On Thu, Mar 12, 2026 at 02:39:34PM +0000, Tvrtko Ursulin wrote:
>
> On 12/03/2026 14:13, Srinivasan Shanmugam wrote:
> > amdgpu_vm_bo_update() allows bo_va->base.bo to be NULL in some paths,
> > such as PRT-only updates.
> >
> > Although amdgpu_vm_is_bo_always_valid() already returns false for a NULL
> > BO, Smatch still warns that bo may be NULL before it is dereferenced
> > later in the block.
> >
> > Add an explicit `bo &&` check before calling
> > amdgpu_vm_is_bo_always_valid() to make the non-NULL condition clear and
> > fixes the below smatch error
> >
> > drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c:1353 amdgpu_vm_bo_update() error: we
> > previously assumed 'bo' could be null (see line 1292)
> >
> > Fixes: 26e20235ce00 ("drm/amdgpu: Add amdgpu_bo_is_vm_bo helper")
> > Cc: Dan Carpenter <[email protected]>
> > Cc: Tvrtko Ursulin <[email protected]>
> > Cc: Christian König <[email protected]>
> > Cc: Alex Deucher <[email protected]>
> > Signed-off-by: Srinivasan Shanmugam <[email protected]>
> > ---
> > drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> > index b89013a6aa0b..0d26346178d4 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> > @@ -1349,7 +1349,7 @@ int amdgpu_vm_bo_update(struct amdgpu_device *adev,
> > struct amdgpu_bo_va *bo_va,
> > * the evicted list so that it gets validated again on the
> > * next command submission.
> > */
> > - if (amdgpu_vm_is_bo_always_valid(vm, bo)) {
> > + if (bo && amdgpu_vm_is_bo_always_valid(vm, bo)) {
>
> That would be unfortunate:
>
> bool amdgpu_vm_is_bo_always_valid(struct amdgpu_vm *vm, struct amdgpu_bo
> *bo)
> {
> return bo && bo->tbo.base.resv == vm->root.bo->tbo.base.resv;
> }
>
> Maybe Dan can make smatch smarter? :) Because I don't think papering
> randomly at a single call site is great. It is even in the same compilation
> unit. Hmm does the order matter to smatch? Should we maybe move
> amdgpu_vm_is_bo_always_valid() to be earlier in the file?
I'm glad moving the function earlier fixed it. :) The function ends
up getting inlined. This warning should only show up if you don't have
the cross function database built.
https://staticthinking.wordpress.com/2023/05/02/the-cross-function-db/
regards,
dan carpenter
