Re: [Adeos-main] Unchecked ipipe_test_pipeline_from

[Jan Kiszka <jan.kiszka@domain.hid>]

Gilles Chanteperdrix wrote:
> Jan Kiszka wrote:
>> Hi Philippe,
>>
>> just noticed: The __ipipe_check_percpu_access of __ipipe_get_cpu_var,
>> added in 2.6.29, makes ipipe_test_pipeline_from unusable for debugging
>> purposes. It now triggers a false positive warning if the caller did not
>> disabled interrupts or stalled its pipeline. One such user under Xenomai
>> is rthal_local_irq_disabled, and that is used to check RTDM driver
>> handlers /wrt leaking IRQ masks.
> 
> It does not look like a false positive. If the task issuing the call to
> rthal_local_irq_disabled function was migrated at the wrong time, it
> could check the stall flag on the wrong cpu.

Unless you want to test the migration logic itself, a plain task in
whatever domain should never see a CPU-depend rthal_local_irq_disabled -
migration should never alter the context in this respect.

> So, it looks like
> rthal_local_irq_disabled should be fixed to turn off irqs during the check.
> 

Would work, but would also be more heavy-weighted then needed.

Jan

-- 
Siemens AG, Corporate Technology, CT SE 2
Corporate Competence Center Embedded Linux