incubator-nuttx/sched/task/task_cancelpt.c

325 lines
11 KiB
C

/****************************************************************************
* sched/task/task_cancelpt.c
*
* Copyright (C) 2016 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.
*
****************************************************************************/
/****************************************************************************
* Cancellation Points.
*
* Cancellation points shall occur when a thread is executing the following
* functions:
*
* accept() mq_timedsend() putpmsg() sigtimedwait()
* aio_suspend() msgrcv() pwrite() sigwait()
* clock_nanosleep() msgsnd() read() sigwaitinfo()
* close() msync() readv() sleep()
* connect() nanosleep() recv() system()
* creat() open() recvfrom() tcdrain()
* fcntl() pause() recvmsg() usleep()
* fdatasync() poll() select() wait()
* fsync() pread() sem_timedwait() waitid()
* getmsg() pselect() sem_wait() waitpid()
* getpmsg() pthread_cond_timedwait() send() write()
* lockf() pthread_cond_wait() sendmsg() writev()
* mq_receive() pthread_join() sendto()
* mq_send() pthread_testcancel() sigpause()
* mq_timedreceive() putmsg() sigsuspend()
*
* Each of the above function must call enter_cancellation_point() on entry
* in order to establish the cancellation point and leave_cancellation_point()
* on exit. These functions are described below.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sched.h>
#include <errno.h>
#include <nuttx/irq.h>
#include <nuttx/cancelpt.h>
#include "sched/sched.h"
#include "semaphore/semaphore.h"
#include "mqueue/mqueue.h"
#include "task/task.h"
#ifdef CONFIG_CANCELLATION_POINTS
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: enter_cancellation_point
*
* Description:
* Called at the beginning of the cancellation point to establish the
* cancellation point. This function does the following:
*
* 1. If deferred cancellation does not apply to this thread, nothing is
* done, otherwise, it
* 2. Sets state information in the caller's TCB and increments a nesting
* count.
* 3. If this is the outermost nesting level, it checks if there is a
* pending cancellation and, if so, calls either exit() or
* pthread_exit(), depending upon the type of the thread.
*
* Input Parameters:
* None
*
* Returned Value
* true is returned if a cancellation is pending but cannot be performed
* now due to the nesting level.
*
****************************************************************************/
bool enter_cancellation_point(void)
{
FAR struct tcb_s *tcb = this_task();
bool ret = false;
/* Disabling pre-emption should provide sufficient protection. We only
* need the TCB to be stationary (no interrupt level modification is
* anticipated).
*
* REVISIT: is locking the scheduler sufficent in SMP mode?
*/
sched_lock();
/* If cancellation is disabled on this thread or if this thread is using
* asynchronous cancellation, then do nothing.
*
* Special case: if the cpcount count is greater than zero, then we are
* nested and the above condition was certainly true at the outermost
* nesting level.
*/
if (((tcb->flags & TCB_FLAG_NONCANCELABLE) == 0 &&
(tcb->flags & TCB_FLAG_CANCEL_DEFERRED) != 0) ||
tcb->cpcount > 0)
{
/* Check if there is a pending cancellation */
if ((tcb->flags & TCB_FLAG_CANCEL_PENDING) != 0)
{
/* Yes... return true (if we don't exit here) */
ret = true;
/* If there is a pending cancellation and we are at the outermost
* nesting level of cancellation function calls, then exit
* according to the type of the thread.
*/
if (tcb->cpcount == 0)
{
#ifndef CONFIG_DISABLE_PTHREAD
if ((tcb->flags & TCB_FLAG_TTYPE_MASK) == TCB_FLAG_TTYPE_PTHREAD)
{
pthread_exit(PTHREAD_CANCELED);
}
else
#endif
{
exit(EXIT_FAILURE);
}
}
}
/* Otherwise, indicate that we are at a cancellation point by
* incrementing the nesting level of the cancellation point
* functions.
