Re: [RFC][PATCH 4/5] tracing/filters: Provide basic regex support

Frederic Weisbecker
2009-08-05T22:47:15Z

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)