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Diffstat (limited to 'nuttx/sched/task_childstatus.c')
-rw-r--r-- | nuttx/sched/task_childstatus.c | 396 |
1 files changed, 396 insertions, 0 deletions
diff --git a/nuttx/sched/task_childstatus.c b/nuttx/sched/task_childstatus.c new file mode 100644 index 000000000..0f6d36c29 --- /dev/null +++ b/nuttx/sched/task_childstatus.c @@ -0,0 +1,396 @@ +/***************************************************************************** + * sched/task_childstatus.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 <sched.h> +#include <errno.h> +#include <debug.h> + +#include "os_internal.h" + +#if defined(CONFIG_SCHED_HAVE_PARENT) && defined(CONFIG_SCHED_CHILD_STATUS) + +/***************************************************************************** + * Pre-processor Definitions + *****************************************************************************/ +/* Note that there cannot be more that CONFIG_MAX_TASKS tasks in total. + * However, the number of child status structures may need to be significantly + * larger because this number includes the maximum number of tasks that are + * running PLUS the number of tasks that have exit'ed without having their + * exit status reaped (via wait(), waitid(), or waitpid()). + * + * Obviously, if tasks spawn children indefinitely and never have the exit + * status reaped, then you have a memory leak! + */ + +#if !defined(CONFIG_PREALLOC_CHILDSTATUS) || CONFIG_PREALLOC_CHILDSTATUS == 0 +# undef CONFIG_PREALLOC_CHILDSTATUS +# define CONFIG_PREALLOC_CHILDSTATUS (2*CONFIG_MAX_TASKS) +#endif + +#ifndef CONFIG_DEBUG +# undef CONFIG_DEBUG_CHILDSTATUS +#endif + +/***************************************************************************** + * Private Types + *****************************************************************************/ +/* Globals are maintained in a structure to minimize name collisions. */ + +struct child_pool_s +{ + struct child_status_s alloc[CONFIG_PREALLOC_CHILDSTATUS]; + FAR struct child_status_s *freelist; +}; + +/***************************************************************************** + * Private Data + *****************************************************************************/ + +static struct child_pool_s g_child_pool; + +/***************************************************************************** + * Private Functions + *****************************************************************************/ + +/***************************************************************************** + * Name: task_dumpchildren + * + * Description: + * Dump all of the children when the part TCB list is modified. + * + * Parameters: + * tcb - The parent TCB. + * + * Return Value: + * None. + * + * Assumptions: + * Called early in initialization. No special precautions are required. + * + *****************************************************************************/ + +#ifdef CONFIG_DEBUG_CHILDSTATUS +static void task_dumpchildren(FAR _TCB *tcb, FAR const char *msg) +{ + FAR struct child_status_s *child; + int i; + + dbg("Parent TCB=%p: %s\n", tcb, msg); + for (i = 0, child = tcb->children; child; i++, child = child->flink) + { + dbg(" %d. ch_flags=%02x ch_pid=%d ch_status=%d\n", + i, child->ch_flags, child->ch_pid, child->ch_status); + } +} +#else +# task_dumpchildren(t,m) +#endif + +/***************************************************************************** + * Public Functions + *****************************************************************************/ + +/***************************************************************************** + * Name: task_initialize + * + * Description: + * Initialize task related status. At present, this includes only the + * initialize of the child status pool. + * + * Parameters: + * None. + * + * Return Value: + * None. + * + * Assumptions: + * Called early in initialization. No special precautions are required. + * + *****************************************************************************/ + +void task_initialize(void) +{ + FAR struct child_status_s *curr; + FAR struct child_status_s *prev; + int i; + + /* Save all of the child status structures in a free list */ + + prev = &g_child_pool.alloc[0]; + g_child_pool.freelist = prev; + for (i = 0; i < CONFIG_PREALLOC_CHILDSTATUS; i++) + { + curr = &g_child_pool.alloc[i]; + prev->flink = curr; + prev = curr; + } +} + +/***************************************************************************** + * Name: task_allocchild + * + * Description: + * Allocate a child status structure by removing the next entry from a + * free list. + * + * Parameters: + * None. + * + * Return Value: + * On success, a non-NULL pointer to a child status structure. NULL is + * returned if there are no remaining, pre-allocated child status structures. + * + * Assumptions: + * Called during task creation in a safe context. No special precautions + * are required here. + * + *****************************************************************************/ + +FAR struct child_status_s *task_allocchild(void) +{ + FAR struct child_status_s *ret; + + /* Return the status block at the head of the free list */ + + ret = g_child_pool.freelist; + if (ret) + { + g_child_pool.freelist = ret->flink; + ret->flink = NULL; + } + + return ret; +} + +/***************************************************************************** + * Name: task_freechild + * + * Description: + * Release a child status structure by returning it to a free list. + * + * Parameters: + * status - The child status structure to be freed. + * + * Return Value: + * None. + * + * Assumptions: + * Called during task creation in a safe context. No special precautions + * are required here. + * + *****************************************************************************/ + +void task_freechild(FAR struct child_status_s *child) +{ + /* Return the child status structure to the free list */ + + if (child) + { + child->flink = g_child_pool.freelist; + g_child_pool.freelist = child; + } +} + +/***************************************************************************** + * Name: task_addchild + * + * Description: + * Add a child status structure in the given TCB. + * + * Parameters: + * tcb - The TCB of the parent task to containing the child status. + * child - The structure to be added + * + * Return Value: + * N + * + * Assumptions: + * Called during task creation processing in a safe context. No special + * precautions are required here. + * + *****************************************************************************/ + +void task_addchild(FAR _TCB *tcb, FAR struct child_status_s *child) +{ + /* Add the entry into the TCB list of children */ + + child->flink = tcb->children; + tcb->children = child; + + task_dumpchildren(tcb, "task_addchild"); +} + +/***************************************************************************** + * Name: task_findchild + * + * Description: + * Find a child status structure in the given TCB. A reference to the + * child structure is returned, but the child remains the the TCB's list + * of children. + * + * Parameters: + * tcb - The TCB of the parent task to containing the child status. + * pid - The ID of the child to find. + * + * Return Value: + * On success, a non-NULL pointer to a child status structure. NULL is + * returned if there is child status structure for that pid in the TCB. + * + * Assumptions: + * Called during SIGCHLD processing in a safe context. No special precautions + * are required here. + * + *****************************************************************************/ + +FAR struct child_status_s *task_findchild(FAR _TCB *tcb, pid_t pid) +{ + FAR struct child_status_s *child; + + /* Find the status structure with the matching PID */ + + for (child = tcb->children; child; child = child->flink) + { + if (child->ch_pid == pid) + { + return child; + } + } + + return NULL; +} + +/***************************************************************************** + * Name: task_removechild + * + * Description: + * Remove one child structure from the TCB. The child is removed, but is + * not yet freed. task_freechild must be called in order to free the child + * status structure. + * + * Parameters: + * tcb - The TCB of the parent task to containing the child status. + * pid - The ID of the child to find. + * + * Return Value: + * On success, a non-NULL pointer to a child status structure. NULL is + * returned if there is child status structure for that pid in the TCB. + * + * Assumptions: + * Called during SIGCHLD processing in a safe context. No special precautions + * are required here. + * + *****************************************************************************/ + +FAR struct child_status_s *task_removechild(FAR _TCB *tcb, pid_t pid) +{ + FAR struct child_status_s *curr; + FAR struct child_status_s *prev; + + /* Find the status structure with the matching PID */ + + for (prev = NULL, curr = tcb->children; + curr; + prev = curr, curr = curr->flink) + { + if (curr->ch_pid == pid) + { + break; + } + } + + /* Did we find it? If so, remove it from the TCB. */ + + if (curr) + { + /* Do we remove it from mid-list? Or from the head of the list? */ + + if (prev) + { + prev->flink = curr->flink; + } + else + { + tcb->children = curr->flink; + } + + curr->flink = NULL; + task_dumpchildren(tcb, "task_removechild"); + } + + return curr; +} + +/***************************************************************************** + * Name: task_removechildren + * + * Description: + * Remove and free all child structure from the TCB. + * + * Parameters: + * tcb - The TCB of the parent task to containing the child status. + * + * Return Value: + * None. + * + * Assumptions: + * Called during task exit processing in a safe context. No special + * precautions are required here. + * + *****************************************************************************/ + +void task_removechildren(FAR _TCB *tcb) +{ + FAR struct child_status_s *curr; + FAR struct child_status_s *next; + + /* Remove all child structures for the TCB and return them to the freelist */ + + for (curr = tcb->children; curr; curr = next) + { + next = curr->flink; + task_freechild(curr); + } + + tcb->children = NULL; + task_dumpchildren(tcb, "task_removechildren"); +} + +#endif /* CONFIG_SCHED_HAVE_PARENT && CONFIG_SCHED_CHILD_STATUS */ |