linux-kernel - Re: [PATCH v2 31/40] tracing: Allow whitespace to surround hist trigger filter

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Message-ID: <1504897701.5276.5.camel@tzanussi-mobl.amr.corp.intel.com>
Date:   Fri, 08 Sep 2017 14:08:21 -0500
From:   Tom Zanussi <tom.zanussi@...ux.intel.com>
To:     Steven Rostedt <rostedt@...dmis.org>
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,
        linux-kernel@...r.kernel.org, linux-rt-users@...r.kernel.org
Subject: Re: [PATCH v2 31/40] tracing: Allow whitespace to surround hist
 trigger filter

On Fri, 2017-09-08 at 14:50 -0400, Steven Rostedt wrote:
> On Tue,  5 Sep 2017 16:57:43 -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.
> > 
> > Signed-off-by: Tom Zanussi <tom.zanussi@...ux.intel.com>
> > ---
> >  kernel/trace/trace_events_hist.c | 19 +++++++++++++++----
> >  1 file changed, 15 insertions(+), 4 deletions(-)
> > 
> > diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
> > index 0a398f3..4f66f2e 100644
> > --- a/kernel/trace/trace_events_hist.c
> > +++ b/kernel/trace/trace_events_hist.c
> > @@ -4819,7 +4819,7 @@ static int event_hist_trigger_func(struct event_command *cmd_ops,
> >  	struct synth_event *se;
> >  	const char *se_name;
> >  	bool remove = false;
> > -	char *trigger;
> > +	char *trigger, *p;
> >  	int ret = 0;
> >  
> >  	if (!param)
> > @@ -4829,9 +4829,19 @@ static int event_hist_trigger_func(struct event_command *cmd_ops,
> >  		remove = true;
> >  
> >  	/* separate the trigger from the filter (k:v [if filter]) */
> > -	trigger = strsep(&param, " \t");
> > -	if (!trigger)
> > -		return -EINVAL;
> > +	trigger = param;
> > +	p = strstr(param, " if");
> > +	if (!p)
> > +		p = strstr(param, "\tif");
> > +	if (p) {
> > +		if (p == trigger)
> > +			return -EINVAL;
> > +		param = p + 1;
> > +		param = strstrip(param);
> > +		*p = '\0';
> > +		trigger = strstrip(trigger);
> > +	} else
> > +		param = NULL;
> 
> This seems rather complex. Wouldn't the following work?
> 
> 	param = skip_spaces(param);
> 	trigger = strsep(&param, " \t");
> 	if (param)
> 		param = strstrip(param);
> 

Yes, much better ;-)

Tom