[Intel-gfx] [PATCH v1 1/5] iommufd: Create access in vfio_iommufd_emulated_bind()

[Tian, Kevin]

> From: Nicolin Chen <nicolinc at nvidia.com>
> Sent: Thursday, March 16, 2023 1:33 PM
> 
> Hi Kevin,
> 
> I've fixed the other two commits. Here is the one that I am
> not sure about:
> 
> On Thu, Mar 16, 2023 at 02:53:50AM +0000, Tian, Kevin wrote:
> 
> > > [2] This adds iommufd_access_detach() in the cdev series:
> > >     "iommufd/device: Add iommufd_access_detach() API"
> > >
> > >
> https://github.com/nicolinc/iommufd/commit/4110522146ca1fc0d5321c04a
> > > 097e2c9d9e26af4
> >
> > also add a check if old_ioas exists it must equal to the new_ioas in attach.
> 
> This is the commit adding detach(). And there's a check in it:
> 	if (WARN_ON(!access->ioas))
> 
> Do you mean having an "if (access->ioas) return -EBUSY;" line
> in the commit adding attach()?

if (access->ioas && access->ioas != new_ioas)
	return -EBUSY;

yes this is for attach. 

> 
> And, how should we check in the detach() if it equals to the
> new_ioas in attach? Isn't the WARN_ON(!access->ioas) enough?
> 

this is not required.