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Commit 121b78e6 authored by Oded Gabbay's avatar Oded Gabbay
Browse files

drm/amdkfd: unbind only existing processes 



When unbinding a process from a device (initiated by amd_iommu_v2), the
driver needs to make sure that process still exists in the process table.
There is a possibility that amdkfd's own notifier handler -
kfd_process_notifier_release() - was called before the unbind function
and it already removed the process from the process table.

v2:
Because there can be only one process with the specified pasid, and
because *p can't be NULL inside the hash_for_each_rcu macro, it is more
reasonable to just put the whole code inside the if statement that
compares the pasid value. That way, when we exit hash_for_each_rcu, we
simply exit the function as well.

Signed-off-by: default avatarOded Gabbay <oded.gabbay@gmail.com>
CC: Stable <stable@vger.kernel.org>
parent ab3ab684

drivers/gpu/drm/amd/amdkfd/kfd_process.c

+35 −25
Original line number Diff line number Diff line
@@ -404,13 +404,17 @@ void kfd_unbind_process_from_device(struct kfd_dev *dev, unsigned int pasid) 


	idx = srcu_read_lock(&kfd_processes_srcu);



	/*

	 * Look for the process that matches the pasid. If there is no such

	 * process, we either released it in amdkfd's own notifier, or there

	 * is a bug. Unfortunately, there is no way to tell...

	 */

	hash_for_each_rcu(kfd_processes_table, i, p, kfd_processes)

		if (p->pasid == pasid)

			break;

		if (p->pasid == pasid) {



			srcu_read_unlock(&kfd_processes_srcu, idx);



	BUG_ON(p->pasid != pasid);

			pr_debug("Unbinding process %d from IOMMU\n", pasid);



			mutex_lock(&p->mutex);
@@ -432,14 +436,20 @@ void kfd_unbind_process_from_device(struct kfd_dev *dev, unsigned int pasid) 
			}



			/*

	 * Just mark pdd as unbound, because we still need it to call

	 * amd_iommu_unbind_pasid() in when the process exits.

			 * Just mark pdd as unbound, because we still need it

			 * to call amd_iommu_unbind_pasid() in when the

			 * process exits.

			 * We don't call amd_iommu_unbind_pasid() here

			 * because the IOMMU called us.

			 */

			pdd->bound = false;



			mutex_unlock(&p->mutex);



			return;

		}



	srcu_read_unlock(&kfd_processes_srcu, idx);

}



struct kfd_process_device *kfd_get_first_process_device_data(struct kfd_process *p)