Messages in this thread | | | Date | Fri, 11 May 2018 10:32:42 +0200 | From | Peter Zijlstra <> | Subject | Re: Is read barrier missed in kfifo? |
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On Fri, May 11, 2018 at 03:25:18PM +0800, Xiao Guangrong wrote: > > Hi, > > Currently, there is no read barrier between reading the index > (kfifo.in) and fetching the real data from the fifo. > > I am afraid that will cause the vfifo is observed as not empty > however the data is not actually ready for read. Right?
That code is decidedly dodgy indeed. I can only see smp_wmb() but no matching barriers at all -- therefore the code is almost certainly as good as not having any barriers at all.
I would suggest you try and convert the code to smp_store_release() and smp_load_acquire() while you're at it.
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