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From: Ian Campbell <ian.campbell@citrix.com>
To: Will Deacon <will.deacon@arm.com>
Cc: Rob Herring <robherring2@gmail.com>,
	"xen-devel@listsxen.org" <xen-devel@lists.xen.org>,
	"Keir (Xen.org)" <keir@xen.org>,
	"Stefano Stabellini" <Stefano.Stabellini@eu.citrix.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	"Tim (Xen.org)" <tim@xen.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Jan Beulich <JBeulich@suse.com>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	Nicolas Pitre <nico@fluxnic.net>
Subject: Re: [PATCH LINUX v5] xen: event channel arrays are xen_ulong_t and not unsigned long
Date: Thu, 7 Mar 2013 07:17:42 +0000	[thread overview]
Message-ID: <1362640662.8941.141.camel@hastur.hellion.org.uk> (raw)
In-Reply-To: <20130307031707.GA25137@mudshark.cambridge.arm.com>

On Thu, 2013-03-07 at 03:17 +0000, Will Deacon wrote:
> > I looked and couldn't see an existing 64 bit xchg, was I looking in the
> > wrong place? Ah, wait, I see atomic64_xchg now. But that needs an
> > atomic64_t while I have a xen_ulong_t (which == 64 bits on ARM). This is
> > a kernel<->hypervisor ABI so I can't just change it to an atomic64_t. I
> > suppose I could cast (see below, untested) but that seems rather icky.
> 
> You can play some container_of tricks, like we do in cmpxchg64 to get this
> right. Alternatively, we could look at an xchg8 implementation which some
> other architectures have (although they seem to be 64-bit machines).

I went with the container of trick + appropriate Kconfig depends and
sent a patch out a couple of seconds ago.

Thanks for your help/advice!

Ian.


  reply	other threads:[~2013-03-07  7:20 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-02-19 14:48 [PATCH V2] " Ian Campbell
2013-02-19 14:49 ` [PATCH LINUX] " Ian Campbell
2013-02-19 17:11   ` Stefano Stabellini
2013-02-19 17:17     ` Ian Campbell
2013-02-19 17:26       ` Tim Deegan
2013-02-19 17:28         ` Ian Campbell
2013-02-19 14:49 ` [PATCH XEN] " Ian Campbell
2013-02-19 16:42   ` Stefano Stabellini
2013-02-21 17:16   ` Ian Campbell
2013-02-21 18:43     ` Keir Fraser
2013-02-22  8:28       ` Ian Campbell
2013-02-22  8:12     ` Jan Beulich
2013-02-22  8:28       ` Ian Campbell
2013-02-22  8:48         ` Jan Beulich
2013-02-22  8:55           ` Ian Campbell
2013-02-22  9:05             ` Jan Beulich
2013-02-19 17:27 ` [PATCH LINUX v3] " Ian Campbell
2013-02-19 17:29 ` [PATCH LINUX v4] " Ian Campbell
2013-02-19 18:12   ` Stefano Stabellini
2013-02-19 18:43     ` Konrad Rzeszutek Wilk
2013-02-20  2:07   ` Konrad Rzeszutek Wilk
2013-02-20  3:09     ` Konrad Rzeszutek Wilk
2013-02-20  9:13       ` Ian Campbell
2013-02-20 11:48 ` [PATCH LINUX v5] " Ian Campbell
2013-02-21 17:11   ` Stefano Stabellini
2013-03-04  2:45   ` Rob Herring
2013-03-05  3:04     ` Will Deacon
2013-03-05  3:45       ` Ian Campbell
2013-03-05  6:55       ` Rob Herring
2013-03-05  7:03         ` Ian Campbell
2013-03-05  8:08         ` Will Deacon
2013-03-05  9:29           ` Ian Campbell
2013-03-07  3:17             ` Will Deacon
2013-03-07  7:17               ` Ian Campbell [this message]
2013-03-05  3:56     ` Ian Campbell
2013-03-05 14:04       ` Konrad Rzeszutek Wilk

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