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[PATCH v2 2/3] powerpc: Call chained reset handlers during reset

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  [PATCH v2 2/3] powerpc: Call chained reset handlers during reset Andrey Smirnov <andrew.smirnov@gmail.com> - 2016-07-29 01:10 +0200
    Re: [PATCH v2 2/3] powerpc: Call chained reset handlers during  reset Nicholas Piggin <npiggin@gmail.com> - 2016-08-01 05:50 +0200
      Re: [PATCH v2 2/3] powerpc: Call chained reset handlers during reset Andrey Smirnov <andrew.smirnov@gmail.com> - 2016-08-09 20:30 +0200

#1452163 — [PATCH v2 2/3] powerpc: Call chained reset handlers during reset

Call out to all restart handlers that were added via
register_restart_handler() API when restarting the machine.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
---

No changes compared to v1

 arch/powerpc/kernel/setup-common.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c
index 5cd3283..205d073 100644
--- a/arch/powerpc/kernel/setup-common.c
+++ b/arch/powerpc/kernel/setup-common.c
@@ -145,6 +145,10 @@ void machine_restart(char *cmd)
 		ppc_md.restart(cmd);
 
 	smp_send_stop();
+
+	do_kernel_restart(cmd);
+	mdelay(1000);
+
 	machine_hang();
 }
 
-- 
2.5.5

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#1452968 — Re: [PATCH v2 2/3] powerpc: Call chained reset handlers during reset

On Thu, 28 Jul 2016 16:07:17 -0700
Andrey Smirnov <andrew.smirnov@gmail.com> wrote:

> Call out to all restart handlers that were added via
> register_restart_handler() API when restarting the machine.
> 
> Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
> ---
> 
> No changes compared to v1
> 
>  arch/powerpc/kernel/setup-common.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/arch/powerpc/kernel/setup-common.c
> b/arch/powerpc/kernel/setup-common.c index 5cd3283..205d073 100644
> --- a/arch/powerpc/kernel/setup-common.c
> +++ b/arch/powerpc/kernel/setup-common.c
> @@ -145,6 +145,10 @@ void machine_restart(char *cmd)
>  		ppc_md.restart(cmd);
>  
>  	smp_send_stop();
> +
> +	do_kernel_restart(cmd);
> +	mdelay(1000);
> +
>  	machine_hang();
>  }
>  

Ah, I see why you don't move smp_send_stop(). 3 other architectures
call do_kernel_restart(). arm and arm64 call it with
local_irq_disabled(). arm and mips insert the 1s delay. All call it
after smp_send_stop(). I don't see the harm in the delay. Should we
call it with local interrupts disabled?

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#1459051

On Sun, Jul 31, 2016 at 8:47 PM, Nicholas Piggin <npiggin@gmail.com> wrote:
> On Thu, 28 Jul 2016 16:07:17 -0700
> Andrey Smirnov <andrew.smirnov@gmail.com> wrote:
>
>> Call out to all restart handlers that were added via
>> register_restart_handler() API when restarting the machine.
>>
>> Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
>> ---
>>
>> No changes compared to v1
>>
>>  arch/powerpc/kernel/setup-common.c | 4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/arch/powerpc/kernel/setup-common.c
>> b/arch/powerpc/kernel/setup-common.c index 5cd3283..205d073 100644
>> --- a/arch/powerpc/kernel/setup-common.c
>> +++ b/arch/powerpc/kernel/setup-common.c
>> @@ -145,6 +145,10 @@ void machine_restart(char *cmd)
>>               ppc_md.restart(cmd);
>>
>>       smp_send_stop();
>> +
>> +     do_kernel_restart(cmd);
>> +     mdelay(1000);
>> +
>>       machine_hang();
>>  }
>>
>
> Ah, I see why you don't move smp_send_stop(). 3 other architectures
> call do_kernel_restart(). arm and arm64 call it with
> local_irq_disabled().

I am not very familiar with low-level SPM code, so take all below with
a grain of salt.

From my understanding of the code ARM's implementation of
smp_send_stop() is different from MIPS/PowerPC ones in that it just
raises an IPI with a special "stop" flag set, which can and probably
should be done with IRQs disabled. Both MIPS and PowerPC call
smp_call_fuction() in their smp_send_stop() implementation, which if I
read the documentation correctly should not be called with interrupts
disabled, so it looks like the call to local_irq_disabled() could only
be placed after the call to smp_send_stop() on those platforms.

> arm and mips insert the 1s delay. All call it
> after smp_send_stop(). I don't see the harm in the delay. Should we
> call it with local interrupts disabled?
>

With all above being said I don't see any harm in disabling interrupts.

Thanks,
Andrey

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