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From: Boqun Feng <boqun.feng@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
	dave@stgolabs.net, kvm@vger.kernel.org, dbueso@suse.de,
	netdev@vger.kernel.org, "Michael S. Tsirkin" <mst@redhat.com>,
	linux-kernel@vger.kernel.org,
	virtualization@lists.linux-foundation.org,
	paulmck@linux.vnet.ibm.com,
	Linus Torvalds <torvalds@linux-foundation.org>,
	dvyukov@google.com
Subject: Re: [PATCH 0/3] virtio/vringh: kill off ACCESS_ONCE()
Date: Fri, 25 Nov 2016 22:56:29 +0800	[thread overview]
Message-ID: <20161125145512.GA4014@Boquns-MacBook-Pro.local> (raw)
In-Reply-To: <20161125124404.GI3174@twins.programming.kicks-ass.net>

On Fri, Nov 25, 2016 at 01:44:04PM +0100, Peter Zijlstra wrote:
> On Fri, Nov 25, 2016 at 01:40:44PM +0100, Peter Zijlstra wrote:
> > #define SINGLE_LOAD(x)						\
> > {(								\
> > 	compiletime_assert_atomic_type(typeof(x));		\
> 
> Should be:
> 
> 	compiletime_assert_atomic_type(x);
> 
> > 	WARN_SINGLE_COPY_ALIGNMENT(&(x));			\

Do we need to worry about the side effect on x? Maybe

#define SINGLE_LOAD(x)					\
({							\
	typeof(x) *_____ptr;				\
							\
	compiletime_assert_atomic_type(typeof(x));	\
							\
	_____ptr = &(x);				\
							\
	WARN_SINGLE_COPY_ALIGNMENT(_____ptr);		\
							\
	READ_ONCE(*_____ptr);				\
})

Ditto for SINGLE_STORE()

Regards,
Boqun

> > 	READ_ONCE(x);						\
> > })
> > 
> > #define SINGLE_STORE(x, v)					\
> > ({								\
> > 	compiletime_assert_atomic_type(typeof(x));		\
> 
> idem
> 
> > 	WARN_SINGLE_COPY_ALIGNMENT(&(x));			\
> > 	WRITE_ONCE(x, v);					\
> > })

  reply	other threads:[~2016-11-25 14:56 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 [this message]
2016-11-25 15:21               ` Dmitry Vyukov
2016-11-25 16:10                 ` Mark Rutland
2016-11-25 16:17                   ` Peter Zijlstra
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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