Subject: Re: [tip:tracing/urgent] tracing: Fix trace_print_seq()
From: Pekka Enberg <penberg@cs.helsinki.fi>
To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org,
       eduard.munteanu@linux360.ro, xiaoguangrong@cn.fujitsu.com,
       fweisbec@gmail.com, rostedt@goodmis.org, tglx@linutronix.de,
       mingo@elte.hu
Cc: linux-tip-commits@vger.kernel.org
In-Reply-To: <tip-5c37f525657e879a17a27c83021602cd55837531@git.kernel.org>
References: <4A4B2351.5010300@cn.fujitsu.com>
	 <tip-5c37f525657e879a17a27c83021602cd55837531@git.kernel.org>
Date: Wed, 01 Jul 2009 17:15:59 +0300
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On Wed, 2009-07-01 at 14:06 +0000, tip-bot for Xiao Guangrong wrote:
> Commit-ID:  5c37f525657e879a17a27c83021602cd55837531
> Gitweb:     http://git.kernel.org/tip/5c37f525657e879a17a27c83021602cd55837531
> Author:     Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
> AuthorDate: Wed, 1 Jul 2009 16:50:25 +0800
> Committer:  Ingo Molnar <mingo@elte.hu>
> CommitDate: Wed, 1 Jul 2009 16:03:50 +0200
> 
> tracing: Fix trace_print_seq()
> 
> We will lose something if trace_seq->buffer[0] is 0, because the copy length
> is calculated by strlen() in seq_puts(), so using seq_write() instead of
> seq_puts().
> 
> There have a example:
> after reboot:
> 
>  # echo kmemtrace > current_tracer
>  # echo 0 > options/kmem_minimalistic
>  # cat trace
>  # tracer: kmemtrace
>  #
>  #
> 
> Nothing is exported, because the first byte of trace_seq->buffer[ ]
> is KMEMTRACE_USER_ALLOC.
> 
> ( the value of KMEMTRACE_USER_ALLOC is zero, seeing
>   kmemtrace_print_alloc_user() in kernel/trace/kmemtrace.c)
> 
> Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
> Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Pekka Enberg <penberg@cs.helsinki.fi>
> LKML-Reference: <4A4B2351.5010300@cn.fujitsu.com>
> Signed-off-by: Ingo Molnar <mingo@elte.hu>

Nice catch!

Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>

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