linux-kernel - Re: [patch] tracing: off by one in __trace_array

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Message-ID: <20141126154635.GI4835@mwanda>
Date:	Wed, 26 Nov 2014 18:46:35 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: Re: [patch] tracing: off by one in __trace_array_vprintk()

On Wed, Nov 26, 2014 at 10:22:44AM -0500, Steven Rostedt wrote:
> On Wed, 26 Nov 2014 18:05:41 +0300
> Dan Carpenter <dan.carpenter@...cle.com> wrote:
> 
> > On Wed, Nov 26, 2014 at 09:43:06AM -0500, Steven Rostedt wrote:
> > > I highly doubt it's much of a speed up. And we do that by sacrificing
> > > that one byte of buffer, which would lose the printk if len does equal
> > > TRACE_BUF_SIZE.
> > > 
> > > I don't see a bug here. What exactly are you trying to fix?
> > 
> > Heh.  vsnprintf() is going to put a NUL char at the end of the string
> > even if you don't plan to use it.  :P
> > 
> > Another option would be to just print truncated output.  We could use
> > vscnprintf() and remove the off by one limit check.
> 
> Yes, that is a better patch. The previous one wasn't really fixing
> anything. But printing truncated output is better than nothing.
> 
> Want to send it officially?
> 

Will do.

regards,
dan carpenter

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