[PATCH] pdc2026x: remove surplus initialiser

[PATCH] pdc2026x: remove surplus initialiser

[Alan Cox]

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);
 

Re: [PATCH] pdc2026x: remove surplus initialiser

[Sergei Shtylyov]

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 
it seems (and there's a lot more of such cases in drivers/ide/pci/ :-)...

MBR, Sergei

Re: [PATCH] pdc2026x: remove surplus initialiser

[Alan Cox]

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 
> it seems (and there's a lot more of such cases in drivers/ide/pci/ :-)..

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"

Alan

Re: [PATCH] pdc2026x: remove surplus initialiser

[Bartlomiej Zolnierkiewicz]

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

Re: [PATCH] pdc2026x: remove surplus initialiser

[Bartlomiej Zolnierkiewicz]

On Saturday 19 January 2008, Alan Cox wrote:
> 
> Signed-off-by: Alan Cox <alan@redhat.com>

applied with:

- s/pdc2026x/pdc202xx_old/ in patch summary
- drive-by CodingStyle fixups

> 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);