Re: [PATCH 1/6] MIPS: Octeon: Implement __smp_store_release()

[Alexander Sverdlin]

Hello Peter,

On 28/01/2021 12:33, Peter Zijlstra wrote:
> This, from commit 6b07d38aaa52 ("MIPS: Octeon: Use optimized memory
> barrier primitives."):
> 
> 	#define smp_mb__before_llsc() smp_wmb()
> 	#define __smp_mb__before_llsc() __smp_wmb()
> 
> is also dodgy as hell and really wants a comment too. I'm not buying the
> Changelog of that commit either, __smp_mb__before_llsc should also
> ensure the LL cannot happen earlier, but SYNCW has no effect on loads.
> So what stops the load from being speculated?

hmm, the commit message you point to above, says:

"Since Octeon does not do speculative reads, this functions as a full barrier."

-- 
Best regards,
Alexander Sverdlin.