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- /****************************************************************************
- * sched/signal/sig_timedwait.c
- *
- * Copyright (C) 2007-2009, 2012-2017 Gregory Nutt. All rights reserved.
- * Author: Gregory Nutt <gnutt@nuttx.org>
- *
- * 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 <nuttx/config.h>
- #include <nuttx/compiler.h>
- #include <stdint.h>
- #include <string.h>
- #include <signal.h>
- #include <time.h>
- #include <assert.h>
- #include <debug.h>
- #include <sched.h>
- #include <errno.h>
- #include <nuttx/irq.h>
- #include <nuttx/arch.h>
- #include <nuttx/wdog.h>
- #include <nuttx/signal.h>
- #include <nuttx/cancelpt.h>
- #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 cancellaction 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 */
- (void)wd_start(rtcb->waitdog, waitticks,
- (wdentry_t)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 store din 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 */
- (void)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;
- }
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