Re: [patch] 2.4.2-pre3: parport_pc init_module bug

James Sutherland (jas88@cam.ac.uk)
Wed, 14 Feb 2001 08:53:06 +0000 (GMT)


On Wed, 14 Feb 2001, Jeff Garzik wrote:

> On Tue, 13 Feb 2001, Tim Waugh wrote:
> > Here's a patch that fixes a bug that can cause PCI driver list
> > corruption. If parport_pc's init_module fails after it calls
> > pci_register_driver, cleanup_module isn't called and so it's still
> > registered when it gets unloaded.
>
> > --- linux/drivers/parport/parport_pc.c.init Tue Feb 13 23:31:25 2001
> > +++ linux/drivers/parport/parport_pc.c Tue Feb 13 23:35:56 2001
> > @@ -89,6 +89,7 @@
> > } superios[NR_SUPERIOS] __devinitdata = { {0,},};
> >
> > static int user_specified __devinitdata = 0;
> > +static int registered_parport;
> >
> > /* frob_control, but for ECR */
> > static void frob_econtrol (struct parport *pb, unsigned char m,
> > @@ -2605,6 +2606,7 @@
> > count += parport_pc_find_nonpci_ports (autoirq, autodma);
> >
> > r = pci_register_driver (&parport_pc_pci_driver);
> > + registered_parport = 1;
> > if (r > 0)
> > count += r;
>
> Bad patch. It should be
>
> if (r >= 0) {
> registered_parport = 1;
> if (r > 0)
> count += r;
> }

The second "if" is redundant here: if r==0, count+=r has no effect. I
don't think gcc would spot that on optimization, would it??

James.

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