*/
DEBUGASSERT(tcb->cpcount < INT16_MAX);
tcb->cpcount++;
}
sched_unlock();
return ret;
}
/****************************************************************************
* Name: leave_cancellation_point
*
* Description:
* Called at the end of the cancellation point. This function does the
* following:
*
* 1. If deferred cancellation does not apply to this thread, nothing is
* done, otherwise, it
* 2. Clears state information in the caller's TCB and decrements a
* nesting count.
* 3. If this is the outermost nesting level, it checks if there is a
* pending cancellation and, if so, calls either exit() or
* pthread_exit(), depending upon the type of the thread.
*
* Input Parameters:
* None
*
* Returned Value
* None
*
****************************************************************************/
void leave_cancellation_point(void)
{
FAR struct tcb_s *tcb = this_task();
/* Disabling pre-emption should provide sufficient protection. We only
* need the TCB to be stationary (no interrupt level modification is
* anticipated).
*
* REVISIT: is locking the scheduler sufficent in SMP mode?
*/
sched_lock();
/* If cancellation is disabled on this thread or if this thread is using
* asynchronous cancellation, then do nothing. Here we check only the
* nesting level: if the cpcount count is greater than zero, then the
* required condition was certainly true at the outermost nesting level.
*/
if (tcb->cpcount > 0)
{
/* Decrement the nesting level. If if would decrement to zero, then
* we are at the outermost nesting level and may need to do more.
*/
if (tcb->cpcount == 1)
{
/* We are no longer at the cancellation point */
tcb->cpcount = 0;
/* If there is a pending cancellation then just exit according to
* the type of the thread.
*/
if ((tcb->flags & TCB_FLAG_CANCEL_PENDING) != 0)
{
#ifndef CONFIG_DISABLE_PTHREAD
if ((tcb->flags & TCB_FLAG_TTYPE_MASK) == TCB_FLAG_TTYPE_PTHREAD)
{
pthread_exit(PTHREAD_CANCELED);
}
else
#endif
{
exit(EXIT_FAILURE);
}
}
}
else
{
/* We are not at the outermost nesting level. Just decrment the
* nesting level count.
*/
tcb->cpcount--;
}
}
sched_unlock();
}
/****************************************************************************
* Name: notify_cancellation
*
* Description:
* Called by task_delete() or pthread_cancel() if the cancellation occurs
* while we the thread is within the cancellation point. This logic
* behaves much like sending a signal: It will cause waiting threads
* to wake up and terminated with ECANCELED. A call to
* leave_cancellation_point() whould then follow, causing the thread to
* exit.
*
****************************************************************************/
void notify_cancellation(FAR struct tcb_s *tcb)
{
irqstate_t flags;
/* We need perform the following operations from within a critical section
* because it can compete with interrupt level activity.
*/
flags = enter_critical_section();
/* Make sure that the cancellation pending indication is set. */
tcb->flags |= TCB_FLAG_CANCEL_PENDING;
/* We only notify the cancellation if (1) the thread has not disabled
* cancellation, (2) the thread uses the deffered cancellation mode,
* (3) the thread is waiting within a cancellation point.
*/
if (((tcb->flags & TCB_FLAG_NONCANCELABLE) == 0 &&
(tcb->flags & TCB_FLAG_CANCEL_DEFERRED) != 0) ||
tcb->cpcount > 0)
{
/* If the thread is blocked waiting for a semaphore, then the thread
* must be unblocked to handle the cancellation.
*/
if (tcb->task_state == TSTATE_WAIT_SEM)
{
sem_waitirq(tcb, ECANCELED);
}
/* If the thread is blocked waiting on a message queue, then the
* thread must be unblocked to handle the cancellation.
*/
#ifndef CONFIG_DISABLE_MQUEUE
if (tcb->task_state == TSTATE_WAIT_MQNOTEMPTY ||
tcb->task_state == TSTATE_WAIT_MQNOTFULL)
{
mq_waitirq(tcb, ECANCELED);
}
#endif
}
leave_critical_section(flags);
}
#endif /* CONFIG_CANCELLATION_POINTS */