linux-kernel - Re: Difference between atomic operations and memory barriers

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Message-ID: <4AE5F9B9.2010707@s5r6.in-berlin.de>
Date:	Mon, 26 Oct 2009 20:34:17 +0100
From:	Stefan Richter <stefanr@...6.in-berlin.de>
To:	Noah Watkins <noah@...hdesu.com>
CC:	"Leonidas ." <leonidas137@...il.com>,
	Chris Friesen <cfriesen@...tel.com>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: Difference between atomic operations and memory barriers

Noah Watkins wrote:
>> So we can safely assume that pointer assignment will be done in an
>> atomic manner?
> 
> See the the comment above rcu_assign_pointer in
> include/linux/rcupdate.h

This comment only talks about ordering, not about atomicity.

Again, AFAIR the ISO C spec should explain what is going to be
guaranteed atomic and what might not be atomic.

rcu_assign_pointer() itself does rely on atomicity of pointer
assignments though, like lots of code elsewhere in the kernel.
-- 
Stefan Richter
-=====-==--= =-=- ==-=-
http://arcgraph.de/sr/
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