lkml.org 
[lkml]   [2017]   [Oct]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v8 5/8] arm64: Use of_cpu_node_to_id helper for CPU topology parsing
From
Date
On 17/10/17 17:11, Will Deacon wrote:
> On Tue, Oct 17, 2017 at 04:24:23PM +0100, Mark Rutland wrote:
>> On Tue, Oct 10, 2017 at 11:33:00AM +0100, Suzuki K Poulose wrote:
>>> Make use of the new generic helper to convert an of_node of a CPU
>>> to the logical CPU id in parsing the topology.
>>>
>>> Cc: Catalin Marinas <catalin.marinas@arm.com>
>>> Cc: Leo Yan <leo.yan@linaro.org>
>>> Cc: Will Deacon <will.deacon@arm.com>
>>> Cc: Mark Rutland <mark.rutland@arm.com>
>>> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
>>
>> This looks sane to me, but it will need an ack from Will or Catalin.
>>
>> FWIW:
>>
>> Acked-by: Mark Rutland <mark.rutland@arm.com>
>>
>> Thanks,
>> Mark.
>>
>>> ---
>>> arch/arm64/kernel/topology.c | 16 ++++++----------
>>> 1 file changed, 6 insertions(+), 10 deletions(-)
>>>
>>> diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
>>> index 8d48b233e6ce..21868530018e 100644
>>> --- a/arch/arm64/kernel/topology.c
>>> +++ b/arch/arm64/kernel/topology.c
>>> @@ -37,18 +37,14 @@ static int __init get_cpu_for_node(struct device_node *node)
>>> if (!cpu_node)
>>> return -1;
>>>
>>> - for_each_possible_cpu(cpu) {
>>> - if (of_get_cpu_node(cpu, NULL) == cpu_node) {
>>> - topology_parse_cpu_capacity(cpu_node, cpu);
>>> - of_node_put(cpu_node);
>>> - return cpu;
>>> - }
>>> - }
>>> -
>>> - pr_crit("Unable to find CPU node for %pOF\n", cpu_node);
>>> + cpu = of_cpu_node_to_id(cpu_node);
>>> + if (cpu >= 0)
>>> + topology_parse_cpu_capacity(cpu_node, cpu);
>>> + else
>>> + pr_crit("Unable to find CPU node for %pOF\n", cpu_node);
>>>
>>> of_node_put(cpu_node);
>
> This of_node_put is confusing me. Since of_cpu_node_to_id appears to be
> balanced with its use of the node refcount, is this one intended to pair
> with the earlier call to of_parse_phandle?

Yes.

If so, does that mainline is
> currently broken here because it doesn't drop the refcount twice for the
> matching node?

No. This of_node_put is for the failure case where we couldn't match a CPU.
In the success case, it is dropped just before we return the result within
the loop.

Cheers
Suzuki


Or do we need to return with that held?
>
> Will
>

\
 
 \ /
  Last update: 2017-10-17 18:20    [W:0.054 / U:3.444 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site