Re: [PATCH] ARM: cache-v7: Disable preemption when reading CCSIDR

On 02/02/12 18:35, Nicolas Pitre wrote:
> On Thu, 2 Feb 2012, Stephen Boyd wrote:
>> On 02/02/12 17:18, Nicolas Pitre wrote:
>>> If you simply disable/restore IRQs around the critical region then you 
>>> don't have to worry about __v7_setup.  Plus this will allow for 
>>> v7_flush_dcache_all to still be callable from atomic context.
>> Ok. Here's a patch. I still need to test it. I'll send another patch
>> series to cleanup the get_thread_info stuff (there's two of them?).
>>
>>  arch/arm/mm/cache-v7.S |    6 ++++++
>>  1 files changed, 6 insertions(+), 0 deletions(-)
>>
>> diff --git a/arch/arm/mm/cache-v7.S b/arch/arm/mm/cache-v7.S
>> index 07c4bc8..654a5fc 100644
>> --- a/arch/arm/mm/cache-v7.S
>> +++ b/arch/arm/mm/cache-v7.S
>>  <at>  <at>  -54,9 +54,15  <at>  <at>  loop1:
>>  	and	r1, r1, #7			 <at>  mask of the bits for current cache only
>>  	cmp	r1, #2				 <at>  see what cache we have at this level
>>  	blt	skip				 <at>  skip if no cache, or just i-cache
>> +#ifdef CONFIG_PREEMPT
>> +	save_and_disable_irqs r9		 <at>  make cssr&csidr read atomic
>> +#endif
>>  	mcr	p15, 2, r10, c0, c0, 0		 <at>  select current cache level in cssr
>>  	isb					 <at>  isb to sych the new cssr&csidr
>>  	mrc	p15, 1, r1, c0, c0, 0		 <at>  read the new csidr
>> +#ifdef CONFIG_PREEMPT
>> +	restore_irqs r9
>> +#endif
> I'd suggest using restore_irqs_notrace instead.  The IRQ-off period is 
> so small that there is no point tracing it.

Thanks. I'll make sure to do that before uploading to the patch tracker.

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