diff options
author | patacongo <patacongo@42af7a65-404d-4744-a932-0658087f49c3> | 2013-01-18 01:52:42 +0000 |
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committer | patacongo <patacongo@42af7a65-404d-4744-a932-0658087f49c3> | 2013-01-18 01:52:42 +0000 |
commit | 76753ad9cb67133892000f19de10f93de78bb525 (patch) | |
tree | 1eae1d92a03b0a2cbd1e83b45704a24d8662cf17 /nuttx/sched | |
parent | 2f653578c632ec95e94f67306af24c7d82700d28 (diff) | |
download | px4-firmware-76753ad9cb67133892000f19de10f93de78bb525.tar.gz px4-firmware-76753ad9cb67133892000f19de10f93de78bb525.tar.bz2 px4-firmware-76753ad9cb67133892000f19de10f93de78bb525.zip |
Add internal API task_reparent(), used in posix_spawn(). Move libc/spawn/lib_ps.c to sched/task_posixspawn.c; Move libc/spawn/spawn.h to include/nuttx/spawn.h
git-svn-id: http://svn.code.sf.net/p/nuttx/code/trunk@5531 42af7a65-404d-4744-a932-0658087f49c3
Diffstat (limited to 'nuttx/sched')
-rw-r--r-- | nuttx/sched/Makefile | 6 | ||||
-rw-r--r-- | nuttx/sched/os_internal.h | 3 | ||||
-rw-r--r-- | nuttx/sched/task_posixspawn.c | 673 | ||||
-rw-r--r-- | nuttx/sched/task_reparent.c | 145 |
4 files changed, 826 insertions, 1 deletions
diff --git a/nuttx/sched/Makefile b/nuttx/sched/Makefile index 3d6b58bac..73c67239e 100644 --- a/nuttx/sched/Makefile +++ b/nuttx/sched/Makefile @@ -48,7 +48,7 @@ TSK_SRCS = prctl.c task_create.c task_init.c task_setup.c task_activate.c \ task_restart.c task_vfork.c exit.c getpid.c sched_addreadytorun.c \ sched_removereadytorun.c sched_addprioritized.c sched_mergepending.c \ sched_addblocked.c sched_removeblocked.c sched_free.c sched_gettcb.c \ - sched_verifytcb.c sched_releasetcb.c + sched_verifytcb.c sched_releasetcb.c task_posixspawn.c SCHED_SRCS = sched_setparam.c sched_setpriority.c sched_getparam.c \ sched_setscheduler.c sched_getscheduler.c \ @@ -67,6 +67,10 @@ ifeq ($(CONFIG_PRIORITY_INHERITANCE),y) SCHED_SRCS += sched_reprioritize.c endif +ifeq ($(CONFIG_SCHED_HAVE_PARENT),y) +SCHED_SRCS += task_reparent.c +endif + ifeq ($(CONFIG_SCHED_WAITPID),y) SCHED_SRCS += sched_waitpid.c ifeq ($(CONFIG_SCHED_HAVE_PARENT),y) diff --git a/nuttx/sched/os_internal.h b/nuttx/sched/os_internal.h index 32d9fb4ac..f21d9654f 100644 --- a/nuttx/sched/os_internal.h +++ b/nuttx/sched/os_internal.h @@ -268,6 +268,9 @@ int task_schedsetup(FAR _TCB *tcb, int priority, start_t start, int task_argsetup(FAR _TCB *tcb, FAR const char *name, FAR const char *argv[]); void task_exithook(FAR _TCB *tcb, int status); int task_deletecurrent(void); +#ifdef CONFIG_SCHED_HAVE_PARENT +int task_reparent(pid_t oldpid, pid_t newpid, pid_t chpid); +#endif #ifndef CONFIG_CUSTOM_STACK int kernel_thread(FAR const char *name, int priority, int stack_size, main_t entry, FAR const char *argv[]); diff --git a/nuttx/sched/task_posixspawn.c b/nuttx/sched/task_posixspawn.c new file mode 100644 index 000000000..4201e759b --- /dev/null +++ b/nuttx/sched/task_posixspawn.c @@ -0,0 +1,673 @@ +/**************************************************************************** + * sched/task_posixspawn.c + * + * 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 <semaphore.h> +#include <signal.h> +#include <sched.h> +#include <fcntl.h> +#include <spawn.h> +#include <errno.h> +#include <assert.h> +#include <debug.h> + +#include <nuttx/binfmt/binfmt.h> +#include <nuttx/spawn.h> + +#include "os_internal.h" + +/**************************************************************************** + * Private Types + ****************************************************************************/ + +struct spawn_parms_s +{ + int result; + FAR pid_t *pid; + FAR const char *path; + FAR const posix_spawn_file_actions_t *file_actions; + FAR const posix_spawnattr_t *attr; + FAR char *const *argv; +}; + +/**************************************************************************** + * Public Data + ****************************************************************************/ + +/**************************************************************************** + * Private