RE: [RFC 01/20] iommu/iommufd: Add /dev/iommu core

[Tian, Kevin]

> From: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Sent: Tuesday, September 21, 2021 11:42 PM
> 
>  - Delete the iommufd_ctx->lock. Use RCU to protect load, erase/alloc does
>    not need locking (order it properly too, it is in the wrong order), and
>    don't check for duplicate devices or dev_cookie duplication, that
>    is user error and is harmless to the kernel.
> 

I'm confused here. yes it's user error, but we check so many user errors
and then return -EINVAL, -EBUSY, etc. Why is this one special?