[PATCH v4 13/14] drm/panfrost: Kill in-flight jobs on FD close

[Steven Price]

On 28/06/2021 08:42, Boris Brezillon wrote:
> If the process who submitted these jobs decided to close the FD before
> the jobs are done it probably means it doesn't care about the result.
> 
> v4:
> * Don't disable/restore irqs when taking the job_lock (not needed since
>   this lock is never taken from an interrupt context)
> 
> v3:
> * Set fence error to ECANCELED when a TERMINATED exception is received
> 
> Signed-off-by: Boris Brezillon <boris.brezillon at collabora.com>
> ---
>  drivers/gpu/drm/panfrost/panfrost_job.c | 42 +++++++++++++++++++++----
>  1 file changed, 36 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c
> index b0f4857ca084..979108dbc323 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_job.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_job.c
> @@ -499,14 +499,21 @@ static void panfrost_job_handle_irq(struct panfrost_device *pfdev, u32 status)
>  
>  		if (status & JOB_INT_MASK_ERR(j)) {
>  			u32 js_status = job_read(pfdev, JS_STATUS(j));
> +			const char *exception_name = panfrost_exception_name(js_status);
>  
>  			job_write(pfdev, JS_COMMAND_NEXT(j), JS_COMMAND_NOP);
>  
> -			dev_err(pfdev->dev, "js fault, js=%d, status=%s, head=0x%x, tail=0x%x",
> -				j,
> -				panfrost_exception_name(js_status),
> -				job_read(pfdev, JS_HEAD_LO(j)),
> -				job_read(pfdev, JS_TAIL_LO(j)));
> +			if (js_status < DRM_PANFROST_EXCEPTION_JOB_CONFIG_FAULT) {

I can see what your trying to do here, but the code isn't very readable
(it's not clear what JOB_CONFIG_FAULT has to do with the decision).

I think there's two options here:

 1. (In Midgard) Bits 7:6 are the "exception class" and are 0 for
"non-fault status codes". So we could rewrite it as ((js_status & 0xC0)
== 0) - or even better with appropriate macros.

 2. Provide a macro definition for DRM_PANFROST_MAX_NON_FAULT_CODE which
(at least currently) just happens to equal JOB_CONFIG_FAULT - 1 and use
that instead.

(1) is nice, but sadly Bifrost doesn't define things in terms of
exception class any more and the exception type is described as just an
8-bit enumeration. Of course we're entirely relying on any new non-fault
status codes being ordered nicely, and option 1 and 2 are actually
exactly the same check.

> +				dev_dbg(pfdev->dev, "js interrupt, js=%d, status=%s, head=0x%x, tail=0x%x",
> +					j, exception_name,
> +					job_read(pfdev, JS_HEAD_LO(j)),
> +					job_read(pfdev, JS_TAIL_LO(j)));
> +			} else {
> +				dev_err(pfdev->dev, "js fault, js=%d, status=%s, head=0x%x, tail=0x%x",
> +					j, exception_name,
> +					job_read(pfdev, JS_HEAD_LO(j)),
> +					job_read(pfdev, JS_TAIL_LO(j)));
> +			}
>  
>  			/* If we need a reset, signal it to the timeout
>  			 * handler, otherwise, update the fence error field and
> @@ -515,7 +522,16 @@ static void panfrost_job_handle_irq(struct panfrost_device *pfdev, u32 status)
>  			if (panfrost_exception_needs_reset(pfdev, js_status)) {
>  				drm_sched_fault(&pfdev->js->queue[j].sched);
>  			} else {
> -				dma_fence_set_error(pfdev->jobs[j]->done_fence, -EINVAL);
> +				int error = 0;
> +
> +				if (js_status == DRM_PANFROST_EXCEPTION_TERMINATED)
> +					error = -ECANCELED;
> +				else if (js_status >= DRM_PANFROST_EXCEPTION_JOB_CONFIG_FAULT)

As above.

> +					error = -EINVAL;
> +
> +				if (error)
> +					dma_fence_set_error(pfdev->jobs[j]->done_fence, error);
> +
>  				status |= JOB_INT_MASK_DONE(j);
>  			}
>  		}
> @@ -681,10 +697,24 @@ int panfrost_job_open(struct panfrost_file_priv *panfrost_priv)
>  
>  void panfrost_job_close(struct panfrost_file_priv *panfrost_priv)
>  {
> +	struct panfrost_device *pfdev = panfrost_priv->pfdev;
>  	int i;
>  
>  	for (i = 0; i < NUM_JOB_SLOTS; i++)
>  		drm_sched_entity_destroy(&panfrost_priv->sched_entity[i]);
> +
> +	/* Kill in-flight jobs */
> +	spin_lock(&pfdev->js->job_lock);
> +	for (i = 0; i < NUM_JOB_SLOTS; i++) {
> +		struct drm_sched_entity *entity = &panfrost_priv->sched_entity[i];
> +		struct panfrost_job *job = pfdev->jobs[i];
> +
> +		if (!job || job->base.entity != entity)
> +			continue;
> +
> +		job_write(pfdev, JS_COMMAND(i), JS_COMMAND_HARD_STOP);
> +	}
> +	spin_unlock(&pfdev->js->job_lock);
>  }
>  
>  int panfrost_job_is_idle(struct panfrost_device *pfdev)
>