Re: [PATCH 0/3] virtio/vringh: kill off ACCESS_ONCE()
From: Peter Zijlstra <peterz@infradead.org>
Date: 2016-11-25 16:17:26
Also in:
kvm, lkml, virtualization
On Fri, Nov 25, 2016 at 04:10:04PM +0000, Mark Rutland wrote:
On Fri, Nov 25, 2016 at 04:21:39PM +0100, Dmitry Vyukov wrote:
quoted
What are use cases for such primitive that won't be OK with "read once _and_ atomically"?I have none to hand.
Whatever triggers the __builtin_memcpy() paths, and even the size==8
paths on 32bit.
You could put a WARN in there to easily find them.
The advantage of introducing the SINGLE_{LOAD,STORE}() helpers is that
they compiletime validate this the size is 'right' and can runtime check
alignment constraints.
IE, they are strictly stronger than {READ,WRITE}_ONCE().