/* * Copyright (c) 1995-1998 John Birrell * 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. * * $Id: uthread_kern.c,v 1.14 1998/10/09 19:01:30 dt Exp $ * */ #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef _THREAD_SAFE #include #include "pthread_private.h" /* Static function prototype definitions: */ static void _thread_kern_select(int wait_reqd); static inline void thread_run_switch_hook(pthread_t thread_out, pthread_t thread_in); void _thread_kern_sched(struct sigcontext * scp) { #ifndef __alpha__ char *fdata; #endif pthread_t pthread; pthread_t pthread_h = NULL; pthread_t last_thread = NULL; struct itimerval itimer; struct timespec ts; struct timespec ts1; struct timeval tv; struct timeval tv1; /* * 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 (scp != NULL) { /* * Copy the signal context to the current thread's jump * buffer: */ memcpy(&_thread_run->saved_sigcontext, scp, sizeof(_thread_run->saved_sigcontext)); #ifndef __alpha__ /* Point to the floating point data in the running thread: */ fdata = _thread_run->saved_fp; /* Save the floating point data: */ __asm__("fnsave %0": :"m"(*fdata)); #endif /* Flag the signal context as the last state saved: */ _thread_run->sig_saved = 1; } /* Save the state of the current thread: */ else if (setjmp(_thread_run->saved_jmp_buf) != 0) { /* * 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 (_sched_switch_hook != NULL) { /* Run the installed switch hook: */ thread_run_switch_hook(_last_user_thread, _thread_run); } return; } else /* Flag the jump buffer was the last state saved: */ _thread_run->sig_saved = 0; /* If the currently running thread is a user thread, save it: */ if ((_thread_run->flags & PTHREAD_FLAGS_PRIVATE) == 0) _last_user_thread = _thread_run; /* * 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 (_thread_link_list != NULL) { /* Get the current time of day: */ gettimeofday(&tv, NULL); TIMEVAL_TO_TIMESPEC(&tv, &ts); /* * Poll file descriptors to update the state of threads * waiting on file I/O where data may be available: */ _thread_kern_select(0); /* * Define the maximum time before a scheduling signal * is required: */ itimer.it_value.tv_sec = 0; itimer.it_value.tv_usec = TIMESLICE_USEC; /* * The interval timer is not reloaded when it * times out. The interval time needs to be * calculated every time. */ itimer.it_interval.tv_sec = 0; itimer.it_interval.tv_usec = 0; /* * Enter a loop to look for sleeping threads that are ready * or timedout. While we're at it, also find the smallest * timeout value for threads waiting for a time. */ _waitingq_check_reqd = 0; /* reset flag before loop */ TAILQ_FOREACH(pthread, &_waitingq, pqe) { /* Check if this thread is ready: */ if (pthread->state == PS_RUNNING) { PTHREAD_WAITQ_REMOVE(pthread); PTHREAD_PRIOQ_INSERT_TAIL(pthread); } /* * Check if this thread is blocked by an * atomic lock: */ else if (pthread->state == PS_SPINBLOCK) { /* * If the lock is available, let * the thread run. */ if (pthread->data.spinlock->access_lock == 0) { PTHREAD_NEW_STATE(pthread,PS_RUNNING); } /* Check if this thread is to timeout: */ } else if (pthread->state == PS_COND_WAIT || pthread->state == PS_SLEEP_WAIT || pthread->state == PS_FDR_WAIT || pthread->state == PS_FDW_WAIT || pthread->state == PS_SELECT_WAIT) { /* Check if this thread is to wait forever: */ if (pthread->wakeup_time.tv_sec == -1) { } /* * Check if this thread is to wakeup * immediately or if it is past its wakeup * time: */ else if ((pthread->wakeup_time.tv_sec == 0 && pthread->wakeup_time.tv_nsec == 0) || (ts.tv_sec > pthread->wakeup_time.tv_sec) || ((ts.tv_sec == pthread->wakeup_time.tv_sec) && (ts.tv_nsec >= pthread->wakeup_time.tv_nsec))) { /* * Check if this thread is waiting on * select: */ if (pthread->state == PS_SELECT_WAIT) { /* * The select has timed out, so * zero the file descriptor * sets: */ FD_ZERO(&pthread->data.select_data->readfds); FD_ZERO(&pthread->data.select_data->writefds); FD_ZERO(&pthread->data.select_data->exceptfds); pthread->data.select_data->nfds = 0; } /* * Return an error as an interrupted * wait: */ _thread_seterrno(pthread, EINTR); /* * Flag the timeout in the thread * structure: */ pthread->timeout = 1; /* * Change the threads state to allow * it to be restarted: */ PTHREAD_NEW_STATE(pthread,PS_RUNNING); } else { /* * Calculate the time until this thread * is ready, allowing for the clock * resolution: */ ts1.tv_sec = pthread->wakeup_time.tv_sec - ts.tv_sec; ts1.tv_nsec = pthread->wakeup_time.tv_nsec - ts.tv_nsec + CLOCK_RES_NSEC; /* * Check for underflow of the * nanosecond field: */ if (ts1.tv_nsec < 0) { /* * Allow for the underflow * of the nanosecond field: */ ts1.tv_sec--; ts1.tv_nsec += 1000000000; } /* * Check for overflow of the nanosecond * field: */ if (ts1.tv_nsec >= 1000000000) { /* * Allow for the overflow of * the nanosecond field: */ ts1.tv_sec++; ts1.tv_nsec -= 1000000000; } /* * Convert the timespec structure * to a timeval structure: */ TIMESPEC_TO_TIMEVAL(&tv1, &ts1); /* * Check if the thread will be ready * sooner than the earliest ones found * so far: */ if (timercmp(&tv1, &itimer.it_value, <)) { /* * Update the time value: */ itimer.it_value.tv_sec = tv1.tv_sec; itimer.it_value.tv_usec = tv1.tv_usec; } } } } /* Check if there is a current thread: */ if (_thread_run != &_thread_kern_thread) { /* * This thread no longer needs to yield the CPU. */ _thread_run->yield_on_sched_undefer = 0; /* * Save the current time as the time that the thread * became inactive: */ _thread_run->last_inactive.tv_sec = tv.tv_sec; _thread_run->last_inactive.tv_usec = tv.tv_usec; /* * Accumulate the number of microseconds that this * thread has run for: */ if ((_thread_run->slice_usec != -1) && (_thread_run->attr.sched_policy != SCHED_FIFO)) { _thread_run->slice_usec += (_thread_run->last_inactive.tv_sec - _thread_run->last_active.tv_sec) * 1000000 + _thread_run->last_inactive.tv_usec - _thread_run->last_active.tv_usec; /* Check for time quantum exceeded: */ if (_thread_run->slice_usec > TIMESLICE_USEC) _thread_run->slice_usec = -1; } if (_thread_run->state == PS_RUNNING) { if (_thread_run->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(_thread_run); } else { /* * The thread hasn't exceeded its * interval. Place it at the head * of the queue for its priority. */ PTHREAD_PRIOQ_INSERT_HEAD(_thread_run); } } else if (_thread_run->state == PS_DEAD) { /* * Don't add dead threads to the waiting * queue, because when they're reaped, it * will corrupt the queue. */ } else { /* * This thread has changed state and needs * to be placed in the waiting queue. */ PTHREAD_WAITQ_INSERT(_thread_run); /* Restart the time slice: */ _thread_run->slice_usec = -1; } } /* * 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: */ _thread_run = &_thread_kern_thread; /* * There are no threads ready to run, so wait until * something happens that changes this condition: */ _thread_kern_select(1); } else { /* Make the selected thread the current thread: */ _thread_run = pthread_h; /* Remove the thread from the ready queue. */ PTHREAD_PRIOQ_REMOVE(_thread_run); /* * Save the current time as the time that the thread * became active: */ _thread_run->last_active.tv_sec = tv.tv_sec; _thread_run->last_active.tv_usec = tv.tv_usec; /* * Check if this thread is running for the first time * or running again after using its full time slice * allocation: */ if (_thread_run->slice_usec == -1) { /* Reset the accumulated time slice period: */ _thread_run->slice_usec = 0; } /* Check if there is more than one thread: */ if (_thread_run != _thread_link_list || _thread_run->nxt != NULL) { /* * Start the interval timer for the * calculated time interval: */ if (setitimer(_ITIMER_SCHED_TIMER, &itimer, NULL) != 0) { /* * Cannot initialise the timer, so * abort this process: */ PANIC("Cannot set scheduling timer"); } } /* Check if a signal context was saved: */ if (_thread_run->sig_saved == 1) { #ifndef __alpha__ /* * Point to the floating point data in the * running thread: */ fdata = _thread_run->saved_fp; /* Restore