diff options
Diffstat (limited to 'lib/libthr/thread/thr_cond.c')
| -rw-r--r-- | lib/libthr/thread/thr_cond.c | 557 |
1 files changed, 557 insertions, 0 deletions
diff --git a/lib/libthr/thread/thr_cond.c b/lib/libthr/thread/thr_cond.c new file mode 100644 index 000000000000..0eb3dac068ca --- /dev/null +++ b/lib/libthr/thread/thr_cond.c @@ -0,0 +1,557 @@ +/*- + * SPDX-License-Identifier: BSD-2-Clause + * + * Copyright (c) 2005 David Xu <davidxu@freebsd.org> + * Copyright (c) 2015 The FreeBSD Foundation + * All rights reserved. + * + * Portions of this software were developed by Konstantin Belousov + * under sponsorship from the FreeBSD Foundation. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice unmodified, this list of conditions, and the following + * disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#include "namespace.h" +#include <stdlib.h> +#include <errno.h> +#include <string.h> +#include <pthread.h> +#include <limits.h> +#include "un-namespace.h" + +#include "thr_private.h" + +_Static_assert(sizeof(struct pthread_cond) <= THR_PAGE_SIZE_MIN, + "pthread_cond too large"); + +/* + * Prototypes + */ +int __pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex, + const struct timespec * abstime); +static int cond_init(pthread_cond_t *cond, const pthread_condattr_t *attr); +static int cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex, + const struct timespec *abstime, int cancel); +static int cond_signal_common(pthread_cond_t *cond); +static int cond_broadcast_common(pthread_cond_t *cond); + +/* + * Double underscore versions are cancellation points. Single underscore + * versions are not and are provided for libc internal usage (which + * shouldn't introduce cancellation points). + */ +__weak_reference(__thr_cond_wait, pthread_cond_wait); +__weak_reference(__thr_cond_wait, __pthread_cond_wait); +__weak_reference(_thr_cond_wait, _pthread_cond_wait); +__weak_reference(__pthread_cond_timedwait, pthread_cond_timedwait); +__weak_reference(_thr_cond_timedwait, _pthread_cond_timedwait); +__weak_reference(_thr_cond_init, pthread_cond_init); +__weak_reference(_thr_cond_init, _pthread_cond_init); +__weak_reference(_thr_cond_destroy, pthread_cond_destroy); +__weak_reference(_thr_cond_destroy, _pthread_cond_destroy); +__weak_reference(_thr_cond_signal, pthread_cond_signal); +__weak_reference(_thr_cond_signal, _pthread_cond_signal); +__weak_reference(_thr_cond_broadcast, pthread_cond_broadcast); +__weak_reference(_thr_cond_broadcast, _pthread_cond_broadcast); + +#define CV_PSHARED(cvp) (((cvp)->kcond.c_flags & USYNC_PROCESS_SHARED) != 0) + +static void +cond_init_body(struct pthread_cond *cvp, const struct pthread_cond_attr *cattr) +{ + + if (cattr == NULL) { + cvp->kcond.c_clockid = CLOCK_REALTIME; + } else { + if (cattr->c_pshared) + cvp->kcond.c_flags |= USYNC_PROCESS_SHARED; + cvp->kcond.c_clockid = cattr->c_clockid; + } +} + +static int +cond_init(pthread_cond_t *cond, const pthread_condattr_t *cond_attr) +{ + struct pthread_cond *cvp; + const struct pthread_cond_attr *cattr; + int pshared; + + cattr = cond_attr != NULL ? *cond_attr : NULL; + if (cattr == NULL || cattr->c_pshared == PTHREAD_PROCESS_PRIVATE) { + pshared = 0; + cvp = calloc(1, sizeof(struct pthread_cond)); + if (cvp == NULL) + return (ENOMEM); + } else { + pshared = 1; + cvp = __thr_pshared_offpage(cond, 1); + if (cvp == NULL) + return (EFAULT); + } + + /* + * Initialise the condition variable structure: + */ + cond_init_body(cvp, cattr); + *cond = pshared ? THR_PSHARED_PTR : cvp; + return (0); +} + +static int +init_static(struct pthread *thread, pthread_cond_t *cond) +{ + int ret; + + THR_LOCK_ACQUIRE(thread, &_cond_static_lock); + + if (*cond == NULL) + ret = cond_init(cond, NULL); + else + ret = 0; + + THR_LOCK_RELEASE(thread, &_cond_static_lock); + + return (ret); +} + +#define CHECK_AND_INIT_COND \ + if (*cond == THR_PSHARED_PTR) { \ + cvp = __thr_pshared_offpage(cond, 0); \ + if (cvp == NULL) \ + return (EINVAL); \ + } else if (__predict_false((cvp = (*cond)) <= THR_COND_DESTROYED)) { \ + if (cvp == THR_COND_INITIALIZER) { \ + int ret; \ + ret = init_static(_get_curthread(), cond); \ + if (ret) \ + return (ret); \ + } else if (cvp == THR_COND_DESTROYED) { \ + return (EINVAL); \ + } \ + cvp = *cond; \ + } + +int +_thr_cond_init(pthread_cond_t * __restrict cond, + const pthread_condattr_t * __restrict cond_attr) +{ + + *cond = NULL; + return (cond_init(cond, cond_attr)); +} + +int +_thr_cond_destroy(pthread_cond_t *cond) +{ + struct pthread_cond *cvp; + int error; + + error = 0; + if (*cond == THR_PSHARED_PTR) { + cvp = __thr_pshared_offpage(cond, 0); + if (cvp != NULL) { + if (cvp->kcond.c_has_waiters) + error = EBUSY; + else + __thr_pshared_destroy(cond); + } + if (error == 0) + *cond = THR_COND_DESTROYED; + } else if ((cvp = *cond) == THR_COND_INITIALIZER) { + /* nothing */ + } else if (cvp == THR_COND_DESTROYED) { + error = EINVAL; + } else { + cvp = *cond; + if (cvp->__has_user_waiters || cvp->kcond.c_has_waiters) + error = EBUSY; + else { + *cond = THR_COND_DESTROYED; + free(cvp); + } + } + return (error); +} + +/* + * Cancellation behavior: + * Thread may be canceled at start, if thread is canceled, it means it + * did not get a wakeup from pthread_cond_signal(), otherwise, it is + * not canceled. + * Thread cancellation never cause wakeup from pthread_cond_signal() + * to be lost. + */ +static int +cond_wait_kernel(struct pthread_cond *cvp, struct pthread_mutex *mp, + const struct timespec *abstime, int cancel) +{ + struct pthread *curthread; + int error, error2, recurse, robust; + + curthread = _get_curthread(); + robust = _mutex_enter_robust(curthread, mp); + + error = _mutex_cv_detach(mp, &recurse); + if (error != 0) { + if (robust) + _mutex_leave_robust(curthread, mp); + return (error); + } + + if (cancel) + _thr_cancel_enter2(curthread, 0); + error = _thr_ucond_wait(&cvp->kcond, &mp->m_lock, abstime, + CVWAIT_ABSTIME | CVWAIT_CLOCKID); + if (cancel) + _thr_cancel_leave(curthread, 0); + + /* + * Note that PP mutex and ROBUST mutex may return + * interesting error codes. + */ + if (error == 0) { + error2 = _mutex_cv_lock(mp, recurse, true); + } else if (error == EINTR || error == ETIMEDOUT) { + error2 = _mutex_cv_lock(mp, recurse, true); + /* + * Do not do cancellation on EOWNERDEAD there. The + * cancellation cleanup handler will use the protected + * state and unlock the mutex without making the state + * consistent and the state will be unrecoverable. + */ + if (error2 == 0 && cancel) { + if (robust) { + _mutex_leave_robust(curthread, mp); + robust = false; + } + _thr_testcancel(curthread); + } + + if (error == EINTR) + error = 0; + } else { + /* We know that it didn't unlock the mutex. */ + _mutex_cv_attach(mp, recurse); + if (cancel) { + if (robust) { + _mutex_leave_robust(curthread, mp); + robust = false; + } + _thr_testcancel(curthread); + } + error2 = 0; + } + if (robust) + _mutex_leave_robust(curthread, mp); + return (error2 != 0 ? error2 : error); +} + +/* + * Thread waits in userland queue whenever possible, when thread + * is signaled or broadcasted, it is removed from the queue, and + * is saved in curthread's defer_waiters[] buffer, but won't be + * woken up until mutex is unlocked. + */ + +static int +cond_wait_user(struct pthread_cond *cvp, struct pthread_mutex *mp, + const struct timespec *abstime, int cancel) +{ + struct pthread *curthread; + struct sleepqueue *sq; + int deferred, error, error2, recurse; + + curthread = _get_curthread(); + if (curthread->wchan != NULL) + PANIC("thread %p was already on queue.", curthread); + + if (cancel) + _thr_testcancel(curthread); + + _sleepq_lock(cvp); + /* + * set __has_user_waiters before unlocking mutex, this allows + * us to check it without locking in pthread_cond_signal(). + */ + cvp->__has_user_waiters = 1; + deferred = 0; + (void)_mutex_cv_unlock(mp, &recurse, &deferred); + curthread->mutex_obj = mp; + _sleepq_add(cvp, curthread); + for(;;) { + _thr_clear_wake(curthread); + _sleepq_unlock(cvp); + if (deferred) { + deferred = 0; + if ((mp->m_lock.m_owner & UMUTEX_CONTESTED) == 0) + (void)_umtx_op_err(&mp->m_lock, + UMTX_OP_MUTEX_WAKE2, mp->m_lock.m_flags, + 0, 0); + } + if (curthread->nwaiter_defer > 0) { + _thr_wake_all(curthread->defer_waiters, + curthread->nwaiter_defer); + curthread->nwaiter_defer = 0; + } + + if (cancel) + _thr_cancel_enter2(curthread, 0); + error = _thr_sleep(curthread, cvp->kcond.c_clockid, abstime); + if (cancel) + _thr_cancel_leave(curthread, 0); + + _sleepq_lock(cvp); + if (curthread->wchan == NULL) { + error = 0; + break; + } else if (cancel && SHOULD_CANCEL(curthread)) { + sq = _sleepq_lookup(cvp); + cvp->__has_user_waiters = _sleepq_remove(sq, curthread); + _sleepq_unlock(cvp); + curthread->mutex_obj = NULL; + error2 = _mutex_cv_lock(mp, recurse, false); + if (!THR_IN_CRITICAL(curthread)) + _pthread_exit(PTHREAD_CANCELED); + else /* this should not happen */ + return (error2); + } else if (error == ETIMEDOUT) { + sq = _sleepq_lookup(cvp); + cvp->__has_user_waiters = + _sleepq_remove(sq, curthread); + break; + } + } + _sleepq_unlock(cvp); + curthread->mutex_obj = NULL; + error2 = _mutex_cv_lock(mp, recurse, false); + if (error == 0) + error = error2; + return (error); +} + +static int +cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex, + const struct timespec *abstime, int cancel) +{ + struct pthread *curthread = _get_curthread(); + struct pthread_cond *cvp; + struct pthread_mutex *mp; + int error; + + CHECK_AND_INIT_COND + + if (*mutex == THR_PSHARED_PTR) { + mp = __thr_pshared_offpage(mutex, 0); + if (mp == NULL) + return (EINVAL); + } else { + mp = *mutex; + } + + if ((error = _mutex_owned(curthread, mp)) != 0) + return (error); + + if (curthread->attr.sched_policy != SCHED_OTHER || + (mp->m_lock.m_flags & (UMUTEX_PRIO_PROTECT | UMUTEX_PRIO_INHERIT | + USYNC_PROCESS_SHARED)) != 0 || CV_PSHARED(cvp)) + return (cond_wait_kernel(cvp, mp, abstime, cancel)); + else + return (cond_wait_user(cvp, mp, abstime, cancel)); +} + +int +_thr_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex) +{ + + return (cond_wait_common(cond, mutex, NULL, 0)); +} + +int +__thr_cond_wait(pthread_cond_t * __restrict cond, + pthread_mutex_t * __restrict mutex) +{ + + return (cond_wait_common(cond, mutex, NULL, 1)); +} + +int +_thr_cond_timedwait(pthread_cond_t * __restrict cond, + pthread_mutex_t * __restrict mutex, + const