linux-kernel - Re: [PATCH v2 07/16] rpmsg: char: clean up rpmsg class

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Date:   Mon, 4 Jan 2021 18:54:05 -0600
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>,
        Andy Gross <agross@...nel.org>,
        linux-remoteproc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH v2 07/16] rpmsg: char: clean up rpmsg class

On Mon 04 Jan 18:47 CST 2021, Bjorn Andersson wrote:

> On Tue 22 Dec 04:57 CST 2020, Arnaud Pouliquen wrote:
> 
> This patch doesn't "clean up" the class, as described in $subject. It
> just removes it.
> 
> > Suppress the management of the rpmsg class as attribute. It is already
> > handled in /sys/bus rpmsg as specified in
> > documentation/ABI/testing/sysfs-bus-rpmsg.
> 
> Afaict it doesn't relate to /sys/bus/rpmsg, but rather what attributes
> should be associated with the rpmsg_device (and thereby present in its
> sysfs directory). But if these attributes are also added by the bus,
> then why do we have this code? If that's the case this seems like a nice
> cleanup that we should do outside/before merging the other patches.
> 
> > This patch prepares the migration of the control device in rpmsg_ctrl.
> > 
> 
> It would be useful if the commit message described how it prepares for
> the migration and why.
> 

Now I see what this patch does, it removes the attributes from the
character device's struct device, because they are provided by the
struct rpmsg_device's bus!

I wish your commit message made this obvious.

Also, this implies that for a few patches here rpmsg_char is just
broken - which I don't like.

Regards,
Bjorn

> Regards,
> Bjorn
> 
> > Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@...s.st.com>
> > ---
> >  drivers/rpmsg/rpmsg_char.c | 48 --------------------------------------
> >  1 file changed, 48 deletions(-)
> > 
> > diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
> > index 4bbbacdbf3bb..732f5caf068a 100644
> > --- a/drivers/rpmsg/rpmsg_char.c
> > +++ b/drivers/rpmsg/rpmsg_char.c
> > @@ -27,7 +27,6 @@
> >  #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);
> > @@ -291,41 +290,6 @@ static const struct file_operations rpmsg_eptdev_fops = {
> >  	.compat_ioctl = compat_ptr_ioctl,
> >  };
> >  
> > -static ssize_t name_show(struct device *dev, struct device_attribute *attr,
> > -			 char *buf)
> > -{
> > -	struct rpmsg_eptdev *eptdev = dev_get_drvdata(dev);
> > -
> > -	return sprintf(buf, "%s\n", eptdev->chinfo.name);
> > -}
> > -static DEVICE_ATTR_RO(name);
> > -
> > -static ssize_t src_show(struct device *dev, struct device_attribute *attr,
> > -			 char *buf)
> > -{
> > -	struct rpmsg_eptdev *eptdev = dev_get_drvdata(dev);
> > -
> > -	return sprintf(buf, "%d\n", eptdev->chinfo.src);
> > -}
> > -static DEVICE_ATTR_RO(src);
> > -
> > -static ssize_t dst_show(struct device *dev, struct device_attribute *attr,
> > -			 char *buf)
> > -{
> > -	struct rpmsg_eptdev *eptdev = dev_get_drvdata(dev);
> > -
> > -	return sprintf(buf, "%d\n", eptdev->chinfo.dst);
> > -}
> > -static DEVICE_ATTR_RO(dst);
> > -
> > -static struct attribute *rpmsg_eptdev_attrs[] = {
> > -	&dev_attr_name.attr,
> > -	&dev_attr_src.attr,
> > -	&dev_attr_dst.attr,
> > -	NULL
> > -};
> > -ATTRIBUTE_GROUPS(rpmsg_eptdev);
> > -
> >  static void rpmsg_eptdev_release_device(struct device *dev)
> >  {
> >  	struct rpmsg_eptdev *eptdev = dev_to_eptdev(dev);
> > @@ -358,9 +322,7 @@ static int rpmsg_eptdev_create(struct rpmsg_ctrldev *ctrldev,
> >  	init_waitqueue_head(&eptdev->readq);
> >  
> >  	device_initialize(dev);
> > -	dev->class = rpmsg_class;
> >  	dev->parent = &ctrldev->dev;
> > -	dev->groups = rpmsg_eptdev_groups;
> >  	dev_set_drvdata(dev, eptdev);
> >  
> >  	cdev_init(&eptdev->cdev, &rpmsg_eptdev_fops);
> > @@ -477,7 +439,6 @@ static int rpmsg_chrdev_probe(struct rpmsg_device *rpdev)
> >  	dev = &ctrldev->dev;
> >  	device_initialize(dev);
> >  	dev->parent = &rpdev->dev;
> > -	dev->class = rpmsg_class;
> >  
> >  	cdev_init(&ctrldev->cdev, &rpmsg_ctrldev_fops);
> >  	ctrldev->cdev.owner = THIS_MODULE;
> > @@ -553,17 +514,9 @@ static int rpmsg_char_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);
> >  	}
> >  
> > @@ -574,7 +527,6 @@ postcore_initcall(rpmsg_char_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);
> > -- 
> > 2.17.1
> >