diff options
Diffstat (limited to 'nuttx/sched/task_vfork.c')
| -rw-r--r-- | nuttx/sched/task_vfork.c | 330 |
1 files changed, 0 insertions, 330 deletions
diff --git a/nuttx/sched/task_vfork.c b/nuttx/sched/task_vfork.c deleted file mode 100644 index ac86ddc56..000000000 --- a/nuttx/sched/task_vfork.c +++ /dev/null @@ -1,330 +0,0 @@ -/**************************************************************************** - * sched/task_vfork - * - * Copyright (C) 2013 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 <sys/wait.h> -#include <stdint.h> -#include <assert.h> -#include <queue.h> -#include <errno.h> -#include <debug.h> - -#include <nuttx/sched.h> - -#include "os_internal.h" -#include "group_internal.h" - -/**************************************************************************** - * Pre-processor Definitions - ****************************************************************************/ - -/**************************************************************************** - * Private Functions - ****************************************************************************/ - -/**************************************************************************** - * Public Functions - ****************************************************************************/ - -/**************************************************************************** - * Name: task_vforksetup - * - * Description: - * The vfork() function has the same effect as fork(), except that the - * behavior is undefined if the process created by vfork() either modifies - * any data other than a variable of type pid_t used to store the return - * value from vfork(), or returns from the function in which vfork() was - * called, or calls any other function before successfully calling _exit() - * or one of the exec family of functions. - * - * This functin provides one step in the overall vfork() sequence: It - * Allocates and initializes the child task's TCB. The overall sequence is: - * - * 1) User code calls vfork(). vfork() is provided in architecture-specific - * code. - * 2) vfork()and calls task_vforksetup(). - * 3) task_vforksetup() allocates and configures the child task's TCB. This - * consists of: - * - Allocation of the child task's TCB. - * - Initialization of file descriptors and streams - * - Configuration of environment variables - * - Setup the intput parameters for the task. - * - Initialization of the TCB (including call to up_initial_state() - * 4) up_vfork() provides any additional operating context. up_vfork must: - * - Allocate and initialize the stack - * - Initialize special values in any CPU registers that were not - * already configured by up_initial_state() - * 5) up_vfork() then calls task_vforkstart() - * 6) task_vforkstart() then executes the child thread. - * - * Input Paremeters: - * retaddr - The return address from vfork() where the child task - * will be started. - * - * Returned Value: - * Upon successful completion, task_vforksetup() returns a pointer to - * newly allocated and initalized child task's TCB. NULL is returned - * on any failure and the errno is set appropriately. - * - ****************************************************************************/ - -FAR _TCB *task_vforksetup(start_t retaddr) -{ - _TCB *parent = (FAR _TCB *)g_readytorun.head; - _TCB *child; - int priority; - int ret; - - DEBUGASSERT(retaddr); - - /* Allocate a TCB for the child task. */ - - child = (FAR _TCB*)kzalloc(sizeof(_TCB)); - if (!child) - { - set_errno(ENOMEM); - return NULL; - } - - /* Associate file descriptors with the new task */ - -#if CONFIG_NFILE_DESCRIPTORS > 0 || CONFIG_NSOCKET_DESCRIPTORS > 0 - ret = group_setuptaskfiles(child); - if (ret != OK) - { - goto errout_with_tcb; - } -#endif - - /* Get the priority of the parent task */ - -#ifdef CONFIG_PRIORITY_INHERITANCE - priority = parent->base_priority; /* "Normal," unboosted priority */ -#else - priority = parent->sched_priority; /* Current priority */ -#endif - - /* Initialize the task control block. This calls up_initial_state() */ - - svdbg("Child priority=%d start=%p\n", priority, retaddr); - ret = task_schedsetup(child, priority, retaddr, parent->entry.main, - TCB_FLAG_TTYPE_TASK); - if (ret != OK) - { - goto errout_with_tcb; - } - - svdbg("parent=%p, returning child=%p\n", parent, child); - return child; - -errout_with_tcb: - sched_releasetcb(child); - set_errno(-ret); - return NULL; -} - -/**************************************************************************** - * Name: task_vforkstart - * - * Description: - * The vfork() function has the same effect as fork(), except that the - * behavior is undefined if the process created by vfork() either modifies - * any data other than a variable of type pid_t used to store the return - * value from vfork(), or returns from the function in which vfork() was - * called, or calls any other function before