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1 | /*****************************************************************************\ | |
2 | * Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC. | |
3 | * Copyright (C) 2007 The Regents of the University of California. | |
4 | * Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER). | |
5 | * Written by Brian Behlendorf <behlendorf1@llnl.gov>. | |
6 | * UCRL-CODE-235197 | |
7 | * | |
8 | * This file is part of the SPL, Solaris Porting Layer. | |
9 | * For details, see <http://github.com/behlendorf/spl/>. | |
10 | * | |
11 | * The SPL is free software; you can redistribute it and/or modify it | |
12 | * under the terms of the GNU General Public License as published by the | |
13 | * Free Software Foundation; either version 2 of the License, or (at your | |
14 | * option) any later version. | |
15 | * | |
16 | * The SPL is distributed in the hope that it will be useful, but WITHOUT | |
17 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
18 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
19 | * for more details. | |
20 | * | |
21 | * You should have received a copy of the GNU General Public License along | |
22 | * with the SPL. If not, see <http://www.gnu.org/licenses/>. | |
23 | ***************************************************************************** | |
24 | * Solaris Porting Layer (SPL) Credential Implementation. | |
25 | \*****************************************************************************/ | |
26 | ||
27 | #include <sys/condvar.h> | |
28 | #include <spl-debug.h> | |
29 | ||
30 | #ifdef SS_DEBUG_SUBSYS | |
31 | #undef SS_DEBUG_SUBSYS | |
32 | #endif | |
33 | ||
34 | #define SS_DEBUG_SUBSYS SS_CONDVAR | |
35 | ||
36 | void | |
37 | __cv_init(kcondvar_t *cvp, char *name, kcv_type_t type, void *arg) | |
38 | { | |
39 | int flags = KM_SLEEP; | |
40 | ||
41 | SENTRY; | |
42 | ASSERT(cvp); | |
43 | ASSERT(name); | |
44 | ASSERT(type == CV_DEFAULT); | |
45 | ASSERT(arg == NULL); | |
46 | ||
47 | cvp->cv_magic = CV_MAGIC; | |
48 | init_waitqueue_head(&cvp->cv_event); | |
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 | SEXIT; | |
65 | } | |
66 | EXPORT_SYMBOL(__cv_init); | |
67 | ||
68 | void | |
69 | __cv_destroy(kcondvar_t *cvp) | |
70 | { | |
71 | SENTRY; | |
72 | ASSERT(cvp); | |
73 | ASSERT(cvp->cv_magic == CV_MAGIC); | |
74 | ASSERT(cvp->cv_mutex == NULL); | |
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 | ASSERT3P(memset(cvp, CV_POISON, sizeof(*cvp)), ==, cvp); | |
82 | SEXIT; | |
83 | } | |
84 | EXPORT_SYMBOL(__cv_destroy); | |
85 | ||
86 | static void | |
87 | cv_wait_common(kcondvar_t *cvp, kmutex_t *mp, int state) | |
88 | { | |
89 | DEFINE_WAIT(wait); | |
90 | SENTRY; | |
91 | ||
92 | ASSERT(cvp); | |
93 | ASSERT(mp); | |
94 | ASSERT(cvp->cv_magic == CV_MAGIC); | |
95 | ASSERT(mutex_owned(mp)); | |
96 | ||
97 | if (cvp->cv_mutex == NULL) | |
98 | cvp->cv_mutex = mp; | |
99 | ||
100 | /* Ensure the same mutex is used by all callers */ | |
101 | ASSERT(cvp->cv_mutex == mp); | |
102 | ||
103 | prepare_to_wait_exclusive(&cvp->cv_event, &wait, state); | |
104 | atomic_inc(&cvp->cv_waiters); | |
105 | ||
106 | /* Mutex should be dropped after prepare_to_wait() this | |
107 | * ensures we're linked in to the waiters list and avoids the | |
108 | * race where 'cvp->cv_waiters > 0' but the list is empty. */ | |
109 | mutex_exit(mp); | |
110 | schedule(); | |
111 | mutex_enter(mp); | |
112 | ||
113 | /* No more waiters a different mutex could be used */ | |
114 | if (atomic_dec_and_test(&cvp->cv_waiters)) | |
115 | cvp->cv_mutex = NULL; | |
116 | ||
117 | finish_wait(&cvp->cv_event, &wait); | |
