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[6/6] drm/omap: protect omap_crtc's event with event_lock spinlock

Message ID 1397201015-2807-7-git-send-email-archit@ti.com (mailing list archive)
State New, archived
Headers show

Commit Message

archit taneja April 11, 2014, 7:23 a.m. UTC
The vblank_cb callback and the page_flip ioctl can occur together in different
CPU contexts. vblank_cb uses takes tje drm device's event_lock spinlock when
sending the vblank event and updating omap_crtc->event and omap_crtc->od_fb.

Use the same spinlock in page_flip, to make sure the above omap_crtc parameters
are configured sequentially.

Signed-off-by: Archit Taneja <archit@ti.com>
---
 drivers/gpu/drm/omapdrm/omap_crtc.c | 4 ++++
 1 file changed, 4 insertions(+)

Comments

Tomi Valkeinen April 14, 2014, 12:36 p.m. UTC | #1
On 11/04/14 10:23, Archit Taneja wrote:
> The vblank_cb callback and the page_flip ioctl can occur together in different
> CPU contexts. vblank_cb uses takes tje drm device's event_lock spinlock when
> sending the vblank event and updating omap_crtc->event and omap_crtc->od_fb.
> 
> Use the same spinlock in page_flip, to make sure the above omap_crtc parameters
> are configured sequentially.
> 
> Signed-off-by: Archit Taneja <archit@ti.com>
> ---
>  drivers/gpu/drm/omapdrm/omap_crtc.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/omapdrm/omap_crtc.c b/drivers/gpu/drm/omapdrm/omap_crtc.c
> index d74c72c..9c7af42 100644
> --- a/drivers/gpu/drm/omapdrm/omap_crtc.c
> +++ b/drivers/gpu/drm/omapdrm/omap_crtc.c
> @@ -350,6 +350,7 @@ static int omap_crtc_page_flip_locked(struct drm_crtc *crtc,
>  	struct drm_device *dev = crtc->dev;
>  	struct omap_crtc *omap_crtc = to_omap_crtc(crtc);
>  	struct drm_gem_object *bo;
> +	unsigned long flags;
>  
>  	DBG("%d -> %d (event=%p)", crtc->fb ? crtc->fb->base.id : -1,
>  			fb->base.id, event);
> @@ -359,9 +360,12 @@ static int omap_crtc_page_flip_locked(struct drm_crtc *crtc,
>  		return -EINVAL;
>  	}
>  
> +	spin_lock_irqsave(&dev->event_lock, flags);
> +
>  	omap_crtc->event = event;
>  	omap_crtc->old_fb = crtc->fb = fb;
>  
> +	spin_unlock_irqrestore(&dev->event_lock, flags);

There's

if (omap_crtc->old_fb)

just above the code you changed. Shouldn't that also be inside the spinlock?

Also, the description contains a few typos.

 Tomi
archit taneja April 16, 2014, 7:06 a.m. UTC | #2
Hi,

On Monday 14 April 2014 06:06 PM, Tomi Valkeinen wrote:
> On 11/04/14 10:23, Archit Taneja wrote:
>> The vblank_cb callback and the page_flip ioctl can occur together in different
>> CPU contexts. vblank_cb uses takes tje drm device's event_lock spinlock when
>> sending the vblank event and updating omap_crtc->event and omap_crtc->od_fb.
>>
>> Use the same spinlock in page_flip, to make sure the above omap_crtc parameters
>> are configured sequentially.
>>
>> Signed-off-by: Archit Taneja <archit@ti.com>
>> ---
>>   drivers/gpu/drm/omapdrm/omap_crtc.c | 4 ++++
>>   1 file changed, 4 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/omapdrm/omap_crtc.c b/drivers/gpu/drm/omapdrm/omap_crtc.c
>> index d74c72c..9c7af42 100644
>> --- a/drivers/gpu/drm/omapdrm/omap_crtc.c
>> +++ b/drivers/gpu/drm/omapdrm/omap_crtc.c
>> @@ -350,6 +350,7 @@ static int omap_crtc_page_flip_locked(struct drm_crtc *crtc,
>>   	struct drm_device *dev = crtc->dev;
>>   	struct omap_crtc *omap_crtc = to_omap_crtc(crtc);
>>   	struct drm_gem_object *bo;
>> +	unsigned long flags;
>>
>>   	DBG("%d -> %d (event=%p)", crtc->fb ? crtc->fb->base.id : -1,
>>   			fb->base.id, event);
>> @@ -359,9 +360,12 @@ static int omap_crtc_page_flip_locked(struct drm_crtc *crtc,
>>   		return -EINVAL;
>>   	}
>>
>> +	spin_lock_irqsave(&dev->event_lock, flags);
>> +
>>   	omap_crtc->event = event;
>>   	omap_crtc->old_fb = crtc->fb = fb;
>>
>> +	spin_unlock_irqrestore(&dev->event_lock, flags);
>
> There's
>
> if (omap_crtc->old_fb)
>
> just above the code you changed. Shouldn't that also be inside the spinlock?

Yes, that should come within the spinlock too.

On a related note, the mdp5_crtc->event in mdp5_crtc_page_flip(and for 
mdp4 crtc) should also be inside the spinlock.

>
> Also, the description contains a few typos.

I'll fix these.

Thanks,
Archit
diff mbox

Patch

diff --git a/drivers/gpu/drm/omapdrm/omap_crtc.c b/drivers/gpu/drm/omapdrm/omap_crtc.c
index d74c72c..9c7af42 100644
--- a/drivers/gpu/drm/omapdrm/omap_crtc.c
+++ b/drivers/gpu/drm/omapdrm/omap_crtc.c
@@ -350,6 +350,7 @@  static int omap_crtc_page_flip_locked(struct drm_crtc *crtc,
 	struct drm_device *dev = crtc->dev;
 	struct omap_crtc *omap_crtc = to_omap_crtc(crtc);
 	struct drm_gem_object *bo;
+	unsigned long flags;
 
 	DBG("%d -> %d (event=%p)", crtc->fb ? crtc->fb->base.id : -1,
 			fb->base.id, event);
@@ -359,9 +360,12 @@  static int omap_crtc_page_flip_locked(struct drm_crtc *crtc,
 		return -EINVAL;
 	}
 
+	spin_lock_irqsave(&dev->event_lock, flags);
+
 	omap_crtc->event = event;
 	omap_crtc->old_fb = crtc->fb = fb;
 
+	spin_unlock_irqrestore(&dev->event_lock, flags);
 	/*
 	 * Hold a reference temporarily until the crtc is updated
 	 * and takes the reference to the bo.  This avoids it