309 lines
10 KiB
C
309 lines
10 KiB
C
/****************************************************************************
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* sched/pthread_condtimedwait.c
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*
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* Copyright (C) 2007-2009 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 <unistd.h>
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#include <pthread.h>
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#include <signal.h>
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#include <time.h>
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#include <errno.h>
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#include <wdog.h>
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#include <debug.h>
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#include "os_internal.h"
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#include "pthread_internal.h"
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#include "clock_internal.h"
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/****************************************************************************
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* Definitions
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****************************************************************************/
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/****************************************************************************
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* Private Type Declarations
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****************************************************************************/
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/****************************************************************************
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* Global Variables
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****************************************************************************/
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/****************************************************************************
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* Private Variables
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****************************************************************************/
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: pthread_condtimedout
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*
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* Description:
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* This function is called if the timeout elapses before
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* the condition is signaled.
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*
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* Parameters:
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* argc - the number of arguments (should be 2)
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* pid - the task ID of the task to wakeup
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* signo - The signal to use to wake up the task
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*
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* Return Value:
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* None
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*
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* Assumptions:
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*
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****************************************************************************/
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static void pthread_condtimedout(int argc, uint32_t pid, uint32_t signo)
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{
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#ifdef CONFIG_CAN_PASS_STRUCTS
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union sigval value;
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/* Send the specified signal to the specified task. */
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value.sival_ptr = NULL;
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(void)sigqueue((int)pid, (int)signo, value);
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#else
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(void)sigqueue((int)pid, (int)signo, NULL);
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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: pthread_cond_timedwait
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*
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* Description:
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* A thread can perform a timed wait on a condition variable.
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*
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* Parameters:
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* cond - the condition variable to wait on
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* mutex - the mutex that protects the condition variable
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* abstime - wait until this absolute time
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*
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* Return Value:
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* OK (0) on success; ERROR (-1) on failure with errno
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* set appropriately.
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*
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* Assumptions:
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* Timing is of resolution 1 msec, with +/-1 millisecond
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* accuracy.
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*
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****************************************************************************/
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int pthread_cond_timedwait(FAR pthread_cond_t *cond, FAR pthread_mutex_t *mutex,
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FAR const struct timespec *abstime)
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{
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WDOG_ID wdog;
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int ticks;
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int mypid = (int)getpid();
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irqstate_t int_state;
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int ret = OK;
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int status;
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sdbg("cond=0x%p mutex=0x%p abstime=0x%p\n", cond, mutex, abstime);
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/* Make sure that non-NULL references were provided. */
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if (!cond || !mutex)
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{
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ret = EINVAL;
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}
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/* Make sure that the caller holds the mutex */
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else if (mutex->pid != mypid)
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{
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ret = EPERM;
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}
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/* If no wait time is provided, this function degenerates to
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* the same behavior as pthread_cond_wait().
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*/
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else if (!abstime)
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{
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ret = pthread_cond_wait(cond, mutex);
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}
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else
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{
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/* Create a watchdog */
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wdog = wd_create();
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if (!wdog)
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{
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ret = EINVAL;
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}
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else
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{
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sdbg("Give up mutex...\n");
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/* We must disable pre-emption and interrupts here so that
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* the time stays valid until the wait begins. This adds
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* complexity because we assure that interrupts and
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* pre-emption are re-enabled correctly.
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*/
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sched_lock();
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int_state = irqsave();
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/* Convert the timespec to clock ticks. We must disable pre-emption
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* here so that this time stays valid until the wait begins.
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*/
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ret = clock_abstime2ticks(CLOCK_REALTIME, abstime, &ticks);
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if (ret)
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{
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/* Restore interrupts (pre-emption will be enabled when
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* we fall through the if/then/else
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*/
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irqrestore(int_state);
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}
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else
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{
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/* Check the absolute time to wait. If it is now or in the past, then
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* just return with the timedout condition.
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*/
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if (ticks <= 0)
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{
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/* Restore interrupts and indicate that we have already timed out.
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* (pre-emption will be enabled when we fall through the
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* if/then/else
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*/
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irqrestore(int_state);
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ret = ETIMEDOUT;
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}
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else
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{
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/* Give up the mutex */
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mutex->pid = 0;
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ret = pthread_givesemaphore((sem_t*)&mutex->sem);
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if (ret)
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{
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/* Restore interrupts (pre-emption will be enabled when
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* we fall through the if/then/else)
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*/
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irqrestore(int_state);
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}
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else
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{
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/* Start the watchdog */
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wd_start(wdog, ticks, (wdentry_t)pthread_condtimedout,
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2, (uint32_t)mypid, (uint32_t)SIGCONDTIMEDOUT);
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/* Take the condition semaphore. Do not restore interrupts
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* until we return from the wait. This is necessary to
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* make sure that the watchdog timer and the condition wait
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* are started atomically.
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*/
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status = sem_wait((sem_t*)&cond->sem);
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/* Did we get the condition semaphore. */
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if (status != OK)
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{
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/* NO.. Handle the special case where the semaphore wait was
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* awakened by the receipt of a signal -- presumably the
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* signal posted by pthread_condtimedout().
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*/
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if (get_errno() == EINTR)
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{
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sdbg("Timedout!\n");
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ret = ETIMEDOUT;
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}
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else
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{
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ret = EINVAL;
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}
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}
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/* The interrupts stay disabled until after we sample the errno.
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* This is because when debug is enabled and the console is used
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* for debug output, then the errno can be altered by interrupt
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* handling! (bad)
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*/
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irqrestore(int_state);
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}
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/* Reacquire the mutex (retaining the ret). */
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sdbg("Re-locking...\n");
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status = pthread_takesemaphore((sem_t*)&mutex->sem);
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if (!status)
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{
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mutex->pid = mypid;
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}
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else if (!ret)
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{
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ret = status;
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}
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}
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/* Re-enable pre-emption (It is expected that interrupts
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* have already been re-enabled in the above logic)
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*/
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sched_unlock();
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}
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/* We no longer need the watchdog */
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wd_delete(wdog);
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}
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}
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sdbg("Returning %d\n", ret);
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return ret;
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}
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