From: "chenzhen (R)" <chenzhen105@huawei.com>
To: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: <gregkh@linuxfoundation.org>, <jirislaby@kernel.org>,
<andriy.shevchenko@linux.intel.com>, <lukas@wunner.de>,
<Sergey.Semin@baikalelectronics.ru>, <vigneshr@ti.com>,
<rose.chen@huawei.com>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] tty/serial/8250: make touch watchdog settable
Date: Wed, 6 Jan 2021 17:28:57 +0800 [thread overview]
Message-ID: <db5f51df-3a3e-41a6-00e3-234575c07ec6@huawei.com> (raw)
In-Reply-To: <X/VnrvmN4k8UrXad@jagdpanzerIV.localdomain>
On 21/1/6 15:33, Sergey Senozhatsky wrote:
> On (21/01/06 14:46), chenzhen wrote:
>> Since 54f19b4a6(tty/serial/8250: Touch NMI watchdog in wait_for_xmitr), serial8250
>> will always touch watchdog in write and wait_for_xmitr. However, serial8250 may
>> become low speed thus take a long time to print. In this process, nmi and soft
>> watchdog on current CPU will be invalid.
>>
>> To resolve this problem, add a cmdline option "tty_watchdog_enable" to control
>> the touchdog in serial8250.
> Sorry, I don't understand - what does this fix?
>
> -ss
> .
It fixes that if serial8250 is low speed on some machine, when it writes for a long time, NMI/softlockup watchdog will never bark and potential rlock will not be detected. So an option to control the touchdog in serial8250 may help.
Thanks for your reply!
-Zhen Chen
next parent reply other threads:[~2021-01-06 9:29 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20210106064641.2621838-1-chenzhen105@huawei.com>
[not found] ` <X/VnrvmN4k8UrXad@jagdpanzerIV.localdomain>
2021-01-06 9:28 ` chenzhen (R) [this message]
2021-01-06 10:14 ` Sergey Senozhatsky
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