118 | SEXIT; | |
119 | } | |
120 | ||
121 | void | |
122 | __cv_wait(kcondvar_t *cvp, kmutex_t *mp) | |
123 | { | |
124 | cv_wait_common(cvp, mp, TASK_UNINTERRUPTIBLE); | |
125 | } | |
126 | EXPORT_SYMBOL(__cv_wait); | |
127 | ||
128 | void | |
129 | __cv_wait_interruptible(kcondvar_t *cvp, kmutex_t *mp) | |
130 | { | |
131 | cv_wait_common(cvp, mp, TASK_INTERRUPTIBLE); | |
132 | } | |
133 | EXPORT_SYMBOL(__cv_wait_interruptible); | |
134 | ||
135 | /* 'expire_time' argument is an absolute wall clock time in jiffies. | |
136 | * Return value is time left (expire_time - now) or -1 if timeout occurred. | |
137 | */ | |
138 | static clock_t | |
139 | __cv_timedwait_common(kcondvar_t *cvp, kmutex_t *mp, | |
140 | clock_t expire_time, int state) | |
141 | { | |
142 | DEFINE_WAIT(wait); | |
143 | clock_t time_left; | |
144 | SENTRY; | |
145 | ||
146 | ASSERT(cvp); | |
147 | ASSERT(mp); | |
148 | ASSERT(cvp->cv_magic == CV_MAGIC); | |
149 | ASSERT(mutex_owned(mp)); | |
150 | ||
151 | if (cvp->cv_mutex == NULL) | |
152 | cvp->cv_mutex = mp; | |
153 | ||
154 | /* Ensure the same mutex is used by all callers */ | |
155 | ASSERT(cvp->cv_mutex == mp); | |
156 | ||
157 | /* XXX - Does not handle jiffie wrap properly */ | |
158 | time_left = expire_time - jiffies; | |
159 | if (time_left <= 0) | |
160 | SRETURN(-1); | |
161 | ||
162 | prepare_to_wait_exclusive(&cvp->cv_event, &wait, state); | |
163 | atomic_inc(&cvp->cv_waiters); | |
164 | ||
165 | /* Mutex should be dropped after prepare_to_wait() this | |
166 | * ensures we're linked in to the waiters list and avoids the | |
167 | * race where 'cvp->cv_waiters > 0' but the list is empty. */ | |
168 | mutex_exit(mp); | |
169 | time_left = schedule_timeout(time_left); | |
170 | mutex_enter(mp); | |
171 | ||
172 | /* No more waiters a different mutex could be used */ | |
173 | if (atomic_dec_and_test(&cvp->cv_waiters)) | |
174 | cvp->cv_mutex = NULL; | |
175 | ||
176 | finish_wait(&cvp->cv_event, &wait); | |
177 | ||
178 | SRETURN(time_left > 0 ? time_left : -1); | |
179 | } | |
180 | ||
181 | clock_t | |
182 | __cv_timedwait(kcondvar_t *cvp, kmutex_t *mp, clock_t exp_time) | |
183 | { | |
184 | return __cv_timedwait_common(cvp, mp, exp_time, TASK_UNINTERRUPTIBLE); | |
185 | } | |
186 | EXPORT_SYMBOL(__cv_timedwait); | |
187 | ||
188 | clock_t | |
189 | __cv_timedwait_interruptible(kcondvar_t *cvp, kmutex_t *mp, clock_t exp_time) | |
190 | { | |
191 | return __cv_timedwait_common(cvp, mp, exp_time, TASK_INTERRUPTIBLE); | |
192 | } | |
193 | EXPORT_SYMBOL(__cv_timedwait_interruptible); | |
194 | ||
195 | void | |
196 | __cv_signal(kcondvar_t *cvp) | |
197 | { | |
198 | SENTRY; | |
199 | ASSERT(cvp); | |
200 | ASSERT(cvp->cv_magic == CV_MAGIC); | |
201 | ||
202 | /* All waiters are added with WQ_FLAG_EXCLUSIVE so only one | |
203 | * waiter will be set runable with each call to wake_up(). | |
204 | * Additionally wake_up() holds a spin_lock assoicated with | |
205 | * the wait queue to ensure we don't race waking up processes. */ | |
206 | if (atomic_read(&cvp->cv_waiters) > 0) | |
207 | wake_up(&cvp->cv_event); | |
208 | ||
209 | SEXIT; | |
210 | } | |
211 | EXPORT_SYMBOL(__cv_signal); | |
212 | ||
213 | void | |
214 | __cv_broadcast(kcondvar_t *cvp) | |
215 | { | |
216 | ASSERT(cvp); | |
217 | ASSERT(cvp->cv_magic == CV_MAGIC); | |
218 | SENTRY; | |
219 | ||
220 | /* Wake_up_all() will wake up all waiters even those which | |
221 | * have the WQ_FLAG_EXCLUSIVE flag set. */ | |
222 | if (atomic_read(&cvp->cv_waiters) > 0) | |
223 | wake_up_all(&cvp->cv_event); | |
224 | ||
225 | SEXIT; | |
226 | } | |
227 | EXPORT_SYMBOL(__cv_broadcast); |