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sleepq.c revision 1.2.6.2 
      1  1.2.6.2  yamt /*	$NetBSD: sleepq.c,v 1.2.6.2 2009/05/04 08:14:30 yamt Exp $	*/
      2  1.2.6.2  yamt 
      3  1.2.6.2  yamt /*
      4  1.2.6.2  yamt  * Copyright (c) 2008 Antti Kantee.  All Rights Reserved.
      5  1.2.6.2  yamt  *
      6  1.2.6.2  yamt  * Redistribution and use in source and binary forms, with or without
      7  1.2.6.2  yamt  * modification, are permitted provided that the following conditions
      8  1.2.6.2  yamt  * are met:
      9  1.2.6.2  yamt  * 1. Redistributions of source code must retain the above copyright
     10  1.2.6.2  yamt  *    notice, this list of conditions and the following disclaimer.
     11  1.2.6.2  yamt  * 2. Redistributions in binary form must reproduce the above copyright
     12  1.2.6.2  yamt  *    notice, this list of conditions and the following disclaimer in the
     13  1.2.6.2  yamt  *    documentation and/or other materials provided with the distribution.
     14  1.2.6.2  yamt  *
     15  1.2.6.2  yamt  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
     16  1.2.6.2  yamt  * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     17  1.2.6.2  yamt  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
     18  1.2.6.2  yamt  * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     19  1.2.6.2  yamt  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     20  1.2.6.2  yamt  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
     21  1.2.6.2  yamt  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     22  1.2.6.2  yamt  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     23  1.2.6.2  yamt  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     24  1.2.6.2  yamt  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     25  1.2.6.2  yamt  * SUCH DAMAGE.
     26  1.2.6.2  yamt  */
     27  1.2.6.2  yamt 
     28  1.2.6.2  yamt #include <sys/cdefs.h>
     29  1.2.6.2  yamt __KERNEL_RCSID(0, "$NetBSD: sleepq.c,v 1.2.6.2 2009/05/04 08:14:30 yamt Exp $");
     30  1.2.6.2  yamt 
     31  1.2.6.2  yamt #include <sys/param.h>
     32  1.2.6.2  yamt #include <sys/condvar.h>
     33  1.2.6.2  yamt #include <sys/mutex.h>
     34  1.2.6.2  yamt #include <sys/queue.h>
     35  1.2.6.2  yamt #include <sys/sleepq.h>
     36  1.2.6.2  yamt #include <sys/syncobj.h>
     37  1.2.6.2  yamt 
     38  1.2.6.2  yamt /*
     39  1.2.6.2  yamt  * Flimsy and minimalistic sleepq implementation.  This is implemented
     40  1.2.6.2  yamt  * only for the use of callouts in kern_timeout.c.  locking etc is
     41  1.2.6.2  yamt  * completely incorrect, horrible, etc etc etc.
     42  1.2.6.2  yamt  */
     43  1.2.6.2  yamt 
     44  1.2.6.2  yamt syncobj_t sleep_syncobj;
     45  1.2.6.2  yamt static kcondvar_t sq_cv;
     46  1.2.6.2  yamt static kmutex_t sq_mtx;
     47  1.2.6.2  yamt 
     48  1.2.6.2  yamt void
     49  1.2.6.2  yamt sleepq_init(sleepq_t *sq)
     50  1.2.6.2  yamt {
     51  1.2.6.2  yamt 
     52  1.2.6.2  yamt 	TAILQ_INIT(sq);
     53  1.2.6.2  yamt 
     54  1.2.6.2  yamt 	cv_init(&sq_cv, "sleepq"); /* XXX */
     55  1.2.6.2  yamt 	mutex_init(&sq_mtx, MUTEX_DEFAULT, IPL_NONE); /* multi-XXX */
     56  1.2.6.2  yamt }
     57  1.2.6.2  yamt 
     58  1.2.6.2  yamt void
     59  1.2.6.2  yamt sleepq_enqueue(sleepq_t *sq, wchan_t wc, const char *wmsg, syncobj_t *sob)
     60  1.2.6.2  yamt {
     61  1.2.6.2  yamt 	struct lwp *l = curlwp;
     62  1.2.6.2  yamt 
     63  1.2.6.2  yamt 	if (__predict_false(sob != &sleep_syncobj || strcmp(wmsg, "callout"))) {
     64  1.2.6.2  yamt 		panic("sleepq: unsupported enqueue");
     65  1.2.6.2  yamt 	}
     66  1.2.6.2  yamt 
     67  1.2.6.2  yamt 	l->l_wchan = wc;
     68  1.2.6.2  yamt 	TAILQ_INSERT_TAIL(sq, l, l_sleepchain);
     69  1.2.6.2  yamt }
     70  1.2.6.2  yamt 
     71  1.2.6.2  yamt int
     72  1.2.6.2  yamt sleepq_block(int timo, bool hatch)
     73  1.2.6.2  yamt {
     74  1.2.6.2  yamt 	struct lwp *l = curlwp;
     75  1.2.6.2  yamt 
     76  1.2.6.2  yamt 	KASSERT(timo == 0 && !hatch);
     77  1.2.6.2  yamt 
     78  1.2.6.2  yamt 	mutex_enter(&sq_mtx);
     79  1.2.6.2  yamt 	while (l->l_wchan)
     80  1.2.6.2  yamt 		cv_wait(&sq_cv, &sq_mtx);
     81  1.2.6.2  yamt 	mutex_exit(&sq_mtx);
     82  1.2.6.2  yamt 
     83  1.2.6.2  yamt 	return 0;
     84  1.2.6.2  yamt }
     85  1.2.6.2  yamt 
     86  1.2.6.2  yamt lwp_t *
     87  1.2.6.2  yamt sleepq_wake(sleepq_t *sq, wchan_t wchan, u_int expected, kmutex_t *mp)
     88  1.2.6.2  yamt {
     89  1.2.6.2  yamt 	struct lwp *l;
     90  1.2.6.2  yamt 	bool found = false;
     91  1.2.6.2  yamt 
     92  1.2.6.2  yamt 	TAILQ_FOREACH(l, sq, l_sleepchain) {
     93  1.2.6.2  yamt 		if (l->l_wchan == wchan) {
     94  1.2.6.2  yamt 			found = true;
     95  1.2.6.2  yamt 			l->l_wchan = NULL;
     96  1.2.6.2  yamt 		}
     97  1.2.6.2  yamt 	}
     98  1.2.6.2  yamt 	if (found)
     99  1.2.6.2  yamt 		cv_broadcast(&sq_cv);
    100  1.2.6.2  yamt 
    101  1.2.6.2  yamt 	mutex_spin_exit(mp);
    102  1.2.6.2  yamt 	return NULL;
    103  1.2.6.2  yamt }
    104  1.2.6.2  yamt 
    105  1.2.6.2  yamt /*
    106  1.2.6.2  yamt  * XXX: used only by callout, therefore here
    107  1.2.6.2  yamt  *
    108  1.2.6.2  yamt  * We don't fudge around with the lwp mutex at all, therefore
    109  1.2.6.2  yamt  * this is enough.
    110  1.2.6.2  yamt  */
    111  1.2.6.2  yamt kmutex_t *
    112  1.2.6.2  yamt lwp_lock_retry(struct lwp *l, kmutex_t *old)
    113  1.2.6.2  yamt {
    114  1.2.6.2  yamt 
    115  1.2.6.2  yamt 	return old;
    116  1.2.6.2  yamt }
    117