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Date: Thu, 6 Aug 2009 00:47:11 +0200
From: Frederic Weisbecker <fweisbec@gmail.com>
To: Li Zefan <lizf@cn.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>, LKML <linux-kernel@vger.kernel.org>,
       Steven Rostedt <rostedt@goodmis.org>,
       Lai Jiangshan <laijs@cn.fujitsu.com>, Tom Zanussi <tzanussi@gmail.com>,
       Thomas Gleixner <tglx@linutronix.de>,
       Peter Zijlstra <peterz@infradead.org>
Subject: Re: [RFC][PATCH 4/5] tracing/filters: Provide basic regex support
Message-ID: <20090805224709.GH5025@nowhere>
References: <1249111408-8657-1-git-send-email-fweisbec@gmail.com> <1249111408-8657-5-git-send-email-fweisbec@gmail.com> <4A76782E.4030803@cn.fujitsu.com>
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On Mon, Aug 03, 2009 at 01:39:58PM +0800, Li Zefan wrote:
> Frederic Weisbecker wrote:
> > This patch provides basic support for regular expressions in filters.
> > The common filter file doesn't support any regex but a new
> > filter_regex file is created for each subsystem/event.
> > 
> > It supports the following types of regexp:
> > 
> > - *match_beginning
> > - *match_middle*
> > - match_end*
> > - !don't match
> > 
> 
> I don't see why adding "filter_regex" is necessary, why not just make
> "filter" support regex?


I did that because I feared about people beeing unable to filter using
* as a real character inside a filter string.
If we are using only one file, we are forced to get the '*' interpreted.
That would also break the ABI.



> > Every string is now handled as a regexp in the filter framework, which
> > helps to factorize the code for handling both simple strings and
> > regexp comparisons.
> > 
> > (The regexp code has been savagely cherry picked from ftrace.c
> > writtent by Steve. If this patch makes its way, I'll be happy
> > to change ftrace to use the new filter helpers)