Re: [PATCH 1/1] iommu/amd: Use delayed mmu release notifier

From: Oded Gabbay
Date: Thu Nov 06 2014 - 08:49:12 EST




On 11/06/2014 03:33 PM, Joerg Roedel wrote:
On Sat, Oct 18, 2014 at 12:43:27AM +0300, Oded Gabbay wrote:
3. Later, amdkfd's mmu notifier callback (kfd_process_notifier_release()) gets
called and releases more things that are related to the process.
In that function, amd_iommu_unbind_pasid() is explicitly called.

Can't you just register a delayed funtion in
kfd_process_notifier_release() and call amd_iommu_unbind_pasid() from
there?
Maybe, I need to think about that. Anyway, I'm still not convinced, please see next question.

>>I really hate to make that part of the IOMMUv2 driver API,
What do you mean ? I don't see I change anything in the API. All the changes are internal to amd_iommu_unbind_pasid(). I don't think *anyone* calling to amd_iommu_unbind_pasid() will care or will notice the slight change in timing of releasing the pasid_state object (instead of immediate release, it is released after the iteration on the mmu_notifier list has finished)

especially since it is going to be turned into a generic IOMMU-API
extension.

And especially since all these hacks could be avoided if the KFD driver
would just turn down everything on closing the file descriptor.


Joerg

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