successfully calling _exit() - * or one of the exec family of functions. - * - * This functin provides one step in the overall vfork() sequence: It - * starts execution of the previously initialized TCB. The overall - * sequence is: - * - * 1) User code calls vfork() - * 2) Architecture-specific code provides vfork()and calls task_vforksetup(). - * 3) task_vforksetup() allocates and configures the child task's TCB. This - * consists of: - * - Allocation of the child task's TCB. - * - Initialization of file descriptors and streams - * - Configuration of environment variables - * - Setup the intput parameters for the task. - * - Initialization of the TCB (including call to up_initial_state() - * 4) vfork() provides any additional operating context. vfork must: - * - Allocate and initialize the stack - * - Initialize special values in any CPU registers that were not - * already configured by up_initial_state() - * 5) vfork() then calls task_vforkstart() - * 6) task_vforkstart() then executes the child thread. - * - * Input Paremeters: - * retaddr - The return address from vfork() where the child task - * will be started. - * - * Returned Value: - * Upon successful completion, vfork() returns 0 to the child process and - * returns the process ID of the child process to the parent process. - * Otherwise, -1 is returned to the parent, no child process is created, - * and errno is set to indicate the error. - * - ****************************************************************************/ - -pid_t task_vforkstart(FAR _TCB *child) -{ -#if CONFIG_TASK_NAME_SIZE > 0 - _TCB *parent = (FAR _TCB *)g_readytorun.head; -#endif - FAR const char *name; - pid_t pid; -#ifdef CONFIG_SCHED_WAITPID - int rc; -#endif - int ret; - - svdbg("Starting Child TCB=%p, parent=%p\n", child, g_readytorun.head); - DEBUGASSERT(child); - - /* Setup to pass parameters to the new task */ - -#if CONFIG_TASK_NAME_SIZE > 0 - name = parent->name; -#else - name = NULL; -#endif - - (void)task_argsetup(child, name, (const char **)NULL); - - /* Get the assigned pid before we start the task */ - - pid = (int)child->pid; - - /* Activate the task */ - - ret = task_activate(child); - if (ret != OK) - { - task_vforkabort(child, -ret); - return ERROR; - } - - /* Since the child task has the same priority as the parent task, it is - * now ready to run, but has not yet ran. It is a requirement that - * the parent enivornment be stable while vfork runs; the child thread - * is still dependent on things in the parent thread... like the pointers - * into parent thread's stack which will still appear in the child's - * registers and environment. - * - * We do not have SIG_CHILD, so we have to do some silly things here. - * The simplest way to make sure that the child thread runs to completion - * is simply to yield here. Since the child can only do exit() or - * execv/l(), that should be all that is needed. - * - * Hmmm.. this is probably not sufficient. What if we are running - * SCHED_RR? What if the child thread is suspeneded and rescheduled - * after the parent thread again? - */ - -#ifdef CONFIG_SCHED_WAITPID - - /* We can also exploit a bug in the execv() implementation: The PID - * of the task exec'ed by the child will not be the same as the PID of - * the child task. Therefore, waitpid() on the child task's PID will - * accomplish what we need to do. - */ - - rc = 0; - -#ifdef CONFIG_DEBUG - ret = waitpid(pid, &rc, 0); - if (ret < 0) - { - sdbg("ERROR: waitpid failed: %d\n", errno); - } -#else - (void)waitpid(pid, &rc, 0); -#endif - -#else - /* The following logic does not appear to work... It gets stuff in an - * infinite kill() loop and hogs the processor. Therefore, it looks - * as though CONFIG_SCHED_WAITPID may be a requirement to used vfork(). - * - * Again exploiting that execv() bug: Check if the child thread is - * still running. - */ - - while (kill(pid, 0) == OK) - { - /* Yes.. then we can yield to it -- assuming that it has not lowered - * its priority. sleep(0) might be a safer thing to do since it does - * not depend on prioirities: It will halt the parent thread for one - * system clock tick. This will delay the return to the parent thread. - */ - -#ifndef CONFIG_DISABLE_SIGNALS - sleep(0); -#else - sched_yield(); -#endif - } -#endif - - return pid; -} - -/**************************************************************************** - * Name: task_vforkabort - * - * Description: - * Recover from any errors after task_vforksetup() was called. - * - * Returned Value: - * None - * - ****************************************************************************/ - -void task_vforkabort(FAR _TCB *child, int errcode) -{ - /* The TCB was added to the active task list by task_schedsetup() */ - - dq_rem((FAR dq_entry_t*)child, (dq_queue_t*)&g_inactivetasks); - - /* Release the TCB */ - - sched_releasetcb(child); - set_errno(errcode); -} |