From: Guenter Roeck <linux@roeck-us.net>
To: Jan Kiszka <jan.kiszka@siemens.com>,
Wim Van Sebroeck <wim@linux-watchdog.org>,
linux-watchdog@vger.kernel.org
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Tero Kristo <t-kristo@ti.com>
Subject: Re: [PATCH] watchdog: Respect handle_boot_enabled when setting last last_hw_keepalive
Date: Fri, 30 Jul 2021 13:49:52 -0700 [thread overview]
Message-ID: <211cd54b-29b4-e58a-341b-beffc05cfe85@roeck-us.net> (raw)
In-Reply-To: <fe8cf65f-f949-9326-8f32-fda7134c8da6@siemens.com>
On 7/30/21 12:39 PM, Jan Kiszka wrote:
> From: Jan Kiszka <jan.kiszka@siemens.com>
>
> We must not pet a running watchdog when handle_boot_enabled is off
> because this requests to only start doing that via userspace, not during
> probing.
>
The scope of the changed function is quite limited. See the
definition of watchdog_set_last_hw_keepalive(). On top of that,
__watchdog_ping() does a bit more than just ping the watchdog,
and it only pings the watchdog in limited circumstances. On top of that,
the scope of handle_boot_enabled is different: If enabled, it tells
the watchdog core to keep pinging a watchdog until userspace opens
the device. This is about continuous pings, not about an initial one.
Given that, I'd rather have the watchdog subsystem issue an additional
ping than risking a regression.
The only driver calling watchdog_set_last_hw_keepalive() is rti_wdt.c.
Does this patch solve a specific problem observed with that watchdog ?
Guenter
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
> drivers/watchdog/watchdog_dev.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
> index 3bab32485273..3c93d00bb284 100644
> --- a/drivers/watchdog/watchdog_dev.c
> +++ b/drivers/watchdog/watchdog_dev.c
> @@ -1172,7 +1172,10 @@ int watchdog_set_last_hw_keepalive(struct watchdog_device *wdd,
>
> wd_data->last_hw_keepalive = ktime_sub(now, ms_to_ktime(last_ping_ms));
>
> - return __watchdog_ping(wdd);
> + if (handle_boot_enabled)
> + return __watchdog_ping(wdd);
> +
> + return 0;
> }
> EXPORT_SYMBOL_GPL(watchdog_set_last_hw_keepalive);
>
>
next prev parent reply other threads:[~2021-07-30 20:49 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-30 19:39 [PATCH] watchdog: Respect handle_boot_enabled when setting last last_hw_keepalive Jan Kiszka
2021-07-30 20:49 ` Guenter Roeck [this message]
2021-07-30 21:37 ` Jan Kiszka
2021-07-30 22:39 ` Guenter Roeck
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=211cd54b-29b4-e58a-341b-beffc05cfe85@roeck-us.net \
--to=linux@roeck-us.net \
--cc=jan.kiszka@siemens.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-watchdog@vger.kernel.org \
--cc=t-kristo@ti.com \
--cc=wim@linux-watchdog.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).