Re: [Xenomai-core] [RFC] define your own pipe heap

[Jan Kiszka <kiszka@domain.hid>]

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Philippe Gerum wrote:
> Jan Kiszka wrote:
> 
>> Philippe Gerum wrote:
>>
>>> Jan Kiszka wrote:
>>>
>>>> Jan Kiszka wrote:
>>>>
>>>>
>>>>> ...
>>>>> A patch says more than thousand words. ;)
>>>>>
>>>>> As a first approach, I picked the second variant and implemented a new
>>>>> function called rt_pipe_setpool. I also had to extend rt_pipe_alloc
>>>>> and
>>>>> rt_pipe_free so that the right pool is used by them.
>>>>>
>>>>
>>>>
>>>> I thought about this variant again, and it seems to me rather unsafe in
>>>> case some buffer allocation takes place between rt_pipe_create and
>>>> rt_pipe_setpool. So, here is a patch which extends rt_pipe_create
>>>> with a
>>>> new argument poolsize instead.
>>>>
>>>
>>> Yep, looks safer to me too.
>>>
>>
>>
>> Ok, I addressed most your comments, and here is round 2 of variant 2.
>> The only question for me is if we should rt_pipe_create in kernel space
>> from RT context with poolsize=0 if this is prevented effectively for
>> userspace task?
> 
> 
> This is not prevented for user-space, since there is an automatic switch
> to secondary mode caused by the lostage exec bit.

That's what I meant. Anyway, this doesn't change the situation:
rt_pipe_create is not called in primary context from userspace, so the
questions if we should allow this for kernelspace and poolsize=0.

> 
>  So far, I deny any non-RT invocation.
> 
>>
> 
> You likely mean, any non-Linux invocation.
> 

Of course, I did.

Jan

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