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git.proxmox.com Git - mirror_spl-debian.git/blob - module/spl/spl-condvar.c
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>.
8 * This file is part of the SPL, Solaris Porting Layer.
9 * For details, see <http://zfsonlinux.org/>.
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.
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
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/>.
24 * Solaris Porting Layer (SPL) Credential Implementation.
27 #include <sys/condvar.h>
29 #include <linux/hrtimer.h>
32 __cv_init(kcondvar_t
*cvp
, char *name
, kcv_type_t type
, void *arg
)
36 ASSERT(type
== CV_DEFAULT
);
39 cvp
->cv_magic
= CV_MAGIC
;
40 init_waitqueue_head(&cvp
->cv_event
);
41 init_waitqueue_head(&cvp
->cv_destroy
);
42 atomic_set(&cvp
->cv_waiters
, 0);
43 atomic_set(&cvp
->cv_refs
, 1);
46 EXPORT_SYMBOL(__cv_init
);
49 cv_destroy_wakeup(kcondvar_t
*cvp
)
51 if (!atomic_read(&cvp
->cv_waiters
) && !atomic_read(&cvp
->cv_refs
)) {
52 ASSERT(cvp
->cv_mutex
== NULL
);
53 ASSERT(!waitqueue_active(&cvp
->cv_event
));
61 __cv_destroy(kcondvar_t
*cvp
)
64 ASSERT(cvp
->cv_magic
== CV_MAGIC
);
66 cvp
->cv_magic
= CV_DESTROY
;
67 atomic_dec(&cvp
->cv_refs
);
69 /* Block until all waiters are woken and references dropped. */
70 while (cv_destroy_wakeup(cvp
) == 0)
71 wait_event_timeout(cvp
->cv_destroy
, cv_destroy_wakeup(cvp
), 1);
73 ASSERT3P(cvp
->cv_mutex
, ==, NULL
);
74 ASSERT3S(atomic_read(&cvp
->cv_refs
), ==, 0);
75 ASSERT3S(atomic_read(&cvp
->cv_waiters
), ==, 0);
76 ASSERT3S(waitqueue_active(&cvp
->cv_event
), ==, 0);
78 EXPORT_SYMBOL(__cv_destroy
);
81 cv_wait_common(kcondvar_t
*cvp
, kmutex_t
*mp
, int state
, int io
)
88 ASSERT(cvp
->cv_magic
== CV_MAGIC
);
89 ASSERT(mutex_owned(mp
));
90 atomic_inc(&cvp
->cv_refs
);
92 m
= ACCESS_ONCE(cvp
->cv_mutex
);
94 m
= xchg(&cvp
->cv_mutex
, mp
);
95 /* Ensure the same mutex is used by all callers */
96 ASSERT(m
== NULL
|| m
== mp
);
98 prepare_to_wait_exclusive(&cvp
->cv_event
, &wait
, state
);
99 atomic_inc(&cvp
->cv_waiters
);
102 * Mutex should be dropped after prepare_to_wait() this
103 * ensures we're linked in to the waiters list and avoids the
104 * race where 'cvp->cv_waiters > 0' but the list is empty.
112 /* No more waiters a different mutex could be used */
113 if (atomic_dec_and_test(&cvp
->cv_waiters
)) {
115 * This is set without any lock, so it's racy. But this is
116 * just for debug anyway, so make it best-effort
118 cvp
->cv_mutex
= NULL
;
119 wake_up(&cvp
->cv_destroy
);
122 finish_wait(&cvp
->cv_event
, &wait
);
123 atomic_dec(&cvp
->cv_refs
);
126 * Hold mutex after we release the cvp, otherwise we could dead lock
127 * with a thread holding the mutex and call cv_destroy.
133 __cv_wait(kcondvar_t
*cvp
, kmutex_t
*mp
)
135 cv_wait_common(cvp
, mp
, TASK_UNINTERRUPTIBLE
, 0);
137 EXPORT_SYMBOL(__cv_wait
);
140 __cv_wait_sig(kcondvar_t
*cvp
, kmutex_t
*mp
)
142 cv_wait_common(cvp
, mp
, TASK_INTERRUPTIBLE
, 0);
144 EXPORT_SYMBOL(__cv_wait_sig
);
147 __cv_wait_io(kcondvar_t
*cvp
, kmutex_t
*mp
)
149 cv_wait_common(cvp
, mp
, TASK_UNINTERRUPTIBLE
, 1);
151 EXPORT_SYMBOL(__cv_wait_io
);
154 * 'expire_time' argument is an absolute wall clock time in jiffies.
155 * Return value is time left (expire_time - now) or -1 if timeout occurred.
158 __cv_timedwait_common(kcondvar_t
*cvp
, kmutex_t
*mp
, clock_t expire_time
,
167 ASSERT(cvp
->cv_magic
== CV_MAGIC
);
168 ASSERT(mutex_owned(mp
));
170 /* XXX - Does not handle jiffie wrap properly */
171 time_left
= expire_time
- jiffies
;
175 atomic_inc(&cvp
->cv_refs
);
176 m
= ACCESS_ONCE(cvp
->cv_mutex
);
178 m
= xchg(&cvp
->cv_mutex
, mp
);
179 /* Ensure the same mutex is used by all callers */
180 ASSERT(m
== NULL
|| m
== mp
);
182 prepare_to_wait_exclusive(&cvp
->cv_event
, &wait
, state
);
183 atomic_inc(&cvp
->cv_waiters
);
186 * Mutex should be dropped after prepare_to_wait() this
187 * ensures we're linked in to the waiters list and avoids the
188 * race where 'cvp->cv_waiters > 0' but the list is empty.
