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Date: Mon, 3 Mar 2008 15:48:31 +0000
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Pavel Machek <pavel@ucw.cz>
Cc: Alan Stern <stern@rowland.harvard.edu>,
       Linus Torvalds <torvalds@linux-foundation.org>,
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Subject: Re: [patch] Re: using long instead of atomic_t when only set/read
 is required
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> Ok, so linux actually atomicity of long?

No it doesn't. And even if it did you couldn't use long for this because
atomic_t also ensures the points operations complete are defined. You
might just about get away with volatile long * objects on x86 for simple
assignments but for anything else gcc can and will generate code to
update values whichever way it feels best - which includes turning

	long *x = a + b;

into

	*x = a;
	*x += b;

Alan