From: Tim Deegan <Tim.Deegan@citrix.com>
Date: Thu, 10 Feb 2011 08:50:41 +0000 (+0000)
Subject: fix jiffy calculations in calibrate_delay_direct to handle overflow
X-Git-Tag: v2.6.33.8~184
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=66622d09ac2597d858ecbcf1a22c03f8a069638a;p=karo-tx-linux.git

fix jiffy calculations in calibrate_delay_direct to handle overflow

commit 70a062286b9dfcbd24d2e11601aecfead5cf709a upstream.

Fixes a hang when booting as dom0 under Xen, when jiffies can be
quite large by the time the kernel init gets this far.

Signed-off-by: Tim Deegan <Tim.Deegan@citrix.com>
[jbeulich@novell.com: !time_after() -> time_before_eq() as suggested by Jiri Slaby]
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/init/calibrate.c b/init/calibrate.c
index 6eb48e53d61c..24fe022c55f9 100644
--- a/init/calibrate.c
+++ b/init/calibrate.c
@@ -66,7 +66,7 @@ static unsigned long __cpuinit calibrate_delay_direct(void)
 		pre_start = 0;
 		read_current_timer(&start);
 		start_jiffies = jiffies;
-		while (jiffies <= (start_jiffies + 1)) {
+		while (time_before_eq(jiffies, start_jiffies + 1)) {
 			pre_start = start;
 			read_current_timer(&start);
 		}
@@ -74,8 +74,8 @@ static unsigned long __cpuinit calibrate_delay_direct(void)
 
 		pre_end = 0;
 		end = post_start;
-		while (jiffies <=
-		       (start_jiffies + 1 + DELAY_CALIBRATION_TICKS)) {
+		while (time_before_eq(jiffies, start_jiffies + 1 +
+					       DELAY_CALIBRATION_TICKS)) {
 			pre_end = end;
 			read_current_timer(&end);
 		}