1552e52e14
reproduce:
static void *pthread(void *arg)
{
system(arg);
}
void test (int argc, char *argv[])
{
pthread_create(&pthread0, &attr, pthread, argv[1]);
pthread_create(&pthread1, &attr, pthread, argv[2]);
}
only one pthread system() returnd, othres hanged
rootcause:
As we known, system() will create a new task called:
system -c XX
The example:
parent group child groups
pthread0 -> waitpid() -> system -c ps -> exit() -> nxtask_signalparent()
pthread1 -> waitpid() -> system -c ls -> exit() -> nxtask_signalparent()
Each child group exit with function nxtask_signalparent(),
As we expect:
system -c ps will signal pthread0
system -c ls will signal pthread1
But actually:
system -c ps will signal pthread0/1
system -c ls will signal pthread0/1
As the spec, we know, this behavior is normal:
https://man7.org/linux/man-pages/man2/sigwaitinfo.2.html
So for this situation, when the signo is SIGCHLD, we broadcast.
Signed-off-by: ligd <liguiding1@xiaomi.com>
280 lines
8.1 KiB
C
280 lines
8.1 KiB
C
/****************************************************************************
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* sched/group/group_signal.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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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 <nuttx/signal.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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/****************************************************************************
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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 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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* Input 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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* Returned 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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/* Get the TCB associated with the group member */
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tcb = nxsched_get_tcb(pid);
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DEBUGASSERT(tcb != NULL && tcb->group != NULL && info != NULL);
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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
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* default.
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*/
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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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ret = nxsig_ismember(&tcb->sigwaitmask, info->siginfo->si_signo);
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if (ret == 1 && (!info->atcb || info->siginfo->si_signo == SIGCHLD))
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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 = nxsig_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 && info->siginfo->si_signo != SIGCHLD)
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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 (!nxsig_ismember(&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 a action associated with the task group? */
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sigact = nxsig_find_action(tcb->group, 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 = nxsig_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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* Input Parameters:
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* group - The task group that needs to be signalled.
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*
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* Returned 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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#ifdef CONFIG_SMP
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irqstate_t flags = enter_critical_section();
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#else
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sched_lock();
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#endif
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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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tcb = info.dtcb;
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}
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else
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{
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ret = -ECHILD;
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goto errout;
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}
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/* Now deliver the signal to the selected group member */
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ret = nxsig_tcbdispatch(tcb, siginfo);
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}
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errout:
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#ifdef CONFIG_SMP
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leave_critical_section(flags);
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#else
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sched_unlock();
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#endif
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return ret;
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#else
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UNUSED(group);
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UNUSED(siginfo);
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return -ENOSYS;
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#endif
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}
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