[PATCH 5/7] drm/amdkfd: Remove duplicate pqm_uninit()

[Oded Gabbay]

On Sat, Sep 10, 2016 at 4:31 AM, Edward O'Callaghan
<funfunctor at folklore1984.net> wrote:
> pqm_uninit() will be called in kfd_process_notifier_release(), which
> is when the process exits. Calling it in kfd_unbind_process_from_device()
> is duplicate and in fact incorrect, because pqm should not be
> uninitalized as long as the process still exists.

Hmm, I don't agree with this patch and the above explanation.

kfd_unbind_process_from_device is called from the IOMMUv2 driver, when
its callback from the mm subsystem is called (mn_release). That
callback is called when the process _is_ shutting down. The IOMMUv2
driver then unmaps all its mappings, and if we won't destroy our
queues before that happens (as pqm_uninit does), and we have a pending
operation on the queue which would get submitted before
kfd_process_notifier_release() is called, then I believe we may get an
IOMMU fault.

    Oded

>
> Original author: Yong Zhao <yong.zhao at amd.com>
> Hand ported for mainline.
>
> Signed-off-by: Edward O'Callaghan <funfunctor at folklore1984.net>
> ---
>  drivers/gpu/drm/amd/amdkfd/kfd_process.c | 2 --
>  1 file changed, 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> index 8d78052..ef2266a 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> @@ -427,8 +427,6 @@ void kfd_unbind_process_from_device(struct kfd_dev *dev, unsigned int pasid)
>                         if ((dev->dbgmgr) && (dev->dbgmgr->pasid == p->pasid))
>                                 kfd_dbgmgr_destroy(dev->dbgmgr);
>
> -                       pqm_uninit(&p->pqm);
> -
>                         pdd = kfd_get_process_device_data(dev, p);
>
>                         if (!pdd) {
> --
> 2.7.4
>
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