From mboxrd@z Thu Jan  1 00:00:00 1970
From: Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH v3 1/4] wait.[ch]: Introduce the simple waitqueue (swait)
 implementation
Date: Mon, 26 Oct 2015 13:28:25 +0100
Message-ID: <20151026122825.GS2508@worktop.programming.kicks-ass.net>
References: <1445326090-1698-1-git-send-email-daniel.wagner@bmw-carit.de>
 <1445326090-1698-2-git-send-email-daniel.wagner@bmw-carit.de>
 <20151026120426.GA1497@fixme-laptop.cn.ibm.com>
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Cc: Daniel Wagner <daniel.wagner@bmw-carit.de>,
	linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org,
	Paul Gortmaker <paul.gortmaker@windriver.com>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Thomas Gleixner <tglx@linutronix.de>
To: Boqun Feng <boqun.feng@gmail.com>
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On Mon, Oct 26, 2015 at 08:04:26PM +0800, Boqun Feng wrote:
> Hi Daniel,
> 
> On Tue, Oct 20, 2015 at 09:28:07AM +0200, Daniel Wagner wrote:
> > +
> > +/*
> > + * The thing about the wake_up_state() return value; I think we can ignore it.
> > + *
> > + * If for some reason it would return 0, that means the previously waiting
> > + * task is already running, so it will observe condition true (or has already).
> > + */
> > +void swake_up_locked(struct swait_queue_head *q)
> > +{
> > +	struct swait_queue *curr;
> > +
> > +	list_for_each_entry(curr, &q->task_list, task_list) {
> > +		wake_up_process(curr->task);
> > +		list_del_init(&curr->task_list);
> > +		break;
> 
> Just be curious, what's this break for? Or what's this loop(?) for?

Lazy way of writing: if (!empty) { curr = first-entry;