From: Guenter Roeck <linux@roeck-us.net>
To: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Cc: "linux-watchdog@vger.kernel.org" <linux-watchdog@vger.kernel.org>,
Wim Van Sebroeck <wim@linux-watchdog.org>,
Jonathan Corbet <corbet@lwn.net>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
Esben Haabendal <esben@haabendal.dk>,
Jerry Hoemann <jerry.hoemann@hpe.com>,
Rasmus Villemoes <Rasmus.Villemoes@prevas.se>
Subject: Re: [PATCH v10 3/3] watchdog: make the device time out at open_deadline when open_timeout is used
Date: Fri, 7 Jun 2019 11:38:27 -0700 [thread overview]
Message-ID: <20190607183827.GA32475@roeck-us.net> (raw)
In-Reply-To: <20190605140628.618-4-rasmus.villemoes@prevas.dk>
On Wed, Jun 05, 2019 at 02:06:44PM +0000, Rasmus Villemoes wrote:
> When the watchdog device is not open by userspace, the kernel takes
> care of pinging it. When the open_timeout feature is in use, we should
> ensure that the hardware fires close to open_timeout seconds after the
> kernel has assumed responsibility for the device.
>
> To do this, simply reuse the logic that is already in place for
> ensuring the same thing when userspace is responsible for regularly
> pinging the device:
>
> - When watchdog_active(wdd), this patch doesn't change anything.
>
> - When !watchdoc_active(wdd), the "virtual timeout" should be taken to
s/watchdoc_active/watchdog_active/
otherwise
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
> be ->open_deadline". When the open_timeout feature is not used or the
> device has been opened at least once, ->open_deadline is KTIME_MAX,
> and the arithmetic ends up returning keepalive_interval as we used to.
>
> This has been tested on a Wandboard with various combinations of
> open_timeout and timeout-sec properties for the on-board watchdog by
> booting with 'init=/bin/sh', timestamping the lines on the serial
> console, and comparing the timestamp of the 'imx2-wdt 20bc000.wdog:
> timeout nnn sec' line with the timestamp of the 'U-Boot SPL ...'
> line (which appears just after reset).
>
> Suggested-by: Guenter Roeck <linux@roeck-us.net>
> Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
> ---
> drivers/watchdog/watchdog_dev.c | 11 ++++++-----
> 1 file changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
> index 334b810db2cf..edfb884044e0 100644
> --- a/drivers/watchdog/watchdog_dev.c
> +++ b/drivers/watchdog/watchdog_dev.c
> @@ -133,14 +133,15 @@ static ktime_t watchdog_next_keepalive(struct watchdog_device *wdd)
> ktime_t virt_timeout;
> unsigned int hw_heartbeat_ms;
>
> - virt_timeout = ktime_add(wd_data->last_keepalive,
> - ms_to_ktime(timeout_ms));
> + if (watchdog_active(wdd))
> + virt_timeout = ktime_add(wd_data->last_keepalive,
> + ms_to_ktime(timeout_ms));
> + else
> + virt_timeout = wd_data->open_deadline;
> +
> hw_heartbeat_ms = min_not_zero(timeout_ms, wdd->max_hw_heartbeat_ms);
> keepalive_interval = ms_to_ktime(hw_heartbeat_ms / 2);
>
> - if (!watchdog_active(wdd))
> - return keepalive_interval;
> -
> /*
> * To ensure that the watchdog times out wdd->timeout seconds
> * after the most recent ping from userspace, the last
next prev parent reply other threads:[~2019-06-07 18:38 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-05 14:06 [PATCH v10 0/3] watchdog: allow setting deadline for opening /dev/watchdogN Rasmus Villemoes
2019-06-05 14:06 ` [PATCH v10 1/3] watchdog: introduce watchdog.open_timeout commandline parameter Rasmus Villemoes
2019-06-07 18:38 ` Guenter Roeck
2019-06-05 14:06 ` [PATCH v10 2/3] watchdog: introduce CONFIG_WATCHDOG_OPEN_TIMEOUT Rasmus Villemoes
2019-06-07 18:39 ` Guenter Roeck
2019-06-05 14:06 ` [PATCH v10 3/3] watchdog: make the device time out at open_deadline when open_timeout is used Rasmus Villemoes
2019-06-07 18:38 ` Guenter Roeck [this message]
2019-06-14 8:41 ` Rasmus Villemoes
2019-06-14 12:37 ` Guenter Roeck
2019-06-15 10:02 ` Wim Van Sebroeck
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