diff options
Diffstat (limited to 'lib/libpthread/thread/thr_kern.c')
| -rw-r--r-- | lib/libpthread/thread/thr_kern.c | 1139 |
1 files changed, 1139 insertions, 0 deletions
diff --git a/lib/libpthread/thread/thr_kern.c b/lib/libpthread/thread/thr_kern.c new file mode 100644 index 0000000..a4cc3c3 --- /dev/null +++ b/lib/libpthread/thread/thr_kern.c @@ -0,0 +1,1139 @@ +/* + * Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au> + * All rights reserved. + * + * 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, 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. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by John Birrell. + * 4. Neither the name of the author nor the names of any co-contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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. + * + * $FreeBSD$ + * + */ +#include <errno.h> +#include <poll.h> +#include <stdlib.h> +#include <stdarg.h> +#include <string.h> +#include <unistd.h> +#include <setjmp.h> +#include <sys/param.h> +#include <sys/types.h> +#include <sys/signalvar.h> +#include <sys/stat.h> +#include <sys/time.h> +#include <sys/socket.h> +#include <sys/uio.h> +#include <sys/syscall.h> +#include <fcntl.h> +#include <pthread.h> +#include "pthread_private.h" + +/* #define DEBUG_THREAD_KERN */ +#ifdef DEBUG_THREAD_KERN +#define DBG_MSG stdout_debug +#else +#define DBG_MSG(x...) +#endif + +/* Static function prototype definitions: */ +static void +thread_kern_poll(int wait_reqd); + +static void +dequeue_signals(void); + +static inline void +thread_run_switch_hook(pthread_t thread_out, pthread_t thread_in); + +/* Static variables: */ +static int last_tick = 0; +static int called_from_handler = 0; + +/* + * This is called when a signal handler finishes and wants to + * return to a previous frame. + */ +void +_thread_kern_sched_frame(struct pthread_signal_frame *psf) +{ + struct pthread *curthread = _get_curthread(); + + /* + * Flag the pthread kernel as executing scheduler code + * to avoid a signal from interrupting this execution and + * corrupting the (soon-to-be) current frame. + */ + _thread_kern_in_sched = 1; + + /* Restore the signal frame: */ + _thread_sigframe_restore(curthread, psf); + + /* The signal mask was restored; check for any pending signals: */ + curthread->check_pending = 1; + + /* Switch to the thread scheduler: */ + ___longjmp(_thread_kern_sched_jb, 1); +} + + +void +_thread_kern_sched(ucontext_t *ucp) +{ + struct pthread *curthread = _get_curthread(); + + /* + * Flag the pthread kernel as executing scheduler code + * to avoid a scheduler signal from interrupting this + * execution and calling the scheduler again. + */ + _thread_kern_in_sched = 1; + + /* Check if this function was called from the signal handler: */ + if (ucp != NULL) { + /* XXX - Save FP registers? */ + FP_SAVE_UC(ucp); + called_from_handler = 1; + DBG_MSG("Entering scheduler due to signal\n"); + } + + /* Save the state of the current thread: */ + if (_setjmp(curthread->ctx.jb) != 0) { + DBG_MSG("Returned from ___longjmp, thread %p\n", + curthread); + /* + * This point is reached when a longjmp() is called + * to restore the state of a thread. + * + * This is the normal way out of the scheduler. + */ + _thread_kern_in_sched = 0; + + if (curthread->sig_defer_count == 0) { + if (((curthread->cancelflags & + PTHREAD_AT_CANCEL_POINT) == 0) && + ((curthread->cancelflags & + PTHREAD_CANCEL_ASYNCHRONOUS) != 0)) + /* + * Cancellations