[PATCH] iommu/dart: Fix return code in apple_dart_domain_alloc_paging()

[Jason Gunthorpe]

On Mon, Oct 30, 2023 at 03:00:56PM +0300, Dan Carpenter wrote:
> On Mon, Oct 30, 2023 at 08:56:50AM -0300, Jason Gunthorpe wrote:
> > On Mon, Oct 30, 2023 at 12:03:12PM +0300, Dan Carpenter wrote:
> > > The apple_dart_domain_alloc_paging() function is supposed to return NULL
> > > on error.  Returning an error pointer will lead to an Oops in
> > > __iommu_domain_alloc().
> > > 
> > > Fixes: 482feb5c6492 ("iommu/dart: Call apple_dart_finalize_domain() as part of alloc_paging()")
> > > Signed-off-by: Dan Carpenter <dan.carpenter at linaro.org>
> > > ---
> > >  drivers/iommu/apple-dart.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > Reviewed-by: Jason Gunthorpe <jgg at nvidia.com>
> > 
> > Really need to fix this so the function does return ERR_PTR..
> 
> It's called as a function pointer.  Changing that will create a
> backporting hazard unless we rename the pointer or something.

You can make that argument about almost any change in the kernel..

IMHO we needed an annotation like __user/__iomem/etc to indicate
ERR_PTR so at least there is some hope of trivially finding it.

Jason