linux-kernel - Re: [RFC][PATCH 3/3] printk: do not preliminary split up cont buffer

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Date:   Tue, 9 Oct 2018 21:31:51 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Dmitriy Vyukov <dvyukov@...gle.com>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Tejun Heo <tj@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Subject: Re: [RFC][PATCH 3/3] printk: do not preliminary split up cont buffer

On (10/09/18 10:42), Petr Mladek wrote:
> On Tue 2018-10-02 11:38:36, Sergey Senozhatsky wrote:
> > We have a proper 'overflow' check which tells us that we need to
> > split up existing cont buffer in separate records:
> > 
> > 	if (cont.len + len > sizeof(cont.buf))
> > 		cont_flush();
> > 
> > At the same time we also have one extra flush: "if cont buffer is
> > 80% full then split it up" in cont_add():
> > 
> > 	if (cont.len > (sizeof(cont.buf) * 80) / 100)
> > 		cont_flush();
> > 
> > This looks to be redundant, since the existing "overflow" check
> > should work just fine, so remove this 80% check and wait for either
> > a normal cont termination \n, for preliminary flush due to
> > possible buffer overflow or for preliminary flush due to cont race.
> > 
> > Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
> 
> I wonder if this check ever triggered ;-) It is a nice clean up:
> 
> Reviewed-by: Petr Mladek <pmladek@...e.com>

Thanks.

	-ss