the floating point state: */ __asm__("frstor %0": :"m"(*fdata)); #endif /* * Do a sigreturn to restart the thread that * was interrupted by a signal: */ _thread_kern_in_sched = 0; /* * If we had a context switch, run any * installed switch hooks. */ if ((_sched_switch_hook != NULL) && (_last_user_thread != _thread_run)) { thread_run_switch_hook(_last_user_thread, _thread_run); } _thread_sys_sigreturn(&_thread_run->saved_sigcontext); } else { /* * Do a longjmp to restart the thread that * was context switched out (by a longjmp to * a different thread): */ longjmp(_thread_run->saved_jmp_buf, 1); } /* 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) { /* Change the state of the current thread: */ _thread_run->state = state; _thread_run->fname = fname; _thread_run->lineno = lineno; /* Schedule the next thread that is ready: */ _thread_kern_sched(NULL); return; } void _thread_kern_sched_state_unlock(enum pthread_state state, spinlock_t *lock, char *fname, int lineno) { /* Change the state of the current thread: */ _thread_run->state = state; _thread_run->fname = fname; _thread_run->lineno = lineno; _SPINUNLOCK(lock); /* Schedule the next thread that is ready: */ _thread_kern_sched(NULL); return; } static void _thread_kern_select(int wait_reqd) { char bufr[128]; fd_set fd_set_except; fd_set fd_set_read; fd_set fd_set_write; int count = 0; int count_dec; int found_one; int i; int nfds = -1; int settimeout; pthread_t pthread; ssize_t num; struct timespec ts; struct timespec ts1; struct timeval *p_tv; struct timeval tv; struct timeval tv1; /* Zero the file descriptor sets: */ FD_ZERO(&fd_set_read); FD_ZERO(&fd_set_write); FD_ZERO(&fd_set_except); /* Check if the caller wants to wait: */ if (wait_reqd) { /* * Add the pthread kernel pipe file descriptor to the read * set: */ FD_SET(_thread_kern_pipe[0], &fd_set_read); nfds = _thread_kern_pipe[0]; /* Get the current time of day: */ gettimeofday(&tv, NULL); TIMEVAL_TO_TIMESPEC(&tv, &ts); } /* Initialise the time value structure: */ tv.tv_sec = 0; tv.tv_usec = 0; /* * Enter a loop to process threads waiting on either file descriptors * or times: */ _waitingq_check_reqd = 0; /* reset flag before loop */ TAILQ_FOREACH (pthread, &_waitingq, pqe) { /* Assume that this state does not time out: */ settimeout = 0; /* Process according to thread state: */ switch (pthread->state) { /* * States which do not depend on file descriptor I/O * operations or timeouts: */ case PS_DEAD: case PS_DEADLOCK: case PS_FDLR_WAIT: case PS_FDLW_WAIT: case PS_FILE_WAIT: case PS_JOIN: case PS_MUTEX_WAIT: case PS_SIGTHREAD: case PS_SIGWAIT: case PS_STATE_MAX: case PS_WAIT_WAIT: case PS_SUSPENDED: /* Nothing to do here. */ break; case PS_RUNNING: /* * A signal occurred and made this thread ready * while in the scheduler or while the scheduling * queues were protected. */ PTHREAD_WAITQ_REMOVE(pthread); PTHREAD_PRIOQ_INSERT_TAIL(pthread); break; /* File descriptor read wait: */ case PS_FDR_WAIT: /* Add the file descriptor to the read set: */ FD_SET(pthread->data.fd.fd, &fd_set_read); /* * Check if this file descriptor is greater than any * of those seen so far: */ if (pthread->data.fd.fd > nfds) { /* Remember this file descriptor: */ nfds = pthread->data.fd.fd; } /* Increment the file descriptor count: */ count++; /* This state can time out: */ settimeout = 1; break; /* File descriptor write wait: */ case PS_FDW_WAIT: /* Add the file descriptor to the write set: */ FD_SET(pthread->data.fd.fd, &fd_set_write); /* * Check if this file descriptor is greater than any * of those seen so far: */ if (pthread->data.fd.fd > nfds) { /* Remember this file descriptor: */ nfds = pthread->data.fd.fd; } /* Increment the file descriptor count: */ count++; /* This state can time out: */ settimeout = 1; break; /* States that time out: */ case PS_SLEEP_WAIT: case PS_COND_WAIT: /* Flag a timeout as required: */ settimeout = 1; break; /* Select wait: */ case PS_SELECT_WAIT: /* * Enter a loop to process each file descriptor in * the