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From: Peter Zijlstra <peterz@infradead.org>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org, mingo@kernel.org,
	laijs@cn.fujitsu.com, dipankar@in.ibm.com,
	akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
	josh@joshtriplett.org, tglx@linutronix.de, rostedt@goodmis.org,
	dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com,
	fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com,
	<""@rjwysocki.net>,
	tianyu.lan@intel.com
Subject: Re: [PATCH RFC tip/core/rcu] Eliminate deadlock between CPU hotplug and expedited grace periods
Date: Mon, 1 Sep 2014 18:17:35 +0200	[thread overview]
Message-ID: <20140901161735.GA5806@worktop.ger.corp.intel.com> (raw)
In-Reply-To: <20140901160550.GL5001@linux.vnet.ibm.com>

On Mon, Sep 01, 2014 at 09:05:50AM -0700, Paul E. McKenney wrote:
> > URGH.. I really hate that. The hotplug interface is already too
> > horrible, we should not add such hacks to it.
> 
> We do have try_ interfaces to a number of other subsystems, so I don't
> believe that it qualifies as such a hack.

We do indeed, but I'm not sure about adding this to the hotplug stuff.

Also; not really understanding the problem doesn't help. 

> > How about ripping that rcu_expedited stuff out instead? That's all
> > conditional anyhow, so might as well not do it.
> 
> In what way is the expedited stuff conditional?

synchronize_sched() conditionally calls synchronize_sched_expedited()
and its condition: rcu_expedited, gets set/cleared on pm notifiers and
nr_cpu_ids.



  reply	other threads:[~2014-09-01 16:17 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-08-28 19:47 Paul E. McKenney
2014-08-29  6:54 ` Lan Tianyu
2014-08-29 13:11   ` Paul E. McKenney
2014-09-01 11:20 ` Peter Zijlstra
2014-09-01 16:05   ` Paul E. McKenney
2014-09-01 16:17     ` Peter Zijlstra [this message]
2014-09-02 16:36       ` Paul E. McKenney
2014-09-03 11:31         ` Peter Zijlstra
2014-09-03 15:03           ` Paul E. McKenney
2014-09-03 15:28             ` Peter Zijlstra
2014-09-03 16:38               ` Paul E. McKenney
2014-09-17  7:11 ` Lan Tianyu
2014-09-17 13:10   ` Paul E. McKenney
2014-09-18  7:15     ` Lan Tianyu
2014-09-18 12:38       ` Paul E. McKenney
2014-09-18 22:55         ` Rafael J. Wysocki
2014-09-18 22:57           ` Paul E. McKenney

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