Subject: Re: [PATCH v2 03/14] arm: arm64: Don't use disable_nonboot_cpus()

From: Russell King - ARM Linux admin <[email-masked]>
Date: Tue, 21 Jan 2020 16:53:21 +0000

On Tue, Jan 21, 2020 at 04:50:31PM +0000, Qais Yousef wrote:
> On 11/25/19 11:27, Qais Yousef wrote:
> > disable_nonboot_cpus() is not safe to use when doing machine_down(),
> > because it relies on freeze_secondary_cpus() which in return is
> > a suspend/resume related freeze and could abort if the logic detects any
> > pending activities that can prevent finishing the offlining process.
> > 
> > Beside disable_nonboot_cpus() is dependent on CONFIG_PM_SLEEP_SMP which
> > is an othogonal config to rely on to ensure this function works
> > correctly.
> > 
> > Signed-off-by: Qais Yousef <[email-masked]>
> > CC: Russell King <[email-masked]>
> > CC: Catalin Marinas <[email-masked]>
> > CC: Will Deacon <[email-masked]>
> > CC: [email-masked]
> > CC: [email-masked]
> > ---
> 
> Ping :)
> 
> I'm missing ACKs on this patch and patch 4 for arm64. Hopefully none should be
> controversial.

ARM and ARM64 are maintained separately, so you can't submit a single
patch covering both.  Sorry.

> 
> Thanks!
> 
> --
> Qais Yousef
> 
> >  arch/arm/kernel/reboot.c    | 4 ++--
> >  arch/arm64/kernel/process.c | 4 ++--
> >  2 files changed, 4 insertions(+), 4 deletions(-)
> > 
> > diff --git a/arch/arm/kernel/reboot.c b/arch/arm/kernel/reboot.c
> > index bb18ed0539f4..58ad1a70f770 100644
> > --- a/arch/arm/kernel/reboot.c
> > +++ b/arch/arm/kernel/reboot.c
> > @@ -88,11 +88,11 @@ void soft_restart(unsigned long addr)
> >   * to execute e.g. a RAM-based pin loop is not sufficient. This allows the
> >   * kexec'd kernel to use any and all RAM as it sees fit, without having to
> >   * avoid any code or data used by any SW CPU pin loop. The CPU hotplug
> > - * functionality embodied in disable_nonboot_cpus() to achieve this.
> > + * functionality embodied in smp_shutdown_nonboot_cpus() to achieve this.
> >   */
> >  void machine_shutdown(void)
> >  {
> > -	disable_nonboot_cpus();
> > +	smp_shutdown_nonboot_cpus(0);
> >  }
> >  
> >  /*
> > diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
> > index 71f788cd2b18..3bcc9bfc581e 100644
> > --- a/arch/arm64/kernel/process.c
> > +++ b/arch/arm64/kernel/process.c
> > @@ -141,11 +141,11 @@ void arch_cpu_idle_dead(void)
> >   * to execute e.g. a RAM-based pin loop is not sufficient. This allows the
> >   * kexec'd kernel to use any and all RAM as it sees fit, without having to
> >   * avoid any code or data used by any SW CPU pin loop. The CPU hotplug
> > - * functionality embodied in disable_nonboot_cpus() to achieve this.
> > + * functionality embodied in smpt_shutdown_nonboot_cpus() to achieve this.
> >   */
> >  void machine_shutdown(void)
> >  {
> > -	disable_nonboot_cpus();
> > +	smp_shutdown_nonboot_cpus(0);
> >  }
> >  
> >  /*
> > -- 
> > 2.17.1
> > 
> 

-- 
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