288 lines
9.0 KiB
C
288 lines
9.0 KiB
C
/*****************************************************************************
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* sched/group/group_signal.c
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*
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* Copyright (C) 2013 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 <sched.h>
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#include <assert.h>
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#include <signal.h>
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#include <errno.h>
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#include <debug.h>
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#include "sched/sched.h"
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#include "group/group.h"
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#include "signal/signal.h"
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#if defined(HAVE_TASK_GROUP) && !defined(CONFIG_DISABLE_SIGNALS)
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/*****************************************************************************
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* Pre-processor Definitions
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*****************************************************************************/
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/*****************************************************************************
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* Private Types
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*****************************************************************************/
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#ifdef HAVE_GROUP_MEMBERS
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struct group_signal_s
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{
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FAR siginfo_t *siginfo; /* Signal to be dispatched */
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FAR struct tcb_s *dtcb; /* Default, valid TCB */
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FAR struct tcb_s *utcb; /* TCB with this signal unblocked */
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FAR struct tcb_s *atcb; /* This TCB was awakened */
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FAR struct tcb_s *ptcb; /* This TCB received the signal */
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};
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#endif
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/*****************************************************************************
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* Private Data
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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: group_signal_handler
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*
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* Description:
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* Callback from group_foreachchild that handles one member of the group.
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*
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* Parameters:
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* pid - The ID of the group member that may be signalled.
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* arg - A pointer to a struct group_signal_s instance.
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*
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* Return Value:
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* 0 (OK) on success; a negated errno value on failure.
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*
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*****************************************************************************/
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#ifdef HAVE_GROUP_MEMBERS
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static int group_signal_handler(pid_t pid, FAR void *arg)
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{
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FAR struct group_signal_s *info = (FAR struct group_signal_s *)arg;
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FAR struct tcb_s *tcb;
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FAR sigactq_t *sigact;
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int ret;
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DEBUGASSERT(info);
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/* Get the TCB associated with the group member */
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tcb = sched_gettcb(pid);
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DEBUGASSERT(tcb);
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if (tcb)
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{
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/* Set this one as the default if we have not already set the default. */
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if (!info->dtcb)
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{
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info->dtcb = tcb;
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}
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/* Is the thread waiting for this signal (in this case, the signal is
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* probably blocked).
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*/
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if (sigismember(&tcb->sigwaitmask, info->siginfo->si_signo) && !info->atcb)
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{
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/* Yes.. This means that the task is suspended, waiting for this
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* signal to occur. Stop looking and use this TCB. The
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* requirement is this: If a task group receives a signal and
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* more than one thread is waiting on that signal, then one and
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* only one indeterminate thread out of that waiting group will
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* receive the signal.
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*/
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ret = sig_tcbdispatch(tcb, info->siginfo);
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if (ret < 0)
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{
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return ret;
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}
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/* Limit to one thread */
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info->atcb = tcb;
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if (info->ptcb != NULL);
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{
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return 1; /* Terminate the search */
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}
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}
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/* Is this signal unblocked on this thread? */
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if (!sigismember(&tcb->sigprocmask, info->siginfo->si_signo) &&
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!info->ptcb && tcb != info->atcb)
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{
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/* Yes.. remember this TCB if we have not encountered any
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* other threads that have the signal unblocked.
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*/
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if (!info->utcb)
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{
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info->utcb = tcb;
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}
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/* Is there also an action associated with the task? */
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sigact = sig_findaction(tcb, info->siginfo->si_signo);
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if (sigact)
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{
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/* Yes.. then use this thread. The requirement is this:
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* If a task group receives a signal then one and only one
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* indeterminate thread in the task group which is not
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* blocking the signal will receive the signal.
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*/
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ret = sig_tcbdispatch(tcb, info->siginfo);
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if (ret < 0)
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{
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return ret;
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}
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/* Limit to one thread */
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info->ptcb = tcb;
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if (info->atcb != NULL)
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{
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return 1; /* Terminate the search */
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}
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}
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}
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}
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return 0; /* Keep searching */
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}
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#endif
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/*****************************************************************************
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* Public Functions
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*****************************************************************************/
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/*****************************************************************************
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* Name: group_signal
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*
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* Description:
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* Send a signal to every member of the group.
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*
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* Parameters:
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* group - The task group that needs to be signalled.
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*
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* Return Value:
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* 0 (OK) on success; a negated errno value on failure.
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*
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* Assumptions:
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* Called during task termination in a safe context. No special precautions
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* are required here. Because signals can be sent from interrupt handlers,
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* this function may be called indirectly in the context of an interrupt
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* handler.
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*
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*****************************************************************************/
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int group_signal(FAR struct task_group_s *group, FAR siginfo_t *siginfo)
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{
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#ifdef HAVE_GROUP_MEMBERS
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struct group_signal_s info;
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FAR struct tcb_s *tcb;
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int ret;
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DEBUGASSERT(group && siginfo);
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info.siginfo = siginfo;
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info.dtcb = NULL; /* Default, valid TCB */
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info.utcb = NULL; /* TCB with this signal unblocked */
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info.atcb = NULL; /* This TCB was awakened */
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info.ptcb = NULL; /* This TCB received the signal */
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/* Make sure that pre-emption is disabled to that we signal all of the
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* members of the group before any of them actually run. (This does
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* nothing if were were called from an interrupt handler).
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*/
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sched_lock();
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/* Now visit each member of the group and perform signal handling checks. */
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ret = group_foreachchild(group, group_signal_handler, &info);
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if (ret < 0)
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{
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goto errout;
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}
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/* We need to dispatch the signal in any event (if nothing else so that it
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* can be added to the pending signal list). If we found a thread with the
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* signal unblocked, then use that thread.
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*/
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if (info.atcb == NULL && info.ptcb == NULL)
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{
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if (info.utcb)
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{
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tcb = info.utcb;
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}
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/* Otherwise use the default TCB. There should always be a default
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* TCB. It will have the signal blocked, but can be used to get the
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* signal to a pending state.
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*/
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else /* if (info.dtcb) */
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{
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DEBUGASSERT(info.dtcb);
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tcb = info.dtcb;
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}
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/* Now deliver the signal to the selected group member */
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ret = sig_tcbdispatch(tcb, siginfo);
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}
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errout:
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sched_unlock();
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return ret;
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#else
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return -ENOSYS;
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#endif
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}
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#endif /* HAVE_TASK_GROUP && !CONFIG_DISABLE_SIGNALS */
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