[PATCH 8/9] arch/powerpc/kernel: Drop unnecessary null test

[PATCH 8/9] arch/powerpc/kernel: Drop unnecessary null test

[Julia Lawall]

From: Julia Lawall <julia@diku.dk>

list_for_each_entry binds its first argument to a non-null value, and thus
any null test on the value of that argument is superfluous.

The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@@
iterator I;
expression x,E,E1,E2;
statement S,S1,S2;
@@

I(x,...) { <...
- if (x != NULL || ...)
  S
  ...> }
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>

---
 arch/powerpc/kernel/pci_of_scan.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/pci_of_scan.c b/arch/powerpc/kernel/pci_of_scan.c
index 6ddb795..62dd363 100644
--- a/arch/powerpc/kernel/pci_of_scan.c
+++ b/arch/powerpc/kernel/pci_of_scan.c
@@ -336,8 +336,7 @@ static void __devinit __of_scan_bus(struct device_node *node,
 		if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE ||
 		    dev->hdr_type == PCI_HEADER_TYPE_CARDBUS) {
 			struct device_node *child = pci_device_to_OF_node(dev);
-			if (dev)
-				of_scan_pci_bridge(child, dev);
+			of_scan_pci_bridge(child, dev);
 		}
 	}
 }

Re: [PATCH 8/9] arch/powerpc/kernel: Drop unnecessary null test

[Dan Carpenter]

On Tue, Aug 03, 2010 at 11:35:17PM +0200, Julia Lawall wrote:
> diff --git a/arch/powerpc/kernel/pci_of_scan.c b/arch/powerpc/kernel/pci_of_scan.c
> index 6ddb795..62dd363 100644
> --- a/arch/powerpc/kernel/pci_of_scan.c
> +++ b/arch/powerpc/kernel/pci_of_scan.c
> @@ -336,8 +336,7 @@ static void __devinit __of_scan_bus(struct device_node *node,
>  		if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE ||
>  		    dev->hdr_type == PCI_HEADER_TYPE_CARDBUS) {
>  			struct device_node *child = pci_device_to_OF_node(dev);
> -			if (dev)
> -				of_scan_pci_bridge(child, dev);
> +			of_scan_pci_bridge(child, dev);

The intention was probably to check "child" instead of "dev".
pci_device_to_OF_node() can return NULL.  On the other hand the code
has been this way for a year and no one has complained...

regards,
dan carpenter

>  		}
>  	}
>  }

Re: [PATCH 8/9] arch/powerpc/kernel: Drop unnecessary null test

[Grant Likely]

On Tue, Aug 3, 2010 at 3:51 PM, Dan Carpenter <error27@gmail.com> wrote:
> On Tue, Aug 03, 2010 at 11:35:17PM +0200, Julia Lawall wrote:
>> diff --git a/arch/powerpc/kernel/pci_of_scan.c b/arch/powerpc/kernel/pci=
_of_scan.c
>> index 6ddb795..62dd363 100644
>> --- a/arch/powerpc/kernel/pci_of_scan.c
>> +++ b/arch/powerpc/kernel/pci_of_scan.c
>> @@ -336,8 +336,7 @@ static void __devinit __of_scan_bus(struct device_no=
de *node,
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (dev->hdr_type =3D=3D PCI_HEADER_TYPE_BRI=
DGE ||
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 dev->hdr_type =3D=3D PCI_HEADER_TYPE=
_CARDBUS) {
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 struct device_node *child =
=3D pci_device_to_OF_node(dev);
>> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (dev)
>> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 of_scan_pci_br=
idge(child, dev);
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 of_scan_pci_bridge(child, dev)=
;
>
> The intention was probably to check "child" instead of "dev".
> pci_device_to_OF_node() can return NULL. =A0On the other hand the code
> has been this way for a year and no one has complained...

Still, it should be fixed.  It is likely that I'll be generalizing
this code for other architectures in the near future.  I'll spin a
patch.

g.