linux-kernel - [PATCH] watchdog: davinci: Use div64_ul instead of do

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Message-Id: <20211125014924.46297-1-deng.changcheng@zte.com.cn>
Date:   Thu, 25 Nov 2021 01:49:24 +0000
From:   cgel.zte@...il.com
To:     wim@...ux-watchdog.org
Cc:     linux@...ck-us.net, linux-watchdog@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Changcheng Deng <deng.changcheng@....com.cn>,
        Zeal Robot <zealci@....com.cn>
Subject: [PATCH] watchdog: davinci: Use div64_ul instead of do_div

From: Changcheng Deng <deng.changcheng@....com.cn>

do_div() does a 64-by-32 division. Here the divisor is an unsigned long
which on some platforms is 64 bit wide. So use div64_ul instead of do_div
to avoid a possible truncation.

Reported-by: Zeal Robot <zealci@....com.cn>
Signed-off-by: Changcheng Deng <deng.changcheng@....com.cn>
---
 drivers/watchdog/davinci_wdt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/watchdog/davinci_wdt.c b/drivers/watchdog/davinci_wdt.c
index e6eaba6bae5b..584a56893b81 100644
--- a/drivers/watchdog/davinci_wdt.c
+++ b/drivers/watchdog/davinci_wdt.c
@@ -134,7 +134,7 @@ static unsigned int davinci_wdt_get_timeleft(struct watchdog_device *wdd)
 	timer_counter = ioread32(davinci_wdt->base + TIM12);
 	timer_counter |= ((u64)ioread32(davinci_wdt->base + TIM34) << 32);
 
-	do_div(timer_counter, freq);
+	timer_counter = div64_ul(timer_counter, freq);
 
 	return wdd->timeout - timer_counter;
 }
-- 
2.25.1