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.
