412 lines
10 KiB
C
412 lines
10 KiB
C
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/*
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* Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
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* Copyright (C) 2007 The Regents of the University of California.
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* Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
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* Written by Brian Behlendorf <behlendorf1@llnl.gov>.
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* UCRL-CODE-235197
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*
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* This file is part of the SPL, Solaris Porting Layer.
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* For details, see <http://zfsonlinux.org/>.
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*
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* The SPL is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*
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* The SPL is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with the SPL. If not, see <http://www.gnu.org/licenses/>.
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*
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* Solaris Porting Layer (SPL) Credential Implementation.
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*/
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#include <sys/condvar.h>
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#include <sys/time.h>
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#include <linux/hrtimer.h>
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#include <linux/compiler_compat.h>
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void
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__cv_init(kcondvar_t *cvp, char *name, kcv_type_t type, void *arg)
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{
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ASSERT(cvp);
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ASSERT(name == NULL);
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ASSERT(type == CV_DEFAULT);
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ASSERT(arg == NULL);
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cvp->cv_magic = CV_MAGIC;
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init_waitqueue_head(&cvp->cv_event);
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init_waitqueue_head(&cvp->cv_destroy);
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atomic_set(&cvp->cv_waiters, 0);
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atomic_set(&cvp->cv_refs, 1);
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cvp->cv_mutex = NULL;
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}
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EXPORT_SYMBOL(__cv_init);
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static int
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cv_destroy_wakeup(kcondvar_t *cvp)
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{
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if (!atomic_read(&cvp->cv_waiters) && !atomic_read(&cvp->cv_refs)) {
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ASSERT(cvp->cv_mutex == NULL);
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ASSERT(!waitqueue_active(&cvp->cv_event));
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return (1);
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}
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return (0);
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}
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void
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__cv_destroy(kcondvar_t *cvp)
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{
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ASSERT(cvp);
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ASSERT(cvp->cv_magic == CV_MAGIC);
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cvp->cv_magic = CV_DESTROY;
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atomic_dec(&cvp->cv_refs);
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/* Block until all waiters are woken and references dropped. */
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while (cv_destroy_wakeup(cvp) == 0)
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wait_event_timeout(cvp->cv_destroy, cv_destroy_wakeup(cvp), 1);
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ASSERT3P(cvp->cv_mutex, ==, NULL);
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ASSERT3S(atomic_read(&cvp->cv_refs), ==, 0);
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ASSERT3S(atomic_read(&cvp->cv_waiters), ==, 0);
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ASSERT3S(waitqueue_active(&cvp->cv_event), ==, 0);
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}
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EXPORT_SYMBOL(__cv_destroy);
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static void
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cv_wait_common(kcondvar_t *cvp, kmutex_t *mp, int state, int io)
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{
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DEFINE_WAIT(wait);
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kmutex_t *m;
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ASSERT(cvp);
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ASSERT(mp);
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ASSERT(cvp->cv_magic == CV_MAGIC);
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ASSERT(mutex_owned(mp));
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atomic_inc(&cvp->cv_refs);
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m = READ_ONCE(cvp->cv_mutex);
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if (!m)
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m = xchg(&cvp->cv_mutex, mp);
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/* Ensure the same mutex is used by all callers */
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ASSERT(m == NULL || m == mp);
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prepare_to_wait_exclusive(&cvp->cv_event, &wait, state);
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atomic_inc(&cvp->cv_waiters);
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/*
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* Mutex should be dropped after prepare_to_wait() this
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* ensures we're linked in to the waiters list and avoids the
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* race where 'cvp->cv_waiters > 0' but the list is empty.
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*/
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mutex_exit(mp);
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if (io)
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io_schedule();
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else
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schedule();
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/* No more waiters a different mutex could be used */
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if (atomic_dec_and_test(&cvp->cv_waiters)) {
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/*
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* This is set without any lock, so it's racy. But this is
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* just for debug anyway, so make it best-effort
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*/
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cvp->cv_mutex = NULL;
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wake_up(&cvp->cv_destroy);
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}
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finish_wait(&cvp->cv_event, &wait);
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atomic_dec(&cvp->cv_refs);
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/*
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* Hold mutex after we release the cvp, otherwise we could dead lock
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* with a thread holding the mutex and call cv_destroy.