191 time_left
= schedule_timeout(time_left
);
193 /* No more waiters a different mutex could be used */
194 if (atomic_dec_and_test(&cvp
->cv_waiters
)) {
196 * This is set without any lock, so it's racy. But this is
197 * just for debug anyway, so make it best-effort
199 cvp
->cv_mutex
= NULL
;
200 wake_up(&cvp
->cv_destroy
);
203 finish_wait(&cvp
->cv_event
, &wait
);
204 atomic_dec(&cvp
->cv_refs
);
207 * Hold mutex after we release the cvp, otherwise we could dead lock
208 * with a thread holding the mutex and call cv_destroy.
211 return (time_left
> 0 ? time_left
: -1);
215 __cv_timedwait(kcondvar_t
*cvp
, kmutex_t
*mp
, clock_t exp_time
)
217 return (__cv_timedwait_common(cvp
, mp
, exp_time
, TASK_UNINTERRUPTIBLE
));
219 EXPORT_SYMBOL(__cv_timedwait
);
222 __cv_timedwait_sig(kcondvar_t
*cvp
, kmutex_t
*mp
, clock_t exp_time
)
224 return (__cv_timedwait_common(cvp
, mp
, exp_time
, TASK_INTERRUPTIBLE
));
226 EXPORT_SYMBOL(__cv_timedwait_sig
);
229 * 'expire_time' argument is an absolute clock time in nanoseconds.
230 * Return value is time left (expire_time - now) or -1 if timeout occurred.
233 __cv_timedwait_hires(kcondvar_t
*cvp
, kmutex_t
*mp
, hrtime_t expire_time
,
243 ASSERT(cvp
->cv_magic
== CV_MAGIC
);
244 ASSERT(mutex_owned(mp
));
246 time_left
= expire_time
- gethrtime();
250 atomic_inc(&cvp
->cv_refs
);
251 m
= ACCESS_ONCE(cvp
->cv_mutex
);
253 m
= xchg(&cvp
->cv_mutex
, mp
);
254 /* Ensure the same mutex is used by all callers */
255 ASSERT(m
== NULL
|| m
== mp
);
257 prepare_to_wait_exclusive(&cvp
->cv_event
, &wait
, state
);
258 atomic_inc(&cvp
->cv_waiters
);
261 * Mutex should be dropped after prepare_to_wait() this
262 * ensures we're linked in to the waiters list and avoids the
263 * race where 'cvp->cv_waiters > 0' but the list is empty.
267 * Allow a 100 us range to give kernel an opportunity to coalesce
270 ktime_left
= ktime_set(0, time_left
);
271 schedule_hrtimeout_range(&ktime_left
, 100 * NSEC_PER_USEC
,
274 /* No more waiters a different mutex could be used */
275 if (atomic_dec_and_test(&cvp
->cv_waiters
)) {
277 * This is set without any lock, so it's racy. But this is
278 * just for debug anyway, so make it best-effort
280 cvp
->cv_mutex
= NULL
;
281 wake_up(&cvp
->cv_destroy
);
284 finish_wait(&cvp
->cv_event
, &wait
);
285 atomic_dec(&cvp
->cv_refs
);
288 time_left
= expire_time
- gethrtime();
289 return (time_left
> 0 ? NSEC_TO_TICK(time_left
) : -1);
293 * Compatibility wrapper for the cv_timedwait_hires() Illumos interface.
296 cv_timedwait_hires_common(kcondvar_t
*cvp
, kmutex_t
*mp
, hrtime_t tim
, hrtime_t res
,
301 * Align expiration to the specified resolution.
303 if (flag
& CALLOUT_FLAG_ROUNDUP
)
305 tim
= (tim
/ res
) * res
;
308 if (!(flag
& CALLOUT_FLAG_ABSOLUTE
))
311 return (__cv_timedwait_hires(cvp
, mp
, tim
, state
));
315 cv_timedwait_hires(kcondvar_t
*cvp
, kmutex_t
*mp
, hrtime_t tim
, hrtime_t res
,
318 return (cv_timedwait_hires_common(cvp
, mp
, tim
, res
, flag
,
319 TASK_UNINTERRUPTIBLE
));
321 EXPORT_SYMBOL(cv_timedwait_hires
);
324 cv_timedwait_sig_hires(kcondvar_t
*cvp
, kmutex_t
*mp
, hrtime_t tim
, hrtime_t res
,
327 return (cv_timedwait_hires_common(cvp
, mp
, tim
, res
, flag
,
328 TASK_INTERRUPTIBLE
));
330 EXPORT_SYMBOL(cv_timedwait_sig_hires
);
333 __cv_signal(kcondvar_t
*cvp
)
336 ASSERT(cvp
->cv_magic
== CV_MAGIC
);
337 atomic_inc(&cvp
->cv_refs
);
340 * All waiters are added with WQ_FLAG_EXCLUSIVE so only one
341 * waiter will be set runable with each call to wake_up().
342 * Additionally wake_up() holds a spin_lock assoicated with
343 * the wait queue to ensure we don't race waking up processes.
345 if (atomic_read(&cvp
->cv_waiters
) > 0)
346 wake_up(&cvp
->cv_event
);
348 atomic_dec(&cvp
->cv_refs
);
350 EXPORT_SYMBOL(__cv_signal
);
353 __cv_broadcast(kcondvar_t
*cvp
)
356 ASSERT(cvp
->cv_magic
== CV_MAGIC
);
357 atomic_inc(&cvp
->cv_refs
);
360 * Wake_up_all() will wake up all waiters even those which
361 * have the WQ_FLAG_EXCLUSIVE flag set.
363 if (atomic_read(&cvp
->cv_waiters
) > 0)
364 wake_up_all(&cvp
->cv_event
);
366 atomic_dec(&cvp
->cv_refs
);
368 EXPORT_SYMBOL(__cv_broadcast
);