Data + ****************************************************************************/ + +static sem_t g_ps_parmsem = SEM_INITIALIZER(1); +#ifndef CONFIG_SCHED_WAITPID +static sem_t g_ps_execsem = SEM_INITIALIZER(0); +#endif +static struct spawn_parms_s g_ps_parms; + +/**************************************************************************** + * Private Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: spawn_semtake and spawn_semgive + * + * Description: + * Give and take semaphores + * + * Input Parameters: + * + * sem - The semaphore to act on. + * + * Returned Value: + * None + * + ****************************************************************************/ + +static void spawn_semtake(FAR sem_t *sem) +{ + int ret; + + do + { + ret = sem_wait(sem); + ASSERT(ret == 0 || errno == EINTR); + } + while (ret != 0); +} + +#define spawn_semgive(sem) sem_post(sem) + +/**************************************************************************** + * Name: spawn_exec + * + * Description: + * Execute the task from the file system. + * + * Input Parameters: + * + * pidp - Upon successful completion, this will return the task ID of the + * child task in the variable pointed to by a non-NULL 'pid' argument.| + * + * path - The 'path' argument identifies the file to execute. If + * CONFIG_BINFMT_EXEPATH is defined, this may be either a relative or + * or an absolute path. Otherwise, it must be an absolute path. + * + * attr - If the value of the 'attr' parameter is NULL, the all default + * values for the POSIX spawn attributes will be used. Otherwise, the + * attributes will be set according to the spawn flags. The + * following spawn flags are supported: + * + * - POSIX_SPAWN_SETSCHEDPARAM: Set new tasks priority to the sched_param + * value. + * - POSIX_SPAWN_SETSCHEDULER: Set the new tasks scheduler priority to + * the sched_policy value. + * + * NOTE: POSIX_SPAWN_SETSIGMASK is handled in ps_proxy(). + * + * argv - argv[] is the argument list for the new task. argv[] is an + * array of pointers to null-terminated strings. The list is terminated + * with a null pointer. + * + * Returned Value: + * This function will return zero on success. Otherwise, an error number + * will be returned as the function return value to indicate the error. + * This errno value may be that set by execv(), sched_setpolicy(), or + * sched_setparam(). + * + ****************************************************************************/ + +static int spawn_exec(FAR pid_t *pidp, FAR const char *path, + FAR const posix_spawnattr_t *attr, + FAR char *const argv[]) +{ + struct sched_param param; + FAR const struct symtab_s *symtab; + int nsymbols; + int pid; + int ret = OK; + + DEBUGASSERT(path); + + /* Get the current symbol table selection */ + + exec_getsymtab(&symtab, &nsymbols); + + /* Disable pre-emption so that we can modify the task parameters after + * we start the new task; the new task will not actually begin execution + * until we re-enable pre-emption. + */ + + sched_lock(); + + /* Start the task */ + + pid = exec(path, (FAR const char **)argv, symtab, nsymbols); + if (pid < 0) + { + ret = errno; + sdbg("ERROR: exec failed: %d\n", ret); + goto errout; + } + + /* Return the task ID to the caller */ + + if (pid) + { + *pidp = pid; + } + + /* Now set the attributes. Note that we ignore all of the return values + * here because we have already successfully started the task. If we + * return an error value, then we would also have to stop the task. + */ + + if (attr) + { + /* If we are only setting the priority, then call sched_setparm() + * to set the priority of the of the new task. + */ + + if ((attr->flags & POSIX_SPAWN_SETSCHEDPARAM) != 0) + { + /* Get the priority from the attrributes */ + + param.sched_priority = attr->priority; + + /* If we are setting *both* the priority and the scheduler, + * then we will call sched_setscheduler() below. + */ + + if ((attr->flags & POSIX_SPAWN_SETSCHEDULER) == 0) + { + svdbg("Setting