Re: [Adeos-main] irq masking in ipipe_restore_pipeline_head

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

Philippe Gerum wrote:
> On Fri, 2010-06-18 at 13:26 +0200, Jan Kiszka wrote:
>> Hi Philippe,
>>
>> don't we need this in ipipe_restore_pipeline_head to play safe
> 
> I can't see what this is supposed to fix. Any hint?

You enter ipipe_restore_pipeline_head with hard IRQs enabled and you
don't take the slow path as the domain is not stalled and the passed
flags do not change this. Then you leave with hard IRQs disabled. Corner
case, but I think it's not per se impossible.

Jan

> 
>>  (includes
>> some UP optimization as well):
>>
>> diff --git a/include/linux/ipipe.h b/include/linux/ipipe.h
>> index c458883..bf1f94d 100644
>> --- a/include/linux/ipipe.h
>> +++ b/include/linux/ipipe.h
>> @@ -518,9 +518,13 @@ void __ipipe_restore_pipeline_head(unsigned long x);
>>  
>>  static inline void ipipe_restore_pipeline_head(unsigned long x)
>>  {
>> -	local_irq_disable_hw();
>> +	unsigned long flags;
>> +
>> +	local_irq_save_hw_smp(flags);
>>  	if ((x ^ test_bit(IPIPE_STALL_FLAG, &ipipe_head_cpudom_var(status))) & 1)
>>  		__ipipe_restore_pipeline_head(x);
>> +	else
>> +		local_irq_restore_hw_smp(flags);
>>  }
>>  
>>  #define ipipe_unstall_pipeline() \
>> diff --git a/kernel/ipipe/core.c b/kernel/ipipe/core.c
>> index e2503bd..60a6433 100644
>> --- a/kernel/ipipe/core.c
>> +++ b/kernel/ipipe/core.c
>> @@ -422,6 +422,9 @@ void __ipipe_restore_pipeline_head(unsigned long x) /* hw interrupt off */
>>  	struct ipipe_percpu_domain_data *p = ipipe_head_cpudom_ptr();
>>  	struct ipipe_domain *head_domain;
>>  
>> +#ifndef CONFIG_SMP
>> +	local_irq_disable_hw();
>> +#endif
>>  	if (x) {
>>  #ifdef CONFIG_DEBUG_KERNEL
>>  		static int warned;
>>
>>
>> Untested, just thoughts ATM.
>>
>> Jan
>>
> 
> 

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