[PATCH v2 2/2] watchdog: dw_wdt: keepalive the watchdog at write time

From: Doug Anderson
Date: Fri May 08 2015 - 00:28:19 EST

If you've got code that does this in a tight loop
1. Open watchdog
2. Send 'expect close'
3. Close watchdog
...you'll eventually trigger a watchdog reset. You can reproduce this
by using daisydog (1) and running:
while true; do daisydog -c > /dev/null; done

The problem is that each time you write to the watchdog for 'expect
close' it moves the timer .5 seconds out. The timer thus never fires
and never pats the watchdog for you.

1: http://git.chromium.org/gitweb/?p=chromiumos/third_party/daisydog.git

Signed-off-by: Doug Anderson <dianders@xxxxxxxxxxxx>
Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Tested-by: Jisheng Zhang <jszhang@xxxxxxxxxxx>
Changes in v2: None

drivers/watchdog/dw_wdt.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/watchdog/dw_wdt.c b/drivers/watchdog/dw_wdt.c
index a284abd..6ea0634 100644
--- a/drivers/watchdog/dw_wdt.c
+++ b/drivers/watchdog/dw_wdt.c
@@ -215,6 +215,7 @@ static ssize_t dw_wdt_write(struct file *filp, const char __user *buf,

+ dw_wdt_keepalive();
mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);

return len;

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