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Revision 95ef1e52922cf75b1ea2eae54ef886f2cc47eecb authored by Avi Kivity on 15 November 2011, 12:59:07 UTC, committed by Avi Kivity on 20 November 2011, 08:53:48 UTC 
KVM guest: prevent tracing recursion with kvmclock
 
Prevent tracing of preempt_disable() in get_cpu_var() in
kvm_clock_read(). When CONFIG_DEBUG_PREEMPT is enabled,
preempt_disable/enable() are traced and this causes the function_graph
tracer to go into an infinite recursion. By open coding the
preempt_disable() around the get_cpu_var(), we can use the notrace
version which prevents preempt_disable/enable() from being traced and
prevents the recursion.

Based on a similar patch for Xen from Jeremy Fitzhardinge.

Tested-by: Gleb Natapov <gleb@redhat.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Avi Kivity <avi@redhat.com>
1 parent bb75c62
Raw File
dcbevent.h 
/*
 * Copyright (c) 2010, Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place - Suite 330, Boston, MA 02111-1307 USA.
 *
 * Author: John Fastabend <john.r.fastabend@intel.com>
 */

#ifndef _DCB_EVENT_H
#define _DCB_EVENT_H

enum dcbevent_notif_type {
	DCB_APP_EVENT = 1,
};

#ifdef CONFIG_DCB
extern int register_dcbevent_notifier(struct notifier_block *nb);
extern int unregister_dcbevent_notifier(struct notifier_block *nb);
extern int call_dcbevent_notifiers(unsigned long val, void *v);
#else
static inline int
register_dcbevent_notifier(struct notifier_block *nb)
{
	return 0;
}

static inline int unregister_dcbevent_notifier(struct notifier_block *nb)
{
	return 0;
}

static inline int call_dcbevent_notifiers(unsigned long val, void *v)
{
	return 0;
}
#endif /* CONFIG_DCB */

#endif
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