override signals. + * + * Stick a cancellation point at the + * start of each async-cancellable + * thread's resumption. + * + * We allow threads woken at cancel + * points to do their own checks. + */ + pthread_testcancel(); + } + + if (_sched_switch_hook != NULL) { + /* Run the installed switch hook: */ + thread_run_switch_hook(_last_user_thread, curthread); + } + if (ucp == NULL) + return; + else { + /* XXX - Restore FP registers? */ + FP_RESTORE_UC(ucp); + + /* + * Set the process signal mask in the context; it + * could have changed by the handler. + */ + ucp->uc_sigmask = _process_sigmask; + + /* Resume the interrupted thread: */ + __sys_sigreturn(ucp); + } + } + /* Switch to the thread scheduler: */ + ___longjmp(_thread_kern_sched_jb, 1); +} + +void +_thread_kern_sched_sig(void) +{ + struct pthread *curthread = _get_curthread(); + + curthread->check_pending = 1; + _thread_kern_sched(NULL); +} + + +void +_thread_kern_scheduler(void) +{ + struct timespec ts; + struct timeval tv; + struct pthread *curthread = _get_curthread(); + pthread_t pthread, pthread_h; + unsigned int current_tick; + int add_to_prioq; + + /* If the currently running thread is a user thread, save it: */ + if ((curthread->flags & PTHREAD_FLAGS_PRIVATE) == 0) + _last_user_thread = curthread; + + if (called_from_handler != 0) { + called_from_handler = 0; + + /* + * We were called from a signal handler; restore the process + * signal mask. + */ + if (__sys_sigprocmask(SIG_SETMASK, + &_process_sigmask, NULL) != 0) + PANIC("Unable to restore process mask after signal"); + } + + /* + * Enter a scheduling loop that finds the next thread that is + * ready to run. This loop completes when there are no more threads + * in the global list or when a thread has its state restored by + * either a sigreturn (if the state was saved as a sigcontext) or a + * longjmp (if the state was saved by a setjmp). + */ + while (!(TAILQ_EMPTY(&_thread_list))) { + /* Get the current time of day: */ + GET_CURRENT_TOD(tv); + TIMEVAL_TO_TIMESPEC(&tv, &ts); + current_tick = _sched_ticks; + + /* + * Protect the scheduling queues from access by the signal + * handler. + */ + _queue_signals = 1; + add_to_prioq = 0; + + if (curthread != &_thread_kern_thread) { + /* + * This thread no longer needs to yield the CPU. + */ + curthread->yield_on_sig_undefer = 0; + + if (curthread->state != PS_RUNNING) { + /* + * Save the current time as the time that the + * thread became inactive: + */ + curthread->last_inactive = (long)current_tick; + if (curthread->last_inactive < + curthread->last_active) { + /* Account for a rollover: */ + curthread->last_inactive =+ + UINT_MAX + 1; + } + } + + /* + * Place the currently running thread into the + * appropriate queue(s). + */ + switch (curthread->state) { + case PS_DEAD: + case PS_STATE_MAX: /* to silence -Wall */ + case PS_SUSPENDED: + /* + * Dead and suspended threads are not placed + * in any queue: + */ + break; + + case PS_RUNNING: + /* + * Runnable threads can't be placed in the + * priority queue until after waiting threads + * are polled (to preserve round-robin + * scheduling). + */ + add_to_prioq = 1; + break; + + /* + * States which do not depend on file descriptor I/O + * operations or timeouts: + */ + case PS_DEADLOCK: + case PS_FDLR_WAIT: + case PS_FDLW_WAIT: + case PS_FILE_WAIT: + case PS_JOIN: + case PS_MUTEX_WAIT: + case PS_SIGSUSPEND: + case PS_SIGTHREAD: + case PS_SIGWAIT: + case PS_WAIT_WAIT: + /* No timeouts for these states: */ + curthread->wakeup_time.tv_sec = -1; + curthread->wakeup_time.tv_nsec = -1; + + /* Restart the time slice: */ + curthread->slice_usec = -1; + + /* Insert into the waiting queue: */ + PTHREAD_WAITQ_INSERT(curthread); + break; + + /* States which can timeout: */ + case PS_COND_WAIT: + case PS_SLEEP_WAIT: + /* Restart the time slice: */ + curthread->slice_usec = -1; + + /* Insert into the waiting queue: */ + PTHREAD_WAITQ_INSERT(curthread); + break; + + /* States that require periodic work: */ + case PS_SPINBLOCK: + /* No timeouts for this state: */ + curthread->wakeup_time.tv_sec = -1; + curthread->wakeup_time.tv_nsec = -1; + + /* Increment spinblock count: */ + _spinblock_count++; + + /* FALLTHROUGH */ + case PS_FDR_WAIT: + case PS_FDW_WAIT: + case PS_POLL_WAIT: + case PS_SELECT_WAIT: + /* Restart the time slice: */ + curthread->slice_usec = -1; + + /* Insert into the waiting queue: */ + PTHREAD_WAITQ_INSERT(curthread); + + /* Insert into the work queue: */ + PTHREAD_WORKQ_INSERT(curthread); + break; + } + + /* + * Are there pending signals for this thread? + * + * This check has to be performed after the thread + * has been placed in the queue(s) appropriate for + * its state. The process of adding pending signals + * can change a threads state, which in turn will + * attempt to add or remove the thread from any + * scheduling queue to which it belongs. + */ + if (curthread->check_pending != 0) { + curthread->check_pending = 0; + _thread_sig_check_pending(curthread); + } + } + + /* + * Avoid polling file descriptors if there are none + * waiting: + */ + if (TAILQ_EMPTY(&_workq) != 0) { + } + /* + * Poll file descriptors only if a new scheduling signal + * has occurred or if we have no more runnable threads. + */ + else if (((current_tick = _sched_ticks) != last_tick) || + ((curthread->state != PS_RUNNING) && + (PTHREAD_PRIOQ_FIRST() == NULL))) { + /* Unprotect the scheduling queues: */ + _queue_signals = 0; + + /* + * Poll file descriptors to update the state of threads + * waiting on file I/O where data may be available: + */ + thread_kern_poll(0); + + /* Protect the scheduling queues: */ + _queue_signals = 1; + } + last_tick = current_tick; + + /* + * Wake up threads that have timedout. This has to be + * done after polling in case a thread does a poll or + * select with zero time. + */ + PTHREAD_WAITQ_SETACTIVE(); + while (((pthread = TAILQ_FIRST(&_waitingq)) != NULL) && + (pthread->wakeup_time.tv_sec != -1) && + (((pthread->wakeup_time.tv_sec == 0) && + (pthread->wakeup_time.tv_nsec == 0)) || + (pthread->wakeup_time.tv_sec < ts.tv_sec) || + ((pthread->wakeup_time.tv_sec == ts.tv_sec) && + (pthread->wakeup_time.tv_nsec <= ts.tv_nsec)))) { + switch (pthread->state) { + case PS_POLL_WAIT: + case PS_SELECT_WAIT: + /* Return zero file descriptors ready: */ + pthread->data.poll_data->nfds = 0; + /* fall through */ + default: + /* + * Remove this thread from the waiting queue + * (and work queue if necessary) and place it + * in the ready queue. + */ + PTHREAD_WAITQ_CLEARACTIVE(); + if (pthread->flags & PTHREAD_FLAGS_IN_WORKQ) + PTHREAD_WORKQ_REMOVE(pthread); + PTHREAD_NEW_STATE(pthread, PS_RUNNING); + PTHREAD_WAITQ_SETACTIVE(); + break; + } + /* + * Flag the timeout in the thread structure: + */ + pthread->timeout = 1; + } + PTHREAD_WAITQ_CLEARACTIVE(); + + /* + * Check to see if the current thread needs to be added + * to the priority queue: + */ + if (add_to_prioq != 0) { + /* + * Save the current time as the time that the + * thread became inactive: + */ + current_tick = _sched_ticks; + curthread->last_inactive = (long)current_tick; + if (curthread->last_inactive < + curthread->last_active) { + /* Account for a rollover: */ + curthread->last_inactive =+ UINT_MAX + 1; + } + + if ((curthread->slice_usec != -1) && + (curthread->attr.sched_policy != SCHED_FIFO)) { + /* + * Accumulate the number of microseconds for + * which the current thread has run: + */ + curthread->slice_usec += + (curthread->last_inactive - + curthread->last_active) * + (long)_clock_res_usec; + /* Check for time quantum exceeded: */ + if (curthread->slice_usec > TIMESLICE_USEC) + curthread->slice_usec = -1; + } + + if (curthread->slice_usec == -1) { + /* + * The thread exceeded its time + * quantum or it yielded the CPU; + * place it at the tail of the + * queue for its priority. + */ + PTHREAD_PRIOQ_INSERT_TAIL(curthread); + } else { + /* + * The thread hasn't exceeded its + * interval. Place it at the head + * of the queue for its priority. + */ + PTHREAD_PRIOQ_INSERT_HEAD(curthread); + } + } + + /* + * Get the highest priority thread in the ready queue. + */ + pthread_h = PTHREAD_PRIOQ_FIRST(); + + /* Check if there are no threads ready to run: */ + if (pthread_h == NULL) { + /* + * Lock the pthread kernel by changing the pointer to + * the running thread to point to the global kernel + * thread structure: + */ + _set_curthread(&_thread_kern_thread); + curthread = &_thread_kern_thread; + + DBG_MSG("No runnable threads, using kernel thread %p\n", + curthread); + + /* Unprotect the scheduling queues: */ + _queue_signals = 0; + + /* + * There are no threads ready to run, so wait until + * something happens that changes this condition: + */ + thread_kern_poll(1); + + /* + * This process' usage will likely be very small + * while waiting in a poll. Since the scheduling + * clock is based on the profiling timer, it is + * unlikely that the profiling timer will fire + * and update the time of day. To account for this, + * get the time of day after polling with a timeout. + */ + gettimeofday((struct timeval *) &_sched_tod, NULL); + + /* Check once more for a runnable thread: */ + _queue_signals = 1; + pthread_h = PTHREAD_PRIOQ_FIRST(); + _queue_signals = 0; + } + + if (pthread_h != NULL) { + /* Remove the thread from the ready queue: */ + PTHREAD_PRIOQ_REMOVE(pthread_h); + + /* Unprotect the scheduling queues: */ + _queue_signals = 0; + + /* + * Check for signals queued while the scheduling + * queues were protected: + */ + while (_sigq_check_reqd != 0) { + /* Clear before handling queued signals: */ + _sigq_check_reqd = 0; + + /* Protect the scheduling queues again: */ + _queue_signals = 1; + + dequeue_signals(); + + /* + * Check for a higher priority thread that + * became runnable due to signal handling. + */ + if (((pthread = PTHREAD_PRIOQ_FIRST()) != NULL) && + (pthread->active_priority > pthread_h->active_priority)) { + /* Remove the thread from the ready queue: */ + PTHREAD_PRIOQ_REMOVE(pthread); + + /* + * Insert the lower priority thread + * at the head of its priority list: + */ + PTHREAD_PRIOQ_INSERT_HEAD(pthread_h); + + /* There's a new thread in town: */ + pthread_h = pthread; + } + + /* Unprotect the scheduling queues: */ + _queue_signals = 0; + } + + /* Make the selected thread the current thread: */ + _set_curthread(pthread_h); + curthread = pthread_h; + + /* + * Save the current time as the time that the thread + * became active: + */ + current_tick = _sched_ticks; + curthread->last_active = (long) current_tick; + + /* + * Check if this thread is running for the first time + * or running again after using its full time slice + * allocation: + */ + if (curthread->slice_usec == -1) { + /* Reset the accumulated time slice period: */ + curthread->slice_usec = 0; + } + + /* + * If we had a context switch, run any + * installed switch hooks. + */ + if ((_sched_switch_hook != NULL) && + (_last_user_thread != curthread)) { + thread_run_switch_hook(_last_user_thread, + curthread); + } + /* + * Continue the thread at its current frame: + */ +#if NOT_YET + _setcontext(&curthread->ctx.uc); +#else + ___longjmp(curthread->ctx.jb, 1); +#endif + /* This point should not be reached. */ + PANIC("Thread has returned from sigreturn or longjmp"); + } + } + + /* There are no more threads, so exit this process: */ + exit(0); +} + +void +_thread_kern_sched_state(enum pthread_state state, char *fname, int lineno) +{ + struct pthread *curthread = _get_curthread(); + + /* + * Flag the pthread kernel as executing scheduler code + * to avoid a scheduler signal from interrupting this + * execution and calling the scheduler again. + */ + _thread_kern_in_sched = 1; + + /* + * Prevent the signal handler from fiddling with this thread + * before its state is set and is placed into the proper queue. + */ + _queue_signals = 1; + + /* Change the state of the current thread: */ + curthread->state = state; + curthread->fname = fname; + curthread->lineno = lineno; + + /* Schedule the next thread that is ready: */ + _thread_kern_sched(NULL); +} + +void +_thread_kern_sched_state_unlock(enum pthread_state state, + spinlock_t *lock, char *fname, int lineno) +{ + struct pthread *curthread = _get_curthread(); + + /* + * Flag the pthread kernel as executing scheduler code + * to avoid a scheduler signal from interrupting this + * execution and calling the scheduler again. + */ + _thread_kern_in_sched = 1; + + /* + * Prevent the signal handler from fiddling with this thread + * before its state is set and it is placed into the proper + * queue(s). + */ + _queue_signals = 1; + + /* Change the state of the current thread: */ + curthread->state = state; + curthread->fname = fname; + curthread->lineno = lineno; + + _SPINUNLOCK(lock); + + /* Schedule the next thread that is ready: */ + _thread_kern_sched(NULL); +} + +static void +thread_kern_poll(int wait_reqd) +{ + int count = 0; + int i, found; + int kern_pipe_added = 0; + int nfds = 0; + int timeout_ms = 0; + struct pthread *pthread; + struct timespec ts; + struct timeval tv; + + /* Check if the caller wants to wait: */ + if (wait_reqd == 0) { + timeout_ms = 0; + } + else { + /* Get the current time of day: */ + GET_CURRENT_TOD(tv); + TIMEVAL_TO_TIMESPEC(&tv, &ts); + + _queue_signals = 1; + pthread = TAILQ_FIRST(&_waitingq); + _queue_signals = 0; + + if ((pthread == NULL) || (pthread->wakeup_time.tv_sec == -1)) { + /* + * Either there are no threads in the waiting queue, + * or there are no threads that can timeout. + */ + timeout_ms = INFTIM; + } + else if (pthread->wakeup_time.tv_sec - ts.tv_sec > 60000) + /* Limit maximum timeout to prevent rollover. */ + timeout_ms = 60000; + else { + /* + * Calculate the time left for the next thread to + * timeout: + */ + timeout_ms = ((pthread->wakeup_time.tv_sec - ts.tv_sec) * + 