linux-kernel - Re: [PATCH -next] panic: complete the flush of the hard deadlock log messages to the serial port

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Message-ID: <080e8065-c696-eeec-3390-13b4458f67b6@huawei.com>
Date:   Tue, 24 Nov 2020 11:22:11 +0800
From:   "xuqiang (M)" <xuqiang36@...wei.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
CC:     <keescook@...omium.org>, <mingo@...nel.org>,
        <peterz@...radead.org>, <mcgrof@...nel.org>, <huyue2@...ong.com>,
        <yangtiezhu@...ngson.cn>, <will@...nel.org>, <aquini@...hat.com>,
        <gpiccoli@...onical.com>, <aik@...abs.ru>,
        <linux-kernel@...r.kernel.org>, <rui.xiang@...wei.com>
Subject: Re: [PATCH -next] panic: complete the flush of the hard deadlock log
 messages to the serial port


在 2020/11/24 3:52, Andrew Morton 写道:
> On Mon, 23 Nov 2020 13:13:59 +0000 Xu Qiang <xuqiang36@...wei.com> wrote:
>
>> when hardlockup_all_cpu_backtrace is on, and there are
>> a large number of cores in the system, it takes
>> a long time to output the hard deadlock logs of all cores
>> to the serial port. When the console_flush_on_panic function
>> in panic is executed, console_locked is still held.
>> As a result, garbled characters are displayed in the serial port log.
>>
>> To solve this problem, wait for a maximum of 10s for the serial port
>> to be released before console_flush_on_panic.
> Wouldn't it be better to wait until all the printing of all those
> backtraces has completed?
>
>
> .

The fear that there may be some unexpected abnormal situation,

resulting in the serial port has been occupied without release.


Thanks

         Xu.