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

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Message-Id: <a3d57a7e-6134-4da5-bd4a-b150d2c97912@app.fastmail.com>
Date: Tue, 18 Jun 2024 15:50:33 +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18日六月 上午4:51，Huacai Chen写道：
> On Tue, Jun 18, 2024 at 6:10 AM Jiaxun Yang <jiaxun.yang@...goat.com> wrote:
>>
>>
>>
>> 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.
> It is not in smp_setup() now, then how do you move it from smp_setup()?
[...]

Well I was trying to justify where should I move it to, not where
does it from.

I should improve the commit message to justify the reason first.

Thanks
- Jiaxun
>
> Huacai
>
>>
>> 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

-- 
- Jiaxun