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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 | ||
35 | void | |
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 | } | |
66 | EXPORT_SYMBOL(__cv_init); | |
67 | ||
68 | void | |
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 | ||
4efd4118 | 81 | spin_unlock(&cvp->cv_lock); |
73035a29 | 82 | memset(cvp, CV_POISON, sizeof(*cvp)); |
4efd4118 | 83 | EXIT; |
84 | } | |
85 | EXPORT_SYMBOL(__cv_destroy); | |
86 | ||
87 | void | |
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 | } | |
121 | EXPORT_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 | */ | |
126 | clock_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 | } | |
167 | EXPORT_SYMBOL(__cv_timedwait); | |
168 | ||
169 | void | |
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 | } | |
185 | EXPORT_SYMBOL(__cv_signal); | |
186 | ||
187 | void | |
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 | } | |
201 | EXPORT_SYMBOL(__cv_broadcast); |