Re: [RFC][PATCH 02/11] sched: Create preempt_count invariant

From	Peter Zijlstra <peterz@infradead.org>
Newsgroups	linux.kernel
Subject	Re: [RFC][PATCH 02/11] sched: Create preempt_count invariant
Date	2015-09-29 16:20 +0200
Message-ID	<qe3V9-rR-23@gated-at.bofh.it> (permalink)
References	<qdZHQ-2IS-3@gated-at.bofh.it> <qdZHS-2IS-41@gated-at.bofh.it> <qe2Z4-7xW-7@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Tue, Sep 29, 2015 at 03:11:56PM +0200, Thomas Gleixner wrote:
> On Tue, 29 Sep 2015, Peter Zijlstra wrote:
> > +	/*
> > +	 * Still have preempt_count() == 2, from:
> > +	 *
> > +	 *	schedule()
> > +	 *	  preempt_disable();			// 1
> > +	 *	  __schedule()
> > +	 *	    raw_spin_lock_irq(&rq->lock)	// 2
> > +	 */
> > +	rq = finish_task_switch(prev); /* drops rq->lock, preempt_count() == 1 */
> >  	balance_callback(rq);
> > -	preempt_enable();
> > +	preempt_enable(); /* preempt_count() == 0 */
> 
> Bah. I so hate tail comments. What's wrong with
> 
> +	 /* preempt_count() ==> 0 */
> 	preempt_enable();
> 
> Hmm?

I find the tail comments more readable in this case; clearly I don't
share your hatred :-). But I can change them if you insist.

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[RFC][PATCH 02/11] sched: Create preempt_count invariant Peter Zijlstra <peterz@infradead.org> - 2015-09-29 11:50 +0200
  [tip:sched/core] sched/core: Create preempt_count invariant tip-bot for Peter Zijlstra <tipbot@zytor.com> - 2015-09-29 12:40 +0200
  Re: [RFC][PATCH 02/11] sched: Create preempt_count invariant Frederic Weisbecker <fweisbec@gmail.com> - 2015-09-29 15:00 +0200
    Re: [RFC][PATCH 02/11] sched: Create preempt_count invariant Peter Zijlstra <peterz@infradead.org> - 2015-09-29 15:10 +0200
      Re: [RFC][PATCH 02/11] sched: Create preempt_count invariant Steven Rostedt <rostedt@goodmis.org> - 2015-09-29 16:50 +0200
  Re: [RFC][PATCH 02/11] sched: Create preempt_count invariant Thomas Gleixner <tglx@linutronix.de> - 2015-09-29 15:20 +0200
    Re: [RFC][PATCH 02/11] sched: Create preempt_count invariant Peter Zijlstra <peterz@infradead.org> - 2015-09-29 16:20 +0200

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