[PATCH] drm/i915/gvt: stop scheduling workload when vgpu is inactive

[Zhenyu Wang]

On 2019.02.27 15:36:58 +0800, Weinan Li wrote:
> There is one corner case that workload_thread may pick and dispatch one
> workload of vgpu after it's already deactivated. Below is the scenario:
> 
> 1. deactive_vgpu got the vgpu_lock, it found pending workload was
> submitted, then it released the vgpu_lock and wait for vgpu idle.
> 2. before deactive_vgpu got the vgpu_lock back, workload_thread might pick
> one new valid workload, then it was blocked by the vgpu_lock.
> 3. deactive_vgpu got the vgpu_lock again, finished the last processes of
> deactivating, then release the vgpu_lock.
> 4. workload_thread got the vgpu_lock, then it will try to dispatch the
> fetched workload. It's not expected one workload of deactivated vgpu is
> dispatched.
> 
> The solution is to add condition check of the vgpu's active flag and stop
> to schedule when it's inactive.
> 
> Signed-off-by: Weinan Li <weinan.z.li at intel.com>
> ---
>  drivers/gpu/drm/i915/gvt/scheduler.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/gvt/scheduler.c b/drivers/gpu/drm/i915/gvt/scheduler.c
> index 1bb8f93..2bcb701 100644
> --- a/drivers/gpu/drm/i915/gvt/scheduler.c
> +++ b/drivers/gpu/drm/i915/gvt/scheduler.c
> @@ -739,7 +739,8 @@ static struct intel_vgpu_workload *pick_next_workload(
>  		goto out;
>  	}
>  
> -	if (list_empty(workload_q_head(scheduler->current_vgpu, ring_id)))
> +	if (!scheduler->current_vgpu->active ||
> +	    list_empty(workload_q_head(scheduler->current_vgpu, ring_id)))
>  		goto out;
>  
>  	/*

looks sane to me.

Reviewed-by: Zhenyu Wang <zhenyuw at linux.intel.com>

-- 
Open Source Technology Center, Intel ltd.

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