[PATCH] iommufd: Remove iommufd_ref_to_users()

[PATCH] iommufd: Remove iommufd_ref_to_users()

[Jason Gunthorpe]

This no longer has any callers, remove the function

Kevin noticed that after commit 99f98a7c0d69 ("iommufd: IOMMUFD_DESTROY
should not increase the refcount") there was only one other user and it
turns out the rework in commit 9227da7816dd ("iommufd: Add
iommufd_access_change_ioas(_id) helpers") got rid of the last one.

Suggested-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
 drivers/iommu/iommufd/iommufd_private.h | 23 -----------------------
 1 file changed, 23 deletions(-)

This is possible once the rc branch is merged up with iommufd to join the two
commits.

diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index 15596a08a0571e..5a45b8ba2e26cb 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -149,29 +149,6 @@ static inline void iommufd_put_object(struct iommufd_object *obj)
 	up_read(&obj->destroy_rwsem);
 }
 
-/**
- * iommufd_ref_to_users() - Switch from destroy_rwsem to users refcount
- *        protection
- * @obj - Object to release
- *
- * Objects have two refcount protections (destroy_rwsem and the refcount_t
- * users). Holding either of these will prevent the object from being destroyed.
- *
- * Depending on the use case, one protection or the other is appropriate.  In
- * most cases references are being protected by the destroy_rwsem. This allows
- * orderly destruction of the object because iommufd_object_destroy_user() will
- * wait for it to become unlocked. However, as a rwsem, it cannot be held across
- * a system call return. So cases that have longer term needs must switch
- * to the weaker users refcount_t.
- *
- * With users protection iommufd_object_destroy_user() will return false,
- * refusing to destroy the object, causing -EBUSY to userspace.
- */
-static inline void iommufd_ref_to_users(struct iommufd_object *obj)
-{
-	up_read(&obj->destroy_rwsem);
-	/* iommufd_lock_obj() obtains users as well */
-}
 void iommufd_object_abort(struct iommufd_ctx *ictx, struct iommufd_object *obj);
 void iommufd_object_abort_and_destroy(struct iommufd_ctx *ictx,
 				      struct iommufd_object *obj);

base-commit: 83f968d8ba18e550acaef6921bf64cffe672df82
-- 
2.41.0

RE: [PATCH] iommufd: Remove iommufd_ref_to_users()

[Tian, Kevin]

> From: Jason Gunthorpe <jgg@nvidia.com>
> Sent: Tuesday, August 15, 2023 7:25 AM
> 
> This no longer has any callers, remove the function
> 
> Kevin noticed that after commit 99f98a7c0d69 ("iommufd:
> IOMMUFD_DESTROY
> should not increase the refcount") there was only one other user and it
> turns out the rework in commit 9227da7816dd ("iommufd: Add
> iommufd_access_change_ioas(_id) helpers") got rid of the last one.
> 
> Suggested-by: Kevin Tian <kevin.tian@intel.com>
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

Reviewed-by: Kevin Tian <kevin.tian@intel.com>

Re: [PATCH] iommufd: Remove iommufd_ref_to_users()

[Jason Gunthorpe]

On Mon, Aug 14, 2023 at 08:24:34PM -0300, Jason Gunthorpe wrote:
> This no longer has any callers, remove the function
> 
> Kevin noticed that after commit 99f98a7c0d69 ("iommufd: IOMMUFD_DESTROY
> should not increase the refcount") there was only one other user and it
> turns out the rework in commit 9227da7816dd ("iommufd: Add
> iommufd_access_change_ioas(_id) helpers") got rid of the last one.
> 
> Suggested-by: Kevin Tian <kevin.tian@intel.com>
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
> ---
>  drivers/iommu/iommufd/iommufd_private.h | 23 -----------------------
>  1 file changed, 23 deletions(-)

Applied to for-next, thanks

Jason