[PATCH 2/2] omap3: ISP: Kernel crash when attempting suspend

[PATCH 2/2] omap3: ISP: Kernel crash when attempting suspend

[Deepthy Ravi]

From: Abhilash K V <abhilash.kv@ti.com>

This patch fixes the kernel crash introduced by the previous 
patch: 
	omap3: ISP: Fix the failure of CCDC capture during 
	suspend/resume.
This null pointer exception happens when attempting suspend
while the ISP driver is not being used. The current patch
fixes this by deferring the code (as introduced in the
aforementioned patch) to handle  buffer-starvation to get
called only if the ISP reference count is non-zero.
An additional safety check is also added to ensure that
buffer-starvation logic kicks in for an empty dmaqueue only
if the ISP pipeline is not in the stopped state.

Signed-off-by: Abhilash K V <abhilash.kv@ti.com>
Signed-off-by: Deepthy Ravi <deepthy.ravi@ti.com>
---
 drivers/media/video/omap3isp/isp.c      |   12 ++++++------
 drivers/media/video/omap3isp/ispvideo.c |    4 +++-
 2 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/media/video/omap3isp/isp.c b/drivers/media/video/omap3isp/isp.c
index 6604fbd..6acdedc 100644
--- a/drivers/media/video/omap3isp/isp.c
+++ b/drivers/media/video/omap3isp/isp.c
@@ -1573,6 +1573,9 @@ static int isp_pm_prepare(struct device *dev)
 	unsigned long flags;
 
 	WARN_ON(mutex_is_locked(&isp->isp_mutex));
+	if (isp->ref_count == 0)
+		return 0;
+
 	spin_lock_irqsave(&pipe->lock, flags);
 	pipe->state |= ISP_PIPELINE_PREPARE_SUSPEND;
 	spin_unlock_irqrestore(&pipe->lock, flags);
@@ -1581,9 +1584,6 @@ static int isp_pm_prepare(struct device *dev)
 	if (err < 0)
 		return err;
 
-	if (isp->ref_count == 0)
-		return 0;
-
 	reset = isp_suspend_modules(isp);
 	isp_disable_interrupts(isp);
 	isp_save_ctx(isp);
@@ -1613,13 +1613,13 @@ static int isp_pm_resume(struct device *dev)
 	struct isp_pipeline *pipe = to_isp_pipeline(&video->video.entity);
 	unsigned long flags;
 
+	if (isp->ref_count == 0)
+		return 0;
+
 	spin_lock_irqsave(&pipe->lock, flags);
 	pipe->state &= ~ISP_PIPELINE_PREPARE_SUSPEND;
 	spin_unlock_irqrestore(&pipe->lock, flags);
 
-	if (isp->ref_count == 0)
-		return 0;
-
 	return isp_enable_clocks(isp);
 }
 
diff --git a/drivers/media/video/omap3isp/ispvideo.c b/drivers/media/video/omap3isp/ispvideo.c
index bf149a7..ffb339c 100644
--- a/drivers/media/video/omap3isp/ispvideo.c
+++ b/drivers/media/video/omap3isp/ispvideo.c
@@ -726,8 +726,10 @@ int isp_video_handle_buffer_starvation(struct isp_video *video)
 	struct isp_video_queue *queue = video->queue;
 	struct isp_video_buffer *buf;
 	struct list_head *head = &video->dmaqueue;
+	struct isp_ccdc_device *ccdc = &video->isp->isp_ccdc;
 
-	if (list_empty(&video->dmaqueue)) {
+	if (list_empty(&video->dmaqueue)
+		&& ccdc->state != ISP_PIPELINE_STREAM_STOPPED) {
 		err = isp_video_deq_enq(queue);
 	} else if (head->next->next == head) {
 		/* only one buffer is left on dmaqueue */
-- 
1.7.0.4

Re: [PATCH 2/2] omap3: ISP: Kernel crash when attempting suspend

[Laurent Pinchart]

