linux-kernel - [PATCH 1/4] watchdog: fix rounding issues in get_sample

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Message-Id: <1306127423-3347-1-git-send-email-msb@chromium.org>
Date:	Sun, 22 May 2011 22:10:20 -0700
From:	Mandeep Singh Baines <msb@...omium.org>
To:	linux-kernel@...r.kernel.org
Cc:	Mandeep Singh Baines <msb@...omium.org>,
	Marcin Slusarz <marcin.slusarz@...il.com>,
	Don Zickus <dzickus@...hat.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH 1/4] watchdog: fix rounding issues in get_sample_period()

In get_sample_period(), softlockup_thresh is integer divided by 5 before
the multiplication by NSEC_PER_SEC. This results in softlockup_thresh
being rounded down to the nearest integer multiple of 5.

For example, a softlockup_thresh of 4 rounds down to 0.

Signed-off-by: Mandeep Singh Baines <msb@...omium.org>
Cc: Marcin Slusarz <marcin.slusarz@...il.com>
Cc: Don Zickus <dzickus@...hat.com>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Andrew Morton <akpm@...ux-foundation.org>
---
 kernel/watchdog.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 14733d4..a06972d 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -110,7 +110,7 @@ static unsigned long get_sample_period(void)
 	 * increment before the hardlockup detector generates
 	 * a warning
 	 */
-	return softlockup_thresh / 5 * NSEC_PER_SEC;
+	return softlockup_thresh * (NSEC_PER_SEC / 5);
 }
 
 /* Commands for resetting the watchdog */
-- 
1.7.3.1

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