[Intel-gfx] [PATCH] drm/i915/gvt: Remove bogus retry around i915_wait_request

[Dong, Chuanxiao]

> -----Original Message-----
> From: Chris Wilson [mailto:chris.ickle.wilson at gmail.com] On Behalf Of Chris
> Wilson
> Sent: Thursday, March 9, 2017 6:08 AM
> To: intel-gfx at lists.freedesktop.org
> Cc: intel-gvt-dev at lists.freedesktop.org; Chris Wilson <chris at chris-
> wilson.co.uk>; Dong, Chuanxiao <chuanxiao.dong at intel.com>; Zhenyu
> Wang <zhenyuw at linux.intel.com>; Wang, Zhi A <zhi.a.wang at intel.com>
> Subject: [PATCH] drm/i915/gvt: Remove bogus retry around
> i915_wait_request
> 
> commit 8f1117abb408 ("drm/i915/gvt: handle workload lifecycle properly")
> includes some nonsense to retry a indefinite wait - i915_wait_request() does
> not return until the request is completed when used from an uninterruptible
> context.
> 
> Fixes: 8f1117abb408 ("drm/i915/gvt: handle workload lifecycle properly"
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Chuanxiao Dong <chuanxiao.dong at intel.com>
> Cc: Zhenyu Wang <zhenyuw at linux.intel.com>
> Cc: Zhi Wang <zhi.a.wang at intel.com>
> ---
>  drivers/gpu/drm/i915/gvt/scheduler.c | 14 +-------------
>  1 file changed, 1 insertion(+), 13 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gvt/scheduler.c
> b/drivers/gpu/drm/i915/gvt/scheduler.c
> index cfd9f7a38c27..8024904c0d58 100644
> --- a/drivers/gpu/drm/i915/gvt/scheduler.c
> +++ b/drivers/gpu/drm/i915/gvt/scheduler.c
> @@ -465,19 +465,7 @@ static int workload_thread(void *priv)
> 
>  		gvt_dbg_sched("ring id %d wait workload %p\n",
>  				workload->ring_id, workload);
> -retry:
> -		i915_wait_request(workload->req,
> -					 0, MAX_SCHEDULE_TIMEOUT);
> -		/* I915 has replay mechanism and a request will be replayed
> -		 * if there is i915 reset. So the seqno will be updated anyway.
> -		 * If the seqno is not updated yet after waiting, which means
> -		 * the replay may still be in progress and we can wait again.
> -		 */
> -		if (!i915_gem_request_completed(workload->req)) {
> -			gvt_dbg_sched("workload %p not completed, wait
> again\n",
> -					workload);
> -			goto retry;
> -		}
> +		i915_wait_request(workload->req, 0,
> MAX_SCHEDULE_TIMEOUT);

Thanks Chris for pointing this out. So per the comment, i915_wait_request will make sure to return until the request completed, even if a GPU hang happened and replay occurred during i915_wait_request(), this function will only return after the replay completed, right?

> 
>  complete:
>  		gvt_dbg_sched("will complete workload %p, status: %d\n",
> --
> 2.11.0