/**************************************************************************** * sched/signal/sig_timedwait.c * * Copyright (C) 2007-2009, 2012-2017 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * 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. Neither the name NuttX nor the names of its contributors may be * used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 * COPYRIGHT OWNER 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. * ****************************************************************************/ /**************************************************************************** * Included Files ****************************************************************************/ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "sched/sched.h" #include "signal/signal.h" #include "clock/clock.h" /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ /* These are special values of si_signo that mean that either the wait was * awakened with a timeout, or the wait was canceled... not the receipt of a * signal. */ #define SIG_CANCEL_TIMEOUT 0xfe #define SIG_WAIT_TIMEOUT 0xff /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Name: nxsig_timeout * * Description: * A timeout elapsed while waiting for signals to be queued. * * Assumptions: * This function executes in the context of the timer interrupt handler. * Local interrupts are assumed to be disabled on entry. * ****************************************************************************/ static void nxsig_timeout(int argc, wdparm_t itcb, ...) { #ifdef CONFIG_SMP irqstate_t flags; #endif /* On many small machines, pointers are encoded and cannot be simply cast * from uint32_t to struct tcb_s *. The following union works around this * (see wdogparm_t). This odd logic could be conditioned on * CONFIG_CAN_CAST_POINTERS, but it is not too bad in any case. */ union { FAR struct tcb_s *wtcb; wdparm_t itcb; } u; u.itcb = itcb; DEBUGASSERT(u.wtcb); #ifdef CONFIG_SMP /* We must be in a critical section in order to call up_unblock_task() * below. If we are running on a single CPU architecture, then we know * interrupts a disabled an there is no need to explicitly call * enter_critical_section(). However, in the SMP case, * enter_critical_section() does much more than just disable interrupts on * the local CPU; it also manages spinlocks to assure the stability of the * TCB that we are manipulating. */ flags = enter_critical_section(); #endif /* There may be a race condition -- make sure the task is * still waiting for a signal */ if (u.wtcb->task_state == TSTATE_WAIT_SIG) { u.wtcb->sigunbinfo.si_signo = SIG_WAIT_TIMEOUT; u.wtcb->sigunbinfo.si_code = SI_TIMER; u.wtcb->sigunbinfo.si_errno = ETIMEDOUT; u.wtcb->sigunbinfo.si_value.sival_int = 0; #ifdef CONFIG_SCHED_HAVE_PARENT u.wtcb->sigunbinfo.si_pid = 0; /* Not applicable */ u.wtcb->sigunbinfo.si_status = OK; #endif up_unblock_task(u.wtcb); } #ifdef CONFIG_SMP leave_critical_section(flags); #endif } /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: nxsig_wait_irq * * Description: * An error event has occurred and the signal wait must be terminated with * an error. * ****************************************************************************/ #ifdef CONFIG_CANCELLATION_POINTS void nxsig_wait_irq(FAR struct tcb_s *wtcb, int errcode) { #ifdef CONFIG_SMP irqstate_t flags; /* We must be in a critical section in order to call up_unblock_task() * below. If we are running on a single CPU architecture, then we know * interrupts a disabled an there is no need to explicitly call * enter_critical_section(). However, in the SMP case, * enter_critical_section() does much more than just disable interrupts on * the local CPU; it also manages spinlocks to assure the stability of the * TCB that we are manipulating. */ flags = enter_critical_section(); #endif /* There may be a race condition -- make sure the task is * still waiting for a signal */ if (wtcb->task_state == TSTATE_WAIT_SIG) { wtcb->sigunbinfo.si_signo = SIG_CANCEL_TIMEOUT; wtcb->sigunbinfo.si_code = SI_USER; wtcb->sigunbinfo.si_errno = errcode; wtcb->sigunbinfo.si_value.sival_int = 0; #ifdef CONFIG_SCHED_HAVE_PARENT wtcb->sigunbinfo.si_pid = 0; /* Not applicable */ wtcb->sigunbinfo.si_status = OK; #endif up_unblock_task(wtcb); } #ifdef CONFIG_SMP leave_critical_section(flags); #endif } #endif /* CONFIG_CANCELLATION_POINTS */ /**************************************************************************** * Name: nxsig_timedwait * * Description: * This function selects the pending signal set specified by the argument * set. If multiple signals are pending in set, it will remove and return * the lowest numbered one. If no signals in set are pending at the time * of the call, the calling process will be suspended until one of the * signals in set becomes pending, OR until the process is interrupted by * an unblocked signal, OR until the time interval specified by timeout * (if any), has expired. If timeout is NULL, then the timeout interval * is forever. * * If the info argument is non-NULL, the selected signal number is stored * in the si_signo member and the cause of the signal is store din the * si_code member. The content of si_value is only meaningful if the * signal was generated by sigqueue() (or nxsig_queue). * * This is an internal OS interface. It is functionally equivalent to * sigtimedwait() except that: * * - It is not a cancellation point, and * - It does not modify the errno value. * * Input Parameters: * set - The pending signal set. * info - The returned value (may be NULL). * timeout - The amount of time to wait (may be NULL) * * Returned Value: * This is an internal OS interface and should not be used by applications. * It follows the NuttX internal error return policy: Zero (OK) is * returned on success. A negated errno value is returned on failure. * * EAGAIN - No signal specified by set was generated within the specified * timeout period. * EINTR - The wait was interrupted by an unblocked, caught signal. * ****************************************************************************/ int nxsig_timedwait(FAR const sigset_t *set, FAR struct siginfo *info, FAR const struct timespec *timeout) { FAR struct tcb_s *rtcb = this_task(); sigset_t intersection; FAR sigpendq_t *sigpend; irqstate_t flags; int32_t waitticks; int ret; DEBUGASSERT(set != NULL && rtcb->waitdog == NULL); /* Several operations must be performed below: We must determine if any * signal is pending and, if not, wait for the signal. Since signals can * be posted from the interrupt level, there is a race condition that * can only be eliminated by disabling interrupts! */ flags = enter_critical_section(); /* Check if there is a pending signal corresponding to one of the * signals in the pending signal set argument. */ intersection = *set & nxsig_pendingset(rtcb); if (intersection != NULL_SIGNAL_SET) { /* One or more of the signals in intersections is sufficient to cause * us to not wait. Pick the lowest numbered signal and mark it not * pending. */ sigpend = nxsig_remove_pendingsignal(rtcb, nxsig_lowest(&intersection)); DEBUGASSERT(sigpend); /* Return the signal info to the caller if so requested */ if (info != NULL) { memcpy(info, &sigpend->info, sizeof(struct siginfo)); } /* The return value is the number of the signal that awakened us */ ret = sigpend->info.si_signo; /* Then dispose of the pending signal structure properly */ nxsig_release_pendingsignal(sigpend); leave_critical_section(flags); } /* We will have to wait for a signal to be posted to this task. */ else { #ifdef CONFIG_CANCELLATION_POINTS /* nxsig_timedwait() is not a cancellation point, but it may be called * from a cancellation point. So if a cancellation is pending, we * must exit immediately without waiting. */ if (check_cancellation_point()) { /* If there is a pending cancellation, then do not perform * the wait. Exit now with ECANCELED. */ leave_critical_section(flags); return -ECANCELED; } #endif /* Save the set of pending signals to wait for */ rtcb->sigwaitmask = *set; /* Check if we should wait for the timeout */ if (timeout != NULL) { /* Convert the timespec to system clock ticks, making sure that * the resulting delay is greater than or equal to the requested * time in nanoseconds. */ #ifdef CONFIG_HAVE_LONG_LONG uint64_t waitticks64 = ((uint64_t)timeout->tv_sec * NSEC_PER_SEC + (uint64_t)timeout->tv_nsec + NSEC_PER_TICK - 1) / NSEC_PER_TICK; DEBUGASSERT(waitticks64 <= UINT32_MAX); waitticks = (uint32_t)waitticks64; #else uint32_t waitmsec; DEBUGASSERT(timeout->tv_sec < UINT32_MAX / MSEC_PER_SEC); waitmsec = timeout->tv_sec * MSEC_PER_SEC + (timeout->tv_nsec + NSEC_PER_MSEC - 1) / NSEC_PER_MSEC; waitticks = MSEC2TICK(waitmsec); #endif /* Create a watchdog */ rtcb->waitdog = wd_create(); DEBUGASSERT(rtcb->waitdog); if (rtcb->waitdog) { /* This little bit of nonsense is necessary for some * processors where sizeof(pointer) < sizeof(uint32_t). * see wdog.h. */ union wdparm_u wdparm; wdparm.pvarg = (FAR void *)rtcb; /* Start the watchdog */ wd_start(rtcb->waitdog, waitticks, nxsig_timeout, 1, wdparm.pvarg); /* Now wait for either the signal or the watchdog, but * first, make sure this is not the idle task, * descheduling that isn't going to end well. */ DEBUGASSERT(NULL != rtcb->flink); up_block_task(rtcb, TSTATE_WAIT_SIG); /* We no longer need the watchdog */ wd_delete(rtcb->waitdog); rtcb->waitdog = NULL; } /* REVISIT: And do what if there are no watchdog timers? The wait * will fail and we will return something bogus. */ } /* No timeout, just wait */ else { /* And wait until one of the unblocked signals is posted, * but first make sure this is not the idle task, * descheduling that isn't going to end well. */ DEBUGASSERT(NULL != rtcb->flink); up_block_task(rtcb, TSTATE_WAIT_SIG); } /* We are running again, clear the sigwaitmask */ rtcb->sigwaitmask = NULL_SIGNAL_SET; /* When we awaken, the cause will be in the TCB. Get the signal number * or timeout) that awakened us. */ if (GOOD_SIGNO(rtcb->sigunbinfo.si_signo)) { /* We were awakened by a signal... but is it one of the signals * that we were waiting for? */ if (sigismember(set, rtcb->sigunbinfo.si_signo)) { /* Yes.. the return value is the number of the signal that * awakened us. */ ret = rtcb->sigunbinfo.si_signo; } else { /* No... then report the EINTR error */ ret = -EINTR; } } else { /* Otherwise, we must have been awakened by the timeout or, * perhaps, the wait was cancelled. */ #ifdef CONFIG_CANCELLATION_POINTS if (rtcb->sigunbinfo.si_signo == SIG_CANCEL_TIMEOUT) { /* The wait was canceled */ ret = -rtcb->sigunbinfo.si_errno; DEBUGASSERT(ret < 0); } else #endif { /* We were awakened by a timeout. Set EAGAIN and return an * error. */ DEBUGASSERT(rtcb->sigunbinfo.si_signo == SIG_WAIT_TIMEOUT); ret = -EAGAIN; } } /* Return the signal info to the caller if so requested */ if (info) { memcpy(info, &rtcb->sigunbinfo, sizeof(struct siginfo)); } leave_critical_section(flags); } return ret; } /**************************************************************************** * Name: sigtimedwait * * Description: * This function selects the pending signal set specified by the argument * set. If multiple signals are pending in set, it will remove and return * the lowest numbered one. If no signals in set are pending at the time * of the call, the calling process will be suspended until one of the * signals in set becomes pending, OR until the process is interrupted by * an unblocked signal, OR until the time interval specified by timeout * (if any), has expired. If timeout is NULL, then the timeout interval * is forever. * * If the info argument is non-NULL, the selected signal number is stored * in the si_signo member and the cause of the signal is stored in the * si_code member. The content of si_value is only meaningful if the * signal was generated by sigqueue(). * * The following values for si_code are defined in signal.h: * SI_USER - Signal sent from kill, raise, or abort * SI_QUEUE - Signal sent from sigqueue * SI_TIMER - Signal is result of timer expiration * SI_ASYNCIO - Signal is the result of asynch IO completion * SI_MESGQ - Signal generated by arrival of a message on an * empty message queue. * * Input Parameters: * set - The pending signal set. * info - The returned value (may be NULL). * timeout - The amount of time to wait (may be NULL) * * Returned Value: * Signal number that cause the wait to be terminated, otherwise -1 (ERROR) * is returned with errno set to either: * * EAGAIN - No signal specified by set was generated within the specified * timeout period. * EINTR - The wait was interrupted by an unblocked, caught signal. * ****************************************************************************/ int sigtimedwait(FAR const sigset_t *set, FAR struct siginfo *info, FAR const struct timespec *timeout) { int ret; /* sigtimedwait() is a cancellation point */ enter_cancellation_point(); /* Let nxsig_timedwait() do the work. */ ret = nxsig_timedwait(set, info, timeout); if (ret < 0) { set_errno(-ret); ret = ERROR; } leave_cancellation_point(); return ret; }