Use guard() to simplify mutex locking. No functional change.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
 drivers/staging/media/imx/imx6-mipi-csi2.c | 54 +++++++++++-------------------
 1 file changed, 19 insertions(+), 35 deletions(-)

diff --git a/drivers/staging/media/imx/imx6-mipi-csi2.c b/drivers/staging/media/imx/imx6-mipi-csi2.c
index f8d0b3b8b250774af51f2aba731e639131aceff9..54e9491d3428686288a5bc9bb58a5a0a25aca696 100644
--- a/drivers/staging/media/imx/imx6-mipi-csi2.c
+++ b/drivers/staging/media/imx/imx6-mipi-csi2.c
@@ -413,21 +413,17 @@ static int csi2_s_stream(struct v4l2_subdev *sd, int enable)
 	struct csi2_dev *csi2 = sd_to_dev(sd);
 	int i, ret = 0;
 
-	mutex_lock(&csi2->lock);
+	guard(mutex)(&csi2->lock);
 
-	if (!csi2->src_sd) {
-		ret = -EPIPE;
-		goto out;
-	}
+	if (!csi2->src_sd)
+		return -EPIPE;
 
 	for (i = 0; i < CSI2_NUM_SRC_PADS; i++) {
 		if (csi2->sink_linked[i])
 			break;
 	}
-	if (i >= CSI2_NUM_SRC_PADS) {
-		ret = -EPIPE;
-		goto out;
-	}
+	if (i >= CSI2_NUM_SRC_PADS)
+		return -EPIPE;
 
 	/*
 	 * enable/disable streaming only if stream_count is
@@ -442,14 +438,12 @@ static int csi2_s_stream(struct v4l2_subdev *sd, int enable)
 	else
 		csi2_stop(csi2);
 	if (ret)
-		goto out;
+		return ret;
 
 update_count:
 	csi2->stream_count += enable ? 1 : -1;
 	if (csi2->stream_count < 0)
 		csi2->stream_count = 0;
-out:
-	mutex_unlock(&csi2->lock);
 	return ret;
 }
 
@@ -467,32 +461,28 @@ static int csi2_link_setup(struct media_entity *entity,
 
 	remote_sd = media_entity_to_v4l2_subdev(remote->entity);
 
-	mutex_lock(&csi2->lock);
+	guard(mutex)(&csi2->lock);
 
 	if (local->flags & MEDIA_PAD_FL_SOURCE) {
 		if (flags & MEDIA_LNK_FL_ENABLED) {
-			if (csi2->sink_linked[local->index - 1]) {
-				ret = -EBUSY;
-				goto out;
-			}
+			if (csi2->sink_linked[local->index - 1])
+				return -EBUSY;
+
 			csi2->sink_linked[local->index - 1] = true;
 		} else {
 			csi2->sink_linked[local->index - 1] = false;
 		}
 	} else {
 		if (flags & MEDIA_LNK_FL_ENABLED) {
-			if (csi2->src_sd) {
-				ret = -EBUSY;
-				goto out;
-			}
+			if (csi2->src_sd)
+				return -EBUSY;
+
 			csi2->src_sd = remote_sd;
 		} else {
 			csi2->src_sd = NULL;
 		}
 	}
 
-out:
-	mutex_unlock(&csi2->lock);
 	return ret;
 }
 
@@ -513,14 +503,12 @@ static int csi2_get_fmt(struct v4l2_subdev *sd,
 	struct csi2_dev *csi2 = sd_to_dev(sd);
 	struct v4l2_mbus_framefmt *fmt;
 
-	mutex_lock(&csi2->lock);
+	guard(mutex)(&csi2->lock);
 
 	fmt = __csi2_get_fmt(csi2, sd_state, sdformat->pad, sdformat->which);
 
 	sdformat->format = *fmt;
 
