160 lines
4.9 KiB
C
160 lines
4.9 KiB
C
/****************************************************************************
|
|
* sched/signal/sig_suspend.c
|
|
*
|
|
* SPDX-License-Identifier: Apache-2.0
|
|
*
|
|
* Licensed to the Apache Software Foundation (ASF) under one or more
|
|
* contributor license agreements. See the NOTICE file distributed with
|
|
* this work for additional information regarding copyright ownership. The
|
|
* ASF licenses this file to you under the Apache License, Version 2.0 (the
|
|
* "License"); you may not use this file except in compliance with the
|
|
* License. You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
|
|
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
|
|
* License for the specific language governing permissions and limitations
|
|
* under the License.
|
|
*
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Included Files
|
|
****************************************************************************/
|
|
|
|
#include <nuttx/config.h>
|
|
|
|
#include <signal.h>
|
|
#include <assert.h>
|
|
#include <debug.h>
|
|
#include <sched.h>
|
|
|
|
#include <nuttx/irq.h>
|
|
#include <nuttx/arch.h>
|
|
#include <nuttx/cancelpt.h>
|
|
|
|
#include "sched/sched.h"
|
|
#include "signal/signal.h"
|
|
|
|
/****************************************************************************
|
|
* Public Functions
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Name: sigsuspend
|
|
*
|
|
* Description:
|
|
*
|
|
* The sigsuspend() function replaces the signal mask of the task with the
|
|
* set of signals pointed to by the argument 'set' and then suspends the
|
|
* process until delivery of a signal to the task.
|
|
*
|
|
* If the effect of the set argument is to unblock a pending signal, then
|
|
* no wait is performed.
|
|
*
|
|
* The original signal mask is restored when this function returns.
|
|
*
|
|
* Waiting for an empty signal set stops a task without freeing any
|
|
* resources.
|
|
*
|
|
* Input Parameters:
|
|
* set - signal mask to use while suspended.
|
|
*
|
|
* Returned Value:
|
|
* -1 (ERROR) always
|
|
*
|
|
* Assumptions:
|
|
*
|
|
* POSIX Compatibility:
|
|
* int sigsuspend(const sigset_t *set);
|
|
*
|
|
* POSIX states that sigsuspend() "suspends the process until delivery of
|
|
* a signal whose action is either to execute a signal-catching function
|
|
* or to terminate the process." Only the deliver of a signal is required
|
|
* in the present implementation (even if the signal is ignored).
|
|
*
|
|
****************************************************************************/
|
|
|
|
int sigsuspend(FAR const sigset_t *set)
|
|
{
|
|
FAR struct tcb_s *rtcb = this_task();
|
|
sigset_t saved_sigprocmask;
|
|
irqstate_t flags;
|
|
|
|
/* sigsuspend() is a cancellation point */
|
|
|
|
enter_cancellation_point();
|
|
|
|
/* 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!
|
|
*/
|
|
|
|
sched_lock(); /* Not necessary */
|
|
flags = enter_critical_section();
|
|
|
|
/* Save a copy of the old sigprocmask and install
|
|
* the new (temporary) sigprocmask
|
|
*/
|
|
|
|
saved_sigprocmask = rtcb->sigprocmask;
|
|
rtcb->sigprocmask = *set;
|
|
sigemptyset(&rtcb->sigwaitmask);
|
|
|
|
/* Check if there is a pending signal corresponding to one of the
|
|
* signals that will be unblocked by the new sigprocmask.
|
|
*/
|
|
|
|
if (nxsig_unmask_pendingsignal())
|
|
{
|
|
/* Dispatching one or more of the signals is sufficient to cause
|
|
* us to not wait. Restore the original sigprocmask.
|
|
*/
|
|
|
|
rtcb->sigprocmask = saved_sigprocmask;
|
|
leave_critical_section(flags);
|
|
}
|
|
else
|
|
{
|
|
/* Its time to wait until one of the unblocked signals is posted,
|
|
* but first, ensure this is not the idle task, descheduling that
|
|
* isn't going to end well.
|
|
*/
|
|
|
|
DEBUGASSERT(!is_idle_task(rtcb));
|
|
|
|
/* Remove the tcb task from the running list. */
|
|
|
|
nxsched_remove_self(rtcb);
|
|
|
|
/* Add the task to the specified blocked task list */
|
|
|
|
rtcb->task_state = TSTATE_WAIT_SIG;
|
|
dq_addlast((FAR dq_entry_t *)rtcb, list_waitingforsignal());
|
|
|
|
/* Now, perform the context switch */
|
|
|
|
up_switch_context(this_task(), rtcb);
|
|
|
|
/* We are running again, restore the original sigprocmask */
|
|
|
|
rtcb->sigprocmask = saved_sigprocmask;
|
|
leave_critical_section(flags);
|
|
|
|
/* Now, handle the (rare?) case where (a) a blocked signal was received
|
|
* while the task was suspended but (b) restoring the original
|
|
* sigprocmask will unblock the signal.
|
|
*/
|
|
|
|
nxsig_unmask_pendingsignal();
|
|
}
|
|
|
|
sched_unlock();
|
|
leave_cancellation_point();
|
|
set_errno(EINTR);
|
|
return ERROR;
|
|
}
|