Re: [patch 3/6] New Generic HW RNG (#2)

Michael Buesch
2006-05-07T15:33:03Z

On Sunday 07 May 2006 17:22, you wrote:
> On Sun, May 07, 2006 at 04:38:09PM +0200, Michael Buesch wrote:
> > Add a driver for the x86 RNG.
> > This driver is ported from the old hw_random.c
> >
> [skip]
> > +static int __init intel_init(struct hwrng *rng)
>
> Cannot be __init anymore - now rng->init could be called at any time.

Sure, will fix this.

> Also, there is another problem with putting this function into
> rng->init - if another RNG has been registered when this module is
> loaded, ->init will not be called during hwrng_register(), so the
> module load will succeed even if the chipset does not have RNG
> hardware.

Ok, I see. The question is, are we going to hwrng_register() the
intel, althought there is no device? We check for the PCI IDs.
Anyway. This should be fixed.
And I think this is also a good time to split the x86 driver,
so all this init-stuff is much cleaner.

> > +{
> > + void __iomem *rng_mem;
> > + int rc;
> > + u8 hw_status;
> > +
> > + DPRINTK ("ENTER\n");
> > +
> > + rng_mem = ioremap (INTEL_RNG_ADDR, INTEL_RNG_ADDR_LEN);
> > + if (rng_mem == NULL) {
> > + printk (KERN_ERR PFX "cannot ioremap RNG Memory\n");
> > + rc = -EBUSY;
> > + goto err_out;
> > + }
> > + rng->priv = (unsigned long)rng_mem;
> > +
> > + /* Check for Intel 82802 */
> > + hw_status = intel_hwstatus (rng_mem);
> > + if ((hw_status & INTEL_RNG_PRESENT) == 0) {
> > + printk (KERN_ERR PFX "RNG not detected\n");
> > + rc = -ENODEV;
> > + goto err_out_free_map;
> > + }
> > +
> > + /* turn RNG h/w on, if it's off */
> > + if ((hw_status & INTEL_RNG_ENABLED) == 0)
> > + hw_status = intel_hwstatus_set (rng_mem, hw_status | INTEL_RNG_ENABLED);
> > + if ((hw_status & INTEL_RNG_ENABLED) == 0) {
> > + printk (KERN_ERR PFX "cannot enable RNG, aborting\n");
> > + rc = -EIO;
> > + goto err_out_free_map;
> > + }
> > +
> > + DPRINTK ("EXIT, returning 0\n");
> > + return 0;
> > +
> > +err_out_free_map:
> > + iounmap (rng_mem);
> > +err_out:
> > + DPRINTK ("EXIT, returning %d\n", rc);
> > + return rc;
> > +}
> > +
> [skip]
> > +static int __init amd_init(struct hwrng *rng)
>
> Again, __init is wrong.
>
> [skip]
> > +static int __init via_init(struct hwrng *rng)
>
> This __init is wrong too.
>
> [skip]
>

Ah, and I found another bug in hwrng_unregister:
current_rng = list_entry(rng_list.prev, struct hwrng, list);
current_rng->init() should be called here (if nonNULL). If that fails
current_rng = NULL;

Will fix that, too.

--
Greetings Michael.