Re: [PATCH] riscv: Prevent a bad reference count on CPU nodes

Miquel Sabaté Solà
2024-10-08T13:43:31Z

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On dl., de set. 30 2024, Miquel Sabaté Solà wrote:

> On dv., de set. 13 2024, Miquel Sabaté Solà wrote:
>
>> When populating cache leaves we previously fetched the CPU device node
>> at the very beginning. But when ACPI is enabled we go through a
>> specific branch which returns early and does not call 'of_node_put' for
>> the node that was acquired.
>>
>> Since we are not using a CPU device node for the ACPI code anyways, we
>> can simply move the initialization of it just passed the ACPI block, and
>> we are guaranteed to have an 'of_node_put' call for the acquired node.
>> This prevents a bad reference count of the CPU device node.
>>
>> Moreover, the previous function did not check for errors when acquiring
>> the device node, so a return -ENOENT has been added for that case.
>>
>> Signed-off-by: Miquel Sabaté Solà <mikisabate@gmail.com>
>> ---
>> I was wondering if this should also be sent to stable, but I have not seen
>> a report on it, and this is not responsible for an oops or anything like that.
>> So in the end I decided not to, but maybe you consider otherwise.
>>
>> arch/riscv/kernel/cacheinfo.c | 7 +++++--
>> 1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/riscv/kernel/cacheinfo.c b/arch/riscv/kernel/cacheinfo.c
>> index d6c108c50cba..d32dfdba083e 100644
>> --- a/arch/riscv/kernel/cacheinfo.c
>> +++ b/arch/riscv/kernel/cacheinfo.c
>> @@ -75,8 +75,7 @@ int populate_cache_leaves(unsigned int cpu)
>> {
>> struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
>> struct cacheinfo *this_leaf = this_cpu_ci->info_list;
>> - struct device_node *np = of_cpu_device_node_get(cpu);
>> - struct device_node *prev = NULL;
>> + struct device_node *np, *prev;
>> int levels = 1, level = 1;
>>
>> if (!acpi_disabled) {
>> @@ -100,6 +99,10 @@ int populate_cache_leaves(unsigned int cpu)
>> return 0;
>> }
>>
>> + np = of_cpu_device_node_get(cpu);
>> + if (!np)
>> + return -ENOENT;
>> +
>> if (of_property_read_bool(np, "cache-size"))
>> ci_leaf_init(this_leaf++, CACHE_TYPE_UNIFIED, level);
>> if (of_property_read_bool(np, "i-cache-size"))
>
> Gently ping :)
>
> Could you take a look at this fix?
>
> Thanks,
> Miquel

Hello,

Would it make sense to have this fix for rc3?

Thanks,
Miquel

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