linux-kernel - Re: [PATCH v6 02/10] rpmsg: create the rpmsg class in core instead of in rpmsg char

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Date:   Mon, 1 Nov 2021 11:57:04 -0500
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Arnaud Pouliquen <arnaud.pouliquen@...s.st.com>
Cc:     Ohad Ben-Cohen <ohad@...ery.com>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        linux-remoteproc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com, julien.massot@....bzh
Subject: Re: [PATCH v6 02/10] rpmsg: create the rpmsg class in core instead
 of in rpmsg char

On Fri 22 Oct 07:54 CDT 2021, Arnaud Pouliquen wrote:

> Migrate the creation of the rpmsg class from the rpmsg_char
> to the core that the class is usable by all rpmsg services.
> 
> Suggested-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@...s.st.com>
> ---
>  drivers/rpmsg/rpmsg_char.c | 14 ++------------
>  drivers/rpmsg/rpmsg_core.c | 26 ++++++++++++++++++++++++--
>  include/linux/rpmsg.h      | 10 ++++++++++
>  3 files changed, 36 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
> index 941c5c54dd72..327ed739a3a7 100644
> --- a/drivers/rpmsg/rpmsg_char.c
> +++ b/drivers/rpmsg/rpmsg_char.c
> @@ -28,7 +28,6 @@
>  #define RPMSG_DEV_MAX	(MINORMASK + 1)
>  
>  static dev_t rpmsg_major;
> -static struct class *rpmsg_class;
>  
>  static DEFINE_IDA(rpmsg_ctrl_ida);
>  static DEFINE_IDA(rpmsg_ept_ida);
> @@ -362,7 +361,7 @@ int rpmsg_chrdev_eptdev_create(struct rpmsg_device *rpdev, struct device *parent
>  	init_waitqueue_head(&eptdev->readq);
>  
>  	device_initialize(dev);
> -	dev->class = rpmsg_class;
> +	dev->class = rpmsg_get_class();
>  	dev->parent = parent;
>  	dev->groups = rpmsg_eptdev_groups;
>  	dev_set_drvdata(dev, eptdev);
> @@ -482,7 +481,7 @@ static int rpmsg_chrdev_probe(struct rpmsg_device *rpdev)
>  	dev = &ctrldev->dev;
>  	device_initialize(dev);
>  	dev->parent = &rpdev->dev;
> -	dev->class = rpmsg_class;
> +	dev->class = rpmsg_get_class();
>  
>  	cdev_init(&ctrldev->cdev, &rpmsg_ctrldev_fops);
>  	ctrldev->cdev.owner = THIS_MODULE;
> @@ -558,17 +557,9 @@ static int rpmsg_chrdev_init(void)
>  		return ret;
>  	}
>  
> -	rpmsg_class = class_create(THIS_MODULE, "rpmsg");
> -	if (IS_ERR(rpmsg_class)) {
> -		pr_err("failed to create rpmsg class\n");
> -		unregister_chrdev_region(rpmsg_major, RPMSG_DEV_MAX);
> -		return PTR_ERR(rpmsg_class);
> -	}
> -
>  	ret = register_rpmsg_driver(&rpmsg_chrdev_driver);
>  	if (ret < 0) {
>  		pr_err("rpmsgchr: failed to register rpmsg driver\n");
> -		class_destroy(rpmsg_class);
>  		unregister_chrdev_region(rpmsg_major, RPMSG_DEV_MAX);
>  	}
>  
> @@ -579,7 +570,6 @@ postcore_initcall(rpmsg_chrdev_init);
>  static void rpmsg_chrdev_exit(void)
>  {
>  	unregister_rpmsg_driver(&rpmsg_chrdev_driver);
> -	class_destroy(rpmsg_class);
>  	unregister_chrdev_region(rpmsg_major, RPMSG_DEV_MAX);
>  }
>  module_exit(rpmsg_chrdev_exit);
> diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
> index 9151836190ce..53162038254d 100644
> --- a/drivers/rpmsg/rpmsg_core.c
> +++ b/drivers/rpmsg/rpmsg_core.c
> @@ -20,6 +20,8 @@
>  
>  #include "rpmsg_internal.h"
>  
> +static struct class *rpmsg_class;
> +
>  /**
>   * rpmsg_create_channel() - create a new rpmsg channel
>   * using its name and address info.
> @@ -296,6 +298,19 @@ __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp,
>  }
>  EXPORT_SYMBOL(rpmsg_poll);
>  
> +/**
> + * rpmsg_get_class() - get reference to the sysfs rpmsg class
> + *
> + * This function return the pointer to the "rpmsg" class created by the rpmsg core.
> + *
> + * Returns the struct class pointer
> + */
> +struct class *rpmsg_get_class(void)

What value does this helper function add? Can't we just expose
rpmsg_class directly?

> +{
> +	return rpmsg_class;
> +}
> +EXPORT_SYMBOL(rpmsg_get_class);
> +
>  /**
>   * rpmsg_trysend_offchannel() - send a message using explicit src/dst addresses
>   * @ept: the rpmsg endpoint
> @@ -629,10 +644,17 @@ static int __init rpmsg_init(void)
>  {
>  	int ret;
>  
> +	rpmsg_class = class_create(THIS_MODULE, "rpmsg");
> +	if (IS_ERR(rpmsg_class)) {
> +		pr_err("failed to create rpmsg class\n");
> +		return PTR_ERR(rpmsg_class);
> +	}
> +
>  	ret = bus_register(&rpmsg_bus);
> -	if (ret)
> +	if (ret) {
>  		pr_err("failed to register rpmsg bus: %d\n", ret);
> -
> +		class_destroy(rpmsg_class);
> +	}
>  	return ret;
>  }
>  postcore_initcall(rpmsg_init);
> diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h

Isn't this just going to be used by rpmsg_char and rpmsg_ctrl? Do we
really need to expose it in the client-facing API?

Regards,
Bjorn

> index a8dcf8a9ae88..6fe51549d931 100644
> --- a/include/linux/rpmsg.h
> +++ b/include/linux/rpmsg.h
> @@ -186,6 +186,8 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
>  __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp,
>  			poll_table *wait);
>  
> +struct class *rpmsg_get_class(void);
> +
>  #else
>  
>  static inline int rpmsg_register_device(struct rpmsg_device *rpdev)
> @@ -296,6 +298,14 @@ static inline __poll_t rpmsg_poll(struct rpmsg_endpoint *ept,
>  	return 0;
>  }
>  
> +static inline struct class *rpmsg_get_class(void)
> +{
> +	/* This shouldn't be possible */
> +	WARN_ON(1);
> +
> +	return NULL;
> +}
> +
>  #endif /* IS_ENABLED(CONFIG_RPMSG) */
>  
>  /* use a macro to avoid include chaining to get THIS_MODULE */
> -- 
> 2.17.1
>