1 /* $NetBSD: ltsleep.c,v 1.36 2020/03/14 20:23:51 ad Exp $ */
2
3 /*
4 * Copyright (c) 2009, 2010 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 /*
29 * Implementation of the tsleep/mtsleep kernel sleep interface. There
30 * are two sides to our implementation. For historic spinlocks we
31 * assume the kernel is giantlocked and use kernel giantlock as the
32 * wait interlock. For mtsleep, we use the interlock supplied by
33 * the caller. This duality leads to some if/else messiness in the code ...
34 */
35
36 #include <sys/cdefs.h>
37 __KERNEL_RCSID(0, "$NetBSD: ltsleep.c,v 1.36 2020/03/14 20:23:51 ad Exp $");
38
39 #include <sys/param.h>
40 #include <sys/kernel.h>
41 #include <sys/proc.h>
42 #include <sys/queue.h>
43
44 #include <rump-sys/kern.h>
45
46 #include <rump/rumpuser.h>
47
48 struct ltsleeper {
49 wchan_t id;
50 union {
51 struct rumpuser_cv *user;
52 kcondvar_t kern;
53 } u;
54 bool iskwait;
55 LIST_ENTRY(ltsleeper) entries;
56 };
57 #define ucv u.user
58 #define kcv u.kern
59
60 static LIST_HEAD(, ltsleeper) sleepers = LIST_HEAD_INITIALIZER(sleepers);
61 static kmutex_t qlock;
62
63 static int
sleeper(wchan_t ident,int timo,bool kinterlock)64 sleeper(wchan_t ident, int timo, bool kinterlock)
65 {
66 struct ltsleeper lts;
67 struct timespec ts;
68 int rv;
69
70 lts.id = ident;
71 if (kinterlock) {
72 lts.iskwait = true;
73 cv_init(<s.kcv, "mtsleep");
74 } else {
75 lts.iskwait = false;
76 rumpuser_cv_init(<s.ucv);
77 }
78
79 LIST_INSERT_HEAD(&sleepers, <s, entries);
80
81 if (timo) {
82 if (kinterlock) {
83 rv = cv_timedwait(<s.kcv, &qlock, timo);
84 } else {
85 /*
86 * Calculate wakeup-time.
87 */
88 ts.tv_sec = timo / hz;
89 ts.tv_nsec = (timo % hz) * (1000000000/hz);
90 mutex_spin_exit(&qlock);
91 rv = rumpuser_cv_timedwait(lts.ucv, rump_giantlock,
92 ts.tv_sec, ts.tv_nsec);
93 mutex_spin_enter(&qlock);
94 }
95
96 if (rv != 0)
97 rv = EWOULDBLOCK;
98 } else {
99 if (kinterlock) {
100 cv_wait(<s.kcv, &qlock);
101 } else {
102 mutex_spin_exit(&qlock);
103 rumpuser_cv_wait(lts.ucv, rump_giantlock);
104 mutex_spin_enter(&qlock);
105 }
106 rv = 0;
107 }
108
109 LIST_REMOVE(<s, entries);
110 mutex_spin_exit(&qlock);
111
112 if (kinterlock)
113 cv_destroy(<s.kcv);
114 else
115 rumpuser_cv_destroy(lts.ucv);
116
117 return rv;
118 }
119
120 int
tsleep(wchan_t ident,pri_t prio,const char * wmesg,int timo)121 tsleep(wchan_t ident, pri_t prio, const char *wmesg, int timo)
122 {
123 int rv, nlocks;
124
125 /*
126 * Since we cannot use slock as the rumpuser interlock,
127 * require that everyone using this prehistoric interface
128 * is biglocked. Wrap around the biglock and drop lockcnt,
129 * but retain the rumpuser mutex so that we can use it as an
130 * interlock to rumpuser_cv_wait().
131 */
132 rump_kernel_bigwrap(&nlocks);
133 mutex_spin_enter(&qlock);
134 rv = sleeper(ident, timo, false);
135 rump_kernel_bigunwrap(nlocks);
136
137 return rv;
138 }
139
140 int
mtsleep(wchan_t ident,pri_t prio,const char * wmesg,int timo,kmutex_t * lock)141 mtsleep(wchan_t ident, pri_t prio, const char *wmesg, int timo, kmutex_t *lock)
142 {
143 int rv;
144
145 mutex_spin_enter(&qlock);
146 mutex_exit(lock);
147 rv = sleeper(ident, timo, true);
148 if ((prio & PNORELOCK) == 0)
149 mutex_enter(lock);
150
151 return rv;
152 }
153
154 void
wakeup(wchan_t ident)155 wakeup(wchan_t ident)
156 {
157 struct ltsleeper *ltsp;
158
159 mutex_spin_enter(&qlock);
160 LIST_FOREACH(ltsp, &sleepers, entries) {
161 if (ltsp->id == ident) {
162 if (ltsp->iskwait) {
163 cv_broadcast(<sp->kcv);
164 } else {
165 rumpuser_cv_broadcast(ltsp->ucv);
166 }
167 }
168 }
169 mutex_exit(&qlock);
170 }
171
172 void
rump_tsleep_init()173 rump_tsleep_init()
174 {
175
176 mutex_init(&qlock, MUTEX_SPIN, IPL_NONE);
177 }
178