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From: Ingo Molnar <mingo@kernel.org>
To: jbaron@akamai.com
Cc: rostedt@goodmis.org, andi@firstfloor.org,
	linux-kernel@vger.kernel.org, peterz@infradead.org
Subject: Re: [PATCH 0/3] static keys: fix test/set races
Date: Sat, 29 Jun 2013 09:20:16 +0200	[thread overview]
Message-ID: <20130629072016.GA14746@gmail.com> (raw)
In-Reply-To: <cover.1372457176.git.jbaron@akamai.com>


* jbaron@akamai.com <jbaron@akamai.com> wrote:

> Hi,
> 
> As pointed out by Andi Kleen, some static key users can be racy because they
> check the value of the key->enabled, and then subsequently update the branch
> direction. A number of call sites have 'higher' level locking that avoids this
> race, but the usage in the scheduler features does not. See:
> http://lkml.indiana.edu/hypermail/linux/kernel/1304.2/01655.html

But that's not an issue at all - switching the scheduler features is for 
development and debugging only, and in some cases higher level locking 
would be needed to solve it 'properly', beyond what the keys API could 
give ...

So this is pretty pointless, sorry, please don't complicate this facility.

Thanks,

	Ingo

  parent reply	other threads:[~2013-06-29  7:20 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-06-28 22:30 [PATCH 0/3] static keys: fix test/set races jbaron
2013-06-28 22:30 ` [PATCH 1/3] static_keys: Add a static_key_slow_set_true()/false() interface jbaron
2013-06-29  3:00   ` Steven Rostedt
2013-06-28 22:30 ` [PATCH 2/3] sched: fix static keys race in sched_feat jbaron
2013-06-29  3:03   ` Steven Rostedt
2013-06-28 22:30 ` [PATCH 3/3] udp: make use of static_key_slow_set_true() interface jbaron
2013-06-29  3:13   ` Steven Rostedt
2013-07-01  4:20     ` Jason Baron
2013-07-01 14:28       ` Steven Rostedt
2013-06-29  7:20 ` Ingo Molnar [this message]
2013-07-01  4:12   ` [PATCH 0/3] static keys: fix test/set races Jason Baron
2013-07-02  8:03     ` Peter Zijlstra
2013-07-02  9:38       ` Ingo Molnar
2014-06-24  2:28 ` Steven Rostedt
2014-06-24  2:41   ` Jason Baron
2014-06-30 21:43   ` Jason Baron
2014-06-30 22:36     ` Steven Rostedt

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