1000) + ((pthread->wakeup_time.tv_nsec - ts.tv_nsec) / + 1000000); + /* + * Don't allow negative timeouts: + */ + if (timeout_ms < 0) + timeout_ms = 0; + } + } + + /* Protect the scheduling queues: */ + _queue_signals = 1; + + /* + * Check to see if the signal queue needs to be walked to look + * for threads awoken by a signal while in the scheduler. + */ + if (_sigq_check_reqd != 0) { + /* Reset flag before handling queued signals: */ + _sigq_check_reqd = 0; + + dequeue_signals(); + } + + /* + * Check for a thread that became runnable due to a signal: + */ + if (PTHREAD_PRIOQ_FIRST() != NULL) { + /* + * Since there is at least one runnable thread, + * disable the wait. + */ + timeout_ms = 0; + } + + /* + * Form the poll table: + */ + nfds = 0; + if (timeout_ms != 0) { + /* Add the kernel pipe to the poll table: */ + _thread_pfd_table[nfds].fd = _thread_kern_pipe[0]; + _thread_pfd_table[nfds].events = POLLRDNORM; + _thread_pfd_table[nfds].revents = 0; + nfds++; + kern_pipe_added = 1; + } + + PTHREAD_WAITQ_SETACTIVE(); + TAILQ_FOREACH(pthread, &_workq, qe) { + switch (pthread->state) { + case PS_SPINBLOCK: + /* + * If the lock is available, let the thread run. + */ + if (pthread->data.spinlock->access_lock == 0) { + PTHREAD_WAITQ_CLEARACTIVE(); + PTHREAD_WORKQ_REMOVE(pthread); + PTHREAD_NEW_STATE(pthread,PS_RUNNING); + PTHREAD_WAITQ_SETACTIVE(); + /* One less thread in a spinblock state: */ + _spinblock_count--; + /* + * Since there is at least one runnable + * thread, disable the wait. + */ + timeout_ms = 0; + } + break; + + /* File descriptor read wait: */ + case PS_FDR_WAIT: + /* Limit number of polled files to table size: */ + if (nfds < _thread_dtablesize) { + _thread_pfd_table[nfds].events = POLLRDNORM; + _thread_pfd_table[nfds].fd = pthread->data.fd.fd; + nfds++; + } + break; + + /* File descriptor write wait: */ + case PS_FDW_WAIT: + /* Limit number of polled files to table size: */ + if (nfds < _thread_dtablesize) { + _thread_pfd_table[nfds].events = POLLWRNORM; + _thread_pfd_table[nfds].fd = pthread->data.fd.fd; + nfds++; + } + break; + + /* File descriptor poll or select wait: */ + case PS_POLL_WAIT: + case PS_SELECT_WAIT: + /* Limit number of polled files to table size: */ + if (pthread->data.poll_data->nfds + nfds < + _thread_dtablesize) { + for (i = 0; i < pthread->data.poll_data->nfds; i++) { + _thread_pfd_table[nfds + i].fd = + pthread->data.poll_data->fds[i].fd; + _thread_pfd_table[nfds + i].events = + pthread->data.poll_data->fds[i].events; + } + nfds += pthread->data.poll_data->nfds; + } + break; + + /* Other states do not depend on file I/O. */ + default: + break; + } + } + PTHREAD_WAITQ_CLEARACTIVE(); + + /* + * Wait for a file descriptor to be ready for read, write, or + * an exception, or a timeout to occur: + */ + count = __sys_poll(_thread_pfd_table, nfds, timeout_ms); + + if (kern_pipe_added != 0) + /* + * Remove the pthread kernel pipe file descriptor + * from the pollfd table: + */ + nfds = 1; + else + nfds = 0; + + /* + * Check if it is possible that there are bytes in the kernel + * read pipe waiting to be read: + */ + if (count < 0 || ((kern_pipe_added != 0) && + (_thread_pfd_table[0].revents & POLLRDNORM))) { + /* + * If the kernel read pipe was included in the + * count: + */ + if (count > 0) { + /* Decrement the count of file descriptors: */ + count--; + } + + if (_sigq_check_reqd != 0) { + /* Reset flag before handling signals: */ + _sigq_check_reqd = 