Re: [PATCH tip/core/rcu 08/10] rcu: Add a TINY_PREEMPT_RCU

[Lai Jiangshan]

On 08/17/2010 06:24 AM, Paul E. McKenney wrote:

>> --(t->rcu_read_lock_nesting)
>>
>> could be split in two distinct operations:
>>
>> read t->rcu_read_lock_nesting
>> decrement t->rcu_read_lock_nesting
>>
>> Note that in order to know the result required to pass the sequence
>> point "&&" (the test), we only need to perform the read, not the
>> decrement. AFAIU, gcc would be in its rights to move the
>> t->rcu_read_lock_nesting update after the volatile access.
> 
> I will run this by some compiler experts.
> 

We can just use "read and decrement statements" instead of "--" to
avoid dependency from compilers.
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