struct timespec * __restrict abstime) +{ + + if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 || + abstime->tv_nsec >= 1000000000) + return (EINVAL); + + return (cond_wait_common(cond, mutex, abstime, 0)); +} + +int +__pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex, + const struct timespec *abstime) +{ + + if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 || + abstime->tv_nsec >= 1000000000) + return (EINVAL); + + return (cond_wait_common(cond, mutex, abstime, 1)); +} + +static int +cond_signal_common(pthread_cond_t *cond) +{ + struct pthread *curthread = _get_curthread(); + struct pthread *td; + struct pthread_cond *cvp; + struct pthread_mutex *mp; + struct sleepqueue *sq; + int *waddr; + int pshared; + + /* + * If the condition variable is statically initialized, perform dynamic + * initialization. + */ + CHECK_AND_INIT_COND + + pshared = CV_PSHARED(cvp); + + _thr_ucond_signal(&cvp->kcond); + + if (pshared || cvp->__has_user_waiters == 0) + return (0); + + curthread = _get_curthread(); + waddr = NULL; + _sleepq_lock(cvp); + sq = _sleepq_lookup(cvp); + if (sq == NULL) { + _sleepq_unlock(cvp); + return (0); + } + + td = _sleepq_first(sq); + mp = td->mutex_obj; + cvp->__has_user_waiters = _sleepq_remove(sq, td); + if (PMUTEX_OWNER_ID(mp) == TID(curthread)) { + if (curthread->nwaiter_defer >= MAX_DEFER_WAITERS) { + _thr_wake_all(curthread->defer_waiters, + curthread->nwaiter_defer); + curthread->nwaiter_defer = 0; + } + curthread->defer_waiters[curthread->nwaiter_defer++] = + &td->wake_addr->value; + mp->m_flags |= PMUTEX_FLAG_DEFERRED; + } else { + waddr = &td->wake_addr->value; + } + _sleepq_unlock(cvp); + if (waddr != NULL) + _thr_set_wake(waddr); + return (0); +} + +struct broadcast_arg { + struct pthread *curthread; + unsigned int *waddrs[MAX_DEFER_WAITERS]; + int count; +}; + +static void +drop_cb(struct pthread *td, void *arg) +{ + struct broadcast_arg *ba = arg; + struct pthread_mutex *mp; + struct pthread *curthread = ba->curthread; + + mp = td->mutex_obj; + if (PMUTEX_OWNER_ID(mp) == TID(curthread)) { + if (curthread->nwaiter_defer >= MAX_DEFER_WAITERS) { + _thr_wake_all(curthread->defer_waiters, + curthread->nwaiter_defer); + curthread->nwaiter_defer = 0; + } + curthread->defer_waiters[curthread->nwaiter_defer++] = + &td->wake_addr->value; + mp->m_flags |= PMUTEX_FLAG_DEFERRED; + } else { + if (ba->count >= MAX_DEFER_WAITERS) { + _thr_wake_all(ba->waddrs, ba->count); + ba->count = 0; + } + ba->waddrs[ba->count++] = &td->wake_addr->value; + } +} + +static int +cond_broadcast_common(pthread_cond_t *cond) +{ + int pshared; + struct pthread_cond *cvp; + struct sleepqueue *sq; + struct broadcast_arg ba; + + /* + * If the condition variable is statically initialized, perform dynamic + * initialization. + */ + CHECK_AND_INIT_COND + + pshared = CV_PSHARED(cvp); + + _thr_ucond_broadcast(&cvp->kcond); + + if (pshared || cvp->__has_user_waiters == 0) + return (0); + + ba.curthread = _get_curthread(); + ba.count = 0; + + _sleepq_lock(cvp); + sq = _sleepq_lookup(cvp); + if (sq == NULL) { + _sleepq_unlock(cvp); + return (0); + } + _sleepq_drop(sq, drop_cb, &ba); + cvp->__has_user_waiters = 0; + _sleepq_unlock(cvp); + if (ba.count > 0) + _thr_wake_all(ba.waddrs, ba.count); + return (0); +} + +int +_thr_cond_signal(pthread_cond_t * cond) +{ + + return (cond_signal_common(cond)); +} + +int +_thr_cond_broadcast(pthread_cond_t * cond) +{ + + return (cond_broadcast_common(cond)); +} |