a7265d71c6
Squashed commit of the following:
Add procfs support to show stopped tasks. Add nxsig_action() to solve a chicken and egg problem: We needed to use sigaction to set default actions, but sigaction() would refuse to set actions if the default actions could not be caught or ignored.
sched/signal: Add configuration option to selectively enabled/disable default signal actions for SIGSTOP/SIGSTP/SIGCONT and SIGKILL/SIGINT. Fix some compilation issues.
sched/sched: Okay.. I figured out a way to handle state changes that may occur while they were stopped. If a task/thread was already blocked when SIGSTOP/SIGSTP was received, it will restart in the running state. I will appear that to the task/thread that the blocked condition was interrupt by a signal and returns the EINTR error.
sched/group and sched/sched: Finish framework for continue/resume logic.
sched/signal: Roughing out basic structure to support task suspend/resume
511 lines
15 KiB
C
511 lines
15 KiB
C
/****************************************************************************
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* sched/signal/sig_dispatch.c
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*
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* Copyright (C) 2007, 2009, 2011, 2016, 2018 Gregory Nutt. All rights
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* 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 <string.h>
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#include <signal.h>
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#include <unistd.h>
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#include <sched.h>
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#include <errno.h>
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#include <debug.h>
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#include <nuttx/irq.h>
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#include <nuttx/arch.h>
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#include "sched/sched.h"
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#include "group/group.h"
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#include "semaphore/semaphore.h"
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#include "signal/signal.h"
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#include "mqueue/mqueue.h"
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: nxsig_queue_action
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*
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* Description:
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* Queue a signal action for delivery to a task.
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*
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* Returned Value:
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* Returns 0 (OK) on success or a negated errno value on failure.
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*
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****************************************************************************/
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static int nxsig_queue_action(FAR struct tcb_s *stcb, siginfo_t *info)
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{
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FAR sigactq_t *sigact;
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FAR sigq_t *sigq;
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irqstate_t flags;
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int ret = OK;
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sched_lock();
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DEBUGASSERT(stcb != NULL && stcb->group != NULL);
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/* Find the group sigaction associated with this signal */
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sigact = nxsig_find_action(stcb->group, info->si_signo);
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/* Check if a valid signal handler is available and if the signal is
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* unblocked. NOTE: There is no default action.
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*/
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if ((sigact) && (sigact->act.sa_u._sa_sigaction))
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{
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/* Allocate a new element for the signal queue. NOTE:
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* nxsig_alloc_pendingsigaction will force a system crash if it is
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* unable to allocate memory for the signal data */
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sigq = nxsig_alloc_pendingsigaction();
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if (!sigq)
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{
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ret = -ENOMEM;
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}
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else
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{
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/* Populate the new signal queue element */
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sigq->action.sighandler = sigact->act.sa_u._sa_sigaction;
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sigq->mask = sigact->act.sa_mask;
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memcpy(&sigq->info, info, sizeof(siginfo_t));
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/* Put it at the end of the pending signals list */
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flags = enter_critical_section();
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sq_addlast((FAR sq_entry_t *)sigq, &(stcb->sigpendactionq));
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leave_critical_section(flags);
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}
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}
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sched_unlock();
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return ret;
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}
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/****************************************************************************
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* Name: nxsig_alloc_pendingsignal
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*
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* Description:
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* Allocate a pending signal list entry
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*
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****************************************************************************/
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static FAR sigpendq_t *nxsig_alloc_pendingsignal(void)
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{
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FAR sigpendq_t *sigpend;
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irqstate_t flags;
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/* Check if we were called from an interrupt handler. */
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if (up_interrupt_context())
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{
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/* Try to get the pending signal structure from the free list */
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sigpend = (FAR sigpendq_t *)sq_remfirst(&g_sigpendingsignal);
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if (!sigpend)
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{
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/* If no pending signal structure is available in the free list,
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* then try the special list of structures reserved for
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* interrupt handlers
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*/
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sigpend = (FAR sigpendq_t *)sq_remfirst(&g_sigpendingirqsignal);
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}
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}
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/* If we were not called from an interrupt handler, then we are
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* free to allocate pending action structures if necessary.
