn't catch the missing error code but
actually we return the error code...  #ABitConfusing

b06d47be7c83165 Matthew Brost         2023-07-07  2496  }

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