Hi Hans!
On 8 Apr 11:47, Hans Verkuil wrote:
> On 05/03/2024 14:26, Ricardo B. Marliere wrote:
> > Since commit 43a7206b0963 ("driver core: class: make class_register() take
> > a const *"), the driver core allows for struct class to be in read-only
> > memory, so move the dvb_class structure to be declared at build time
> > placing it into read-only memory, instead of having to be dynamically
> > allocated at boot time.
> >
> > Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > Suggested-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Ricardo B. Marliere <ricardo@xxxxxxxxxxxx>
> > ---
> > drivers/media/dvb-core/dvbdev.c | 23 +++++++++++++----------
> > 1 file changed, 13 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/media/dvb-core/dvbdev.c b/drivers/media/dvb-core/dvbdev.c
> > index 733d0bc4b4cc..dcbf68b00240 100644
> > --- a/drivers/media/dvb-core/dvbdev.c
> > +++ b/drivers/media/dvb-core/dvbdev.c
> > @@ -78,7 +78,13 @@ static const u8 minor_type[] = {
> > #define MAX_DVB_MINORS (DVB_MAX_ADAPTERS * 64)
> > #endif
> >
> > -static struct class *dvb_class;
> > +static int dvb_uevent(const struct device *dev, struct kobj_uevent_env *env);
> > +static char *dvb_devnode(const struct device *dev, umode_t *mode);
>
> Forward references are typically something you want to avoid.
>
> Looking at the code, I think it makes sense to just move those two functions
> to just before this dvb_class.
Ack.
>
> > +static const struct class dvb_class = {
> > + .name = "dvb",
> > + .dev_uevent = dvb_uevent,
> > + .devnode = dvb_devnode,
> > +};
> >
> > static struct dvb_device *dvb_minors[MAX_DVB_MINORS];
> > static DECLARE_RWSEM(minor_rwsem);
>
> Also move the dvb_class (+ the two functions) to after this line. I think that's
> a more suitable place for this.
Ack.
>
> > @@ -561,7 +567,7 @@ int dvb_register_device(struct dvb_adapter *adap, struct dvb_device **pdvbdev,
> > return ret;
> > }
> >
> > - clsdev = device_create(dvb_class, adap->device,
> > + clsdev = device_create(&dvb_class, adap->device,
> > MKDEV(DVB_MAJOR, minor),
> > dvbdev, "dvb%d.%s%d", adap->num, dnames[type], id);
> > if (IS_ERR(clsdev)) {
> > @@ -600,7 +606,7 @@ void dvb_remove_device(struct dvb_device *dvbdev)
> >
> > dvb_media_device_free(dvbdev);
> >
> > - device_destroy(dvb_class, MKDEV(DVB_MAJOR, dvbdev->minor));
> > + device_destroy(&dvb_class, MKDEV(DVB_MAJOR, dvbdev->minor));
> >
> > list_del(&dvbdev->list_head);
> > }
> > @@ -1096,13 +1102,10 @@ static int __init init_dvbdev(void)
> > goto error;
> > }
> >
> > - dvb_class = class_create("dvb");
> > - if (IS_ERR(dvb_class)) {
> > - retval = PTR_ERR(dvb_class);
> > + retval = class_register(&dvb_class);
> > + if (retval != 0)
>
> This can just be 'if (retval)'.
But then it would be on a different style than the rest of the function:
static int __init init_dvbdev(void)
{
int retval;
dev_t dev = MKDEV(DVB_MAJOR, 0);
retval = register_chrdev_region(dev, MAX_DVB_MINORS, "DVB");
if (retval != 0) {
pr_err("dvb-core: unable to get major %d\n", DVB_MAJOR);
return retval;
}
cdev_init(&dvb_device_cdev, &dvb_device_fops);
retval = cdev_add(&dvb_device_cdev, dev, MAX_DVB_MINORS);
if (retval != 0) {
pr_err("dvb-core: unable register character device\n");
goto error;
}
retval = class_register(&dvb_class);
if (retval != 0)
goto error;
return 0;
error:
cdev_del(&dvb_device_cdev);
unregister_chrdev_region(dev, MAX_DVB_MINORS);
return retval;
}
>
> > goto error;
> > - }
> > - dvb_class->dev_uevent = dvb_uevent;
> > - dvb_class->devnode = dvb_devnode;
> > +
> > return 0;
> >
> > error:
> > @@ -1115,7 +1118,7 @@ static void __exit exit_dvbdev(void)
> > {
> > struct dvbdevfops_node *node, *next;
> >
> > - class_destroy(dvb_class);
> > + class_unregister(&dvb_class);
> > cdev_del(&dvb_device_cdev);
> > unregister_chrdev_region(MKDEV(DVB_MAJOR, 0), MAX_DVB_MINORS);
> >
> >
>
> Regards,
>
> Hans
