[PATCH] drm/amdgpu: fix deadlock of reservation between cs and gpu reset

[Zhang, Jerry (Junwei)]

On 04/27/2017 04:25 PM, Chunming Zhou wrote:
> the case could happen when gpu reset:
> 1. when gpu reset, cs can be continue until sw queue is full, then push job will wait with holding pd reservation.
> 2. gpu_reset routine will also need pd reservation to restore page table from their shadow.
> 3. cs is waiting for gpu_reset complete, but gpu reset is waiting for cs releases reservation.
>
> Change-Id: I0f66d04b2bef3433035109623c8a5c5992c84202
> Signed-off-by: Chunming Zhou <David1.Zhou at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> index 9edb1a4..a6722a7 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> @@ -1076,6 +1076,7 @@ static int amdgpu_cs_submit(struct amdgpu_cs_parser *p,
>   	amdgpu_job_free_resources(job);
>
>   	trace_amdgpu_cs_ioctl(job);
> +	amdgpu_cs_parser_fini(p, 0, true);

Please confirm:
It will not free/release more things that may be accessed in job working 
process, as cs_parse_fini free so many things related to parser.

Or we can just release the pd reservation here?

Jerry

>   	amd_sched_entity_push_job(&job->base);
>
>   	return 0;
> @@ -1130,6 +1131,7 @@ int amdgpu_cs_ioctl(struct drm_device *dev, void *data, struct drm_file *filp)
>
>   	r = amdgpu_cs_submit(&parser, cs);
>
> +	return r;
>   out:
>   	amdgpu_cs_parser_fini(&parser, r, reserved_buffers);
>   	return r;
>