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715f6251 1/*
2 * This file is part of the SPL: Solaris Porting Layer.
3 *
4 * Copyright (c) 2008 Lawrence Livermore National Security, LLC.
5 * Produced at Lawrence Livermore National Laboratory
6 * Written by:
7 * Brian Behlendorf <behlendorf1@llnl.gov>,
8 * Herb Wartens <wartens2@llnl.gov>,
9 * Jim Garlick <garlick@llnl.gov>
10 * UCRL-CODE-235197
11 *
12 * This is free software; you can redistribute it and/or modify it
13 * under the terms of the GNU General Public License as published by
14 * the Free Software Foundation; either version 2 of the License, or
15 * (at your option) any later version.
16 *
17 * This is distributed in the hope that it will be useful, but WITHOUT
18 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
19 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
20 * for more details.
21 *
22 * You should have received a copy of the GNU General Public License along
23 * with this program; if not, write to the Free Software Foundation, Inc.,
24 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
25 */
26
4efd4118 27#include <sys/condvar.h>
28
29#ifdef DEBUG_SUBSYSTEM
30#undef DEBUG_SUBSYSTEM
31#endif
32
33#define DEBUG_SUBSYSTEM S_CONDVAR
34
35void
36__cv_init(kcondvar_t *cvp, char *name, kcv_type_t type, void *arg)
37{
38 int flags = KM_SLEEP;
39
40 ENTRY;
41 ASSERT(cvp);
42 ASSERT(name);
43 ASSERT(type == CV_DEFAULT);
44 ASSERT(arg == NULL);
45
46 cvp->cv_magic = CV_MAGIC;
47 init_waitqueue_head(&cvp->cv_event);
48 spin_lock_init(&cvp->cv_lock);
49 atomic_set(&cvp->cv_waiters, 0);
50 cvp->cv_mutex = NULL;
51 cvp->cv_name = NULL;
52 cvp->cv_name_size = strlen(name) + 1;
53
54 /* We may be called when there is a non-zero preempt_count or
55 * interrupts are disabled is which case we must not sleep.
56 */
57 if (current_thread_info()->preempt_count || irqs_disabled())
58 flags = KM_NOSLEEP;
59
60 cvp->cv_name = kmem_alloc(cvp->cv_name_size, flags);
61 if (cvp->cv_name)
62 strcpy(cvp->cv_name, name);
63
64 EXIT;
65}
66EXPORT_SYMBOL(__cv_init);
67
68void
69__cv_destroy(kcondvar_t *cvp)
70{
71 ENTRY;
72 ASSERT(cvp);
73 ASSERT(cvp->cv_magic == CV_MAGIC);
74 spin_lock(&cvp->cv_lock);
75 ASSERT(atomic_read(&cvp->cv_waiters) == 0);
76 ASSERT(!waitqueue_active(&cvp->cv_event));
77
78 if (cvp->cv_name)
79 kmem_free(cvp->cv_name, cvp->cv_name_size);
80
81 memset(cvp, CV_POISON, sizeof(*cvp));
82 spin_unlock(&cvp->cv_lock);
83 EXIT;
84}
85EXPORT_SYMBOL(__cv_destroy);
86
87void
88__cv_wait(kcondvar_t *cvp, kmutex_t *mp)
89{
90 DEFINE_WAIT(wait);
91 ENTRY;
92
93 ASSERT(cvp);
94 ASSERT(mp);
95 ASSERT(cvp->cv_magic == CV_MAGIC);
96 spin_lock(&cvp->cv_lock);
97 ASSERT(mutex_owned(mp));
98
99 if (cvp->cv_mutex == NULL)
100 cvp->cv_mutex = mp;
101
102 /* Ensure the same mutex is used by all callers */
103 ASSERT(cvp->cv_mutex == mp);
104 spin_unlock(&cvp->cv_lock);
105
106 prepare_to_wait_exclusive(&cvp->cv_event, &wait,
107 TASK_UNINTERRUPTIBLE);
108 atomic_inc(&cvp->cv_waiters);
109
110 /* Mutex should be dropped after prepare_to_wait() this
111 * ensures we're linked in to the waiters list and avoids the
112 * race where 'cvp->cv_waiters > 0' but the list is empty. */
113 mutex_exit(mp);
114 schedule();
115 mutex_enter(mp);
116
117 atomic_dec(&cvp->cv_waiters);
118 finish_wait(&cvp->cv_event, &wait);
119 EXIT;
120}
121EXPORT_SYMBOL(__cv_wait);
122
123/* 'expire_time' argument is an absolute wall clock time in jiffies.
124 * Return value is time left (expire_time - now) or -1 if timeout occurred.
125 */
126clock_t
127__cv_timedwait(kcondvar_t *cvp, kmutex_t *mp, clock_t expire_time)
128{
129 DEFINE_WAIT(wait);
130 clock_t time_left;
131 ENTRY;
132
133 ASSERT(cvp);
134 ASSERT(mp);
135 ASSERT(cvp->cv_magic == CV_MAGIC);
136 spin_lock(&cvp->cv_lock);
137 ASSERT(mutex_owned(mp));
138
139 if (cvp->cv_mutex == NULL)
140 cvp->cv_mutex = mp;
141
142 /* Ensure the same mutex is used by all callers */
143 ASSERT(cvp->cv_mutex == mp);
144 spin_unlock(&cvp->cv_lock);
145
146 /* XXX - Does not handle jiffie wrap properly */
147 time_left = expire_time - jiffies;
148 if (time_left <= 0)
149 RETURN(-1);
150
151 prepare_to_wait_exclusive(&cvp->cv_event, &wait,
152 TASK_UNINTERRUPTIBLE);
153 atomic_inc(&cvp->cv_waiters);
154
155 /* Mutex should be dropped after prepare_to_wait() this
156 * ensures we're linked in to the waiters list and avoids the
157 * race where 'cvp->cv_waiters > 0' but the list is empty. */
158 mutex_exit(mp);
159 time_left = schedule_timeout(time_left);
160 mutex_enter(mp);
161
162 atomic_dec(&cvp->cv_waiters);
163 finish_wait(&cvp->cv_event, &wait);
164
165 RETURN(time_left > 0 ? time_left : -1);
166}
167EXPORT_SYMBOL(__cv_timedwait);
168
169void
170__cv_signal(kcondvar_t *cvp)
171{
172 ENTRY;
173 ASSERT(cvp);
174 ASSERT(cvp->cv_magic == CV_MAGIC);
175
176 /* All waiters are added with WQ_FLAG_EXCLUSIVE so only one
177 * waiter will be set runable with each call to wake_up().
178 * Additionally wake_up() holds a spin_lock assoicated with
179 * the wait queue to ensure we don't race waking up processes. */
180 if (atomic_read(&cvp->cv_waiters) > 0)
181 wake_up(&cvp->cv_event);
182
183 EXIT;
184}
185EXPORT_SYMBOL(__cv_signal);
186
187void
188__cv_broadcast(kcondvar_t *cvp)
189{
190 ASSERT(cvp);
191 ASSERT(cvp->cv_magic == CV_MAGIC);
192 ENTRY;
193
194 /* Wake_up_all() will wake up all waiters even those which
195 * have the WQ_FLAG_EXCLUSIVE flag set. */
196 if (atomic_read(&cvp->cv_waiters) > 0)
197 wake_up_all(&cvp->cv_event);
198
199 EXIT;
200}
201EXPORT_SYMBOL(__cv_broadcast);