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*/
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mutex_enter(mp);
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}
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void
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__cv_wait(kcondvar_t *cvp, kmutex_t *mp)
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{
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cv_wait_common(cvp, mp, TASK_UNINTERRUPTIBLE, 0);
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}
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EXPORT_SYMBOL(__cv_wait);
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void
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__cv_wait_io(kcondvar_t *cvp, kmutex_t *mp)
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{
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cv_wait_common(cvp, mp, TASK_UNINTERRUPTIBLE, 1);
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}
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EXPORT_SYMBOL(__cv_wait_io);
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void
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__cv_wait_sig(kcondvar_t *cvp, kmutex_t *mp)
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{
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cv_wait_common(cvp, mp, TASK_INTERRUPTIBLE, 0);
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}
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EXPORT_SYMBOL(__cv_wait_sig);
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#if defined(HAVE_IO_SCHEDULE_TIMEOUT)
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#define spl_io_schedule_timeout(t) io_schedule_timeout(t)
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#else
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static void
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__cv_wakeup(unsigned long data)
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{
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wake_up_process((struct task_struct *)data);
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}
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static long
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spl_io_schedule_timeout(long time_left)
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{
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long expire_time = jiffies + time_left;
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struct timer_list timer;
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init_timer(&timer);
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setup_timer(&timer, __cv_wakeup, (unsigned long)current);
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timer.expires = expire_time;
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add_timer(&timer);
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io_schedule();
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del_timer_sync(&timer);
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time_left = expire_time - jiffies;
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return (time_left < 0 ? 0 : time_left);
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}
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#endif
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/*
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* 'expire_time' argument is an absolute wall clock time in jiffies.
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* Return value is time left (expire_time - now) or -1 if timeout occurred.
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*/
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static clock_t
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__cv_timedwait_common(kcondvar_t *cvp, kmutex_t *mp, clock_t expire_time,
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int state, int io)
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{
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DEFINE_WAIT(wait);
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kmutex_t *m;
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clock_t time_left;
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ASSERT(cvp);
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ASSERT(mp);
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ASSERT(cvp->cv_magic == CV_MAGIC);
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ASSERT(mutex_owned(mp));
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/* XXX - Does not handle jiffie wrap properly */
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time_left = expire_time - jiffies;
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if (time_left <= 0)
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return (-1);
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atomic_inc(&cvp->cv_refs);
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m = READ_ONCE(cvp->cv_mutex);
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if (!m)
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m = xchg(&cvp->cv_mutex, mp);
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/* Ensure the same mutex is used by all callers */
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ASSERT(m == NULL || m == mp);
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prepare_to_wait_exclusive(&cvp->cv_event, &wait, state);
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atomic_inc(&cvp->cv_waiters);
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/*
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* Mutex should be dropped after prepare_to_wait() this
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* ensures we're linked in to the waiters list and avoids the
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* race where 'cvp->cv_waiters > 0' but the list is empty.
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*/
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mutex_exit(mp);
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if (io)
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time_left = spl_io_schedule_timeout(time_left);
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else
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time_left = schedule_timeout(time_left);
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/* No more waiters a different mutex could be used */
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if (atomic_dec_and_test(&cvp->cv_waiters)) {
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/*
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* This is set without any lock, so it's racy. But this is
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* just for debug anyway, so make it best-effort
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*/
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cvp->cv_mutex = NULL;
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wake_up(&cvp->cv_destroy);
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}
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finish_wait(&cvp->cv_event, &wait);
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atomic_dec(&cvp->cv_refs);
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/*
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* Hold mutex after we release the cvp, otherwise we could dead lock
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* with a thread holding the mutex and call cv_destroy.
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*/
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mutex_enter(mp);
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return (time_left > 0 ? time_left : -1);
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}
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clock_t
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__cv_timedwait(kcondvar_t *cvp, kmutex_t *mp, clock_t exp_time)
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{
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return (__cv_timedwait_common(cvp, mp, exp_time,
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TASK_UNINTERRUPTIBLE, 0));
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}
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EXPORT_SYMBOL(__cv_timedwait);
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clock_t
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__cv_timedwait_io(kcondvar_t *cvp, kmutex_t *mp, clock_t exp_time)
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{
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return (__cv_timedwait_common(cvp, mp, exp_time,
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TASK_UNINTERRUPTIBLE, 1));
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}
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EXPORT_SYMBOL(__cv_timedwait_io);
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clock_t
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__cv_timedwait_sig(kcondvar_t *cvp, kmutex_t *mp, clock_t exp_time)
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{
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return (__cv_timedwait_common(cvp, mp, exp_time,
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TASK_INTERRUPTIBLE, 0));
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}
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EXPORT_SYMBOL(__cv_timedwait_sig);
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/*
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* 'expire_time' argument is an absolute clock time in nanoseconds.
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* Return value is time left (expire_time - now) or -1 if timeout occurred.
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*/
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static clock_t
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__cv_timedwait_hires(kcondvar_t *cvp, kmutex_t *mp, hrtime_t expire_time,
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int state)
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{
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DEFINE_WAIT(wait);
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kmutex_t *m;
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hrtime_t time_left;
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ktime_t ktime_left;
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ASSERT(cvp);
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ASSERT(mp);
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ASSERT(cvp->cv_magic == CV_MAGIC);
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ASSERT(mutex_owned(mp));
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time_left = expire_time - gethrtime();
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if (time_left <= 0)
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return (-1);
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atomic_inc(&cvp->cv_refs);
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m = READ_ONCE(cvp->cv_mutex);
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if (!m)
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m = xchg(&cvp->cv_mutex, mp);
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/* Ensure the same mutex is used by all callers */
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ASSERT(m == NULL || m == mp);
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prepare_to_wait_exclusive(&cvp->cv_event, &wait, state);
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atomic_inc(&cvp->cv_waiters);
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/*
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* Mutex should be dropped after prepare_to_wait() this
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* ensures we're linked in to the waiters list and avoids the
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* race where 'cvp->cv_waiters > 0' but the list is empty.
