[PATCH RESEND FOR CI] drm/i915: Fix races on fbdev

[PATCH RESEND FOR CI] drm/i915: Fix races on fbdev

[Lukas Wunner]

The ->lastclose callback invokes intel_fbdev_restore_mode() and has
been witnessed to run before intel_fbdev_initial_config_async()
has finished.

We might likewise receive hotplug events or be suspended before
we've had a chance to fully set up the fbdev.

Fix by waiting for the asynchronous thread to finish.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=93580
Reported-by: Gustav Fägerlind <gustav.fagerlind@gmail.com>
Reported-by: "Li, Weinan Z" <weinan.z.li@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: stable@vger.kernel.org
Signed-off-by: Lukas Wunner <lukas@wunner.de>
---
 drivers/gpu/drm/i915/i915_dma.c    | 8 +++-----
 drivers/gpu/drm/i915/intel_fbdev.c | 4 ++++
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 4aa3db6..9d76dfb 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -430,11 +430,9 @@ static int i915_load_modeset_init(struct drm_device *dev)
 	 * Some ports require correctly set-up hpd registers for detection to
 	 * work properly (leading to ghost connected connector status), e.g. VGA
 	 * on gm45.  Hence we can only set up the initial fbdev config after hpd
-	 * irqs are fully enabled. Now we should scan for the initial config
-	 * only once hotplug handling is enabled, but due to screwed-up locking
-	 * around kms/fbdev init we can't protect the fdbev initial config
-	 * scanning against hotplug events. Hence do this first and ignore the
-	 * tiny window where we will loose hotplug notifactions.
+	 * irqs are fully enabled. We protect the fbdev initial config scanning
+	 * against hotplug events by waiting in intel_fbdev_output_poll_changed
+	 * until the asynchronous thread has finished.
 	 */
 	intel_fbdev_initial_config_async(dev);
 
diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
index ae9cf6f..936c3d7 100644
--- a/drivers/gpu/drm/i915/intel_fbdev.c
+++ b/drivers/gpu/drm/i915/intel_fbdev.c
@@ -754,6 +754,7 @@ void intel_fbdev_set_suspend(struct drm_device *dev, int state, bool synchronous
 	struct intel_fbdev *ifbdev = dev_priv->fbdev;
 	struct fb_info *info;
 
+	async_synchronize_full();
 	if (!ifbdev)
 		return;
 
@@ -800,6 +801,8 @@ void intel_fbdev_set_suspend(struct drm_device *dev, int state, bool synchronous
 void intel_fbdev_output_poll_changed(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
+
+	async_synchronize_full();
 	if (dev_priv->fbdev)
 		drm_fb_helper_hotplug_event(&dev_priv->fbdev->helper);
 }
@@ -811,6 +814,7 @@ void intel_fbdev_restore_mode(struct drm_device *dev)
 	struct intel_fbdev *ifbdev = dev_priv->fbdev;
 	struct drm_fb_helper *fb_helper;
 
+	async_synchronize_full();
 	if (!ifbdev)
 		return;
 
-- 
1.8.5.2 (Apple Git-48)

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Re: [PATCH RESEND FOR CI] drm/i915: Fix races on fbdev

[Lukas Wunner]

Hi Damien, Hi Daniel,

I've submitted the patch below for the third time now in an attempt
to get CI to test it, again to no avail. This time I didn't set the
In-Reply-To header and only submitted it as a single patch instead
of as a series because I expected this might confuse CI.

Nevertheless CI misclassified it under "Series" instead of "Patches",
reports that the series consists of 0 patches and doesn't test it:
https://patchwork.freedesktop.org/series/4068/

Earlier attempts:
https://patchwork.freedesktop.org/series/3453/
https://patchwork.freedesktop.org/series/3126/

Sorry, I give up.

