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From: Steven Rostedt <rostedt@goodmis.org>
To: Jason Baron <jbaron@redhat.com>
Cc: Glauber Costa <glommer@parallels.com>,
	cgroups@vger.kernel.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, Li Zefan <lizefan@huawei.com>,
	Tejun Heo <tj@kernel.org>,
	kamezawa.hiroyu@jp.fujitsu.com, linux-mm@kvack.org,
	devel@openvz.org, Johannes Weiner <hannes@cmpxchg.org>,
	Michal Hocko <mhocko@suse.cz>, Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH v4 1/3] make jump_labels wait while updates are in place
Date: Fri, 27 Apr 2012 10:07:10 -0400	[thread overview]
Message-ID: <1335535630.28106.209.camel@gandalf.stny.rr.com> (raw)
In-Reply-To: <20120427135320.GA13762@redhat.com>

On Fri, 2012-04-27 at 09:53 -0400, Jason Baron wrote:

> Right, for x86 which uses stop_machine currently, we guarantee that all
> cpus are going to see the updated code, before the inc of key->enabled.
> However, other arches (sparc, mips, powerpc, for example), seem to be
> using much lighter weight updates, which I hope are ok :)

And x86 will soon be removing stop_machine() from its path too. But all
archs should perform some kind of memory sync after patching code. Thus
the update should be treated as if a memory barrier was added after it,
and before the inc.

-- Steve


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  reply	other threads:[~2012-04-27 14:07 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-04-26 22:51 [PATCH v4 0/3] fix problem with static_branch() for sock memcg Glauber Costa
2012-04-26 22:51 ` [PATCH v4 1/3] make jump_labels wait while updates are in place Glauber Costa
2012-04-27  0:43   ` Steven Rostedt
2012-04-27  1:05     ` KAMEZAWA Hiroyuki
2012-04-27 13:53     ` Jason Baron
2012-04-27 14:07       ` Steven Rostedt [this message]
2012-04-27 14:59       ` Glauber Costa
2012-04-26 22:51 ` [PATCH v4 2/3] Always free struct memcg through schedule_work() Glauber Costa
2012-04-26 22:51 ` [PATCH v4 3/3] decrement static keys on real destroy time Glauber Costa

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