[PATCH] drm: Don't block the kworker waiting for mode_config.lock in output_poll()

[PATCH] drm: Don't block the kworker waiting for mode_config.lock in output_poll()

[Chris Wilson]

If we cannot acquire the mode_config.lock immediately, just back off and
queue a new attempt after the poll interval. This is mostly to stop the
hung task spam when the system is deadlocked, but it will also lessen
the load (in such extreme cases).

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/drm_probe_helper.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
index ff9ba6f35248..0bf629354297 100644
--- a/drivers/gpu/drm/drm_probe_helper.c
+++ b/drivers/gpu/drm/drm_probe_helper.c
@@ -394,7 +394,11 @@ static void output_poll_execute(struct work_struct *work)
 	if (!drm_kms_helper_poll)
 		goto out;
 
-	mutex_lock(&dev->mode_config.mutex);
+	if (!mutex_trylock(&dev->mode_config.mutex)) {
+		repoll = true;
+		goto out;
+	}
+
 	drm_for_each_connector(connector, dev) {
 
 		/* Ignore forced connectors. */
-- 
2.11.0

_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx

Re: [PATCH] drm: Don't block the kworker waiting for mode_config.lock in output_poll()

[Eric Engestrom]

On Tuesday, 2016-12-06 11:37:15 +0000, Chris Wilson wrote:
> If we cannot acquire the mode_config.lock immediately, just back off and

s/mode_config.lock/mode_config.mutex lock/ ?

> queue a new attempt after the poll interval. This is mostly to stop the
> hung task spam when the system is deadlocked, but it will also lessen
> the load (in such extreme cases).
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>

> ---
>  drivers/gpu/drm/drm_probe_helper.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
> index ff9ba6f35248..0bf629354297 100644
> --- a/drivers/gpu/drm/drm_probe_helper.c
> +++ b/drivers/gpu/drm/drm_probe_helper.c
> @@ -394,7 +394,11 @@ static void output_poll_execute(struct work_struct *work)
>  	if (!drm_kms_helper_poll)
>  		goto out;
>  
> -	mutex_lock(&dev->mode_config.mutex);
> +	if (!mutex_trylock(&dev->mode_config.mutex)) {
> +		repoll = true;
> +		goto out;
> +	}
> +
>  	drm_for_each_connector(connector, dev) {
>  
>  		/* Ignore forced connectors. */
> -- 
> 2.11.0
> 
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx

Re: [Intel-gfx] [PATCH] drm: Don't block the kworker waiting for mode_config.lock in output_poll()

[Daniel Vetter]

On Tue, Dec 06, 2016 at 11:55:14AM +0000, Eric Engestrom wrote:
> On Tuesday, 2016-12-06 11:37:15 +0000, Chris Wilson wrote:
> > If we cannot acquire the mode_config.lock immediately, just back off and
> 
> s/mode_config.lock/mode_config.mutex lock/ ?

Fixed
> 
> > queue a new attempt after the poll interval. This is mostly to stop the
> > hung task spam when the system is deadlocked, but it will also lessen
> > the load (in such extreme cases).
> > 
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> 
> Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>

... and applied, thanks.
-Daniel

> 
> > ---
> >  drivers/gpu/drm/drm_probe_helper.c | 6 +++++-
> >  1 file changed, 5 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
> > index ff9ba6f35248..0bf629354297 100644
> > --- a/drivers/gpu/drm/drm_probe_helper.c
> > +++ b/drivers/gpu/drm/drm_probe_helper.c
> > @@ -394,7 +394,11 @@ static void output_poll_execute(struct work_struct *work)
> >  	if (!drm_kms_helper_poll)
> >  		goto out;
> >  
> > -	mutex_lock(&dev->mode_config.mutex);
> > +	if (!mutex_trylock(&dev->mode_config.mutex)) {
> > +		repoll = true;
> > +		goto out;
> > +	}
> > +
> >  	drm_for_each_connector(connector, dev) {
> >  
> >  		/* Ignore forced connectors. */
> > -- 
> > 2.11.0
> > 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel