On Saturday 19 January 2008, Alan Cox wrote:
> On Sat, 19 Jan 2008 19:54:03 +0300
> Sergei Shtylyov <sshtylyov@xxxxxxxxxxxxx> wrote:
>
> > Hello.
> >
> > Alan Cox wrote:
> >
> > > Signed-off-by: Alan Cox <alan@xxxxxxxxxx>
> >
> > > diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.24-rc8-mm1/drivers/ide/pci/pdc202xx_old.c linux-2.6.24-rc8-mm1/drivers/ide/pci/pdc202xx_old.c
> > > --- linux.vanilla-2.6.24-rc8-mm1/drivers/ide/pci/pdc202xx_old.c 2008-01-19 14:47:56.000000000 +0000
> > > +++ linux-2.6.24-rc8-mm1/drivers/ide/pci/pdc202xx_old.c 2008-01-19 15:00:08.000000000 +0000
> > > @@ -138,7 +138,7 @@
> > > static u8 __devinit pdc2026x_old_cable_detect(ide_hwif_t *hwif)
> > > {
> > > struct pci_dev *dev = to_pci_dev(hwif->dev);
> > > - u16 CIS = 0, mask = (hwif->channel) ? (1<<11) : (1<<10);
> > > + u16 CIS, mask = (hwif->channel) ? (1<<11) : (1<<10);
> > >
> > > pci_read_config_word(dev, 0x50, &CIS);
> >
> > Since we ignore the result of this function, if it fails CIS may be left
> > uninitialized if the function fails. So, the initializer is not as useless as
pci_[bus]_read_config_*() functions always assign some value according to
drivers/pci/access.c (except for unaligned access to word/dword register).
> > it seems (and there's a lot more of such cases in drivers/ide/pci/ :-)..
A lot of "patch" opportunities!
> If pci_read_config_word fails you are in very deep doodoo anyway. I don't
> think anyone checks it because there isn't an answer to "now what"
Yep, moreover we cannot just assume that "0" is a safe default value
because it doesn't have to be (i.e. in the above case cable bit set to
"0" means 80-wires cable).
Thanks,
Bart
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