linux-kernel - Re: [PATCH 04/10] MIPS: Move mips_smp_ipi_init call after prepare

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Date: Mon, 17 Jun 2024 23:10:02 +0100
From: "Jiaxun Yang" <jiaxun.yang@...goat.com>
To: "Huacai Chen" <chenhuacai@...nel.org>
Cc: "Thomas Bogendoerfer" <tsbogend@...ha.franken.de>,
 "Florian Fainelli" <florian.fainelli@...adcom.com>,
 "Broadcom internal kernel review list" <bcm-kernel-feedback-list@...adcom.com>,
 "Thomas Gleixner" <tglx@...utronix.de>,
 "Serge Semin" <fancer.lancer@...il.com>,
 "paulburton@...nel.org" <paulburton@...nel.org>,
 "linux-mips@...r.kernel.org" <linux-mips@...r.kernel.org>,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 04/10] MIPS: Move mips_smp_ipi_init call after prepare_cpus



在2024年6月17日六月 下午2:53，Huacai Chen写道：
> Hi, Jiaxun
>
> On Mon, Jun 17, 2024 at 5:03 AM Jiaxun Yang <jiaxun.yang@...goat.com> wrote:
>>
>> This will give platform code a genuine chance to setup
>> IPI IRQ in prepare_cpus.
>>
>> This is the best place for platforms to setup IPI as smp_setup
>> is too early for IRQ subsystem.
> mips_smp_ipi_init() is an early_initcall() function, why do you say it
> is in smp_setup()?

Sorry, I was trying to say that smp_setup is not a good point so we should
go prepare_cpus.

The intention of this patch is to move mips_smp_ipi_init to a certain point
so platform would gain control over it.

Thanks
- Jiaxun

>
>
> Huacai
>>
>> Signed-off-by: Jiaxun Yang <jiaxun.yang@...goat.com>
>> ---
>>  arch/mips/kernel/smp.c | 11 ++++++++++-
>>  1 file changed, 10 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c
>> index fe053fe52147..ddf96c28e2f0 100644
>> --- a/arch/mips/kernel/smp.c
>> +++ b/arch/mips/kernel/smp.c
>> @@ -375,7 +375,6 @@ static int __init mips_smp_ipi_init(void)
>>
>>         return 0;
>>  }
>> -early_initcall(mips_smp_ipi_init);
>>  #endif
>>
>>  /*
>> @@ -460,12 +459,22 @@ void __init smp_cpus_done(unsigned int max_cpus)
>>  /* called from main before smp_init() */
>>  void __init smp_prepare_cpus(unsigned int max_cpus)
>>  {
>> +       int rc;
>> +
>>         init_new_context(current, &init_mm);
>>         current_thread_info()->cpu = 0;
>>         mp_ops->prepare_cpus(max_cpus);
>>         set_cpu_sibling_map(0);
>>         set_cpu_core_map(0);
>>         calculate_cpu_foreign_map();
>> +#ifdef CONFIG_GENERIC_IRQ_IPI
>> +       rc = mips_smp_ipi_init();
>> +       if (rc) {
>> +               pr_err("Failed to initialize IPI - disabling SMP");
>> +               init_cpu_present(cpumask_of(0));
>> +               return;
>> +       }
>> +#endif
>>  #ifndef CONFIG_HOTPLUG_CPU
>>         init_cpu_present(cpu_possible_mask);
>>  #endif
>>
>> --
>> 2.43.0
>>

-- 
- Jiaxun