Re: [PATCH] pdc2026x: remove surplus initialiser

[Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>]

On Saturday 19 January 2008, Alan Cox wrote:
> On Sat, 19 Jan 2008 19:54:03 +0300
> Sergei Shtylyov <sshtylyov@ru.mvista.com> wrote:
> 
> > Hello.
> > 
> > Alan Cox wrote:
> > 
> > > Signed-off-by: Alan Cox <alan@redhat.com>
> > 
> > > 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