[linux-next] powerpc/powermac: Add missing of_node_put

of_node_put is needed before discarding a value received from
of_find_node_by_name, eg in error handling code or when the device
node is no longer used.

The semantic match that catches the bug is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@r exists@
local idexpression struct device_node *n;
position p1, p2;
struct device_node *n1;
statement S;
identifier f;
expression E;
expression *ptr != NULL;
@@

n@p1 = of_find_node_by_name(...)
...
if (!n) S
... when != of_node_put(n)
    when != n1 = f(n,...)
    when != E = n
    when any
    when strict
(
  return \(0\|<+...n...+>\|ptr\);
|
return@p2 ...;
|
  of_node_put(n);
|
  n1 = f(n,...)
|
  E = n
)

@script:python@
p1 << r.p1;
p2 << r.p2;
@@

print "* file: %s of_find_node_by_name %s return %s" % (p1[0].file,p1[0].line,p2[0].line)
// </smpl>

Signed-off-by: Nicolas Palix <npalix@diku.dk>
Signed-off-by: Julia Lawall <julia@diku.dk>
---
 arch/powerpc/platforms/powermac/pci.c     |    2 ++
 arch/powerpc/platforms/powermac/time.c    |    4 +++-
 2 files changed, 5 insertions(+), 1 deletion(-)

Hi Nicolas,

Thanks for all this work.

I think this particular patch is also required against Linus' kernel (not
just linux-next).

On Tue, 2 Dec 2008 14:45:18 +0100 Nicolas Palix <npalix@diku.dk> wrote:
>
> diff --git a/arch/powerpc/platforms/powermac/pci.c b/arch/powerpc/platforms/powermac/pci.c
> index bcf50d7..800fcce 100644
> --- a/arch/powerpc/platforms/powermac/pci.c
> +++ b/arch/powerpc/platforms/powermac/pci.c
> @@ -661,6 +661,7 @@ static void __init init_second_ohare(void)
>  			pci_find_hose_for_OF_device(np);
>  		if (!hose) {
>  			printk(KERN_ERR "Can't find PCI hose for OHare2 !\n");
> +			of_node_put(np);
>  			return;
>  		}
>  		early_read_config_word(hose, bus, devfn, PCI_COMMAND, &cmd);
> @@ -669,6 +670,7 @@ static void __init init_second_ohare(void)
>  		early_write_config_word(hose, bus, devfn, PCI_COMMAND, cmd);
>  	}
>  	has_second_ohare = 1;
> +	of_node_put(np);
>  }

This part looks good.

> diff --git a/arch/powerpc/platforms/powermac/time.c b/arch/powerpc/platforms/powermac/time.c
> index 59eb840..394593c 100644
> --- a/arch/powerpc/platforms/powermac/time.c
> +++ b/arch/powerpc/platforms/powermac/time.c
> @@ -265,12 +265,14 @@ int __init via_calibrate_decr(void)
>  	struct resource rsrc;
>  
>  	vias = of_find_node_by_name(NULL, "via-cuda");
>  	if (vias == 0)
>  		vias = of_find_node_by_name(NULL, "via-pmu");
>  	if (vias == 0)
>  		vias = of_find_node_by_name(NULL, "via");
>  	if (vias == 0 || of_address_to_resource(vias, 0, &rsrc))
>  		return 0;
> +	of_node_put(vias);
> +

But this needs to also do the of_node_put() if the above "return 0" is
taken i.e. if of_address_to_resource() fails.

Hi Nicolas,

On Wed, 3 Dec 2008 10:19:01 +1100 Stephen Rothwell <sfr@canb.auug.org.au> wrote:
>
> I think this particular patch is also required against Linus' kernel (not
> just linux-next).

In fact, I think all these patches can apply to Linus' current tree.