From: Bart Van Assche <bart.vanassche@gmail.com>
Date: Tue, 21 May 2013 18:43:50 +0000 (+0200)
Subject: timer: Fix jiffies wrap behavior of round_jiffies_common()
X-Git-Tag: v3.9.11~12
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a3d56dfedb4ac5e8cdc6e6a0a54ed33ae2253c83;p=thirdparty%2Fkernel%2Fstable.git

timer: Fix jiffies wrap behavior of round_jiffies_common()

commit 9e04d3804d3ac97d8c03a41d78d0f0674b5d01e1 upstream.

Direct compare of jiffies related values does not work in the wrap
around case. Replace it with time_is_after_jiffies().

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Link: http://lkml.kernel.org/r/519BC066.5080600@acm.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/kernel/timer.c b/kernel/timer.c
index 1b399c89e3a05..3361cff2c83de 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -148,9 +148,11 @@ static unsigned long round_jiffies_common(unsigned long j, int cpu,
 	/* now that we have rounded, subtract the extra skew again */
 	j -= cpu * 3;
 
-	if (j <= jiffies) /* rounding ate our timeout entirely; */
-		return original;
-	return j;
+	/*
+	 * Make sure j is still in the future. Otherwise return the
+	 * unmodified value.
+	 */
+	return time_is_after_jiffies(j) ? j : original;
 }
 
 /**