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*/
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else
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{
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/* Try to get the pending signal structure from the free list */
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flags = enter_critical_section();
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sigpend = (FAR sigpendq_t *)sq_remfirst(&g_sigpendingsignal);
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leave_critical_section(flags);
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/* Check if we got one. */
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if (!sigpend)
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{
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/* No... Allocate the pending signal */
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if (!sigpend)
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{
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sigpend = (FAR sigpendq_t *)kmm_malloc((sizeof (sigpendq_t)));
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}
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/* Check if we got an allocated message */
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if (sigpend)
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{
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sigpend->type = SIG_ALLOC_DYN;
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}
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}
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}
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return sigpend;
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}
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/****************************************************************************
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* Name: nxsig_find_pendingsignal
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*
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* Description:
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* Find a specified element in the pending signal list
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*
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****************************************************************************/
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static FAR sigpendq_t *
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nxsig_find_pendingsignal(FAR struct task_group_s *group, int signo)
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{
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FAR sigpendq_t *sigpend = NULL;
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irqstate_t flags;
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DEBUGASSERT(group != NULL);
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/* Pending signals can be added from interrupt level. */
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flags = enter_critical_section();
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/* Search the list for a action pending on this signal */
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for (sigpend = (FAR sigpendq_t *)group->tg_sigpendingq.head;
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(sigpend && sigpend->info.si_signo != signo);
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sigpend = sigpend->flink);
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leave_critical_section(flags);
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return sigpend;
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}
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/****************************************************************************
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* Name: nxsig_add_pendingsignal
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*
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* Description:
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* Add the specified signal to the signal pending list. NOTE: This
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* function will queue only one entry for each pending signal. This
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* was done intentionally so that a run-away sender cannot consume
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* all of memory.
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*
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****************************************************************************/
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static void nxsig_add_pendingsignal(FAR struct tcb_s *stcb,
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FAR siginfo_t *info)
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{
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FAR struct task_group_s *group;
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FAR sigpendq_t *sigpend;
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irqstate_t flags;
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DEBUGASSERT(stcb != NULL && stcb->group != NULL);
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group = stcb->group;
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/* Check if the signal is already pending for the group */
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sigpend = nxsig_find_pendingsignal(group, info->si_signo);
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if (sigpend != NULL)
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{
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/* The signal is already pending... retain only one copy */
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memcpy(&sigpend->info, info, sizeof(siginfo_t));
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}
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/* No... There is nothing pending in the group for this signo */
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else
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{
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/* Allocate a new pending signal entry */
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sigpend = nxsig_alloc_pendingsignal();
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if (sigpend != NULL)
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{
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/* Put the signal information into the allocated structure */
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memcpy(&sigpend->info, info, sizeof(siginfo_t));
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/* Add the structure to the group pending signal list */
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flags = enter_critical_section();
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sq_addlast((FAR sq_entry_t *)sigpend, &group->tg_sigpendingq);
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leave_critical_section(flags);
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}
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}
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DEBUGASSERT(sigpend);
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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_tcbdispatch
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*
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* Description:
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* All signals received the task (whatever the source) go through this
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* function to be processed. This function is responsible for:
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*
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* - Determining if the signal is blocked.
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* - Queuing and dispatching signal actions
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* - Unblocking tasks that are waiting for signals
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* - Queuing pending signals.
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*
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* This function will deliver the signal to the task associated with
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* the specified TCB. This function should *not* typically be used
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* to dispatch signals since it will *not* follow the group signal
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* deliver algorithms.
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*
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* Returned Value:
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* Returns 0 (OK) on success or a negated errno value on failure.
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*
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****************************************************************************/
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int nxsig_tcbdispatch(FAR struct tcb_s *stcb, siginfo_t *info)
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{
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irqstate_t flags;
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int ret = OK;
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sinfo("TCB=0x%08x signo=%d code=%d value=%d mask=%08x\n",
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stcb, info->si_signo, info->si_code,
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info->si_value.sival_int, stcb->sigprocmask);
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DEBUGASSERT(stcb != NULL && info != NULL);
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/************************* MASKED SIGNAL HANDLING ************************/
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/* Check if the signal is masked -- if it is, it will be added to the list
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* of pending signals.
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*/
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if (sigismember(&stcb->sigprocmask, info->si_signo))
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{
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/* Check if the task is waiting for this pending signal. If so, then
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* unblock it. This must be performed in a critical section because
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* signals can be queued * from the interrupt level.
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*/
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flags = enter_critical_section();
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if (stcb->task_state == TSTATE_WAIT_SIG &&
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sigismember(&stcb->sigwaitmask, info->si_signo))
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{
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memcpy(&stcb->sigunbinfo, info, sizeof(siginfo_t));
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stcb->sigwaitmask = NULL_SIGNAL_SET;
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up_unblock_task(stcb);
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leave_critical_section(flags);
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}
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/* Its not one we are waiting for... Add it to the list of pending
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* signals.
