Re: [Xenomai] [PATCH] x86/ipipe: get FPU backup area allocated for all threads

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2013-10-04 10:53, Gilles Chanteperdrix wrote:
> 
> Jan Kiszka wrote:
>>> diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
>>> index a00bed1..4716eb2 100644
>>> --- a/arch/x86/kernel/process.c
>>> +++ b/arch/x86/kernel/process.c
>>> @@ -73,14 +73,6 @@ int arch_dup_task_struct(struct task_struct *dst,
>>> struct task_struct *src)
>>>  		if (ret)
>>>  			return ret;
>>>  		fpu_copy(dst, src);
>>> -	} else {
>>> -#ifdef CONFIG_IPIPE
>>> -		/* unconditionally allocate, RT domain may need it */
>>> -		memset(&dst->thread.fpu, 0, sizeof(dst->thread.fpu));
>>> -		ret = fpu_alloc(&dst->thread.fpu);
>>> -		if (ret)
>>> -			return ret;
>>> -#endif
>>
>> Why removing the systematic allocation? This is not explained above and
>> seems counterproductive.
> 
> Because when we stop deleting the fpu backup area upon exec, no fork ever
> takes place for source thread without an fpu backup area. So, the "else"
> clause never happens, and we can remove it entirely.

OK, please add this to the commit log.

Jan

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