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*/
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mutex_exit(mp);
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/*
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* Allow a 100 us range to give kernel an opportunity to coalesce
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* interrupts
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*/
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ktime_left = ktime_set(0, time_left);
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schedule_hrtimeout_range(&ktime_left, 100 * NSEC_PER_USEC,
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HRTIMER_MODE_REL);
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/* No more waiters a different mutex could be used */
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if (atomic_dec_and_test(&cvp->cv_waiters)) {
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/*
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* This is set without any lock, so it's racy. But this is
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* just for debug anyway, so make it best-effort
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*/
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cvp->cv_mutex = NULL;
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wake_up(&cvp->cv_destroy);
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}
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finish_wait(&cvp->cv_event, &wait);
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atomic_dec(&cvp->cv_refs);
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mutex_enter(mp);
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time_left = expire_time - gethrtime();
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return (time_left > 0 ? NSEC_TO_TICK(time_left) : -1);
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}
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/*
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* Compatibility wrapper for the cv_timedwait_hires() Illumos interface.
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*/
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static clock_t
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cv_timedwait_hires_common(kcondvar_t *cvp, kmutex_t *mp, hrtime_t tim,
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hrtime_t res, int flag, int state)
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{
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if (res > 1) {
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/*
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* Align expiration to the specified resolution.
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*/
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if (flag & CALLOUT_FLAG_ROUNDUP)
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tim += res - 1;
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tim = (tim / res) * res;
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}
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if (!(flag & CALLOUT_FLAG_ABSOLUTE))
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tim += gethrtime();
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return (__cv_timedwait_hires(cvp, mp, tim, state));
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}
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clock_t
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cv_timedwait_hires(kcondvar_t *cvp, kmutex_t *mp, hrtime_t tim, hrtime_t res,
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int flag)
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{
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return (cv_timedwait_hires_common(cvp, mp, tim, res, flag,
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TASK_UNINTERRUPTIBLE));
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}
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EXPORT_SYMBOL(cv_timedwait_hires);
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clock_t
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cv_timedwait_sig_hires(kcondvar_t *cvp, kmutex_t *mp, hrtime_t tim,
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hrtime_t res, int flag)
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{
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return (cv_timedwait_hires_common(cvp, mp, tim, res, flag,
|
||
|
|
TASK_INTERRUPTIBLE));
|
||
|
|
}
|
||
|
|
EXPORT_SYMBOL(cv_timedwait_sig_hires);
|
||
|
|
|
||
|
|
void
|
||
|
|
__cv_signal(kcondvar_t *cvp)
|
||
|
|
{
|
||
|
|
ASSERT(cvp);
|
||
|
|
ASSERT(cvp->cv_magic == CV_MAGIC);
|
||
|
|
atomic_inc(&cvp->cv_refs);
|
||
|
|
|
||
|
|
/*
|
||
|
|
* All waiters are added with WQ_FLAG_EXCLUSIVE so only one
|
||
|
|
* waiter will be set runable with each call to wake_up().
|
||
|
|
* Additionally wake_up() holds a spin_lock assoicated with
|
||
|
|
* the wait queue to ensure we don't race waking up processes.
|
||
|
|
*/
|
||
|
|
if (atomic_read(&cvp->cv_waiters) > 0)
|
||
|
|
wake_up(&cvp->cv_event);
|
||
|
|
|
||
|
|
atomic_dec(&cvp->cv_refs);
|
||
|
|
}
|
||
|
|
EXPORT_SYMBOL(__cv_signal);
|
||
|
|
|
||
|
|
void
|
||
|
|
__cv_broadcast(kcondvar_t *cvp)
|
||
|
|
{
|
||
|
|
ASSERT(cvp);
|
||
|
|
ASSERT(cvp->cv_magic == CV_MAGIC);
|
||
|
|
atomic_inc(&cvp->cv_refs);
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Wake_up_all() will wake up all waiters even those which
|
||
|
|
* have the WQ_FLAG_EXCLUSIVE flag set.
|
||
|
|
*/
|
||
|
|
if (atomic_read(&cvp->cv_waiters) > 0)
|
||
|
|
wake_up_all(&cvp->cv_event);
|
||
|
|
|
||
|
|
atomic_dec(&cvp->cv_refs);
|
||
|
|
}
|
||
|
|
EXPORT_SYMBOL(__cv_broadcast);
|