linux-kernel - Re: [PATCH v3 5/9] powerpc: Use preempt_model

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Message-ID: <93833119-9406-4d30-aa7b-4521adb3a573@csgroup.eu>
Date: Sat, 8 Feb 2025 13:55:31 +0100
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Shrikanth Hegde <sshegde@...ux.ibm.com>,
 Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc: linux-kernel@...r.kernel.org, linux-rt-devel@...ts.linux.dev,
 Ben Segall <bsegall@...gle.com>, Catalin Marinas <catalin.marinas@....com>,
 Dietmar Eggemann <dietmar.eggemann@....com>, Ingo Molnar <mingo@...hat.com>,
 Juri Lelli <juri.lelli@...hat.com>, Mel Gorman <mgorman@...e.de>,
 Peter Zijlstra <peterz@...radead.org>, Steven Rostedt <rostedt@...dmis.org>,
 Thomas Gleixner <tglx@...utronix.de>,
 Valentin Schneider <vschneid@...hat.com>,
 Vincent Guittot <vincent.guittot@...aro.org>, Will Deacon <will@...nel.org>,
 Madhavan Srinivasan <maddy@...ux.ibm.com>,
 Michael Ellerman <mpe@...erman.id.au>, Nicholas Piggin <npiggin@...il.com>,
 Naveen N Rao <naveen@...nel.org>, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v3 5/9] powerpc: Use preempt_model_str().

Le 08/02/2025 à 08:35, Shrikanth Hegde a écrit :
> 
> 
> On 2/4/25 13:52, Sebastian Andrzej Siewior wrote:
>> Use preempt_model_str() instead of manually conducting the preemption
>> model. Use pr_emerg() instead of printk() to pass a loglevel.
> 
> even on powerpc, i see __die ends up calling show_regs_print_info().
> Why print it twice?

I don't understand what you mean, what is printed twice ?

I can't see show_regs_print_info() printing the preemption model, am I 
missing something ?

Christophe

> 
>>
>> Cc: Madhavan Srinivasan <maddy@...ux.ibm.com>
>> Cc: Michael Ellerman <mpe@...erman.id.au>
>> Cc: Nicholas Piggin <npiggin@...il.com>
>> Cc: Christophe Leroy <christophe.leroy@...roup.eu>
>> Cc: Naveen N Rao <naveen@...nel.org>
>> Cc: linuxppc-dev@...ts.ozlabs.org
>> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
>> ---
>> v2…v3:
>>    - Use printk() instead of pr_emerg() to remain consistent with the
>>      other invocations in terms of printing context.
>>
>>   arch/powerpc/kernel/traps.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
>> index edf5cabe5dfdb..d6d77d92b3358 100644
>> --- a/arch/powerpc/kernel/traps.c
>> +++ b/arch/powerpc/kernel/traps.c
>> @@ -263,10 +263,10 @@ static int __die(const char *str, struct pt_regs 
>> *regs, long err)
>>   {
>>       printk("Oops: %s, sig: %ld [#%d]\n", str, err, ++die_counter);
>> -    printk("%s PAGE_SIZE=%luK%s%s%s%s%s%s %s\n",
>> +    printk("%s PAGE_SIZE=%luK%s %s %s%s%s%s %s\n",
>>              IS_ENABLED(CONFIG_CPU_LITTLE_ENDIAN) ? "LE" : "BE",
>>              PAGE_SIZE / 1024, get_mmu_str(),
>> -           IS_ENABLED(CONFIG_PREEMPT) ? " PREEMPT" : "",
>> +           preempt_model_str(),
>>              IS_ENABLED(CONFIG_SMP) ? " SMP" : "",
>>              IS_ENABLED(CONFIG_SMP) ? (" NR_CPUS=" 
>> __stringify(NR_CPUS)) : "",
>>              debug_pagealloc_enabled() ? " DEBUG_PAGEALLOC" : "",
>