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From: Andi Kleen <andi@firstfloor.org>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	mingo@elte.hu, tglx@linutronix.de, marcin.slusarz@gmail.com,
	linux-kernel@vger.kernel.org, David Miller <davem@davemloft.net>,
	Steven Rostedt <rostedt@goodmis.org>,
	Paul E McKenney <paulmck@linux.vnet.ibm.com>
Subject: Re: [PATCH] printk: robustify printk
Date: Fri, 08 Aug 2008 23:35:20 +0200	[thread overview]
Message-ID: <8763qb42cn.fsf@basil.nowhere.org> (raw)
In-Reply-To: <1218219269.29098.5.camel@lappy.programming.kicks-ass.net> (Peter Zijlstra's message of "Fri, 08 Aug 2008 20:14:28 +0200")

Peter Zijlstra <a.p.zijlstra@chello.nl> writes:

Hopefully nobody puts a printk into call_rcu now...
Also I'm not sure if there wouldn't be livelocks if someone puts
printk into some other parts of RCU (e.g. each RCU adding more
RCU events -- haven't checked that in detail so I might be wrong)

So you just trade one "hands off" part to another.


> +	kws = &__get_cpu_var(kws);
> +	if (!kws->pending) {
> +		kws->pending = 1;
> +		call_rcu(&kws->head, __wake_up_klogd);


How about a big comment describing why you do this?
And you should add comments to all the new hands-off parts
where printk is not allowed now.

-Andi

  parent reply	other threads:[~2008-08-08 21:35 UTC|newest]

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-03-24 12:24 [PATCH 0/2] printk vs rq->lock and xtime lock Peter Zijlstra
2008-03-24 12:24 ` [PATCH 1/2] printk_nowakeup() Peter Zijlstra
2008-03-24 12:24 ` [PATCH 2/2] time: xtime lock vs printk Peter Zijlstra
2008-03-24 14:21   ` Daniel Walker
2008-03-24 14:31 ` [PATCH 0/2] printk vs rq->lock and xtime lock Marcin Slusarz
2008-03-24 17:58 ` Linus Torvalds
2008-03-24 18:15   ` Peter Zijlstra
2008-03-24 18:57     ` Andrew Morton
2008-08-08 13:30       ` Peter Zijlstra
2008-08-08 13:46         ` Peter Zijlstra
2008-08-08 16:41         ` Linus Torvalds
2008-08-08 17:10           ` Peter Zijlstra
2008-08-08 17:25             ` Linus Torvalds
2008-08-08 17:40               ` Peter Zijlstra
2008-08-08 17:48                 ` Linus Torvalds
2008-08-08 18:14                   ` [PATCH] printk: robustify printk Peter Zijlstra
2008-08-08 18:30                     ` Linus Torvalds
2008-08-08 18:33                       ` Peter Zijlstra
2008-08-08 19:14                     ` Andrew Morton
2008-08-08 19:21                       ` Peter Zijlstra
2008-08-08 19:37                         ` Andrew Morton
2008-08-08 19:49                           ` Peter Zijlstra
2008-08-08 20:32                           ` Paul E. McKenney
2008-08-08 20:37                             ` Peter Zijlstra
2008-08-08 20:46                               ` Andrew Morton
2008-08-08 20:57                                 ` Linus Torvalds
2008-08-08 21:13                                   ` Andrew Morton
2008-08-08 20:50                               ` Steven Rostedt
2008-08-08 19:47                         ` Peter Zijlstra
2008-08-11 10:45                           ` Ingo Molnar
2008-08-11 11:03                             ` Andi Kleen
2008-08-11 11:22                               ` Peter Zijlstra
2008-08-11 11:42                                 ` Andi Kleen
2008-08-11 14:15                                   ` Valdis.Kletnieks
2008-08-11 14:29                                     ` Andi Kleen
2008-08-11 14:55                                       ` Steven Rostedt
2008-08-11 12:02                                 ` Ingo Molnar
2008-08-11 12:14                                   ` Andi Kleen
2008-08-11 11:04                             ` Peter Zijlstra
2008-08-11 11:51                               ` Ingo Molnar
2008-08-11 12:36                                 ` Ingo Molnar
2008-08-20 12:40                                 ` Jiri Kosina
2008-08-20 12:43                                   ` Peter Zijlstra
2008-08-20 13:40                                     ` Ingo Molnar
2008-08-11 16:09                               ` Paul E. McKenney
2008-08-11 13:22                             ` Paul E. McKenney
2008-08-08 20:30                       ` Paul E. McKenney
2008-08-08 20:20                     ` Paul E. McKenney
2008-08-08 21:35                     ` Andi Kleen [this message]
2008-08-08 23:02                     ` David Miller
2008-08-09  0:18                       ` Paul E. McKenney
2008-08-08 17:52                 ` [PATCH 0/2] printk vs rq->lock and xtime lock Steven Rostedt
2008-03-24 18:16   ` Linus Torvalds

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