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incubator-nuttx/sched/group/group_signal.c

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/****************************************************************************
* sched/group/group_signal.c
*
* Copyright (C) 2013, 2016 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sched.h>
#include <assert.h>
#include <signal.h>
#include <errno.h>
#include <debug.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 = sched_gettcb(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).
*/
if (sigismember(&tcb->sigwaitmask, info->siginfo->si_signo) && !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 (!sigismember(&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).
*/
sched_lock();
/* 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) */
{
DEBUGASSERT(info.dtcb);
tcb = info.dtcb;
}
/* Now deliver the signal to the selected group member */
ret = nxsig_tcbdispatch(tcb, siginfo);
}
errout:
sched_unlock();
return ret;
#else
return -ENOSYS;
#endif
}
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