On 2019-12-18 4:50 a.m., Pan Zhang wrote: > this set adds support for removal of gpu drm dead code. > > patch2: > `num_entries` is a data of unsigned type(compilers always treat as unsigned > int) and SIZE_MAX == ~0, > > so there is a impossible condition: > '(num_entries > ((~0) - 56) / 72) => (max(0-u32) > 256204778801521549)'.
While this looks correct for 64-bit, where size_t is unsigned long, on 32-bit it's unsigned int, in which case this isn't dead code. > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c > b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c > index 85b0515..10a7f30 100644 > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c > @@ -71,10 +71,6 @@ int amdgpu_bo_list_create(struct amdgpu_device *adev, > struct drm_file *filp, > unsigned i; > int r; > > - if (num_entries > (SIZE_MAX - sizeof(struct amdgpu_bo_list)) > - / sizeof(struct amdgpu_bo_list_entry)) > - return -EINVAL; > - > size = sizeof(struct amdgpu_bo_list); > size += num_entries * sizeof(struct amdgpu_bo_list_entry); > list = kvmalloc(size, GFP_KERNEL); > -- Earthling Michel Dänzer | https://redhat.com Libre software enthusiast | Mesa and X developer _______________________________________________ dri-devel mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/dri-devel
