Messages in this thread | | | Date | Mon, 20 Nov 2017 20:28:06 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v2 18/18] arm64: select ARCH_SUPPORTS_LTO_CLANG |
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On Mon, Nov 20, 2017 at 06:05:55PM +0000, Will Deacon wrote: > This is a thorny issue, but RCU (specifically rcu_dereference but probably > also some READ_ONCEs) relies on being able to utilise syntactic dependency > chains to order local accesses to shared variables.
Well, we used to have READ_ONCE() and smp_read_barrier_depends(), but we recently munged them together, in the process getting rid of lockless_dereference().
So for sure, READ_ONCE() must be able to do the address dependency thing, otherwise tons of code comes apart.
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