thread-specific file descriptor sets: */ for (i = 0; i < pthread->data.select_data->nfds; i++) { /* * Check if this file descriptor is set for * exceptions: */ if (FD_ISSET(i, &pthread->data.select_data->exceptfds)) { /* * Add the file descriptor to the * exception set: */ FD_SET(i, &fd_set_except); /* * Increment the file descriptor * count: */ count++; /* * Check if this file descriptor is * greater than any of those seen so * far: */ if (i > nfds) { /* * Remember this file * descriptor: */ nfds = i; } } /* * Check if this file descriptor is set for * write: */ if (FD_ISSET(i, &pthread->data.select_data->writefds)) { /* * Add the file descriptor to the * write set: */ FD_SET(i, &fd_set_write); /* * Increment the file descriptor * count: */ count++; /* * Check if this file descriptor is * greater than any of those seen so * far: */ if (i > nfds) { /* * Remember this file * descriptor: */ nfds = i; } } /* * Check if this file descriptor is set for * read: */ if (FD_ISSET(i, &pthread->data.select_data->readfds)) { /* * Add the file descriptor to the * read set: */ FD_SET(i, &fd_set_read); /* * Increment the file descriptor * count: */ count++; /* * Check if this file descriptor is * greater than any of those seen so * far: */ if (i > nfds) { /* * Remember this file * descriptor: */ nfds = i; } } } /* This state can time out: */ settimeout = 1; break; } /* * Check if the caller wants to wait and if the thread state * is one that times out: */ if (wait_reqd && settimeout) { /* Check if this thread wants to wait forever: */ if (pthread->wakeup_time.tv_sec == -1) { } /* Check if this thread doesn't want to wait at all: */ else if (pthread->wakeup_time.tv_sec == 0 && pthread->wakeup_time.tv_nsec == 0) { /* Override the caller's request to wait: */ wait_reqd = 0; } else { /* * Calculate the time until this thread is * ready, allowing for the clock resolution: */ ts1.tv_sec = pthread->wakeup_time.tv_sec - ts.tv_sec; ts1.tv_nsec = pthread->wakeup_time.tv_nsec - ts.tv_nsec + CLOCK_RES_NSEC; /* * Check for underflow of the nanosecond * field: */ if (ts1.tv_nsec < 0) { /* * Allow for the underflow of the * nanosecond field: */ ts1.tv_sec--; ts1.tv_nsec += 1000000000; } /* * Check for overflow of the nanosecond * field: */ if (ts1.tv_nsec >= 1000000000) { /* * Allow for the overflow of the * nanosecond field: */ ts1.tv_sec++; ts1.tv_nsec -= 1000000000; } /* * Convert the timespec structure to a * timeval structure: */ TIMESPEC_TO_TIMEVAL(&tv1, &ts1); /* * Check if no time value has been found yet, * or if the thread will be ready sooner that * the earliest one found so far: */ if ((tv.tv_sec == 0 && tv.tv_usec == 0) || timercmp(&tv1, &tv, <)) { /* Update the time value: */ tv.tv_sec = tv1.tv_sec; tv.tv_usec = tv1.tv_usec; } } } } /* Check if the caller wants to wait: */ if (wait_reqd) { /* Check if no threads were found with timeouts: */ if (tv.tv_sec == 0 && tv.tv_usec == 0) { /* Wait forever: */ p_tv = NULL; } else { /* * Point to the time value structure which contains * the earliest time that a thread will be ready: */ p_tv = &tv; } /* * Flag the pthread kernel as in a select. This is to avoid * the window between the next statement that unblocks * signals and the select statement which follows. */ _thread_kern_in_select = 1; /* * Wait for a file descriptor to be ready for read, write, or * an exception, or a timeout to occur: */ count = _thread_sys_select(nfds + 1, &fd_set_read, &fd_set_write, &fd_set_except, p_tv); /* Reset the kernel in select flag: */ _thread_kern_in_select = 0; /* * Check if it is possible that there are bytes in the kernel * read pipe waiting to be read: */ if (count < 0 || FD_ISSET(_thread_kern_pipe[0], &fd_set_read)) { /* * Check if the kernel read pipe was included in the * count: */ if (count > 0) { /* * Remove the kernel read pipe from the * count: */ FD_CLR(_thread_kern_pipe[0], &fd_set_read); /* Decrement the count of file descriptors: */ count--; } /* * Enter a loop to read (and trash) bytes from the * pthread kernel