Re: [patch] tracing: off by one in __trace_array_vprintk()

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From: Dan Carpenter <dan.carpenter@oracle.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>,
	linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: Re: [patch] tracing: off by one in __trace_array_vprintk()
Date: Wed, 26 Nov 2014 15:46:35 +0000	[thread overview]
Message-ID: <20141126154635.GI4835@mwanda> (raw)
In-Reply-To: <20141126102244.4bffa4b2@gandalf.local.home>

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@oracle.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

WARNING: multiple messages have this Message-ID (diff)

From: Dan Carpenter <dan.carpenter@oracle.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>,
	linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: Re: [patch] tracing: off by one in __trace_array_vprintk()
Date: Wed, 26 Nov 2014 18:46:35 +0300	[thread overview]
Message-ID: <20141126154635.GI4835@mwanda> (raw)
In-Reply-To: <20141126102244.4bffa4b2@gandalf.local.home>

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@oracle.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

next prev parent reply	other threads:[~2014-11-26 15:46 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-11-26 14:06 [patch] tracing: off by one in __trace_array_vprintk() Dan Carpenter
2014-11-26 14:06 ` Dan Carpenter
2014-11-26 14:25 ` Steven Rostedt
2014-11-26 14:25   ` Steven Rostedt
2014-11-26 14:34   ` Dan Carpenter
2014-11-26 14:34     ` Dan Carpenter
2014-11-26 14:27 ` Steven Rostedt
2014-11-26 14:27   ` Steven Rostedt
2014-11-26 14:37   ` Dan Carpenter
2014-11-26 14:37     ` Dan Carpenter
2014-11-26 14:43     ` Steven Rostedt
2014-11-26 14:43       ` Steven Rostedt
2014-11-26 15:05       ` Dan Carpenter
2014-11-26 15:05         ` Dan Carpenter
2014-11-26 15:22         ` Steven Rostedt
2014-11-26 15:22           ` Steven Rostedt
2014-11-26 15:46           ` Dan Carpenter [this message]
2014-11-26 15:46             ` Dan Carpenter
2014-11-27 15:57           ` [patch v2] tracing: truncated output is better than nothing Dan Carpenter
2014-11-27 15:57             ` Dan Carpenter

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