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*/
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else
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{
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leave_critical_section(flags);
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nxsig_add_pendingsignal(stcb, info);
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}
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}
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/************************ UNMASKED SIGNAL HANDLING ***********************/
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else
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{
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/* Queue any sigaction's requested by this task. */
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ret = nxsig_queue_action(stcb, info);
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/* Deliver of the signal must be performed in a critical section */
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flags = enter_critical_section();
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/* Then schedule execution of the signal handling action on the
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* recipient's thread. SMP related handling will be done in
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* up_schedule_sigaction()
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*/
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up_schedule_sigaction(stcb, nxsig_deliver);
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/* Check if the task is waiting for an unmasked signal. If so, then
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* unblock it. This must be performed in a critical section because
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* signals can be queued from the interrupt level.
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*/
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if (stcb->task_state == TSTATE_WAIT_SIG)
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{
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memcpy(&stcb->sigunbinfo, info, sizeof(siginfo_t));
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stcb->sigwaitmask = NULL_SIGNAL_SET;
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up_unblock_task(stcb);
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}
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leave_critical_section(flags);
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/* If the task neither was waiting for the signal nor had a signal
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* handler attached to the signal, then the default action is
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* simply to ignore the signal
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*/
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/*********************** OTHER SIGNAL HANDLING ***********************/
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/* If the task is blocked waiting for a semaphore, then that task must
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* be unblocked when a signal is received.
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*/
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if (stcb->task_state == TSTATE_WAIT_SEM)
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{
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nxsem_wait_irq(stcb, EINTR);
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}
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#ifndef CONFIG_DISABLE_MQUEUE
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/* If the task is blocked waiting on a message queue, then that task
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* must be unblocked when a signal is received.
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*/
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if (stcb->task_state == TSTATE_WAIT_MQNOTEMPTY ||
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stcb->task_state == TSTATE_WAIT_MQNOTFULL)
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{
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nxmq_wait_irq(stcb, EINTR);
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}
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#endif
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#ifdef CONFIG_SIG_SIGSTOP_ACTION
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/* If the task was stopped by SIGSTOP or SIGSTP, then unblock the task
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* if SIGCONT is received.
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*/
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if (stcb->task_state == TSTATE_TASK_STOPPED &&
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info->si_signo == SIGCONT)
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{
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#ifdef HAVE_GROUP_MEMBERS
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group_continue(stcb);
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#else
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sched_continue(stcb);
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#endif
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}
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#endif
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}
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return ret;
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}
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/****************************************************************************
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* Name: nxsig_dispatch
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*
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* Description:
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* This is the front-end for nxsig_tcbdispatch that should be typically
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* be used to dispatch a signal. If HAVE_GROUP_MEMBERS is defined,
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* then function will follow the group signal delivery algorithms:
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*
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* This front-end does the following things before calling
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* nxsig_tcbdispatch.
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*
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* With HAVE_GROUP_MEMBERS defined:
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* - Get the TCB associated with the pid.
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* - If the TCB was found, get the group from the TCB.
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* - If the PID has already exited, lookup the group that that was
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* started by this task.
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* - Use the group to pick the TCB to receive the signal
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* - Call nxsig_tcbdispatch with the TCB
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*
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* With HAVE_GROUP_MEMBERS *not* defined
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* - Get the TCB associated with the pid.
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* - Call nxsig_tcbdispatch with the TCB
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*
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* Returned Value:
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* Returns 0 (OK) on success or a negated errno value on failure.
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*
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****************************************************************************/
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int nxsig_dispatch(pid_t pid, FAR siginfo_t *info)
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{
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#ifdef HAVE_GROUP_MEMBERS
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FAR struct tcb_s *stcb;
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FAR struct task_group_s *group;
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/* Get the TCB associated with the pid */
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stcb = sched_gettcb(pid);
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if (stcb != NULL)
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{
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/* The task/thread associated with this PID is still active. Get its
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* task group.
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*/
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group = stcb->group;
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}
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else
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{
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/* The task/thread associated with this PID has exited. In the normal
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* usage model, the PID should correspond to the PID of the task that
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* created the task group. Try looking it up.
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*/
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group = group_findbypid(pid);
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}
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/* Did we locate the group? */
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if (group != NULL)
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{
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/* Yes.. call group_signal() to send the signal to the correct group
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* member.
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*/
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return group_signal(group, info);
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}
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else
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{
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return -ESRCH;
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}
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#else
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FAR struct tcb_s *stcb;
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/* Get the TCB associated with the pid */
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stcb = sched_gettcb(pid);
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if (stcb == NULL)
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{
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return -ESRCH;
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}
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return nxsig_tcbdispatch(stcb, info);
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#endif
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}
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