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From: Gavin Shan <gshan@redhat.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: lorenzo.pieralisi@arm.com, catalin.marinas@arm.com,
	robin.murphy@arm.com, shan.gavin@gmail.com, sudeep.holla@arm.com,
	will@kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v4 3/5] arm64: Introduce get_cpu_ops() helper function
Date: Wed, 18 Mar 2020 13:22:20 +1100	[thread overview]
Message-ID: <b3f944f0-d595-eb73-6b16-06f6c0c79b95@redhat.com> (raw)
In-Reply-To: <20200317104833.GE8831@lakrids.cambridge.arm.com>

On 3/17/20 9:48 PM, Mark Rutland wrote:
> On Wed, Feb 26, 2020 at 11:23:54AM +1100, Gavin Shan wrote:
>> This introduces get_cpu_ops() to return the CPU operations according to
>> the given CPU index. For now, it simply returns the @cpu_ops[cpu] as
>> before. So it shouldn't introduce any functional changes.
>>
>> Signed-off-by: Gavin Shan <gshan@redhat.com>
> 
> Generally this looks good to me; I like that it simplifies the cases
> where we get the ops repeatedly today.
> 
> I have one comment below.
> 
>> @@ -383,6 +392,7 @@ void cpu_die(void)
>>   void cpu_die_early(void)
>>   {
>>   	int cpu = smp_processor_id();
>> +	const struct cpu_operations *ops = get_cpu_ops(cpu);
>>   
>>   	pr_crit("CPU%d: will not boot\n", cpu);
>>   
>> @@ -392,8 +402,8 @@ void cpu_die_early(void)
>>   #ifdef CONFIG_HOTPLUG_CPU
>>   	update_cpu_boot_status(CPU_KILL_ME);
>>   	/* Check if we can park ourselves */
>> -	if (cpu_ops[cpu] && cpu_ops[cpu]->cpu_die)
>> -		cpu_ops[cpu]->cpu_die(cpu);
>> +	if (ops && ops->cpu_die)
>> +		ops->cpu_die(cpu);
>>   #endif
> 
> Can we factor this out the die logic into a helper:
> 
> | static void __cpu_try_die(int cpu)
> | {
> | #ifdef CONFIG_HOTPLUG_CPU
> | 	const struct cpu_operations *ops = get_cpu_ops(cpu);
> | 	if (ops && ops->cpu_die)
> | 		ops->cpu_die(cpu);
> | #endif
> | }
> 
> ... with cpu_die_early() having:
> 
> | if (IS_ENABLED(CONFIG_HOTPLUG_CPU)) {
> | 	update_cpu_boot_status(CPU_KILL_ME);
> |	__cpu_try_die(cpu);
> | }
> 
> ... and likewise in ipi_cpu_crash_stop(), without the
> update_cpu_boot_status() ...
> 
>> @@ -855,6 +870,10 @@ static atomic_t waiting_for_crash_ipi = ATOMIC_INIT(0);
>>   
>>   static void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs)
>>   {
>> +#ifdef CONFIG_HOTPLUG_CPU
>> +	const struct cpu_operations *ops;
>> +#endif
> 
> ... where this can go ...
> 
>> +
>>   #ifdef CONFIG_KEXEC_CORE
>>   	crash_save_cpu(regs, cpu);
>>   
>> @@ -864,8 +883,9 @@ static void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs)
>>   	sdei_mask_local_cpu();
>>   
>>   #ifdef CONFIG_HOTPLUG_CPU
>> -	if (cpu_ops[cpu]->cpu_die)
>> -		cpu_ops[cpu]->cpu_die(cpu);
>> +	ops = get_cpu_ops(cpu);
>> +	if (ops->cpu_die)
>> +		ops->cpu_die(cpu);
>>   #endif
> 
> ... and this can be:
> 
> | if (IS_ENABLED(CONFIG_HOTPLUG_CPU))
> | 	__cpu_try_die(cpu);
> 
> Thanks,
> Mark.
> 

Thanks for the detailed comments. With it, the code looks cleaner. I'll
have this in next revision (v5).

Thanks,
Gavin


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  reply	other threads:[~2020-03-18  2:22 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-26  0:23 [PATCH v4 0/5] arm64: Dereference CPU operations indirectly Gavin Shan
2020-02-26  0:23 ` [PATCH v4 1/5] arm64: Declare ACPI parking protocol CPU operation if needed Gavin Shan
2020-03-17 10:28   ` Mark Rutland
2020-03-18  2:06     ` Gavin Shan
2020-02-26  0:23 ` [PATCH v4 2/5] arm64: Rename cpu_read_ops() to init_cpu_ops() Gavin Shan
2020-03-17 10:20   ` Mark Rutland
2020-02-26  0:23 ` [PATCH v4 3/5] arm64: Introduce get_cpu_ops() helper function Gavin Shan
2020-03-17 10:48   ` Mark Rutland
2020-03-18  2:22     ` Gavin Shan [this message]
2020-02-26  0:23 ` [PATCH v4 4/5] arm64: Remove CPU operations dereferencing array Gavin Shan
2020-03-17 10:56   ` Mark Rutland
2020-03-18  3:53     ` Gavin Shan
2020-03-18 22:53       ` Gavin Shan
2020-02-26  0:23 ` [PATCH v4 5/5] arm64: Remove argument @cpu of get_cpu_ops() Gavin Shan
2020-03-16  3:05 ` [PATCH v4 0/5] arm64: Dereference CPU operations indirectly Gavin Shan

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