Re: [PATCH v5 1/5] iommu: Lock group->mutex in iommu_deferred_attach()

[Baolu Lu]

On 11/11/25 13:12, Nicolin Chen wrote:
> The iommu_deferred_attach() function invokes __iommu_attach_device(), but
> doesn't hold the group->mutex like other __iommu_attach_device() callers.
>
> Though there is no pratical bug being triggered so far, it would be better
> to apply the same locking to this __iommu_attach_device(), since the IOMMU
> drivers nowaday are more aware of the group->mutex -- some of them use the
> iommu_group_mutex_assert() function that could be potentially in the path
> of an attach_dev callback function invoked by the __iommu_attach_device().
>
> Worth mentioning that the iommu_deferred_attach() will soon need to check
> group->resetting_domain that must be locked also.
>
> Thus, grab the mutex to guard __iommu_attach_device() like other callers.
>
> Reviewed-by: Jason Gunthorpe<jgg@xxxxxxxxxx>
> Reviewed-by: Kevin Tian<kevin.tian@xxxxxxxxx>
> Signed-off-by: Nicolin Chen<nicolinc@xxxxxxxxxx>
> ---
>   drivers/iommu/iommu.c | 13 ++++++++++---
>   1 file changed, 10 insertions(+), 3 deletions(-)

Reviewed-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>