On Thu, Jun 26, 2025 at 12:34:40PM -0700, Nicolin Chen wrote:
The new HW queue object, as an internal iommufd object, wants to reuse the struct iommufd_access to pin some iova range in the iopt.
However, an access generally takes the refcount of an ictx. So, in such an internal case, a deadlock could happen when the release of the ictx has to wait for the release of the access first when releasing a hw_queue object, which could wait for the release of the ictx that is refcounted: ictx --releases--> hw_queue --releases--> access ^ | |_________________releases________________v
To address this, add a set of lightweight internal APIs to unlink the ictx and the access, i.e. no ictx refcounting by the access: ictx --releases--> hw_queue --releases--> access
Then, there's no point in setting the access->ictx. So simply define !ictx as an flag for an internal use and add an inline helper.
Signed-off-by: Nicolin Chen nicolinc@nvidia.com
drivers/iommu/iommufd/iommufd_private.h | 23 ++++++++++ drivers/iommu/iommufd/device.c | 59 +++++++++++++++++++++---- 2 files changed, 73 insertions(+), 9 deletions(-)
Reviewed-by: Jason Gunthorpe jgg@nvidia.com
Jason