linux-kernel - Re: POC: Alternative solution: Re: [PATCH 0/4] printk: reimplement LOG

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Message-ID: <87k0y1k5gc.fsf@jogness.linutronix.de>
Date:   Fri, 14 Aug 2020 10:22:35 +0206
From:   John Ogness <john.ogness@...utronix.de>
To:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Cc:     Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        kexec@...ts.infradead.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: POC: Alternative solution: Re: [PATCH 0/4] printk: reimplement LOG_CONT handling

On 2020-08-14, Sergey Senozhatsky <sergey.senozhatsky@...il.com> wrote:
> One thing that we need to handle here, I believe, is that the context
> which crashes the kernel should flush its cont buffer, because the
> information there is relevant to the crash:
>
> 	pr_cont_alloc_info(&c);
> 	pr_cont(&c, "1");
> 	pr_cont(&c, "2");
> 	>>
> 	   oops
> 	      panic()
> 	<<
> 	pr_cont_flush(&c);
>
> We better flush that context's pr_cont buffer during panic().

I am not convinced of the general usefulness of partial messages, but as
long as we have an API that includes registration, usage, and
deregistration of some sort of handle, then we leave the window open for
such implementations.

John Ogness