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Subject: Re: [PATCH v11 1/4] cpu/SMT: Provide a default
 topology_is_primary_thread()
To: Dietmar Eggemann <dietmar.eggemann@arm.com>, <catalin.marinas@arm.com>,
	<will@kernel.org>, <sudeep.holla@arm.com>, <tglx@linutronix.de>,
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References: <20250218141018.18082-1-yangyicong@huawei.com>
 <20250218141018.18082-2-yangyicong@huawei.com>
 <e3607ed0-bdf5-4fef-8731-b81fae649312@arm.com>
From: Yicong Yang <yangyicong@huawei.com>
Message-ID: <af8d364e-a5e0-decb-4463-fd6b7c54a0d9@huawei.com>
Date: Mon, 3 Mar 2025 21:35:35 +0800
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On 2025/2/28 19:10, Dietmar Eggemann wrote:
> On 18/02/2025 15:10, Yicong Yang wrote:
>> From: Yicong Yang <yangyicong@hisilicon.com>
> 
> [...]
> 
>> diff --git a/include/linux/topology.h b/include/linux/topology.h
>> index 52f5850730b3..b3aba443c4eb 100644
>> --- a/include/linux/topology.h
>> +++ b/include/linux/topology.h
>> @@ -240,6 +240,28 @@ static inline const struct cpumask *cpu_smt_mask(int cpu)
>>  }
>>  #endif
>>  
>> +#ifndef topology_is_primary_thread
>> +
>> +#define topology_is_primary_thread topology_is_primary_thread
>> +
>> +static inline bool topology_is_primary_thread(unsigned int cpu)
>> +{
>> +	/*
>> +	 * On SMT hotplug the primary thread of the SMT won't be disabled.
>> +	 * Architectures do have a special primary thread (e.g. x86) need
>> +	 * to override this function. Otherwise just make the first thread
>> +	 * in the SMT as the primary thread.
>> +	 *
>> +	 * The sibling cpumask of an offline CPU contains always the CPU
>> +	 * itself for architectures using CONFIG_GENERIC_ARCH_TOPOLOGY.
>> +	 * Other architectures should use this depend on their own
>> +	 * situation.
> 
> This sentence is hard to get. Do you want to say that other
> architectures (CONFIG_GENERIC_ARCH_TOPOLOGY or
> !CONFIG_GENERIC_ARCH_TOPOLOGY) have to check whether they can use this
> default implementation or have to override it?
> 

yes exactly, will improve the comments. thanks.