Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Message-ID: <b44b9b7c0f0d5ace01e56d2bac0251573ea7df17.camel@perches.com>
Subject: Re: [PATCH 2/4] printk: store instead of processing cont parts
From:   Joe Perches <joe@perches.com>
To:     Linus Torvalds <torvalds@linux-foundation.org>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc:     John Ogness <john.ogness@linutronix.de>,
        Petr Mladek <pmladek@suse.com>,
        Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        kexec@lists.infradead.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Date:   Mon, 20 Jul 2020 20:53:52 -0700
In-Reply-To: <CAHk-=whqiemoYRE41+qMuwQ_Qw3pn7gy2-Mso=ZDrwxQCVkncg@mail.gmail.com>
References: <20200717234818.8622-1-john.ogness@linutronix.de>
         <20200717234818.8622-3-john.ogness@linutronix.de>
         <20200719143527.GA566@jagdpanzerIV.localdomain>
         <CAHk-=wg70es2rSYsHbBcWrBPsoHmbZ8vmeqTS_Kypv6zHAwQjA@mail.gmail.com>
         <20200720015057.GA463@jagdpanzerIV.localdomain>
         <CAHk-=whqiemoYRE41+qMuwQ_Qw3pn7gy2-Mso=ZDrwxQCVkncg@mail.gmail.com>
Content-Type: text/plain; charset="ISO-8859-1"
User-Agent: Evolution 3.36.3-0ubuntu1 
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Mon, 2020-07-20 at 11:30 -0700, Linus Torvalds wrote:
> On Sun, Jul 19, 2020 at 6:51 PM Sergey Senozhatsky
> <sergey.senozhatsky@gmail.com> wrote:
> > Do I get it right, what you are saying is - when we process a PR_CONT
> > message the cont buffer should already contain previous non-LOG_NEWLINE
> > and non-PR_CONT message, otherwise it's a bug?
> 
> No.
> 
> I'm saying that the code that does PR_CONT should have done *some*
> printing before, otherwise it's at the very least questionable.
> 
> IOW, you can't just randomly start printing with PR_CONT, without
> having established _some_ context for it.

I believe there are at least a few cases that
_only_ use pr_cont to emit
complete lines.

For example: SEQ_printf in kernel/sched/debug.c