Messages in this thread | | | Subject | Re: [PATCH v8 5/8] arm64: Use of_cpu_node_to_id helper for CPU topology parsing | From | Suzuki K Poulose <> | Date | Tue, 17 Oct 2017 17:42:57 +0100 |
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On 17/10/17 17:20, Suzuki K Poulose wrote: > 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.
As we discussed offline, there is indeed a missing of_node_put() for all the nodes we loop through to match. But with this change, we have fixed that. And I don't think it is worth sending to stable.
Cheers Suzuki
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