linux-kernel - Re: [PATCH 5.10-rt] printk: fix suppressed message print when reboot/panic

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Message-ID: <CAMA88TpV6p4wRhx1dpRf7V2Oc27FzV_HR7mb70oGn83RGnfF-w@mail.gmail.com>
Date:   Mon, 21 Mar 2022 19:57:19 +0800
From:   Shi Schspa <schspa@...il.com>
To:     John Ogness <john.ogness@...utronix.de>
Cc:     pmladek@...e.com, sergey.senozhatsky@...il.com,
        rostedt@...dmis.org, linux-rt-users@...r.kernel.org,
        linux-kernel@...r.kernel.org, bigeasy@...utronix.de,
        tglx@...utronix.de
Subject: Re: [PATCH 5.10-rt] printk: fix suppressed message print when reboot/panic

John Ogness <john.ogness@...utronix.de> writes:

> On 2022-03-21, Schspa Shi <schspa@...il.com> wrote:
>> Update printk_seq for suppressed message.
>>
>> Affects 5.9-rt and 5.10-rt
>>
>> When message is suppressed, printk_seq should be updated, otherwise
>> this message will be printed when reboot. This problem was introduced
>> in commit 3edc0c85d154 ("printk: Rebase on top of new ring buffer").
>>
>> Signed-off-by: Schspa Shi <schspa@...il.com>
>
> Reviewed-by: John Ogness <john.ogness@...utronix.de>
>
> Nice catch. Thanks.
>
> 5.15-rt also has this issue, although the fix is slightly different. For
> 5.15-rt, writing to con->printk_seq (via latched_seq_write()) requires
> the console locked. Would you like to post a patch for 5.15-rt as well,
> or would you like me to do it?
>

I have upload a new patch for 5.15-rt, please review it too.
Message-Id: <20220321111501.68241-1-schspa@...il.com>

> 5.16 and beyond does not have this issue.
>
> John Ogness

BRs

Schspa Shi