-	mutex_unlock(&csi2->lock);
-
 	return 0;
 }
 
@@ -530,17 +518,14 @@ static int csi2_set_fmt(struct v4l2_subdev *sd,
 {
 	struct csi2_dev *csi2 = sd_to_dev(sd);
 	struct v4l2_mbus_framefmt *fmt;
-	int ret = 0;
 
 	if (sdformat->pad >= CSI2_NUM_PADS)
 		return -EINVAL;
 
-	mutex_lock(&csi2->lock);
+	guard(mutex)(&csi2->lock);
 
-	if (csi2->stream_count > 0) {
-		ret = -EBUSY;
-		goto out;
-	}
+	if (csi2->stream_count > 0)
+		return -EBUSY;
 
 	/* Output pads mirror active input pad, no limits on input pads */
 	if (sdformat->pad != CSI2_SINK_PAD)
@@ -549,9 +534,8 @@ static int csi2_set_fmt(struct v4l2_subdev *sd,
 	fmt = __csi2_get_fmt(csi2, sd_state, sdformat->pad, sdformat->which);
 
 	*fmt = sdformat->format;
-out:
-	mutex_unlock(&csi2->lock);
-	return ret;
+
+	return 0;
 }
 
 static int csi2_registered(struct v4l2_subdev *sd)

-- 
2.34.1

On Fr, 2025-11-07 at 15:44 -0500, Frank Li wrote:
> Use guard() to simplify mutex locking. No functional change.
> 
> Signed-off-by: Frank Li <Frank.Li@nxp.com>
> ---
>  drivers/staging/media/imx/imx6-mipi-csi2.c | 54 +++++++++++-------------------
>  1 file changed, 19 insertions(+), 35 deletions(-)
> 
> diff --git a/drivers/staging/media/imx/imx6-mipi-csi2.c b/drivers/staging/media/imx/imx6-mipi-csi2.c
> index f8d0b3b8b250774af51f2aba731e639131aceff9..54e9491d3428686288a5bc9bb58a5a0a25aca696 100644
> --- a/drivers/staging/media/imx/imx6-mipi-csi2.c
> +++ b/drivers/staging/media/imx/imx6-mipi-csi2.c
> @@ -413,21 +413,17 @@ static int csi2_s_stream(struct v4l2_subdev *sd, int enable)
>  	struct csi2_dev *csi2 = sd_to_dev(sd);
>  	int i, ret = 0;
>  
> -	mutex_lock(&csi2->lock);
> +	guard(mutex)(&csi2->lock);
>  
> -	if (!csi2->src_sd) {
> -		ret = -EPIPE;
> -		goto out;
> -	}
> +	if (!csi2->src_sd)
> +		return -EPIPE;
>  
>  	for (i = 0; i < CSI2_NUM_SRC_PADS; i++) {
>  		if (csi2->sink_linked[i])
>  			break;
>  	}
> -	if (i >= CSI2_NUM_SRC_PADS) {
> -		ret = -EPIPE;
> -		goto out;
> -	}
> +	if (i >= CSI2_NUM_SRC_PADS)
> +		return -EPIPE;
>  
>  	/*
>  	 * enable/disable streaming only if stream_count is
> @@ -442,14 +438,12 @@ static int csi2_s_stream(struct v4l2_subdev *sd, int enable)
>  	else
>  		csi2_stop(csi2);
>  	if (ret)
> -		goto out;
> +		return ret;
>  
>  update_count:
>  	csi2->stream_count += enable ? 1 : -1;
>  	if (csi2->stream_count < 0)
>  		csi2->stream_count = 0;
> -out:
> -	mutex_unlock(&csi2->lock);
>  	return ret;

This is mixing goto and cleanup in the same function, which the scope-
based cleanup helpers documentation suggests shouldn't be done.

In this case I see no problem because we only jump to update_count from
under the lock, but since issues with gotos around automatic cleanup
are easy to miss, I think it would be better to also turn the
update_count jump into a conditional block.


regards
Philipp