Re: [Xenomai-core] [PATCH] hal: Ensure atomicity of rthal_local_irq_disabled

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

Philippe Gerum wrote:
> On Tue, 2009-11-10 at 01:34 +0100, Gilles Chanteperdrix wrote:
>> Jan Kiszka wrote:
>>> [Patch is now also available in 'for-upstream']
>>>
>>> ipipe_test_pipeline_from is not atomic /wrt reading the current cpu
>>> number (or an offset for the per-cpu area) and actually reading the
>>> virtualized interrupt state. Work around this by disabling hard IRQs
>>> while accessing this service.
>>>
>>> This fixes false-positives of RTDM driver debug checks.
>>>
>>> Signed-off-by: Jan Kiszka <jan.kiszka@domain.hid>
>>> ---
>>>  include/asm-generic/hal.h |    9 ++++++++-
>>>  1 files changed, 8 insertions(+), 1 deletions(-)
>>>
>>> diff --git a/include/asm-generic/hal.h b/include/asm-generic/hal.h
>>> index 97c549e..3095b85 100644
>>> --- a/include/asm-generic/hal.h
>>> +++ b/include/asm-generic/hal.h
>>> @@ -117,7 +117,14 @@ typedef spinlock_t rthal_spinlock_t;
>>>  #endif /* !CONFIG_XENO_OPT_PIPELINE_HEAD */
>>>  #define rthal_local_irq_flags(x)	((x) = ipipe_test_pipeline_from(&rthal_domain) & 1)
>>>  #define rthal_local_irq_test()		ipipe_test_pipeline_from(&rthal_domain)
>>> -#define rthal_local_irq_disabled()	ipipe_test_pipeline_from(&rthal_domain)
>>> +#define rthal_local_irq_disabled()				\
>>> +({								\
>>> +	unsigned long __flags, __ret;				\
>>> +	local_irq_save_hw(__flags);				\
>>> +	__ret = ipipe_test_pipeline_from(&rthal_domain);	\
>>> +	local_irq_restore_hw(__flags);				\
>>> +	__ret;							\
>>> +})
>> Maybe we can avoid that on UP systems?
>>
> 
> Yes, we should rather use local_irq_save/restore_hw_smp().
> 

Oh, *_hw_smp is new, isn't it? Do we need to wrap it for older I-pipes?

Jan