Best regards,

Lukas

On Thu, Mar 03, 2016 at 06:02:53PM +0100, Lukas Wunner wrote:
> The ->lastclose callback invokes intel_fbdev_restore_mode() and has
> been witnessed to run before intel_fbdev_initial_config_async()
> has finished.
> 
> We might likewise receive hotplug events or be suspended before
> we've had a chance to fully set up the fbdev.
> 
> Fix by waiting for the asynchronous thread to finish.
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=93580
> Reported-by: Gustav Fägerlind <gustav.fagerlind@gmail.com>
> Reported-by: "Li, Weinan Z" <weinan.z.li@intel.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: stable@vger.kernel.org
> Signed-off-by: Lukas Wunner <lukas@wunner.de>
> ---
>  drivers/gpu/drm/i915/i915_dma.c    | 8 +++-----
>  drivers/gpu/drm/i915/intel_fbdev.c | 4 ++++
>  2 files changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> index 4aa3db6..9d76dfb 100644
> --- a/drivers/gpu/drm/i915/i915_dma.c
> +++ b/drivers/gpu/drm/i915/i915_dma.c
> @@ -430,11 +430,9 @@ static int i915_load_modeset_init(struct drm_device *dev)
>  	 * Some ports require correctly set-up hpd registers for detection to
>  	 * work properly (leading to ghost connected connector status), e.g. VGA
>  	 * on gm45.  Hence we can only set up the initial fbdev config after hpd
> -	 * irqs are fully enabled. Now we should scan for the initial config
> -	 * only once hotplug handling is enabled, but due to screwed-up locking
> -	 * around kms/fbdev init we can't protect the fdbev initial config
> -	 * scanning against hotplug events. Hence do this first and ignore the
> -	 * tiny window where we will loose hotplug notifactions.
> +	 * irqs are fully enabled. We protect the fbdev initial config scanning
> +	 * against hotplug events by waiting in intel_fbdev_output_poll_changed
> +	 * until the asynchronous thread has finished.
>  	 */
>  	intel_fbdev_initial_config_async(dev);
>  
> diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
> index ae9cf6f..936c3d7 100644
> --- a/drivers/gpu/drm/i915/intel_fbdev.c
> +++ b/drivers/gpu/drm/i915/intel_fbdev.c
> @@ -754,6 +754,7 @@ void intel_fbdev_set_suspend(struct drm_device *dev, int state, bool synchronous
>  	struct intel_fbdev *ifbdev = dev_priv->fbdev;
>  	struct fb_info *info;
>  
> +	async_synchronize_full();
>  	if (!ifbdev)
>  		return;
>  
> @@ -800,6 +801,8 @@ void intel_fbdev_set_suspend(struct drm_device *dev, int state, bool synchronous
>  void intel_fbdev_output_poll_changed(struct drm_device *dev)
>  {
>  	struct drm_i915_private *dev_priv = dev->dev_private;
> +
> +	async_synchronize_full();
>  	if (dev_priv->fbdev)
>  		drm_fb_helper_hotplug_event(&dev_priv->fbdev->helper);
>  }
> @@ -811,6 +814,7 @@ void intel_fbdev_restore_mode(struct drm_device *dev)
>  	struct intel_fbdev *ifbdev = dev_priv->fbdev;
>  	struct drm_fb_helper *fb_helper;
>  
> +	async_synchronize_full();
>  	if (!ifbdev)
>  		return;
>  
> -- 
> 1.8.5.2 (Apple Git-48)
> 
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Re: [PATCH RESEND FOR CI] drm/i915: Fix races on fbdev

[Jani Nikula]

On Thu, 03 Mar 2016, Lukas Wunner <lukas@wunner.de> wrote:
> Hi Damien, Hi Daniel,
>
> I've submitted the patch below for the third time now in an attempt
> to get CI to test it, again to no avail. This time I didn't set the
> In-Reply-To header and only submitted it as a single patch instead
> of as a series because I expected this might confuse CI.
>
> Nevertheless CI misclassified it under "Series" instead of "Patches",
> reports that the series consists of 0 patches and doesn't test it:
> https://patchwork.freedesktop.org/series/4068/
>
> Earlier attempts:
> https://patchwork.freedesktop.org/series/3453/
> https://patchwork.freedesktop.org/series/3126/
>
> Sorry, I give up.

git send-email is all it takes.

BR,
Jani.


