From: Peter Zijlstra <peterz@infradead.org>
To: Mark Rutland <mark.rutland@arm.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>,
KVM list <kvm@vger.kernel.org>,
"Michael S. Tsirkin" <mst@redhat.com>,
netdev <netdev@vger.kernel.org>,
Boqun Feng <boqun.feng@gmail.com>,
dbueso@suse.de, LKML <linux-kernel@vger.kernel.org>,
virtualization@lists.linux-foundation.org,
Paul McKenney <paulmck@linux.vnet.ibm.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Dmitry Vyukov <dvyukov@google.com>
Subject: Re: [PATCH 0/3] virtio/vringh: kill off ACCESS_ONCE()
Date: Fri, 25 Nov 2016 17:17:09 +0100 [thread overview]
Message-ID: <20161125161709.GQ3092@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20161125161004.GA30181@leverpostej>
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:
> > 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().
next prev parent reply other threads:[~2016-11-25 16:17 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-24 10:25 [PATCH 0/3] virtio/vringh: kill off ACCESS_ONCE() Mark Rutland
2016-11-24 10:25 ` [PATCH 1/3] tools/virtio: fix READ_ONCE() Mark Rutland
2016-11-24 11:34 ` Cornelia Huck
2016-11-25 2:38 ` Jason Wang
2016-11-24 10:25 ` [PATCH 2/3] vringh: kill off ACCESS_ONCE() Mark Rutland
2016-11-24 11:10 ` Christian Borntraeger
2016-11-24 11:35 ` Cornelia Huck
2016-11-25 2:40 ` Jason Wang
2016-11-24 10:25 ` [PATCH 3/3] tools/virtio: use {READ,WRITE}_ONCE() in uaccess.h Mark Rutland
2016-11-24 11:37 ` Cornelia Huck
2016-11-25 2:40 ` Jason Wang
2016-11-24 20:36 ` [PATCH 0/3] virtio/vringh: kill off ACCESS_ONCE() Michael S. Tsirkin
2016-11-25 11:22 ` Mark Rutland
2016-11-25 11:33 ` Christian Borntraeger
2016-11-25 12:23 ` Mark Rutland
2016-11-25 12:40 ` Peter Zijlstra
2016-11-25 12:44 ` Peter Zijlstra
2016-11-25 14:56 ` Boqun Feng
2016-11-25 15:21 ` Dmitry Vyukov
2016-11-25 16:10 ` Mark Rutland
2016-11-25 16:17 ` Peter Zijlstra [this message]
2016-11-25 16:32 ` Mark Rutland
2016-11-25 16:49 ` Christian Borntraeger
2016-11-25 17:28 ` Mark Rutland
2016-11-25 17:42 ` Peter Zijlstra
2016-11-25 18:46 ` Christian Borntraeger
2016-11-25 21:08 ` Michael S. Tsirkin
2016-11-25 21:45 ` Christian Borntraeger
2016-11-25 17:28 ` Dmitry Vyukov
2016-11-25 17:43 ` Mark Rutland
2016-11-25 17:52 ` Linus Torvalds
2016-11-25 18:07 ` Mark Rutland
2016-11-25 18:47 ` Linus Torvalds
2016-11-25 14:35 ` Mark Rutland
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