pipe: */ while ((num = _thread_sys_read(_thread_kern_pipe[0], bufr, sizeof(bufr))) > 0) { /* * The buffer read contains one byte per * signal and each byte is the signal number. * This data is not used, but the fact that * the signal handler wrote to the pipe *is* * used to cause the _select call * to complete if the signal occurred between * the time when signals were unblocked and * the _select select call being * made. */ } } } /* Check if there are file descriptors to poll: */ else if (count > 0) { /* * Point to the time value structure which has been zeroed so * that the call to _select will not wait: */ p_tv = &tv; /* Poll file descrptors without wait: */ count = _thread_sys_select(nfds + 1, &fd_set_read, &fd_set_write, &fd_set_except, p_tv); } /* * 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 * _select syscall: */ TAILQ_FOREACH (pthread, &_waitingq, pqe) { /* Process according to thread state: */ switch (pthread->state) { /* * States which do not depend on file * descriptor I/O operations: */ case PS_COND_WAIT: case PS_DEAD: case PS_DEADLOCK: case PS_FDLR_WAIT: case PS_FDLW_WAIT: case PS_FILE_WAIT: case PS_JOIN: case PS_MUTEX_WAIT: case PS_SIGWAIT: case PS_SLEEP_WAIT: case PS_WAIT_WAIT: case PS_SIGTHREAD: case PS_STATE_MAX: case PS_SUSPENDED: /* Nothing to do here. */ break; case PS_RUNNING: /* * A signal occurred and made this thread * ready while in the scheduler. */ PTHREAD_WAITQ_REMOVE(pthread); PTHREAD_PRIOQ_INSERT_TAIL(pthread); break; /* File descriptor read wait: */ case PS_FDR_WAIT: /* * Check if the file descriptor is available * for read: */ if (FD_ISSET(pthread->data.fd.fd, &fd_set_read)) { /* * Change the thread state to allow * it to read from the file when it * is scheduled next: */ pthread->state = PS_RUNNING; /* * Remove it from the waiting queue * and add it to the ready queue: */ PTHREAD_WAITQ_REMOVE(pthread); PTHREAD_PRIOQ_INSERT_TAIL(pthread); } break; /* File descriptor write wait: */ case PS_FDW_WAIT: /* * Check if the file descriptor is available * for write: */ if (FD_ISSET(pthread->data.fd.fd, &fd_set_write)) { /* * Change the thread state to allow * it to write to the file when it is * scheduled next: */ pthread->state = PS_RUNNING; /* * Remove it from the waiting queue * and add it to the ready queue: */ PTHREAD_WAITQ_REMOVE(pthread); PTHREAD_PRIOQ_INSERT_TAIL(pthread); } break; /* Select wait: */ case PS_SELECT_WAIT: /* * Reset the flag that indicates if a file * descriptor is ready for some type of * operation: */ count_dec = 0; /* * Enter a loop to search though the * thread-specific select file descriptors * for the first descriptor that is ready: */ for (i = 0; i < pthread->data.select_data->nfds && count_dec == 0; i++) { /* * Check if this file descriptor does * not have an exception: */ if (FD_ISSET(i, &pthread->data.select_data->exceptfds) && FD_ISSET(i, &fd_set_except)) { /* * Flag this file descriptor * as ready: */ count_dec = 1; } /* * Check if this file descriptor is * not ready for write: */ if (FD_ISSET(i, &pthread->data.select_data->writefds) && FD_ISSET(i, &fd_set_write)) { /* * Flag this file descriptor * as ready: */ count_dec = 1; } /* * Check if this file descriptor is * not ready for read: */ if (FD_ISSET(i, &pthread->data.select_data->readfds) && FD_ISSET(i, &fd_set_read)) { /* * Flag this file descriptor * as ready: */ count_dec = 1; } } /* * Check if any file descriptors are ready * for the current thread: */ if (count_dec) { /* * Reset the count of file * descriptors that are ready for * this thread: */ found_one = 0; /* * Enter a loop to search though the * thread-specific select file * descriptors: */ for (i = 0; i < pthread->data.select_data->nfds; i++) { /* * Reset the count of * operations for which the * current file descriptor is * ready: */ count_dec = 0; /* * Check if this file * descriptor is selected for * exceptions: */ if (FD_ISSET(i, &pthread->data.select_data->exceptfds)) { /* * Check if this file * descriptor has an * exception: */ if (FD_ISSET(i, &fd_set_except)) { /* * Increment * the count * for this * file: */ count_dec++; } else { /* * Clear the * file * descriptor * in the * thread-spec * ific file * descriptor * set: */ FD_CLR(i, &pthread->data.select_data->exceptfds); } } /* * Check if this file * descriptor is selected for * write: */ if (FD_ISSET(i, &pthread->data.select_data->writefds)) { /* * Check if this file * descriptor is * ready for write: */ if (FD_ISSET(i, &fd_set_write)) { /* * Increment * the count * for this * file: */ count_dec++; } else { /* * Clear the * file * descriptor * in the * thread-spec * ific file * descriptor * set: */ FD_CLR(i, &pthread->data.select_data->writefds); } } /* * Check if this file * descriptor is selected for * read: */ if (FD_ISSET(i, &pthread->data.select_data->readfds)) { /* * Check if this file * descriptor is * ready for read: */ if (FD_ISSET(i, &fd_set_read)) { /* * Increment * the count * for this * file: */ count_dec++; } else { /* * Clear the * file * descriptor * in the * thread-spec * ific file * descriptor * set: */ FD_CLR(i, &pthread->data.select_data->readfds); } } /* * Check if the current file * descriptor is ready for * any one of the operations: */ if (count_dec > 0) { /* * Increment the * count of file * descriptors that * are ready for the * current thread: */ found_one++; } } /* * Return the number of file * descriptors that are ready: */ pthread->data.select_data->nfds = found_one; /* * Change the state of the current * thread to run: */ pthread->state = PS_RUNNING; /* * Remove it from the waiting queue * and add it to the ready queue: */ PTHREAD_WAITQ_REMOVE(pthread); PTHREAD_PRIOQ_INSERT_TAIL(pthread); } break; } } } /* Nothing to return. */ return; } void _thread_kern_set_timeout(struct timespec * timeout) { struct timespec current_time; struct timeval tv; /* Reset the timeout flag for the running thread: */ _thread_run->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: */ _thread_run->wakeup_time.tv_sec = -1; _thread_run->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': */ _thread_run->wakeup_time.tv_sec = 0; _thread_run->wakeup_time.tv_nsec = 0; } else { /* Get the current time: */ gettimeofday(&tv, NULL); TIMEVAL_TO_TIMESPEC(&tv, ¤t_time); /* Calculate the time for the current thread to wake up: */ _thread_run->wakeup_time.tv_sec = current_time.tv_sec + timeout->tv_sec; _thread_run->wakeup_time.tv_nsec = current_time.tv_nsec + timeout->tv_nsec; /* Check if the nanosecond field needs to wrap: */ if (_thread_run->wakeup_time.tv_nsec >= 1000000000) { /* Wrap the nanosecond field: */ _thread_run->wakeup_time.tv_sec += 1; _thread_run->wakeup_time.tv_nsec -= 1000000000; } } return; } void _thread_kern_sched_defer(void) { /* Allow scheduling deferral to be recursive. */ _thread_run->sched_defer_count++; } void _thread_kern_sched_undefer(void) { pthread_t pthread; int need_resched = 0; /* * Perform checks to yield only if we are about to undefer * scheduling. */ if (_thread_run->sched_defer_count == 1) { /* * Check if the waiting queue needs to be examined for * threads that are now ready: */ while (_waitingq_check_reqd != 0) { /* Clear the flag before checking the waiting queue: */ _waitingq_check_reqd = 0; TAILQ_FOREACH(pthread, &_waitingq, pqe) { if (pthread->state == PS_RUNNING) { PTHREAD_WAITQ_REMOVE(pthread); PTHREAD_PRIOQ_INSERT_TAIL(pthread); } } } /* * We need to yield if a thread change of state caused a * higher priority thread to become ready, or if a * scheduling signal occurred while preemption was disabled. */ if ((((pthread = PTHREAD_PRIOQ_FIRST) != NULL) && (pthread->active_priority > _thread_run->active_priority)) || (_thread_run->yield_on_sched_undefer != 0)) { _thread_run->yield_on_sched_undefer = 0; need_resched = 1; } } if (_thread_run->sched_defer_count > 0) { /* Decrement the scheduling deferral count. */ _thread_run->sched_defer_count--; /* Yield the CPU if necessary: */ if (need_resched) _thread_kern_sched(NULL); } } 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); } } #endif