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