Subject: Re: [PATCH] powerpc/pasemi: Use of_root in pas_pci_init()

From: Michael Ellerman <[email-masked]>
Date: Tue, 06 Sep 2022 21:38:34 +1000

Christophe Leroy <[email-masked]> writes:
> Le 06/09/2022 à 03:03, Michael Ellerman a écrit :
>> Currently in pas_pci_init() a reference to the root node is leaked due
>> to a missing of_node_put(). Instead just use of_root directly.
>> 
>> Note that converting to of_find_compatible_node(NULL, ...) would
>> not be entirely equivalent, because that would check the compatible
>> property of the root node, whereas using of_root skips checking the root
>> node and start the search at the first child of the root.
>> 
>
> That seems to simplify code. Should we do the same in all places below ?

I guess so.

There are some places where using of_root complicates things, because it
*doesn't* need refcount handling, eg. the cases in numa.c.

But in most cases it is preferable to use of_root IMHO.

cheers

> $ git grep -n "of_find_node_by_path(\"/\");" arch/powerpc/
> arch/powerpc/kernel/pci_32.c:139:       dn = of_find_node_by_path("/");
> arch/powerpc/kernel/pci_32.c:214:       dn = of_find_node_by_path("/");
> arch/powerpc/kernel/setup-common.c:212: root = of_find_node_by_path("/");
> arch/powerpc/kernel/setup-common.c:793: np = of_find_node_by_path("/");
> arch/powerpc/mm/numa.c:388:             root = of_find_node_by_path("/");
> arch/powerpc/mm/numa.c:456:             root = of_find_node_by_path("/");
> arch/powerpc/platforms/52xx/efika.c:77: root = of_find_node_by_path("/");
> arch/powerpc/platforms/52xx/efika.c:148:        root = of_find_node_by_path("/");
> arch/powerpc/platforms/85xx/xes_mpc85xx.c:119:  root = of_find_node_by_path("/");
> arch/powerpc/platforms/cell/setup.c:67: root = of_find_node_by_path("/");
> arch/powerpc/platforms/cell/setup.c:154:        struct device_node *root > = of_find_node_by_path("/");
> arch/powerpc/platforms/chrp/pci.c:191:  struct device_node *root = of_find_node_by_path("/");
> arch/powerpc/platforms/chrp/pci.c:216:  struct device_node *root = of_find_node_by_path("/");
> arch/powerpc/platforms/chrp/setup.c:105:        root = of_find_node_by_path("/");
> arch/powerpc/platforms/chrp/setup.c:201:        root = of_find_node_by_path("/");
> arch/powerpc/platforms/chrp/setup.c:268:        node = of_find_node_by_path("/");
> arch/powerpc/platforms/chrp/setup.c:299:        struct device_node *root > = of_find_node_by_path("/");
> arch/powerpc/platforms/chrp/setup.c:378:        root = of_find_node_by_path("/");
> arch/powerpc/platforms/maple/pci.c:601: root = of_find_node_by_path("/");
> arch/powerpc/platforms/maple/setup.c:225:       root = of_find_node_by_path("/");
> arch/powerpc/platforms/pasemi/pci.c:276:        root = of_find_node_by_path("/");
> arch/powerpc/platforms/pasemi/setup.c:268:      root = of_find_node_by_path("/");
> arch/powerpc/platforms/powermac/pci.c:910:      root = of_find_node_by_path("/");
> arch/powerpc/platforms/powermac/setup.c:105:    np = of_find_node_by_path("/");
> arch/powerpc/platforms/powernv/setup.c:255:     root = of_find_node_by_path("/");
> arch/powerpc/platforms/ps3/os-area.c:676:       node = of_find_node_by_path("/");
> arch/powerpc/platforms/ps3/os-area.c:774:       node = of_find_node_by_path("/");
> arch/powerpc/platforms/pseries/hotplug-memory.c:166:    parent = of_find_node_by_path("/");
> arch/powerpc/platforms/pseries/ibmebus.c:187:   root = of_find_node_by_path("/");
> arch/powerpc/platforms/pseries/lparcfg.c:232:   root = of_find_node_by_path("/");
> arch/powerpc/platforms/pseries/lparcfg.c:799:   rootdn = of_find_node_by_path("/");
> arch/powerpc/platforms/pseries/setup.c:97:      root = of_find_node_by_path("/");
> arch/powerpc/platforms/pseries/setup.c:486:     struct device_node *root > = of_find_node_by_path("/");
> arch/powerpc/sysdev/xive/spapr.c:714:   rootdn = of_find_node_by_path("/");
>
> Christophe
>
>
>> Reported-by: Liang He <[email-masked]>
>> Signed-off-by: Michael Ellerman <[email-masked]>
>> ---
>>   arch/powerpc/platforms/pasemi/pci.c | 10 ++--------
>>   1 file changed, 2 insertions(+), 8 deletions(-)
>> 
>> diff --git a/arch/powerpc/platforms/pasemi/pci.c b/arch/powerpc/platforms/pasemi/pci.c
>> index 55f0160910bf..f27d31414737 100644
>> --- a/arch/powerpc/platforms/pasemi/pci.c
>> +++ b/arch/powerpc/platforms/pasemi/pci.c
>> @@ -270,18 +270,12 @@ static int __init pas_add_bridge(struct device_node *dev)
>>   
>>   void __init pas_pci_init(void)
>>   {
>> -	struct device_node *np, *root;
>> +	struct device_node *np;
>>   	int res;
>>   
>> -	root = of_find_node_by_path("/");
>> -	if (!root) {
>> -		pr_crit("pas_pci_init: can't find root of device tree\n");
>> -		return;
>> -	}
>> -
>>   	pci_set_flags(PCI_SCAN_ALL_PCIE_DEVS);
>>   
>> -	np = of_find_compatible_node(root, NULL, "pasemi,rootbus");
>> +	np = of_find_compatible_node(of_root, NULL, "pasemi,rootbus");
>>   	if (np) {
>>   		res = pas_add_bridge(np);
>>   		of_node_put(np);