linux-kernel - Re: [PATCH] trace/osnoise: Do not use 'main' as variable name

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Date:   Wed, 8 Sep 2021 09:09:19 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Steven Rostedt <rostedt@...dmis.org>,
        Guenter Roeck <linux@...ck-us.net>
Cc:     Daniel Bristot de Oliveira <bristot@...nel.org>,
        Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH] trace/osnoise: Do not use 'main' as variable name

On 9/8/21 8:53 AM, Steven Rostedt wrote:
> On Wed,  8 Sep 2021 08:14:07 -0700
> Guenter Roeck <linux@...ck-us.net> wrote:
> 
>> gcc 11.x may get a hiccup when encountering 'main' as variable name.
>>
>> kernel/trace/trace_osnoise.c: In function 'start_kthread':
>> kernel/trace/trace_osnoise.c:1515:8: error: 'main' is usually a function
>>
>> Use a different variable name to silence it.
> 
> Egad, no. NACK! Double NACK. Linus already NACK'd this.
> 
> (although it's ironic that he also added -Werror as the default :-/ )
> 
> The bug in is in gcc, go send them a patch.
> 
> THERE IS NO ISSUE WITH HAVING A LOCAL VARIABLE NAMED "main"!!!!
> 
> This has already been discussed:
> 
>    https://lore.kernel.org/all/CAHk-=whHxeUjaNrWOLb0qx=-nibRZzQomwkw9xMPH_aHCf=BWQ@mail.gmail.com/
> 
> For now, the workaround is this patch:
> 
>     https://lore.kernel.org/all/20210813224131.25803-1-rdunlap@infradead.org/
> 
> 
> -- Steve
> 
> 
>>
>> Signed-off-by: Guenter Roeck <linux@...ck-us.net>
>> ---
>>   kernel/trace/trace_osnoise.c | 6 +++---
>>   1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c
>> index 65b08b8e5bf8..7a4c73b4fdcf 100644
>> --- a/kernel/trace/trace_osnoise.c
>> +++ b/kernel/trace/trace_osnoise.c
>> @@ -1512,20 +1512,20 @@ static void stop_per_cpu_kthreads(void)
>>   static int start_kthread(unsigned int cpu)
>>   {
>>   	struct task_struct *kthread;
>> -	void *main = osnoise_main;
>> +	void *func = osnoise_main;
>>   	char comm[24];
>>   
>>   #ifdef CONFIG_TIMERLAT_TRACER
>>   	if (osnoise_data.timerlat_tracer) {
>>   		snprintf(comm, 24, "timerlat/%d", cpu);
>> -		main = timerlat_main;
>> +		func = timerlat_main;
>>   	} else {
>>   		snprintf(comm, 24, "osnoise/%d", cpu);
>>   	}
>>   #else
>>   	snprintf(comm, 24, "osnoise/%d", cpu);
>>   #endif
>> -	kthread = kthread_create_on_cpu(main, NULL, cpu, comm);
>> +	kthread = kthread_create_on_cpu(func, NULL, cpu, comm);
>>   
>>   	if (IS_ERR(kthread)) {
>>   		pr_err(BANNER "could not start sampling thread\n");
> 

Preferably Linus's version:

https://lore.kernel.org/all/73ee98a4-c4a5-04f3-6280-dcd67507d889@infradead.org/


-- 
~Randy