Re: [Xenomai] [Xenomai-git] Jan Kiszka : cobalt/kernel: Allow to restart clock_nanosleep and select after signal processing

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

On 2016-06-14 17:57, Gilles Chanteperdrix wrote:
> On Fri, May 27, 2016 at 08:36:43AM +0200, git repository hosting wrote:
>> diff --git a/kernel/cobalt/include/asm-generic/xenomai/wrappers.h b/kernel/cobalt/include/asm-generic/xenomai/wrappers.h
>> index 060ce85..0f9ab14 100644
>> --- a/kernel/cobalt/include/asm-generic/xenomai/wrappers.h
>> +++ b/kernel/cobalt/include/asm-generic/xenomai/wrappers.h
>> @@ -133,4 +133,10 @@ devm_hwmon_device_register_with_groups(struct device *dev, const char *name,
>>  #error "Xenomai/cobalt requires Linux kernel 3.10 or above"
>>  #endif /* < 3.10 */
>>  
>> +#if LINUX_VERSION_CODE < KERNEL_VERSION(4,0,0)
>> +#define cobalt_get_restart_block(p)	(&task_thread_info(p)->restart_block)
>> +#else
>> +#define cobalt_get_restart_block(p)	(&(p)->restart_block)
>> +#endif
>> +
> 
> This is bad. First off as explained in the comment heading
> wrappers.h the wrappers are ordered by kernel version and the most
> recent is first. Second, no other wrapper has a #else clause, the
> idea is that we want to be able to remove some old wrappers from
> time to time, and removing the #if completely should be enough.
> Obviously, if you put a #else, this does not work. I agree that in
> that case it is going to be hard, but please try anyway...

I'm open for concrete ideas.

> 
> Other than that, I see your patch modifies each syscall handler
> directly, can not the result be achieved in a different way? For
> instance by factoring it in the core? Relying more on Linux syscall
> restart mechanism.

Linux does it similarly, i.e. requires modifications on a per-syscall
basis. As the logic is widely syscall-specific, I also don't see a
generic way under Xenomai either. The good news is that all cases that
Linux covers (minus futexes which we don't have) are already implemented
in the patch, thus this shouldn't spread.

Jan

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