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