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SubjectRe: [PATCH 2/2] watchdog: dw_wdt: keepalive the watchdog at write time
On Thu, 7 May 2015 15:09:24 -0700
Doug Anderson <dianders@chromium.org> wrote:

> 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@chromium.org>
> ---
> 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 3fa2f19..ff5d734 100644
> --- a/drivers/watchdog/dw_wdt.c
> +++ b/drivers/watchdog/dw_wdt.c
> @@ -220,6 +220,7 @@ static ssize_t dw_wdt_write(struct file *filp, const char __user *buf,
> }
>
> dw_wdt_set_next_heartbeat();
> + dw_wdt_keepalive();
> mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
>
> return len;

Tested-by: Jisheng Zhang <jszhang@marvell.com>


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