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Date: Thu, 26 Mar 2009 20:13:24 +0200
From: Pekka Paalanen <pq@iki.fi>
To: Vitaly Mayatskikh <v.mayatskih@gmail.com>
Cc: linux-kernel@vger.kernel.org, Steven Rostedt <rostedt@goodmis.org>,
       Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH] ftrace: advance readpos in trace_seq_to_user() by
 really read bytes
Message-ID: <20090326201324.7952c874@daedalus.pq.iki.fi>
In-Reply-To: <87zlf8kxmd.wl%vmayatsk@redhat.com>
References: <87zlf8kxmd.wl%vmayatsk@redhat.com>
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On Thu, 26 Mar 2009 18:22:18 +0100
Vitaly Mayatskikh <v.mayatskih@gmail.com> wrote:

> If tracer will not provide input buffer of enough size, he will never
> see data between cnt and len bytes.
> 
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 17bb88d..0217615 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -477,7 +477,7 @@ ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt)
>  	if (ret)
>  		return -EFAULT;
>  
> -	s->readpos += len;
> +	s->readpos += cnt;
>  	return cnt;
>  }

This fix seems to be already included in tip/master:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git

It's not in Linus' master, but I guess it's on its way there.

Thanks.

-- 
Pekka Paalanen
http://www.iki.fi/pq/
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