On 10/03/2016 16:45, Xiao Guangrong wrote:
>>
>>> Compared to smp_load_acquire(), smp_mb() adds an ordering between stores
>>> and loads.
>>
>> Here, the ordering is load-store, hence...
>
> Yes, this is why i put smp_mb() in the code. :)
Here is a table of barriers:
'. after| |
before '. | load | store
__________'.|___________________|________________________
| |
| smp_rmb | smp_load_acquire
load | smp_load_acquire | smp_store_release XX
| smp_mb | smp_mb
____________|___________________|________________________
| |
| | smp_wmb
store | smp_mb | smp_store_release
| | smp_mb
| |
Your case is the one marked with XX, so a smp_load_acquire() is
enough---and it's preferrable, because it's cheaper than smp_mb() and
more self-documenting.
Paolo
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