From 3d034aecd8b70d34388a4e40ca50af0d014223e1 Mon Sep 17 00:00:00 2001
From: "Denis V. Lunev" <den@openvz.org>
Date: Tue, 7 Aug 2007 13:13:18 +0400
Subject: PCI: pci_get_device call from interrupt in reboot fixups

The following calltrace is possible now:
 handle_sysrq
   machine_emergency_restart
     mach_reboot_fixups
       pci_get_device
         pci_get_subsys
	   down_read
The patch skips reboot fixup if called from sysrq-B code.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
 arch/x86/kernel/reboot_fixups_32.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/kernel/reboot_fixups_32.c b/arch/x86/kernel/reboot_fixups_32.c
index 03e1cce58f49..139eb03490f5 100644
--- a/arch/x86/kernel/reboot_fixups_32.c
+++ b/arch/x86/kernel/reboot_fixups_32.c
@@ -11,6 +11,7 @@
 
 #include <asm/delay.h>
 #include <linux/pci.h>
+#include <linux/interrupt.h>
 #include <asm/reboot_fixups.h>
 #include <asm/msr.h>
 
@@ -56,6 +57,11 @@ void mach_reboot_fixups(void)
 	struct pci_dev *dev;
 	int i;
 
+	/* we can be called from sysrq-B code. In such a case it is
+	 * prohibited to dig PCI */
+	if (in_interrupt())
+		return;
+
 	for (i=0; i < ARRAY_SIZE(fixups_table); i++) {
 		cur = &(fixups_table[i]);
 		dev = pci_get_device(cur->vendor, cur->device, NULL);
-- 
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