Re: [PATCH] tty/serial/8250: make touch watchdog settable

[chenzhen (R)]

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