[PATCH v2] powerpc: kernel: legacy_serial: Fix missing of_node_put() in add_legacy_soc_port()

[Liang He]

At 2022-09-05 11:25:38, "Michael Ellerman" <mpe at ellerman.id.au> wrote:
>Liang He <windhl at 126.com> writes:
>> We should call of_node_put() for the reference 'tsi' returned by
>> of_get_parent() which will increase the refcount.
>>
>> Signed-off-by: Liang He <windhl at 126.com>
>> ---
>>  changelog:
>>
>>  v2: use more conservative way to call of_node_put()
>>  v1: mov 'of_node_put()' into the 'if' condition
>>
>>  v1 Link: https://lore.kernel.org/all/20220701130203.240023-1-windhl@126.com/
>>
>>  arch/powerpc/kernel/legacy_serial.c | 11 ++++++++---
>>  1 file changed, 8 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/powerpc/kernel/legacy_serial.c b/arch/powerpc/kernel/legacy_serial.c
>> index f048c424c525..cca72081b864 100644
>> --- a/arch/powerpc/kernel/legacy_serial.c
>> +++ b/arch/powerpc/kernel/legacy_serial.c
>> @@ -166,7 +166,7 @@ static int __init add_legacy_soc_port(struct device_node *np,
>>  {
>>  	u64 addr;
>>  	const __be32 *addrp;
>> -	struct device_node *tsi = of_get_parent(np);
>> +	struct device_node *tsi;
>>  
>>  	/* We only support ports that have a clock frequency properly
>>  	 * encoded in the device-tree.
>> @@ -194,12 +194,17 @@ static int __init add_legacy_soc_port(struct device_node *np,
>>  	/* Add port, irq will be dealt with later. We passed a translated
>>  	 * IO port value. It will be fixed up later along with the irq
>>  	 */
>> -	if (of_node_is_type(tsi, "tsi-bridge"))
>> +	tsi = of_get_parent(np);
>> +	if (of_node_is_type(tsi, "tsi-bridge")) {
>> +		of_node_put(tsi);
>>  		return add_legacy_port(np, -1, UPIO_TSI, addr, addr,
>>  				       0, legacy_port_flags, 0);
>> -	else
>> +	}
>> +	else {
>> +		of_node_put(tsi);
>>  		return add_legacy_port(np, -1, UPIO_MEM, addr, addr,
>>  				       0, legacy_port_flags, 0);
>> +	}
>>  }
>
>The two legs of the else end up with duplicated code except for a single
>parameter to add_legacy_port().
>
>Better would be:
>
>{
>	int iotype;
>        ...
>
>	tsi = of_get_parent(np);
>	if (of_node_is_type(tsi, "tsi-bridge"))
>		iotype = UPIO_TSI;
>	else
>		iotype = UPIO_MEM;
>
>	of_node_put(tsi);
>        return add_legacy_port(np, -1, iotype, addr, addr, 0, legacy_port_flags, 0);
>}
>
>
>cheers

Thanks, 
I will give another version of this patch.

Liang