0; + + dequeue_signals(); + } + } + + /* + * Check if any file descriptors are ready: + */ + if (count > 0) { + /* + * Enter a loop to look for threads waiting on file + * descriptors that are flagged as available by the + * _poll syscall: + */ + PTHREAD_WAITQ_SETACTIVE(); + TAILQ_FOREACH(pthread, &_workq, qe) { + switch (pthread->state) { + case PS_SPINBLOCK: + /* + * If the lock is available, let the thread run. + */ + if (pthread->data.spinlock->access_lock == 0) { + PTHREAD_WAITQ_CLEARACTIVE(); + PTHREAD_WORKQ_REMOVE(pthread); + PTHREAD_NEW_STATE(pthread,PS_RUNNING); + PTHREAD_WAITQ_SETACTIVE(); + + /* + * One less thread in a spinblock state: + */ + _spinblock_count--; + } + break; + + /* File descriptor read wait: */ + case PS_FDR_WAIT: + if ((nfds < _thread_dtablesize) && + (_thread_pfd_table[nfds].revents & POLLRDNORM)) { + PTHREAD_WAITQ_CLEARACTIVE(); + PTHREAD_WORKQ_REMOVE(pthread); + PTHREAD_NEW_STATE(pthread,PS_RUNNING); + PTHREAD_WAITQ_SETACTIVE(); + } + nfds++; + break; + + /* File descriptor write wait: */ + case PS_FDW_WAIT: + if ((nfds < _thread_dtablesize) && + (_thread_pfd_table[nfds].revents & POLLWRNORM)) { + PTHREAD_WAITQ_CLEARACTIVE(); + PTHREAD_WORKQ_REMOVE(pthread); + PTHREAD_NEW_STATE(pthread,PS_RUNNING); + PTHREAD_WAITQ_SETACTIVE(); + } + nfds++; + break; + + /* File descriptor poll or select wait: */ + case PS_POLL_WAIT: + case PS_SELECT_WAIT: + if (pthread->data.poll_data->nfds + nfds < + _thread_dtablesize) { + /* + * Enter a loop looking for I/O + * readiness: + */ + found = 0; + for (i = 0; i < pthread->data.poll_data->nfds; i++) { + if (_thread_pfd_table[nfds + i].revents != 0) { + pthread->data.poll_data->fds[i].revents = + _thread_pfd_table[nfds + i].revents; + found++; + } + } + + /* Increment before destroying: */ + nfds += pthread->data.poll_data->nfds; + + if (found != 0) { + pthread->data.poll_data->nfds = found; + PTHREAD_WAITQ_CLEARACTIVE(); + PTHREAD_WORKQ_REMOVE(pthread); + PTHREAD_NEW_STATE(pthread,PS_RUNNING); + PTHREAD_WAITQ_SETACTIVE(); + } + } + else + nfds += pthread->data.poll_data->nfds; + break; + + /* Other states do not depend on file I/O. */ + default: + break; + } + } + PTHREAD_WAITQ_CLEARACTIVE(); + } + else if (_spinblock_count != 0) { + /* + * Enter a loop to look for threads waiting on a spinlock + * that is now available. + */ + PTHREAD_WAITQ_SETACTIVE(); + TAILQ_FOREACH(pthread, &_workq, qe) { + if (pthread->state == PS_SPINBLOCK) { + /* + * If the lock is available, let the thread run. + */ + if (pthread->data.spinlock->access_lock == 0) { + PTHREAD_WAITQ_CLEARACTIVE(); + PTHREAD_WORKQ_REMOVE(pthread); + PTHREAD_NEW_STATE(pthread,PS_RUNNING); + PTHREAD_WAITQ_SETACTIVE(); + + /* + * One less thread in a spinblock state: + */ + _spinblock_count--; + } + } + } + PTHREAD_WAITQ_CLEARACTIVE(); + } + + /* Unprotect the scheduling queues: */ + _queue_signals = 0; + + while (_sigq_check_reqd != 0) { + /* Handle queued signals: */ + _sigq_check_reqd = 0; + + /* Protect the scheduling queues: */ + _queue_signals = 1; + + dequeue_signals(); + + /* Unprotect the scheduling queues: */ + _queue_signals = 0; + } +} + +void +_thread_kern_set_timeout(const struct timespec * timeout) +{ + struct pthread *curthread = _get_curthread(); + struct timespec current_time; + struct timeval tv; + + /* Reset the timeout flag for the running thread: */ + curthread->timeout = 0; + + /* Check if the thread is to wait forever: */ + if (timeout == NULL) { + /* + * Set the wakeup time to something that can be recognised as + * different to an actual time of day: + */ + curthread->wakeup_time.tv_sec = -1; + curthread->wakeup_time.tv_nsec = -1; + } + /* Check if no waiting is required: */ + else if (timeout->tv_sec == 0 && timeout->tv_nsec == 0) { + /* Set the wake up time to 'immediately': */ + curthread->wakeup_time.tv_sec = 0; + curthread->wakeup_time.tv_nsec = 0; + } else { + /* Get the current time: */ + GET_CURRENT_TOD(tv); + TIMEVAL_TO_TIMESPEC(&tv, ¤t_time); + + /* Calculate the time for the current thread to wake up: */ + curthread->wakeup_time.tv_sec = current_time.tv_sec + timeout->tv_sec; + curthread->wakeup_time.tv_nsec = current_time.tv_nsec + timeout->tv_nsec; + + /* Check if the nanosecond field needs to wrap: */ + if (curthread->wakeup_time.tv_nsec >= 1000000000) { + /* Wrap the nanosecond field: */ + curthread->wakeup_time.tv_sec += 1; + curthread->wakeup_time.tv_nsec -= 1000000000; + } + } +} + +void +_thread_kern_sig_defer(void) +{ + struct pthread *curthread = _get_curthread(); + + /* Allow signal deferral to be recursive. */ + curthread->sig_defer_count++; +} + +void +_thread_kern_sig_undefer(void) +{ + struct pthread *curthread = _get_curthread(); + + /* + * Perform checks to yield only if we are about to undefer + * signals. + */ + if (curthread->sig_defer_count > 1) { + /* Decrement the signal deferral count. */ + curthread->sig_defer_count--; + } + else if (curthread->sig_defer_count == 1) { + /* Reenable signals: */ + curthread->sig_defer_count = 0; + + /* + * Check if there are queued signals: + */ + if (_sigq_check_reqd != 0) + _thread_kern_sched(NULL); + + /* + * Check for asynchronous cancellation before delivering any + * pending signals: + */ + if (((curthread->cancelflags & PTHREAD_AT_CANCEL_POINT) == 0) && + ((curthread->cancelflags & PTHREAD_CANCEL_ASYNCHRONOUS) != 0)) + pthread_testcancel(); + + /* + * If there are pending signals or this thread has + * to yield the CPU, call the kernel scheduler: + * + * XXX - Come back and revisit the pending signal problem + */ + if ((curthread->yield_on_sig_undefer != 0) || + SIGNOTEMPTY(curthread->sigpend)) { + curthread->yield_on_sig_undefer = 0; + _thread_kern_sched(NULL); + } + } +} + +static void +dequeue_signals(void) +{ + char bufr[128]; + int num; + + /* + * Enter a loop to clear the pthread kernel pipe: + */ + while (((num = __sys_read(_thread_kern_pipe[0], bufr, + sizeof(bufr))) > 0) || (num == -1 && errno == EINTR)) { + } + if ((num < 0) && (errno != EAGAIN)) { + /* + * The only error we should expect is if there is + * no data to read. + */ + PANIC("Unable to read from thread kernel pipe"); + } + /* Handle any pending signals: */ + _thread_sig_handle_pending(); +} + +static inline void +thread_run_switch_hook(pthread_t thread_out, pthread_t thread_in) +{ + pthread_t tid_out = thread_out; + pthread_t tid_in = thread_in; + + if ((tid_out != NULL) && + (tid_out->flags & PTHREAD_FLAGS_PRIVATE) != 0) + tid_out = NULL; + if ((tid_in != NULL) && + (tid_in->flags & PTHREAD_FLAGS_PRIVATE) != 0) + tid_in = NULL; + + if ((_sched_switch_hook != NULL) && (tid_out != tid_in)) { + /* Run the scheduler switch hook: */ + _sched_switch_hook(tid_out, tid_in); + } +} + +struct pthread * +_get_curthread(void) +{ + if (_thread_initial == NULL) + _thread_init(); + + return (_thread_run); +} + +void +_set_curthread(struct pthread *newthread) +{ + _thread_run = newthread; +} |
