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Message-Id: <20100709225815.109358093@efficios.com>
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Date: Fri, 09 Jul 2010 18:57:29 -0400
From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Steven Rostedt <rostedt@goodmis.org>, LKML <linux-kernel@vger.kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@elte.hu>,
       Frederic Weisbecker <fweisbec@gmail.com>,
       Thomas Gleixner <tglx@linutronix.de>, Christoph Hellwig <hch@lst.de>,
       Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
       Li Zefan <lizf@cn.fujitsu.com>, Lai Jiangshan <laijs@cn.fujitsu.com>,
       Johannes Berg <johannes.berg@intel.com>,
       Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
       Arnaldo Carvalho de Melo <acme@infradead.org>,
       Tom Zanussi <tzanussi@gmail.com>,
       KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
       Andi Kleen <andi@firstfloor.org>,
       Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>,
       Jason Baron <jbaron@redhat.com>
Subject: [patch 02/20] notifier atomic call chain notrace
References: <20100709225727.312232266@efficios.com>
Content-Disposition: inline; filename=notifier-atomic-call-chain-notrace.patch
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Being able to use the atomic notifier from cpu idle entry to ensure the tracer
flush the last events in the current subbuffer requires the rcu read-side to be
marked "notrace".

Also apply to the the die notifier.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Masami Hiramatsu <mhiramat@redhat.com>
CC: Jason Baron <jbaron@redhat.com>
CC: mingo@elte.hu
---
 kernel/notifier.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Index: linux-2.6-lttng/kernel/notifier.c
===================================================================
--- linux-2.6-lttng.orig/kernel/notifier.c	2009-11-12 17:58:56.000000000 -0500
+++ linux-2.6-lttng/kernel/notifier.c	2009-11-12 18:03:28.000000000 -0500
@@ -148,7 +148,7 @@ int atomic_notifier_chain_unregister(str
 	spin_lock_irqsave(&nh->lock, flags);
 	ret = notifier_chain_unregister(&nh->head, n);
 	spin_unlock_irqrestore(&nh->lock, flags);
-	synchronize_rcu();
+	synchronize_sched();
 	return ret;
 }
 EXPORT_SYMBOL_GPL(atomic_notifier_chain_unregister);
@@ -178,9 +178,9 @@ int __kprobes __atomic_notifier_call_cha
 {
 	int ret;
 
-	rcu_read_lock();
+	rcu_read_lock_sched_notrace();
 	ret = notifier_call_chain(&nh->head, val, v, nr_to_call, nr_calls);
-	rcu_read_unlock();
+	rcu_read_unlock_sched_notrace();
 	return ret;
 }
 EXPORT_SYMBOL_GPL(__atomic_notifier_call_chain);