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