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