>
> Best regards,
>
> Lukas
>
> On Thu, Mar 03, 2016 at 06:02:53PM +0100, Lukas Wunner wrote:
>> The ->lastclose callback invokes intel_fbdev_restore_mode() and has
>> been witnessed to run before intel_fbdev_initial_config_async()
>> has finished.
>> 
>> We might likewise receive hotplug events or be suspended before
>> we've had a chance to fully set up the fbdev.
>> 
>> Fix by waiting for the asynchronous thread to finish.
>> 
>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=93580
>> Reported-by: Gustav Fägerlind <gustav.fagerlind@gmail.com>
>> Reported-by: "Li, Weinan Z" <weinan.z.li@intel.com>
>> Cc: Chris Wilson <chris@chris-wilson.co.uk>
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Lukas Wunner <lukas@wunner.de>
>> ---
>>  drivers/gpu/drm/i915/i915_dma.c    | 8 +++-----
>>  drivers/gpu/drm/i915/intel_fbdev.c | 4 ++++
>>  2 files changed, 7 insertions(+), 5 deletions(-)
>> 
>> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
>> index 4aa3db6..9d76dfb 100644
>> --- a/drivers/gpu/drm/i915/i915_dma.c
>> +++ b/drivers/gpu/drm/i915/i915_dma.c
>> @@ -430,11 +430,9 @@ static int i915_load_modeset_init(struct drm_device *dev)
>>  	 * Some ports require correctly set-up hpd registers for detection to
>>  	 * work properly (leading to ghost connected connector status), e.g. VGA
>>  	 * on gm45.  Hence we can only set up the initial fbdev config after hpd
>> -	 * irqs are fully enabled. Now we should scan for the initial config
>> -	 * only once hotplug handling is enabled, but due to screwed-up locking
>> -	 * around kms/fbdev init we can't protect the fdbev initial config
>> -	 * scanning against hotplug events. Hence do this first and ignore the
>> -	 * tiny window where we will loose hotplug notifactions.
>> +	 * irqs are fully enabled. We protect the fbdev initial config scanning
>> +	 * against hotplug events by waiting in intel_fbdev_output_poll_changed
>> +	 * until the asynchronous thread has finished.
>>  	 */
>>  	intel_fbdev_initial_config_async(dev);
>>  
>> diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
>> index ae9cf6f..936c3d7 100644
>> --- a/drivers/gpu/drm/i915/intel_fbdev.c
>> +++ b/drivers/gpu/drm/i915/intel_fbdev.c
>> @@ -754,6 +754,7 @@ void intel_fbdev_set_suspend(struct drm_device *dev, int state, bool synchronous
>>  	struct intel_fbdev *ifbdev = dev_priv->fbdev;
>>  	struct fb_info *info;
>>  
>> +	async_synchronize_full();
>>  	if (!ifbdev)
>>  		return;
>>  
>> @@ -800,6 +801,8 @@ void intel_fbdev_set_suspend(struct drm_device *dev, int state, bool synchronous
>>  void intel_fbdev_output_poll_changed(struct drm_device *dev)
>>  {
>>  	struct drm_i915_private *dev_priv = dev->dev_private;
>> +
>> +	async_synchronize_full();
>>  	if (dev_priv->fbdev)
>>  		drm_fb_helper_hotplug_event(&dev_priv->fbdev->helper);
>>  }
>> @@ -811,6 +814,7 @@ void intel_fbdev_restore_mode(struct drm_device *dev)
>>  	struct intel_fbdev *ifbdev = dev_priv->fbdev;
>>  	struct drm_fb_helper *fb_helper;
>>  
>> +	async_synchronize_full();
>>  	if (!ifbdev)
>>  		return;
>>  
>> -- 
>> 1.8.5.2 (Apple Git-48)
>> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Jani Nikula, Intel Open Source Technology Center
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Re: [PATCH RESEND FOR CI] drm/i915: Fix races on fbdev

[Damien Lespiau]

Hi Lukas,

I'm sorry I haven't reacted sooner. I've enabled the option to only
consider git send-email patches on intel-gfx as we were having a lot of
false positives (ie patchwork considering emails were people were making
suggestions with diffs as patches to test).

I'm not sure how you send your emails, but I can tell why that it didn't
pass the "is this a git send-email patch?" question. We're looking at
two things:

  - The X-Mailer header
  - The Message-Id (git send-email has a special way to craft its
    message IDs)

I've replayed your email by hand with an extra X-Mailer header and
patchwork picked it up (and hopefully we should have a run of our basic
acceptance tests done on it):

  https://patchwork.freedesktop.org/series/4068/

You can keep whatever you're doing now and trick patchwork to take your
patches by added this extra header to your emails:

  X-Mailer: git-send-email 2.4.3

Or use git send-email.

