linux-kernel - Re:Re: [PATCH] sched/rt, powerpc: Prepare for PREEMPT

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Message-ID: <AJAAOQDzDcbjqrJ8gOXru4r0.3.1604989600488.Hmail.wangqing@vivo.com>
Date:   Tue, 10 Nov 2020 14:26:40 +0800 (GMT+08:00)
From:   王擎 <wangqing@...o.com>
To:     Christophe Leroy <christophe.leroy@...roup.eu>
Cc:     Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Alistair Popple <alistair@...ple.id.au>,
        Jordan Niethe <jniethe5@...il.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        tglx@...utronix.de
Subject: Re:Re: [PATCH] sched/rt, powerpc: Prepare for PREEMPT_RT

>Quoting Wang Qing <wangqing@...o.com>:
>
>> Add PREEMPT_RT output to die().
>>
>> Signed-off-by: Wang Qing <wangqing@...o.com>
>> ---
>>  arch/powerpc/kernel/traps.c | 10 +++++++++-
>>  1 file changed, 9 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
>> index 5006dcb..6dfe567
>> --- a/arch/powerpc/kernel/traps.c
>> +++ b/arch/powerpc/kernel/traps.c
>> @@ -258,6 +258,14 @@ static char *get_mmu_str(void)
>>  	return "";
>>  }
>>
>> +#ifdef CONFIG_PREEMPT
>> +#define S_PREEMPT " PREEMPT"
>> +#elif defined(CONFIG_PREEMPT_RT)
>> +#define S_PREEMPT " PREEMPT_RT"
>> +#else
>> +#define S_PREEMPT ""
>> +#endif
>
>I don't like too much that forest of #ifdefs. IS_ENABLED() is prefered  
>whenever possible.
>
>> +
>>  static int __die(const char *str, struct pt_regs *regs, long err)
>>  {
>>  	printk("Oops: %s, sig: %ld [#%d]\n", str, err, ++die_counter);
>> @@ -265,7 +273,7 @@ static int __die(const char *str, struct pt_regs  
>> *regs, long err)
>>  	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" : "",
>> +	       S_PREEMPT,
>>  	       IS_ENABLED(CONFIG_SMP) ? " SMP" : "",
>>  	       IS_ENABLED(CONFIG_SMP) ? (" NR_CPUS=" __stringify(NR_CPUS)) : "",
>>  	       debug_pagealloc_enabled() ? " DEBUG_PAGEALLOC" : "",
>> --
>> 2.7.4
>
>I'd prefer to remain in line with the existing and use IS_ENABLED()  
>instead of #ifdefs, see below:
>
>diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
>index 5006dcbe1d9f..dec7b81c72a4 100644
>--- a/arch/powerpc/kernel/traps.c
>+++ b/arch/powerpc/kernel/traps.c
>@@ -262,10 +262,11 @@ 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 %s\n",
>  	       IS_ENABLED(CONFIG_CPU_LITTLE_ENDIAN) ? "LE" : "BE",
>  	       PAGE_SIZE / 1024, get_mmu_str(),
>  	       IS_ENABLED(CONFIG_PREEMPT) ? " PREEMPT" : "",
>+	       IS_ENABLED(CONFIG_PREEMPT_RT) ? " PREEMPT_RT" : "",
>  	       IS_ENABLED(CONFIG_SMP) ? " SMP" : "",
>  	       IS_ENABLED(CONFIG_SMP) ? (" NR_CPUS=" __stringify(NR_CPUS)) : "",
>  	       debug_pagealloc_enabled() ? " DEBUG_PAGEALLOC" : "",
>---
>Christophe

Yeah, I agree with it.

Wang Qing