priority=%d for pid=%d\n", + param.sched_priority, pid); + + (void)sched_setparam(pid, ¶m); + } + } + + /* If we are only changing the scheduling policy, then reset + * the priority to the default value (the same as this thread) in + * preparation for the sched_setscheduler() call below. + */ + + else if ((attr->flags & POSIX_SPAWN_SETSCHEDULER) != 0) + { + (void)sched_getparam(0, ¶m); + } + + /* Are we setting the scheduling policy? If so, use the priority + * setting determined above. + */ + + if ((attr->flags & POSIX_SPAWN_SETSCHEDULER) != 0) + { + svdbg("Setting policy=%d priority=%d for pid=%d\n", + attr->policy, param.sched_priority, pid); + + (void)sched_setscheduler(pid, attr->policy, ¶m); + } + } + + /* Re-enable pre-emption and return */ + +errout: + sched_unlock(); + return ret; +} + +/**************************************************************************** + * Name: spawn_close, spawn_dup2, and spawn_open + * + * Description: + * Implement individual file actions + * + * Input Parameters: + * action - describes the action to be performed + * + * Returned Value: + * posix_spawn() and posix_spawnp() will return zero on success. + * Otherwise, an error number will be returned as the function return + * value to indicate the error. + * + ****************************************************************************/ + +static inline int spawn_close(FAR struct spawn_close_file_action_s *action) +{ + /* The return value from close() is ignored */ + + svdbg("Closing fd=%d\n", action->fd); + + (void)close(action->fd); + return OK; +} + +static inline int spawn_dup2(FAR struct spawn_dup2_file_action_s *action) +{ + int ret; + + /* Perform the dup */ + + svdbg("Dup'ing %d->%d\n", action->fd1, action->fd2); + + ret = dup2(action->fd1, action->fd2); + if (ret < 0) + { + int errcode = errno; + + sdbg("ERROR: dup2 failed: %d\n", errcode); + return errcode; + } + + return OK; +} + +static inline int spawn_open(FAR struct spawn_open_file_action_s *action) +{ + int fd; + int ret = OK; + + /* Open the file */ + + svdbg("Open'ing path=%s oflags=%04x mode=%04x\n", + action->path, action->oflags, action->mode); + + fd = open(action->path, action->oflags, action->mode); + if (fd < 0) + { + ret = errno; + sdbg("ERROR: open failed: %d\n", ret); + } + + /* Does the return file descriptor happen to match the required file + * desciptor number? + */ + + else if (fd != action->fd) + { + /* No.. dup2 to get the correct file number */ + + svdbg("Dup'ing %d->%d\n", fd, action->fd); + + ret = dup2(fd, action->fd); + if (ret < 0) + { + ret = errno; + sdbg("ERROR: dup2 failed: %d\n", ret); + } + + svdbg("Closing fd=%d\n", fd); + close(fd); + } + + return ret; +} + +/**************************************************************************** + * Name: spawn_proxy + * + * Description: + * Perform file_actions, then execute the task from the file system. + * + * Input Parameters: + * Standard task start-up parameters + * + * Returned Value: + * Standard task return value. + * + ****************************************************************************/ + +static int spawn_proxy(int argc, char *argv[]) +{ + FAR struct spawn_general_file_action_s *entry; + FAR const posix_spawnattr_t *attr = g_ps_parms.attr; + int ret = OK; + + /* Perform file actions and/or set a custom signal mask. We get here only + * if the file_actions parameter to posix_spawn[p] was non-NULL and/or the + * option to change the signal mask was selected. + */ + +#ifndef CONFIG_DISABLE_SIGNALS + DEBUGASSERT((g_ps_parms.file_actions && *g_ps_parms.file_actions) || + (attr && (attr->flags & POSIX_SPAWN_SETSIGMASK) != 0)); +#else + DEBUGASSERT(g_ps_parms.file_actions && *g_ps_parms.file_actions); +#endif + + /* Check if we need to change the signal mask */ + +#ifndef CONFIG_DISABLE_SIGNALS + if (attr && (attr->flags & POSIX_SPAWN_SETSIGMASK) != 0) + { + (void)sigprocmask(SIG_SETMASK, &attr->sigmask, NULL); + } + + /* Were we also requested to perform file actions? */ + + if (g_ps_parms.file_actions) +#endif + { + /* Execute each file action */ + + for (entry = (FAR struct spawn_general_file_action_s *)*g_ps_parms.file_actions; + entry && ret == OK; + entry = entry->flink) + { + switch (entry->action) + { + case SPAWN_FILE_ACTION_CLOSE: + ret = spawn_close((FAR struct spawn_close_file_action_s *)entry); + break; + + case SPAWN_FILE_ACTION_DUP2: + ret = spawn_dup2((FAR struct spawn_dup2_file_action_s *)entry); + break; + + case SPAWN_FILE_ACTION_OPEN: + ret = spawn_open((FAR struct spawn_open_file_action_s *)entry); + break; + + case SPAWN_FILE_ACTION_NONE: + default: + sdbg("ERROR: Unknown action: %d\n", entry->action); + ret = EINVAL; + break; + } + } + } + + /* Check for failures */ + + if (ret == OK) + { + /* Start the task */ + + ret = spawn_exec(g_ps_parms.pid, g_ps_parms.path, attr, + g_ps_parms.argv); + +#ifdef CONFIG_SCHED_HAVE_PARENT + if (ret == OK) + { + /* Change of the parent of the task we just spawned to our parent. + * What should we do in the event of a failure? + */ + + int tmp = task_reparent(0, 0, *g_ps_parms.pid); + if (tmp < 0) + { + sdbg("ERROR: task_reparent() failed: %d\n", tmp); + } + } +#endif + } + + /* Post the semaphore to inform the parent task that we have completed + * what we need to do. + */ + + g_ps_parms.result = ret; +#ifndef CONFIG_SCHED_WAITPID + spawn_semgive(&g_ps_execsem); +#endif + return OK; +} + +/**************************************************************************** + * Public Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: posix_spawn + * + * Description: + * The posix_spawn() and posix_spawnp() functions will create a new, + * child task, constructed from a regular executable file. + * + * Input Parameters: + * + * pid - Upon successful completion, posix_spawn() and posix_spawnp() will + * return the task ID of the child task to the parent task, in the + * variable pointed to by a non-NULL 'pid' argument. If the 'pid' + * argument is a null pointer, the process ID of the child is not + * returned to the caller. + * + * path - The 'path' argument to posix_spawn() is the absolute path that + * identifies the file to execute. The 'path' argument to posix_spawnp() + * may also be a relative path and will be used to construct a pathname + * that identifies the file to execute. In the case of a relative path, + * the path prefix for the file will be obtained by a search of the + * directories passed as the environment variable PATH. + * + * NOTE: NuttX provides only one implementation: If + * CONFIG_BINFMT_EXEPATH is defined, then only posix_spawnp() behavior + * is supported; otherwise, only posix_spawn behavior is supported. + * + * file_actions - If 'file_actions' is a null pointer, then file + * descriptors open in the calling process will remain open in the + * child process (unless CONFIG_FDCLONE_STDIO is defined). If + * 'file_actions' is not NULL, then the file descriptors open in the + * child process will be those open in the calling process as modified + * by the spawn file actions object pointed to by file_actions. + * + * attr - If the value of the 'attr' parameter is NULL, the all default + * values for the POSIX spawn attributes will be used. Otherwise, the + * attributes will be set according to the spawn flags. The + * posix_spawnattr_t spawn attributes object type is defined in spawn.h. + * It will contains these attributes, not all of which are supported by + * NuttX: + * + * - POSIX_SPAWN_SETPGROUP: Setting of the new task's process group is + * not supported. NuttX does not support process groups. + * - POSIX_SPAWN_SETSCHEDPARAM: Set new tasks priority to the sched_param + * value. + * - POSIX_SPAWN_SETSCHEDULER: Set the new task's scheduler policy to + * the sched_policy value. + * - POSIX_SPAWN_RESETIDS: Resetting of the effective user ID of the child + * process is not supported. NuttX does not support effective user + * IDs. + * - POSIX_SPAWN_SETSIGMASK: Set the new task's signal mask. + * - POSIX_SPAWN_SETSIGDEF: Resetting