[PATCH] vb2: Fix compilation breakage when !CONFIG_BUG

[PATCH] vb2: Fix compilation breakage when !CONFIG_BUG

[Laurent Pinchart]

Commit 77a3c6fd90c9 ("[media] vb2: Don't WARN when v4l2_buffer.bytesused
is 0 for multiplanar buffers") uses the __WARN() macro which isn't
defined when CONFIG_BUG isn't set. This introduces a compilation
breakage. Fix it by using WARN_ON() instead.

The commit was also broken in that it merged v1 of the patch while a new
v2 version had been submitted, reviewed and acked. Fix it by
incorporating the changes from v1 to v2.

Fixes: 77a3c6fd90c9 ("[media] vb2: Don't WARN when v4l2_buffer.bytesused is 0 for multiplanar buffers")
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 drivers/media/v4l2-core/videobuf2-core.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

Mauro,

Commit 77a3c6fd90c9 was merged in v4.2-rc1, so this is a v4.2 regression. The
commit was also marked with a Fixes: line for commit f61bf13b6a07, which was
merged in v4.1-rc1. It might thus get backported to the v4.1 stable series, in
which case this fix needs to be backported as well. I'll let you sort this out.

diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index 93b315459098..db11d853b060 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -1244,19 +1244,19 @@ EXPORT_SYMBOL_GPL(vb2_discard_done);
 
 static void vb2_warn_zero_bytesused(struct vb2_buffer *vb)
 {
-	static bool __check_once __read_mostly;
+	static bool check_once;
 
-	if (__check_once)
+	if (check_once)
 		return;
 
-	__check_once = true;
-	__WARN();
+	check_once = true;
+	WARN_ON(1);
 
-	pr_warn_once("use of bytesused == 0 is deprecated and will be removed in the future,\n");
+	pr_warn("use of bytesused == 0 is deprecated and will be removed in the future,\n");
 	if (vb->vb2_queue->allow_zero_bytesused)
-		pr_warn_once("use VIDIOC_DECODER_CMD(V4L2_DEC_CMD_STOP) instead.\n");
+		pr_warn("use VIDIOC_DECODER_CMD(V4L2_DEC_CMD_STOP) instead.\n");
 	else
-		pr_warn_once("use the actual size instead.\n");
+		pr_warn("use the actual size instead.\n");
 }
 
 /**
-- 
Regards,

Laurent Pinchart

Re: [PATCH] vb2: Fix compilation breakage when !CONFIG_BUG

[Larry Finger]

On 07/12/2015 06:08 PM, Laurent Pinchart wrote:
> Commit 77a3c6fd90c9 ("[media] vb2: Don't WARN when v4l2_buffer.bytesused
> is 0 for multiplanar buffers") uses the __WARN() macro which isn't
> defined when CONFIG_BUG isn't set. This introduces a compilation
> breakage. Fix it by using WARN_ON() instead.
>
> The commit was also broken in that it merged v1 of the patch while a new
> v2 version had been submitted, reviewed and acked. Fix it by
> incorporating the changes from v1 to v2.
>
> Fixes: 77a3c6fd90c9 ("[media] vb2: Don't WARN when v4l2_buffer.bytesused is 0 for multiplanar buffers")
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> ---
>   drivers/media/v4l2-core/videobuf2-core.c | 14 +++++++-------
>   1 file changed, 7 insertions(+), 7 deletions(-)
>
> Mauro,
>
> Commit 77a3c6fd90c9 was merged in v4.2-rc1, so this is a v4.2 regression. The
> commit was also marked with a Fixes: line for commit f61bf13b6a07, which was
> merged in v4.1-rc1. It might thus get backported to the v4.1 stable series, in
> which case this fix needs to be backported as well. I'll let you sort this out.
>
> diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
> index 93b315459098..db11d853b060 100644
> --- a/drivers/media/v4l2-core/videobuf2-core.c
> +++ b/drivers/media/v4l2-core/videobuf2-core.c
> @@ -1244,19 +1244,19 @@ EXPORT_SYMBOL_GPL(vb2_discard_done);

Changing from __WARN to WARN_ON fixes the problem that I found. For that part

Acked-by: Larry Finger <Larry.Finger@lwfinger.net>

Larry

>
>   static void vb2_warn_zero_bytesused(struct vb2_buffer *vb)
>   {
> -	static bool __check_once __read_mostly;
> +	static bool check_once;
>
> -	if (__check_once)
> +	if (check_once)
>   		return;
>
> -	__check_once = true;
> -	__WARN();
> +	check_once = true;
> +	WARN_ON(1);
>
> -	pr_warn_once("use of bytesused == 0 is deprecated and will be removed in the future,\n");
> +	pr_warn("use of bytesused == 0 is deprecated and will be removed in the future,\n");
>   	if (vb->vb2_queue->allow_zero_bytesused)
> -		pr_warn_once("use VIDIOC_DECODER_CMD(V4L2_DEC_CMD_STOP) instead.\n");
> +		pr_warn("use VIDIOC_DECODER_CMD(V4L2_DEC_CMD_STOP) instead.\n");
>   	else
> -		pr_warn_once("use the actual size instead.\n");
> +		pr_warn("use the actual size instead.\n");
>   }
>
>   /**
>