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sleepq.c revision 1.6 
      1 /*	$NetBSD: sleepq.c,v 1.6 2009/11/17 15:23:42 pooka Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 2008 Antti Kantee.  All Rights Reserved.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  * 1. Redistributions of source code must retain the above copyright
     10  *    notice, this list of conditions and the following disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  *    notice, this list of conditions and the following disclaimer in the
     13  *    documentation and/or other materials provided with the distribution.
     14  *
     15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
     16  * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     17  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
     18  * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
     21  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     25  * SUCH DAMAGE.
     26  */
     27 
     28 #include <sys/cdefs.h>
     29 __KERNEL_RCSID(0, "$NetBSD: sleepq.c,v 1.6 2009/11/17 15:23:42 pooka Exp $");
     30 
     31 #include <sys/param.h>
     32 #include <sys/condvar.h>
     33 #include <sys/mutex.h>
     34 #include <sys/once.h>
     35 #include <sys/queue.h>
     36 #include <sys/sleepq.h>
     37 #include <sys/syncobj.h>
     38 
     39 #include "rump_private.h"
     40 
     41 /*
     42  * Flimsy and minimalistic sleepq implementation.  This is implemented
     43  * only for the use of callouts in kern_timeout.c.  locking etc is
     44  * completely incorrect, horrible, etc etc etc.
     45  */
     46 
     47 syncobj_t sleep_syncobj;
     48 static kcondvar_t sq_cv;
     49 
     50 static int
     51 sqinit1(void)
     52 {
     53 
     54 	cv_init(&sq_cv, "sleepq");
     55 
     56 	return 0;
     57 }
     58 
     59 void
     60 sleepq_init(sleepq_t *sq)
     61 {
     62 	ONCE_DECL(sqctl);
     63 
     64 	RUN_ONCE(&sqctl, sqinit1);
     65 
     66 	TAILQ_INIT(sq);
     67 }
     68 
     69 void
     70 sleepq_enqueue(sleepq_t *sq, wchan_t wc, const char *wmsg, syncobj_t *sob)
     71 {
     72 	struct lwp *l = curlwp;
     73 
     74 	l->l_wchan = wc;
     75 	l->l_sleepq = sq;
     76 	TAILQ_INSERT_TAIL(sq, l, l_sleepchain);
     77 }
     78 
     79 int
     80 sleepq_block(int timo, bool catch)
     81 {
     82 	struct lwp *l = curlwp;
     83 	int error = 0;
     84 	kmutex_t *mp = l->l_mutex;
     85 	int biglocks = l->l_biglocks;
     86 
     87 	while (l->l_wchan) {
     88 		if ((error=cv_timedwait(&sq_cv, mp, timo)) == EWOULDBLOCK) {
     89 			TAILQ_REMOVE(l->l_sleepq, l, l_sleepchain);
     90 			l->l_wchan = NULL;
     91 		}
     92 	}
     93 	mutex_spin_exit(mp);
     94 
     95 	if (biglocks)
     96 		KERNEL_LOCK(biglocks, curlwp);
     97 
     98 	return error;
     99 }
    100 
    101 lwp_t *
    102 sleepq_wake(sleepq_t *sq, wchan_t wchan, u_int expected, kmutex_t *mp)
    103 {
    104 	struct lwp *l, *l_next;
    105 	bool found = false;
    106 
    107 	if (__predict_false(expected != -1))
    108 		panic("sleepq_wake: \"expected\" not supported");
    109 
    110 	for (l = TAILQ_FIRST(sq); l; l = l_next) {
    111 		l_next = TAILQ_NEXT(l, l_sleepchain);
    112 		if (l->l_wchan == wchan) {
    113 			found = true;
    114 			l->l_wchan = NULL;
    115 			TAILQ_REMOVE(sq, l, l_sleepchain);
    116 		}
    117 	}
    118 	if (found)
    119 		cv_broadcast(&sq_cv);
    120 
    121 	mutex_spin_exit(mp);
    122 	return NULL;
    123 }
    124 
    125 void
    126 sleepq_unsleep(struct lwp *l, bool cleanup)
    127 {
    128 
    129 	l->l_wchan = NULL;
    130 	TAILQ_REMOVE(l->l_sleepq, l, l_sleepchain);
    131 	cv_broadcast(&sq_cv);
    132 
    133 	if (cleanup) {
    134 		mutex_spin_exit(l->l_mutex);
    135 	}
    136 }
    137 
    138 /*
    139  * Thread scheduler handles priorities.  Therefore no action here.
    140  * (maybe do something if we're deperate?)
    141  */
    142 void
    143 sleepq_changepri(struct lwp *l, pri_t pri)
    144 {
    145 
    146 }
    147 
    148 void
    149 sleepq_lendpri(struct lwp *l, pri_t pri)
    150 {
    151 
    152 }
    153 
    154 struct lwp *
    155 syncobj_noowner(wchan_t wc)
    156 {
    157 
    158 	return NULL;
    159 }
    160 
    161 /*
    162  * XXX: used only by callout, therefore here.  should try to use
    163  * one in kern_lwp directly.
    164  */
    165 kmutex_t *
    166 lwp_lock_retry(struct lwp *l, kmutex_t *old)
    167 {
    168 
    169 	while (l->l_mutex != old) {
    170 		mutex_spin_exit(old);
    171 		old = l->l_mutex;
    172 		mutex_spin_enter(old);
    173 	}
    174 	return old;
    175 }
    176