diff options
Diffstat (limited to 'sysdeps/mach/hurd/htl/pt-hurd-cond-timedwait.c')
| -rw-r--r-- | sysdeps/mach/hurd/htl/pt-hurd-cond-timedwait.c | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/sysdeps/mach/hurd/htl/pt-hurd-cond-timedwait.c b/sysdeps/mach/hurd/htl/pt-hurd-cond-timedwait.c new file mode 100644 index 0000000000..263d3bfd27 --- /dev/null +++ b/sysdeps/mach/hurd/htl/pt-hurd-cond-timedwait.c @@ -0,0 +1,169 @@ +/* pthread_hurd_cond_timedwait_np. Hurd-specific wait on a condition. + Copyright (C) 2012-2018 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library 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 + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +#include <pthread.h> +#include <assert.h> +#include <hurd/signal.h> + +#include <pt-internal.h> + +extern int __pthread_hurd_cond_timedwait_internal (pthread_cond_t *cond, + pthread_mutex_t *mutex, + const struct timespec + *abstime); + +int +__pthread_hurd_cond_timedwait_np (pthread_cond_t *cond, + pthread_mutex_t *mutex, + const struct timespec *abstime) +{ + return __pthread_hurd_cond_timedwait_internal (cond, mutex, abstime); +} + +strong_alias (__pthread_hurd_cond_timedwait_np, pthread_hurd_cond_timedwait_np); + +int +__pthread_hurd_cond_timedwait_internal (pthread_cond_t *cond, + pthread_mutex_t *mutex, + const struct timespec *abstime) +{ + struct hurd_sigstate *ss = _hurd_self_sigstate (); + struct __pthread *self = _pthread_self (); + error_t err = 0; + int cancel, drain; + clockid_t clock_id = __pthread_default_condattr.__clock; + + /* This function will be called by hurd_thread_cancel while we are blocked + We wake up our thread if it's still blocking or about to block, so it will + progress and notice the cancellation flag. */ + void cancel_me (void) + { + int unblock; + + __pthread_spin_lock (&cond->__lock); + /* The thread only needs to be awaken if it's blocking or about to block. + If it was already unblocked, it's not queued any more. */ + unblock = self->prevp != NULL; + if (unblock) + __pthread_dequeue (self); + __pthread_spin_unlock (&cond->__lock); + + if (unblock) + __pthread_wakeup (self); + } + + assert (ss->intr_port == MACH_PORT_NULL); /* Sanity check for signal bugs. */ + + if (abstime != NULL && (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)) + return EINVAL; + + /* Atomically enqueue our thread on the condition variable's queue of + waiters, and mark our sigstate to indicate that `cancel_me' must be + called to wake us up. We must hold the sigstate lock while acquiring + the condition variable's lock and tweaking it, so that + hurd_thread_cancel can never suspend us and then deadlock waiting for + the condition variable's lock. */ + + __spin_lock (&ss->lock); + __pthread_spin_lock (&cond->__lock); + cancel = ss->cancel; + if (cancel) + /* We were cancelled before doing anything. Don't block at all. */ + ss->cancel = 0; + else + { + /* Put us on the queue so that pthread_cond_broadcast will know to wake + us up. */ + __pthread_enqueue (&cond->__queue, self); + if (cond->__attr) + clock_id = cond->__attr->__clock; + /* Tell hurd_thread_cancel how to unblock us. */ + ss->cancel_hook = &cancel_me; + } + __pthread_spin_unlock (&cond->__lock); + __spin_unlock (&ss->lock); + + if (cancel) + { + /* Cancelled on entry. Just leave the mutex locked. */ + mutex = NULL; + + __spin_lock (&ss->lock); + } + else + { + /* Release MUTEX before blocking. */ + __pthread_mutex_unlock (mutex); + + /* Block the thread. */ + if (abstime != NULL) + err = __pthread_timedblock (self, abstime, clock_id); + else + { + err = 0; + __pthread_block (self); + } + + /* As it was done when enqueueing, prevent hurd_thread_cancel from + suspending us while the condition lock is held. */ + __spin_lock (&ss->lock); + __pthread_spin_lock (&cond->__lock); + if (self->prevp == NULL) + /* Another thread removed us from the list of waiters, which means + a wakeup message has been sent. It was either consumed while + we were blocking, or queued after we timed out and before we + acquired the condition lock, in which case the message queue + must be drained. */ + drain = err ? 1 : 0; + else + { + /* We're still in the list of waiters. Noone attempted to wake us + up, i.e. we timed out. */ + __pthread_dequeue (self); + drain = 0; + } + __pthread_spin_unlock (&cond->__lock); + + if (drain) + __pthread_block (self); + } + + /* Clear the hook, now that we are done blocking. */ + ss->cancel_hook = NULL; + /* Check the cancellation flag; we might have unblocked due to + cancellation rather than a normal pthread_cond_signal or + pthread_cond_broadcast (or we might have just happened to get cancelled + right after waking up). */ + cancel |= ss->cancel; + ss->cancel = 0; + __spin_unlock (&ss->lock); + + if (mutex != NULL) + /* Reacquire the mutex and return. */ + __pthread_mutex_lock (mutex); + + if (cancel) + return EINTR; + else if (err) + { + assert (err == ETIMEDOUT); + return err; + } + + return 0; +} |