Re: [PATCH v3 3/3] rpmsg: char: Rework exception handling of rpmsg_eptdev_add()

[Mathieu Poirier <mathieu.poirier@linaro.org>]

On Thu, Nov 13, 2025 at 11:39:09PM +0800, Dawei Li wrote:
> Rework  error handling of rpmsg_eptdev_add() and its callers, following
> rule of "release resource where it's allocated".
> 
> Fixes: 2410558f5f11 ("rpmsg: char: Implement eptdev based on anonymous inode")
> Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
> Closes: https://lore.kernel.org/all/aPi6gPZE2_ztOjIW@stanley.mountain/
> 
> Signed-off-by: Dawei Li <dawei.li@linux.dev>
> ---
>  drivers/rpmsg/rpmsg_char.c | 60 +++++++++++++++++++++-----------------
>  1 file changed, 33 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
> index 0919ad0a19df..92c176e9b0e4 100644
> --- a/drivers/rpmsg/rpmsg_char.c
> +++ b/drivers/rpmsg/rpmsg_char.c
> @@ -460,44 +460,34 @@ static int rpmsg_eptdev_add(struct rpmsg_eptdev *eptdev,
>  
>  	eptdev->chinfo = chinfo;
>  
> -	if (cdev) {
> -		ret = ida_alloc_max(&rpmsg_minor_ida, RPMSG_DEV_MAX - 1, GFP_KERNEL);
> -		if (ret < 0)
> -			goto free_eptdev;
> -
> -		dev->devt = MKDEV(MAJOR(rpmsg_major), ret);
> -	}
> -
>  	/* Anonymous inode device still need device name for dev_err() and friends */
>  	ret = ida_alloc(&rpmsg_ept_ida, GFP_KERNEL);
>  	if (ret < 0)
> -		goto free_minor_ida;
> +		return ret;
>  	dev->id = ret;
>  	dev_set_name(dev, "rpmsg%d", ret);
>  
> -	ret = 0;
> -
>  	if (cdev) {
> +		ret = ida_alloc_max(&rpmsg_minor_ida, RPMSG_DEV_MAX - 1, GFP_KERNEL);
> +		if (ret < 0) {
> +			ida_free(&rpmsg_ept_ida, dev->id);
> +			return ret;
> +		}
> +
> +		dev->devt = MKDEV(MAJOR(rpmsg_major), ret);
> +
>  		ret = cdev_device_add(&eptdev->cdev, &eptdev->dev);
> -		if (ret)
> -			goto free_ept_ida;
> +		if (ret) {
> +			ida_free(&rpmsg_ept_ida, dev->id);
> +			ida_free(&rpmsg_minor_ida, MINOR(dev->devt));
> +			return ret;
> +		}
>  	}
>  
>  	/* We can now rely on the release function for cleanup */
>  	dev->release = rpmsg_eptdev_release_device;
>  
> -	return ret;
> -
> -free_ept_ida:
> -	ida_free(&rpmsg_ept_ida, dev->id);
> -free_minor_ida:
> -	if (cdev)
> -		ida_free(&rpmsg_minor_ida, MINOR(dev->devt));
> -free_eptdev:
> -	dev_err(&eptdev->dev, "failed to add %s\n", eptdev->chinfo.name);
> -	kfree(eptdev);
> -
> -	return ret;
> +	return 0;
>  }
>  
>  static int rpmsg_chrdev_eptdev_add(struct rpmsg_eptdev *eptdev, struct rpmsg_channel_info chinfo)
> @@ -509,12 +499,17 @@ int rpmsg_chrdev_eptdev_create(struct rpmsg_device *rpdev, struct device *parent
>  			       struct rpmsg_channel_info chinfo)
>  {
>  	struct rpmsg_eptdev *eptdev;
> +	int ret;
>  
>  	eptdev = rpmsg_chrdev_eptdev_alloc(rpdev, parent);
>  	if (IS_ERR(eptdev))
>  		return PTR_ERR(eptdev);
>  
> -	return rpmsg_chrdev_eptdev_add(eptdev, chinfo);
> +	ret = rpmsg_chrdev_eptdev_add(eptdev, chinfo);
> +	if (ret)
> +		kfree(eptdev);

Previous patch.

> +
> +	return ret;
>  }
>  EXPORT_SYMBOL(rpmsg_chrdev_eptdev_create);
>  
> @@ -545,6 +540,12 @@ int rpmsg_anonymous_eptdev_create(struct rpmsg_device *rpdev, struct device *par
>  
>  	ret =  rpmsg_eptdev_add(eptdev, chinfo, false);
>  	if (ret) {
> +		dev_err(&eptdev->dev, "failed to add %s\n", eptdev->chinfo.name);
> +		/*
> +		 * Avoid put_device() or WARN() will be triggered due to absence of
> +		 * device::release(), refer to device_release().
> +		 */
> +		kfree(eptdev);

Previous patch.

>  		return ret;
>  	}
>  
> @@ -572,6 +573,7 @@ static int rpmsg_chrdev_probe(struct rpmsg_device *rpdev)
>  	struct rpmsg_channel_info chinfo;
>  	struct rpmsg_eptdev *eptdev;
>  	struct device *dev = &rpdev->dev;
> +	int ret;
>  
>  	memcpy(chinfo.name, rpdev->id.name, RPMSG_NAME_SIZE);
>  	chinfo.src = rpdev->src;
> @@ -590,7 +592,11 @@ static int rpmsg_chrdev_probe(struct rpmsg_device *rpdev)
>  	 */
>  	eptdev->default_ept->priv = eptdev;
>  
> -	return rpmsg_chrdev_eptdev_add(eptdev, chinfo);
> +	ret = rpmsg_chrdev_eptdev_add(eptdev, chinfo);
> +	if (ret)
> +		kfree(eptdev);

Previous patch.

> +
> +	return ret;
>  }
>  
>  static void rpmsg_chrdev_remove(struct rpmsg_device *rpdev)
> -- 
> 2.25.1
>