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Subject: Re: [PATCH 05/13] ftrace: Call trace_parser_clear() properly
From: Steven Rostedt <rostedt@goodmis.org>
To: Li Zefan <lizf@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>, Ingo Molnar <mingo@elte.hu>,
       LKML <linux-kernel@vger.kernel.org>
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Date: Tue, 08 Dec 2009 08:28:25 -0500
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On Tue, 2009-12-08 at 18:03 +0800, Li Zefan wrote:

> > 
> > I'm missing something. How that can happen. Anytime we reopen
> > the file, the parser is re-allocated.
> > 
> 
> It happened at file closing..
> 
> static int
> ftrace_regex_release(struct inode *inode, struct file *file, int enable)
> {
> 	...
>         parser = &iter->parser;
>         if (trace_parser_loaded(parser)) {
>                 parser->buffer[parser->idx] = 0;
> 		/* here ! */
>                 ftrace_match_records(parser->buffer, parser->idx, enable);
>         }
> 	...
> }
> 
> > I guess that happens if you open in rw mode? But not using the
> > example in the changelog?
> 
> I've confirmed that example I was using can reveal this bug.

This explanation should have been in the change log. I'll add it.

Thanks,

-- Steve