Re: [Xenomai] Dealing with too small thread stacks

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

On 2015-04-17 19:50, Gilles Chanteperdrix wrote:
> On Fri, Apr 17, 2015 at 07:34:30PM +0200, Jan Kiszka wrote:
>> Hi,
>>
>> analyzing page faults of an application that prefers to set its own
>> stacks, I noticed a problem in Xenomai (2 and 3), at least from the
>> usability POV: We document the minimum stack stack as PTHREAD_STACK_MIN
>> + 1 page, at least in Xenomai 3, and we enforce that on thread creation.
>> However, enforcement is doomed to fail if the stack is preallocated (and
>> that too small).
>>
>> As we cannot detect if the user set a stack address in pthread_attr_t, I
>> would suggest to fail thread creation instead of performing it with
>> improper parameters. Other suggestions? If not, I would prepare a patch
>> for Xenomai 3 (for 2 only if desired).
> 
> It seems to me we can detect the parameters in the pthread_attr_t
> using pthread_attr_getstack. So, we can get __wrap_pthread_create to
> fail if the size is not sufficient.

Nope, unfortunately not:

"If the pthread_attr_getstack() function is called before the stackaddr
attribute has been set, the behavior is unspecified."

Jan

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