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nuttx/sched/signal/sig_dispatch.c

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