Hi,

On Wednesday 10 August 2011 16:03:26 Deepthy Ravi wrote:
> From: Abhilash K V <abhilash.kv@ti.com>
> 
> This patch fixes the kernel crash introduced by the previous
> patch:
> 	omap3: ISP: Fix the failure of CCDC capture during
> 	suspend/resume.
> This null pointer exception happens when attempting suspend
> while the ISP driver is not being used. The current patch
> fixes this by deferring the code (as introduced in the
> aforementioned patch) to handle  buffer-starvation to get
> called only if the ISP reference count is non-zero.
> An additional safety check is also added to ensure that
> buffer-starvation logic kicks in for an empty dmaqueue only
> if the ISP pipeline is not in the stopped state.

What about squashing this with the previous patch then ?

I'll review patch 1/2, just give me a bit more time. The race condition is 
tricky so I need to rest a bit before attacking it :-)

> Signed-off-by: Abhilash K V <abhilash.kv@ti.com>
> Signed-off-by: Deepthy Ravi <deepthy.ravi@ti.com>
> ---
>  drivers/media/video/omap3isp/isp.c      |   12 ++++++------
>  drivers/media/video/omap3isp/ispvideo.c |    4 +++-
>  2 files changed, 9 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/media/video/omap3isp/isp.c
> b/drivers/media/video/omap3isp/isp.c index 6604fbd..6acdedc 100644
> --- a/drivers/media/video/omap3isp/isp.c
> +++ b/drivers/media/video/omap3isp/isp.c
> @@ -1573,6 +1573,9 @@ static int isp_pm_prepare(struct device *dev)
>  	unsigned long flags;
> 
>  	WARN_ON(mutex_is_locked(&isp->isp_mutex));
> +	if (isp->ref_count == 0)
> +		return 0;
> +
>  	spin_lock_irqsave(&pipe->lock, flags);
>  	pipe->state |= ISP_PIPELINE_PREPARE_SUSPEND;
>  	spin_unlock_irqrestore(&pipe->lock, flags);
> @@ -1581,9 +1584,6 @@ static int isp_pm_prepare(struct device *dev)
>  	if (err < 0)
>  		return err;
> 
> -	if (isp->ref_count == 0)
> -		return 0;
> -
>  	reset = isp_suspend_modules(isp);
>  	isp_disable_interrupts(isp);
>  	isp_save_ctx(isp);
> @@ -1613,13 +1613,13 @@ static int isp_pm_resume(struct device *dev)
>  	struct isp_pipeline *pipe = to_isp_pipeline(&video->video.entity);
>  	unsigned long flags;
> 
> +	if (isp->ref_count == 0)
> +		return 0;
> +
>  	spin_lock_irqsave(&pipe->lock, flags);
>  	pipe->state &= ~ISP_PIPELINE_PREPARE_SUSPEND;
>  	spin_unlock_irqrestore(&pipe->lock, flags);
> 
> -	if (isp->ref_count == 0)
> -		return 0;
> -
>  	return isp_enable_clocks(isp);
>  }
> 
> diff --git a/drivers/media/video/omap3isp/ispvideo.c
> b/drivers/media/video/omap3isp/ispvideo.c index bf149a7..ffb339c 100644
> --- a/drivers/media/video/omap3isp/ispvideo.c
> +++ b/drivers/media/video/omap3isp/ispvideo.c
> @@ -726,8 +726,10 @@ int isp_video_handle_buffer_starvation(struct
> isp_video *video) struct isp_video_queue *queue = video->queue;
>  	struct isp_video_buffer *buf;
>  	struct list_head *head = &video->dmaqueue;
> +	struct isp_ccdc_device *ccdc = &video->isp->isp_ccdc;
> 
> -	if (list_empty(&video->dmaqueue)) {
> +	if (list_empty(&video->dmaqueue)
> +		&& ccdc->state != ISP_PIPELINE_STREAM_STOPPED) {
>  		err = isp_video_deq_enq(queue);
>  	} else if (head->next->next == head) {
>  		/* only one buffer is left on dmaqueue */

-- 
Regards,

Laurent Pinchart