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

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Message-ID: <CAAhV-H7RQu6wdBBjOBptZX6R63Ypw1qFCoJnZ335bFKd1f=XdA@mail.gmail.com>
Date: Tue, 18 Jun 2024 11:51:25 +0800
From: Huacai Chen <chenhuacai@...nel.org>
To: Jiaxun Yang <jiaxun.yang@...goat.com>
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

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()?

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