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Subject[004/145] [WATCHDOG] bfin: fix max timeout calculation
2.6.32-stable review patch.  If anyone has any objections, please let me know.

----------------
From: Mike Frysinger <vapier@gentoo.org>

commit 3dae93ec3ee1fceec69f40ef9b97892ce62ba7a5 upstream.

Relying on overflow/wrap around isn't exact because if you wrap far
enough, you get back to "valid" values.

Reported-by: Thorsten Pohlmann <pohlmann@tetronik.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/watchdog/bfin_wdt.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)

--- a/drivers/watchdog/bfin_wdt.c
+++ b/drivers/watchdog/bfin_wdt.c
@@ -1,9 +1,8 @@
/*
* Blackfin On-Chip Watchdog Driver
- * Supports BF53[123]/BF53[467]/BF54[2489]/BF561
*
* Originally based on softdog.c
- * Copyright 2006-2007 Analog Devices Inc.
+ * Copyright 2006-2010 Analog Devices Inc.
* Copyright 2006-2007 Michele d'Amico
* Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>
*
@@ -137,13 +136,15 @@ static int bfin_wdt_running(void)
*/
static int bfin_wdt_set_timeout(unsigned long t)
{
- u32 cnt;
+ u32 cnt, max_t, sclk;
unsigned long flags;

- stampit();
+ sclk = get_sclk();
+ max_t = -1 / sclk;
+ cnt = t * sclk;
+ stamp("maxtimeout=%us newtimeout=%lus (cnt=%#x)", max_t, t, cnt);

- cnt = t * get_sclk();
- if (cnt < get_sclk()) {
+ if (t > max_t) {
printk(KERN_WARNING PFX "timeout value is too large\n");
return -EINVAL;
}



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