linux-kernel - irqsafe_cpu_...() 64-bit operations on 32-bit platform

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Message-Id: <4EF4581C0200007800069BA2@nat28.tlf.novell.com>
Date:	Fri, 23 Dec 2011 09:29:48 +0000
From:	"Jan Beulich" <JBeulich@...e.com>
To:	<cl@...ux.com>
Cc:	<mingo@...e.hu>, <linux-kernel@...r.kernel.org>
Subject: irqsafe_cpu_...() 64-bit operations on 32-bit platform

Christoph,

you introduced these for 2.6.33, but I wonder about their completeness
in the current state: On ix86, I can add, sub, xor, etc a 64-bit variable
this way (through the generic implementation), but there's no way to
read or write such a variable. While not documented explicitly, it seems
like the assumption is that this_cpu_{read,write}() can be used for this
purpose, but that's clearly wrong.

Along the same lines, Ingo, x86 has set_64bit() but no get_64bit()
(and no [gs]et_64bit_local()). Is that really intentional?

Thanks for your thoughts on this,
Jan

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