From 110e7c7e4f8a61a34e0ab88fc9bdf4d5c6d220b2 Mon Sep 17 00:00:00 2001
From: Joe Jin <joe.jin@oracle.com>
Date: Fri, 7 Jan 2011 14:50:12 +0800
Subject: [PATCH] xen/event: validate irq before get evtchn by irq

When retrieving the event channel number from irq, the irq
number may not be valid under some conditions.

So far that can be when we suspend/resume and irq ends with -1.
Validate and return sanitized irq and provide diagnostics information.

[v3: added unlikely on the WARN path]
[v2: reworded the commit message]
Signed-off-by: Joe Jin <joe.jin@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Tested-by: Gurudas Pai <gurudas.pai@oracle.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
 drivers/xen/events.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 4d4a23d..3df7e47 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -170,6 +170,9 @@ static struct irq_info *info_for_irq(unsigned irq)
 
 static unsigned int evtchn_from_irq(unsigned irq)
 {
+	if (unlikely(WARN(irq < 0 || irq >= nr_irqs, "Invalid irq %d!\n", irq)))
+		return 0;
+
 	return info_for_irq(irq)->evtchn;
 }
 
-- 
2.7.4