signal default actions is not + * supported. NuttX does not support default signal actions. + * + * argv - argv[] is the argument list for the new task. argv[] is an + * array of pointers to null-terminated strings. The list is terminated + * with a null pointer. + * + * envp - The envp[] argument is not used by NuttX and may be NULL. In + * standard implementations, envp[] is an array of character pointers to + * null-terminated strings that provide the environment for the new + * process image. The environment array is terminated by a null pointer. + * In NuttX, the envp[] argument is ignored and the new task will simply + * inherit the environment of the parent task. + * + * Returned Value: + * posix_spawn() and posix_spawnp() will return zero on success. + * Otherwise, an error number will be returned as the function return + * value to indicate the error: + * + * - EINVAL: The value specified by 'file_actions' or 'attr' is invalid. + * - Any errors that might have been return if vfork() and excec[l|v]() + * had been called. + * + * Assumptions/Limitations: + * - NuttX provides only posix_spawn() or posix_spawnp() behavior + * depending upon the setting of CONFIG_BINFMT_EXEPATH: If + * CONFIG_BINFMT_EXEPATH is defined, then only posix_spawnp() behavior + * is supported; otherwise, only posix_spawn behavior is supported. + * - The 'envp' argument is not used and the 'environ' variable is not + * altered (NuttX does not support the 'environ' variable). + * - Process groups are not supported (POSIX_SPAWN_SETPGROUP). + * - Effective user IDs are not supported (POSIX_SPAWN_RESETIDS). + * - Signal default actions cannot be modified in the newly task executed + * because NuttX does not support default signal actions + * (POSIX_SPAWN_SETSIGDEF). + * + * POSIX Compatibility + * - The value of the argv[0] received by the child task is assigned by + * NuttX. For the caller of posix_spawn(), the provided argv[0] will + * correspond to argv[1] received by the new task. + * + ****************************************************************************/ + +#ifdef CONFIG_BINFMT_EXEPATH +int posix_spawnp(FAR pid_t *pid, FAR const char *path, + FAR const posix_spawn_file_actions_t *file_actions, + FAR const posix_spawnattr_t *attr, + FAR char *const argv[], FAR char *const envp[]) +#else +int posix_spawn(FAR pid_t *pid, FAR const char *path, + FAR const posix_spawn_file_actions_t *file_actions, + FAR const posix_spawnattr_t *attr, + FAR char *const argv[], FAR char *const envp[]) +#endif +{ + struct sched_param param; + pid_t proxy; +#ifdef CONFIG_SCHED_WAITPID + int status; +#endif + int ret; + + DEBUGASSERT(path); + + svdbg("pid=%p path=%s file_actions=%p attr=%p argv=%p\n", + pid, path, file_actions, attr, argv); + + /* If there are no file actions to be performed and there is no change to + * the signal mask, then start the new child task directly from the parent task. + */ + +#ifndef CONFIG_DISABLE_SIGNALS + if ((file_actions == NULL || *file_actions == NULL) && + (attr == NULL || (attr->flags & POSIX_SPAWN_SETSIGMASK) == 0)) +#else + if (file_actions == NULL || *file_actions == NULL) +#endif + { + return spawn_exec(pid, path, attr, argv); + } + + /* Otherwise, we will have to go through an intermediary/proxy task in order + * to perform the I/O redirection. This would be a natural place to fork(). + * However, true fork() behavior requires an MMU and most implementations + * of vfork() are not capable of these operations. + * + * Even without fork(), we can still do the job, but parameter passing is + * messier. Unfortunately, there is no (clean) way to pass binary values + * as a task parameter, so we will use a semaphore-protected global + * structure. + */ + + /* Get exclusive access to the global parameter structure */ + + spawn_semtake(&g_ps_parmsem); + + /* Populate the parameter structure */ + + g_ps_parms.result = ENOSYS; + g_ps_parms.pid = pid; + g_ps_parms.path = path; + g_ps_parms.file_actions = file_actions; + g_ps_parms.attr = attr; + g_ps_parms.argv = argv; + + /* Get the priority of this (parent) task */ + + ret = sched_getparam(0, ¶m); + if (ret < 0) + { + int errcode = errno; + + sdbg("ERROR: sched_getparam failed: %d\n", errcode); + spawn_semgive(&g_ps_parmsem); + return errcode; + } + + /* Disable pre-emption so that the proxy does not run until we waitpid + * is called. This is probably unnecessary since the spawn_proxy has + * the same priority as this thread; it should be schedule behind this + * task in the ready-to-run list. + */ + +#ifdef CONFIG_SCHED_WAITPID + sched_lock(); +#endif + + /* Start the intermediary/proxy task at the same priority as the parent + * task. + */ + + proxy = TASK_CREATE("spawn_proxy", param.sched_priority, + CONFIG_POSIX_SPAWN_STACKSIZE, (main_t)spawn_proxy, + (FAR const char **)NULL); + if (proxy < 0) + { + ret = get_errno(); + sdbg("ERROR: Failed to start spawn_proxy: %d\n", ret); + + goto errout_with_lock; + } + + /* Wait for the proxy to complete its job */ + +#ifdef CONFIG_SCHED_WAITPID + ret = waitpid(proxy, &status, 0); + if (ret < 0) + { + sdbg("ERROR: waitpid() failed: %d\n", errno); + goto errout_with_lock; + } +#else + spawn_semtake(&g_ps_execsem); +#endif + + /* Get the result and relinquish our access to the parameter structure */ + + ret = g_ps_parms.result; + +errout_with_lock: +#ifdef CONFIG_SCHED_WAITPID + sched_unlock(); +#endif + spawn_semgive(&g_ps_parmsem); + return ret; +} diff --git a/nuttx/sched/task_reparent.c b/nuttx/sched/task_reparent.c new file mode 100644 index 000000000..9daa0743b --- /dev/null +++ b/nuttx/sched/task_reparent.c @@ -0,0 +1,145 @@ +/***************************************************************************** + * sched/task_reparent.c + * + * 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 <errno.h> + +#include "os_internal.h" + +#ifdef CONFIG_SCHED_HAVE_PARENT + +/***************************************************************************** + * Private Functions + *****************************************************************************/ + +/***************************************************************************** + * Public Functions + *****************************************************************************/ + +/***************************************************************************** + * Name: task_reparent + * + * Description: + * Change the parent of a task. + * + * Parameters: + * oldpid - PID of the old parent task (0 if this task) + * newpid - PID ot the new parent task (0 for the parent of this task) + * chpid - PID of the child to be reparented. + * + * Return Value: + * 0 (OK) on success; A negated errno value on failure. + * + *****************************************************************************/ + +int task_reparent(pid_t oldpid, pid_t newpid, pid_t chpid) +{ + _TCB *oldtcb; + _TCB *newtcb; + _TCB *chtcb; + irqstate_t flags; + int ret; + + /* If oldpid is zero, then we are parent task. */ + + if (oldpid == 0) + { + oldpid = getpid(); + } + + /* Get the current parent task's TCB */ + + oldtcb = sched_gettcb(oldpid); + if (!oldtcb) + { + return -ESRCH; + } + + /* Disable interrupts so that nothing can change from this point */ + + flags = irqsave(); + + /* If newpid is zero, then new is the parent of oldpid. */ + + if (newpid == 0) + { + newpid = oldtcb->parent; + } + + /* Get the new parent task's TCB */ + + newtcb = sched_gettcb(newpid); + if (!newtcb) + { + ret = -ESRCH; + goto errout_with_ints; + } + + /* Get the child tasks TCB */ + + chtcb = sched_gettcb(chpid); + if (!chtcb) + { + ret = -ECHILD; + goto errout_with_ints; + } + + /* Verify that oldpid is the parent of chpid */ + + if (chtcb->parent != oldpid) + { + ret = -ECHILD; + goto errout_with_ints; + } + + /* Okay, reparent the child */ + + DEBUGASSERT(oldtcb->nchildren > 0); + chtcb->parent = newpid; + oldtcb->nchildren--; + newtcb->nchildren++; + ret = OK; + +errout_with_ints: + irqrestore(flags); + return ret; +} + +#endif /* CONFIG_SCHED_HAVE_PARENT */ |