[Kgdb-bugreport] 2.6.23-rc3-mm1: kgdb build failure on powerpc

Pete/Piet Delaney pete at bluelane.com
Thu Aug 30 09:43:59 EST 2007


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Jason Wessel wrote:
> Andrew Morton wrote:
>> On Wed, 22 Aug 2007 17:44:12 -0500
>> Jason Wessel <jason.wessel at windriver.com> wrote:
>>
>>  
>>> +    while (!atomic_read(&debugger_active));
>>>     
>>
>> eek.  We're in the process of hunting down and eliminating exactly this
>> construct.  There have been cases where the compiler cached the
>> atomic_read() result in a register, turning the above into an infinite
>> loop.
>>
>> Plus we should never add power-burners like that into the kernel
>> anyway. That loop should have a cpu_relax() in it.  Which will also
>> fix the
>> compiler problem described above.
>>
>>   
> Agreed, and fixed with a cpu_relax.
> 
>> Thirdly, please always add a newline when coding statements like that:
>>
>>     while (expr())
>>         ;
>>   
> 
> The other instances I found of the same problem in the kgdb core are
> fixed too.
> 
> I merged all the changes into the for_mm branch in the kgdb git tree.

Where is the kgdb git tree?

- -piet

> 
> Thanks,
> Jason.
> -
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