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Date: Wed, 27 Nov 2013 10:00:56 -0500
From: Steven Rostedt <rostedt@goodmis.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@gmail.com>, tglx@linutronix.de, mingo@redhat.com,
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Subject: Re: [PATCH 08/14] sched: add latency tracing for -deadline tasks.
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On Wed, 27 Nov 2013 15:26:49 +0100
Peter Zijlstra <peterz@infradead.org> wrote:

> On Wed, Nov 27, 2013 at 09:16:47AM -0500, Steven Rostedt wrote:
> > On Wed, 27 Nov 2013 14:43:45 +0100
> > Juri Lelli <juri.lelli@gmail.com> wrote:
> > diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
> > > index f76f8d6..ad94604 100644
> > > --- a/kernel/trace/trace_selftest.c
> > > +++ b/kernel/trace/trace_selftest.c
> > > @@ -1023,16 +1023,16 @@ trace_selftest_startup_nop(struct tracer *trace, struct trace_array *tr)
> > >  static int trace_wakeup_test_thread(void *data)
> > >  {
> > >  	/* Make this a -deadline thread */
> > > -	struct sched_param2 paramx = {
> > > +	static const struct sched_param2 param = {
> > >  		.sched_priority = 0,
> > > +		.sched_flags = 0,
> > >  		.sched_runtime = 100000ULL,
> > >  		.sched_deadline = 10000000ULL,
> > >  		.sched_period = 10000000ULL
> > > -		.sched_flags = 0
> > 
> > Assigning structures like this, you don't need to set the zero fields.
> > all fields not explicitly stated, are set to zero.
> 
> Only because its static. Otherwise unnamed members have indeterminate
> value after initialization.

Hmm, I wonder if there's a gcc extension that guarantees it. Because I
could have sworn I've seen initialization of structures that expected
zero'd behavior elsewhere in the kernel.

-- Steve