Re: [PATCH v2 8/8] drm/amdgpu: Prevent any job recoveries after device is unplugged.

[Andrey Grodzovsky <Andrey.Grodzovsky@amd.com>]

On 11/17/20 1:52 PM, Daniel Vetter wrote:
> On Tue, Nov 17, 2020 at 01:38:14PM -0500, Andrey Grodzovsky wrote:
>> On 6/22/20 5:53 AM, Daniel Vetter wrote:
>>> On Sun, Jun 21, 2020 at 02:03:08AM -0400, Andrey Grodzovsky wrote:
>>>> No point to try recovery if device is gone, just messes up things.
>>>>
>>>> Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
>>>> ---
>>>>    drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 16 ++++++++++++++++
>>>>    drivers/gpu/drm/amd/amdgpu/amdgpu_job.c |  8 ++++++++
>>>>    2 files changed, 24 insertions(+)
>>>>
>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
>>>> index 6932d75..5d6d3d9 100644
>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
>>>> @@ -1129,12 +1129,28 @@ static int amdgpu_pci_probe(struct pci_dev *pdev,
>>>>    	return ret;
>>>>    }
>>>> +static void amdgpu_cancel_all_tdr(struct amdgpu_device *adev)
>>>> +{
>>>> +	int i;
>>>> +
>>>> +	for (i = 0; i < AMDGPU_MAX_RINGS; ++i) {
>>>> +		struct amdgpu_ring *ring = adev->rings[i];
>>>> +
>>>> +		if (!ring || !ring->sched.thread)
>>>> +			continue;
>>>> +
>>>> +		cancel_delayed_work_sync(&ring->sched.work_tdr);
>>>> +	}
>>>> +}
>>> I think this is a function that's supposed to be in drm/scheduler, not
>>> here. Might also just be your cleanup code being ordered wrongly, or your
>>> split in one of the earlier patches not done quite right.
>>> -Daniel
>>
>> This function iterates across all the schedulers  per amdgpu device and accesses
>> amdgpu specific structures , drm/scheduler deals with single scheduler at most
>> so looks to me like this is the right place for this function
> I guess we could keep track of all schedulers somewhere in a list in
> struct drm_device and wrap this up. That was kinda the idea.
>
> Minimally I think a tiny wrapper with docs for the
> cancel_delayed_work_sync(&sched->work_tdr); which explains what you must
> observe to make sure there's no race.


Will do


> I'm not exactly sure there's no
> guarantee here we won't get a new tdr work launched right afterwards at
> least, so this looks a bit like a hack.


Note that for any TDR work happening post amdgpu_cancel_all_tdr 
amdgpu_job_timedout->drm_dev_is_unplugged
will return true and so it will return early. To make it water proof tight 
against race
i can switch from drm_dev_is_unplugged to drm_dev_enter/exit

Andrey


> -Daniel
>
>> Andrey
>>
>>
>>>> +
>>>>    static void
>>>>    amdgpu_pci_remove(struct pci_dev *pdev)
>>>>    {
>>>>    	struct drm_device *dev = pci_get_drvdata(pdev);
>>>> +	struct amdgpu_device *adev = dev->dev_private;
>>>>    	drm_dev_unplug(dev);
>>>> +	amdgpu_cancel_all_tdr(adev);
>>>>    	ttm_bo_unmap_virtual_address_space(&adev->mman.bdev);
>>>>    	amdgpu_driver_unload_kms(dev);
>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
>>>> index 4720718..87ff0c0 100644
>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
>>>> @@ -28,6 +28,8 @@
>>>>    #include "amdgpu.h"
>>>>    #include "amdgpu_trace.h"
>>>> +#include <drm/drm_drv.h>
>>>> +
>>>>    static void amdgpu_job_timedout(struct drm_sched_job *s_job)
>>>>    {
>>>>    	struct amdgpu_ring *ring = to_amdgpu_ring(s_job->sched);
>>>> @@ -37,6 +39,12 @@ static void amdgpu_job_timedout(struct drm_sched_job *s_job)
>>>>    	memset(&ti, 0, sizeof(struct amdgpu_task_info));
>>>> +	if (drm_dev_is_unplugged(adev->ddev)) {
>>>> +		DRM_INFO("ring %s timeout, but device unplugged, skipping.\n",
>>>> +					  s_job->sched->name);
>>>> +		return;
>>>> +	}
>>>> +
>>>>    	if (amdgpu_ring_soft_recovery(ring, job->vmid, s_job->s_fence->parent)) {
>>>>    		DRM_ERROR("ring %s timeout, but soft recovered\n",
>>>>    			  s_job->sched->name);
>>>> -- 
>>>> 2.7.4
>>>>
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