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SubjectRe: [PATCH] Added devfs support for i386 msr/cpuid driver
Arjan van de Ven writes:
> >
> > int __init msr_init(void)
> > {
> > +#ifdef CONFIG_DEVFS_FS
> > + devfs_handle = devfs_register(NULL, "cpu/msr", DEVFS_FL_DEFAULT, 0, 0,
> > + S_IFREG | S_IRUGO | S_IWUSR,
> > + &msr_fops, NULL);
> > +#else
> > if (register_chrdev(MSR_MAJOR, "cpu/msr", &msr_fops)) {
> > printk(KERN_ERR "msr: unable to get major %d for msr\n",
> > MSR_MAJOR);
> > return -EBUSY;
> > }
> > +#endif
>
> this must be wrong as you don't check for devfs_register failures...

The reason it's wrong is because he put #ifdef's in there. The
functions should just be called unconditionally. The #ifdef's are in
the header.

> Also why devfs can't just use register_chrdev and not touch ALL
> drivers is beyond me, but it has been like that for a while now...

Huh?!? I thought that should be obvious. Think about it,
register_chrdev() registers a *major*, whereas devfs_register()
registers an individual device node. The former has no way of
representing which devices are detected, the latter sets up a 1:1
relationship between devices and device nodes (which is what people
actually want).

Regards,

Richard....
Permanent: rgooch@atnf.csiro.au
Current: rgooch@ras.ucalgary.ca
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