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nuttx/sched/signal/sig_timedwait.c
Xiang Xiao 6a3c2aded6 Fix wait loop and void cast (#24) 
* Simplify EINTR/ECANCEL error handling

1. Add semaphore uninterruptible wait function
2 .Replace semaphore wait loop with a single uninterruptible wait
3. Replace all sem_xxx to nxsem_xxx

* Unify the void cast usage

1. Remove void cast for function because many place ignore the returned value witout cast
2. Replace void cast for variable with UNUSED macro
2020-01-02 10:54:43 -06:00

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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 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,
(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 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;
}
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