linux-kernel - Re: [RFC][PATCH 05/18 v2] ftrace: Do not display non safe RCU functions in available_filter

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Message-ID: <1377981303.26624.2.camel@pippen.local.home>
Date:	Sat, 31 Aug 2013 16:35:03 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	paulmck@...ux.vnet.ibm.com
Cc:	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Jiri Olsa <jolsa@...hat.com>
Subject: Re: [RFC][PATCH 05/18 v2] ftrace: Do not display non safe RCU
 functions in available_filter_functions

On Sat, 2013-08-31 at 12:46 -0700, Paul E. McKenney wrote:

> >  void arch_ftrace_update_code(int command);
> > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> > index 06504b2..be87ac9 100644
> > --- a/kernel/trace/ftrace.c
> > +++ b/kernel/trace/ftrace.c
> > @@ -2645,7 +2645,10 @@ t_next(struct seq_file *m, void *v, loff_t *pos)
> >  		     !ftrace_lookup_ip(ops->notrace_hash, rec->ip)) ||
> > 
> >  		    ((iter->flags & FTRACE_ITER_ENABLED) &&
> > -		     !(rec->flags & FTRACE_FL_ENABLED))) {
> > +		     !(rec->flags & FTRACE_FL_ENABLED)) ||
> > +
> 
> OK, I'll bite...  Why the blank line?

For readability. Here's the full if statement:

                if (((iter->flags & FTRACE_ITER_FILTER) &&
                     !(ftrace_lookup_ip(ops->filter_hash, rec->ip))) ||

                    ((iter->flags & FTRACE_ITER_NOTRACE) &&
                     !ftrace_lookup_ip(ops->notrace_hash, rec->ip)) ||

                    ((iter->flags & FTRACE_ITER_ENABLED) &&
                     !(rec->flags & FTRACE_FL_ENABLED)) ||

                    ((iter->flags & FTRACE_ITER_UNSAFE_ONLY) &&
                     !ftrace_lookup_ip(ftrace_unsafe_rcu, rec->ip)) ||

                    ((iter->flags & FTRACE_ITER_NO_UNSAFE) &&
                     ftrace_lookup_ip(ftrace_unsafe_rcu, rec->ip))) {


They are grouped in pairs.

-- Steve

> 
> 							Thanx, Paul
> 
> > +		    ((iter->flags & FTRACE_ITER_NO_UNSAFE) &&
> > +		     ftrace_lookup_ip(ftrace_unsafe_rcu, rec->ip))) {
> > 
> >  			rec = NULL;
> >  			goto retry;
> > @@ -2773,6 +2776,7 @@ ftrace_avail_open(struct inode *inode, struct file *file)
> >  	iter = __seq_open_private(file, &show_ftrace_seq_ops, sizeof(*iter));
> >  	if (iter) {
> >  		iter->pg = ftrace_pages_start;
> > +		iter->flags = FTRACE_ITER_NO_UNSAFE;
> >  		iter->ops = &global_ops;
> >  	}
> > 
> > -- 
> > 1.7.10.4
> > 
> > 


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