linux-kernel - Re: [PATCH v3 25/33] tracing: Allow whitespace to surround hist trigger filter

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Date:   Wed, 4 Oct 2017 15:28:22 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Tom Zanussi <tom.zanussi@...ux.intel.com>
Cc:     tglx@...utronix.de, mhiramat@...nel.org, namhyung@...nel.org,
        vedang.patel@...el.com, bigeasy@...utronix.de,
        joel.opensrc@...il.com, joelaf@...gle.com,
        mathieu.desnoyers@...icios.com, baohong.liu@...el.com,
        rajvi.jingar@...el.com, linux-kernel@...r.kernel.org,
        linux-rt-users@...r.kernel.org
Subject: Re: [PATCH v3 25/33] tracing: Allow whitespace to surround hist
 trigger filter

On Wed, 04 Oct 2017 14:05:17 -0500
Tom Zanussi <tom.zanussi@...ux.intel.com> wrote:

> Hi Steve,
> 
> On Wed, 2017-10-04 at 14:11 -0400, Steven Rostedt wrote:
> > On Fri, 22 Sep 2017 15:00:05 -0500
> > Tom Zanussi <tom.zanussi@...ux.intel.com> wrote:
> >   
> > > The existing code only allows for one space before and after the 'if'
> > > specifying the filter for a hist trigger.  Add code to make that more
> > > permissive as far as whitespace goes.  Specifically, we want to allow
> > > spaces in the trigger itself now that we have additional syntax
> > > (onmatch/onmax) where spaces are more natural e.g. spaces after commas
> > > in param lists.
> > > 
> > 

> > 
> > I think you forgot to update this:
> >   
> 
> I was going to but on closer inspection realized the simpler form
> wouldn't accomplish the same thing - the problem this is trying to solve
> is to allow bits of whitespace within the trigger (because we now have
> function-like syntax, which should allow whitespace after commas for
> instance) and separating the trigger from the filter ('if').  So we
> explicitly search for 'if' with preceding whitespace, which strsep won't
> accomplish.
> 
> So while it may not be pretty, it accomplishes that, while the below
> won't (it would create a truncated trigger if there were e.g. commas
> followed by spaces).

OK, and I just noticed that you updated the changelog too, which sorta
describes what you are trying to say here.

-- Steve