From: Greg KH <greg@kroah.com>
To: Jean Delvare <jdelvare@suse.de>
Cc: linux-watchdog@vger.kernel.org,
LKML <linux-kernel@vger.kernel.org>,
stable@vger.kernel.org, Jan Kiszka <jan.kiszka@siemens.com>,
Guenter Roeck <linux@roeck-us.net>,
Wim Van Sebroeck <wim@linux-watchdog.org>,
Michael Marley <michael@michaelmarley.com>
Subject: Re: Faulty commit "watchdog: iTCO_wdt: Account for rebooting on second timeout"
Date: Fri, 6 Aug 2021 08:28:39 +0200 [thread overview]
Message-ID: <YQzWl9GeD6OgxzWA@kroah.com> (raw)
In-Reply-To: <20210803165108.4154cd52@endymion>
On Tue, Aug 03, 2021 at 04:51:08PM +0200, Jean Delvare wrote:
> Hi all,
>
> Commit cb011044e34c ("watchdog: iTCO_wdt: Account for rebooting on
> second timeout") causes a regression on several systems. Symptoms are:
> system reboots automatically after a short period of time if watchdog
> is enabled (by systemd for example). This has been reported in bugzilla:
>
> https://bugzilla.kernel.org/show_bug.cgi?id=213809
>
> Unfortunately this commit was backported to all stable kernel branches
> (4.14, 4.19, 5.4, 5.10, 5.12 and 5.13). I'm not sure why that is the
> case, BTW, as there is no Fixes tag and no Cc to stable@vger either.
> And the fix is not trivial, has apparently not seen enough testing,
> and addresses a problem that has a known and simple workaround. IMHO it
> should never have been accepted as a stable patch in the first place.
> Especially when the previous attempt to fix this issue already ended
> with a regression and a revert.
>
> Anyway... After a glance at the patch, I see what looks like a nice
> thinko:
>
> + if (p->smi_res &&
> + (SMI_EN(p) & (TCO_EN | GBL_SMI_EN)) != (TCO_EN | GBL_SMI_EN))
>
> The author most certainly meant inl(SMI_EN(p)) (the register's value)
> and not SMI_EN(p) (the register's address).
Let me go revert this from the stable trees now, thanks for the report.
greg k-h
prev parent reply other threads:[~2021-08-06 6:28 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-03 14:51 Faulty commit "watchdog: iTCO_wdt: Account for rebooting on second timeout" Jean Delvare
2021-08-03 14:59 ` Jan Kiszka
2021-08-03 15:01 ` Jan Kiszka
2021-08-03 15:27 ` Guenter Roeck
2021-08-03 15:32 ` Jean Delvare
2021-08-04 0:04 ` Michael Marley
2021-08-04 6:58 ` Jan Kiszka
2021-08-06 6:28 ` Greg KH [this message]
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