HTH,

-- 
Damien

On Thu, Mar 03, 2016 at 07:30:33PM +0100, Lukas Wunner wrote:
> Hi Damien, Hi Daniel,
> 
> I've submitted the patch below for the third time now in an attempt
> to get CI to test it, again to no avail. This time I didn't set the
> In-Reply-To header and only submitted it as a single patch instead
> of as a series because I expected this might confuse CI.
> 
> Nevertheless CI misclassified it under "Series" instead of "Patches",
> reports that the series consists of 0 patches and doesn't test it:
> https://patchwork.freedesktop.org/series/4068/
> 
> Earlier attempts:
> https://patchwork.freedesktop.org/series/3453/
> https://patchwork.freedesktop.org/series/3126/
> 
> Sorry, I give up.
> 
> Best regards,
> 
> Lukas
> 
> On Thu, Mar 03, 2016 at 06:02:53PM +0100, Lukas Wunner wrote:
> > The ->lastclose callback invokes intel_fbdev_restore_mode() and has
> > been witnessed to run before intel_fbdev_initial_config_async()
> > has finished.
> > 
> > We might likewise receive hotplug events or be suspended before
> > we've had a chance to fully set up the fbdev.
> > 
> > Fix by waiting for the asynchronous thread to finish.
> > 
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=93580
> > Reported-by: Gustav Fägerlind <gustav.fagerlind@gmail.com>
> > Reported-by: "Li, Weinan Z" <weinan.z.li@intel.com>
> > Cc: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Lukas Wunner <lukas@wunner.de>
> > ---
> >  drivers/gpu/drm/i915/i915_dma.c    | 8 +++-----
> >  drivers/gpu/drm/i915/intel_fbdev.c | 4 ++++
> >  2 files changed, 7 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> > index 4aa3db6..9d76dfb 100644
> > --- a/drivers/gpu/drm/i915/i915_dma.c
> > +++ b/drivers/gpu/drm/i915/i915_dma.c
> > @@ -430,11 +430,9 @@ static int i915_load_modeset_init(struct drm_device *dev)
> >  	 * Some ports require correctly set-up hpd registers for detection to
> >  	 * work properly (leading to ghost connected connector status), e.g. VGA
> >  	 * on gm45.  Hence we can only set up the initial fbdev config after hpd
> > -	 * irqs are fully enabled. Now we should scan for the initial config
> > -	 * only once hotplug handling is enabled, but due to screwed-up locking
> > -	 * around kms/fbdev init we can't protect the fdbev initial config
> > -	 * scanning against hotplug events. Hence do this first and ignore the
> > -	 * tiny window where we will loose hotplug notifactions.
> > +	 * irqs are fully enabled. We protect the fbdev initial config scanning
> > +	 * against hotplug events by waiting in intel_fbdev_output_poll_changed
> > +	 * until the asynchronous thread has finished.
> >  	 */
> >  	intel_fbdev_initial_config_async(dev);
> >  
> > diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
> > index ae9cf6f..936c3d7 100644
> > --- a/drivers/gpu/drm/i915/intel_fbdev.c
> > +++ b/drivers/gpu/drm/i915/intel_fbdev.c
> > @@ -754,6 +754,7 @@ void intel_fbdev_set_suspend(struct drm_device *dev, int state, bool synchronous
> >  	struct intel_fbdev *ifbdev = dev_priv->fbdev;
> >  	struct fb_info *info;
> >  
> > +	async_synchronize_full();
> >  	if (!ifbdev)
> >  		return;
> >  
> > @@ -800,6 +801,8 @@ void intel_fbdev_set_suspend(struct drm_device *dev, int state, bool synchronous
> >  void intel_fbdev_output_poll_changed(struct drm_device *dev)
> >  {
> >  	struct drm_i915_private *dev_priv = dev->dev_private;
> > +
> > +	async_synchronize_full();
> >  	if (dev_priv->fbdev)
> >  		drm_fb_helper_hotplug_event(&dev_priv->fbdev->helper);
> >  }
> > @@ -811,6 +814,7 @@ void intel_fbdev_restore_mode(struct drm_device *dev)
> >  	struct intel_fbdev *ifbdev = dev_priv->fbdev;
> >  	struct drm_fb_helper *fb_helper;
> >  
> > +	async_synchronize_full();
> >  	if (!ifbdev)
> >  		return;
> >  
> > -- 
> > 1.8.5.2 (Apple Git-48)
> > 
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