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      1 /*	$NetBSD: pgfs_waitq.c,v 1.1 2011/10/12 01:05:00 yamt Exp $	*/
      2 
      3 /*-
      4  * Copyright (c)2010,2011 YAMAMOTO Takashi,
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     26  * SUCH DAMAGE.
     27  */
     28 
     29 /*
     30  * a dumb wait queue on puffs_cc
     31  */
     32 
     33 #include <sys/cdefs.h>
     34 #ifndef lint
     35 __RCSID("$NetBSD: pgfs_waitq.c,v 1.1 2011/10/12 01:05:00 yamt Exp $");
     36 #endif /* not lint */
     37 
     38 #include <assert.h>
     39 #include <puffs.h>
     40 
     41 #include "pgfs_waitq.h"
     42 #include "pgfs_debug.h"
     43 
     44 struct waiter {
     45 	TAILQ_ENTRY(waiter) list;
     46 	struct puffs_cc *cc;
     47 };
     48 
     49 void
     50 waitq_init(struct waitq *wq)
     51 {
     52 
     53 	TAILQ_INIT(wq);
     54 }
     55 
     56 void
     57 waiton(struct waitq *wq, struct puffs_cc *cc)
     58 {
     59 	struct waiter w;
     60 
     61 	/*
     62 	 * insert to the tail of the queue.
     63 	 * some users rely on the FIFO behaviour.
     64 	 */
     65 	w.cc = cc;
     66 	TAILQ_INSERT_TAIL(wq, &w, list);
     67 	puffs_cc_yield(cc);
     68 }
     69 
     70 struct puffs_cc *
     71 wakeup_one(struct waitq *wq)
     72 {
     73 
     74 	struct waiter *w;
     75 
     76 	w = TAILQ_FIRST(wq);
     77 	if (w != NULL) {
     78 		TAILQ_REMOVE(wq, w, list);
     79 		puffs_cc_schedule(w->cc);
     80 		DPRINTF("waking up %p\n", w->cc);
     81 		return w->cc;
     82 	}
     83 	return NULL;
     84 }
     85 
     86 #if 0
     87 static void
     88 wakeup(struct waitq *wq)
     89 {
     90 
     91 	struct waiter *w;
     92 
     93 	TAILQ_FOREACH(w, wq, list) {
     94 		puffs_cc_schedule(w->cc);
     95 		DPRINTF("waking up %p\n", w->cc);
     96 	}
     97 	TAILQ_INIT(wq);
     98 }
     99 #endif
    100