Re: [PATCH v6 2/4] xen: do not return -EEXIST if iommu_add_dt_device is called twice

[Julien Grall <julien@xxxxxxx>]

Hi Stefano,

On 03/08/2021 01:24, Stefano Stabellini wrote:
> iommu_add_dt_device() returns -EEXIST if the device was already
> registered. At the moment, this can only happen if the device was
> already assigned to a domain (either dom0 at boot or via
> XEN_DOMCTL_assign_device).
>
> In a follow-up patch, we will convert the SMMU driver to use the FW
> spec. When the legacy bindings are used, all the devices will be
> registered at probe. Therefore, iommu_add_dt_device() will always
> returns -EEXIST.
So this patch needs to be first in the series to avoid breaking 
bisection. I will re-order the patches on commit.
> Currently, one caller (XEN_DOMCTL_assign_device) will check the return
> and ignore -EEXIST. All the other will fail because it was technically a
> programming error.
>
> However, there is no harm to call iommu_add_dt_device() twice, so we can
> simply return 0.
>
> With that in place the caller doesn't need to check -EEXIST anymore, so
> remove the check.
>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
Acked-by: Julien Grall <jgrall@xxxxxxxxxx>

Cheers,

--
Julien Grall