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/* IBM_PROLOG_BEGIN_TAG */
/* This is an automatically generated prolog. */
/* */
/* $Source: src/include/sys/task.h $ */
/* */
/* IBM CONFIDENTIAL */
/* */
/* COPYRIGHT International Business Machines Corp. 2010,2013 */
/* */
/* p1 */
/* */
/* Object Code Only (OCO) source materials */
/* Licensed Internal Code Source Materials */
/* IBM HostBoot Licensed Internal Code */
/* */
/* The source code for this program is not published or otherwise */
/* divested of its trade secrets, irrespective of what has been */
/* deposited with the U.S. Copyright Office. */
/* */
/* Origin: 30 */
/* */
/* IBM_PROLOG_END_TAG */
/** @file task.h
* @brief Contains the prototypes for system calls related to tasking.
*/
#ifndef __SYS_TASK_H
#define __SYS_TASK_H
#include <stdint.h>
#include <builtins.h>
#include <kernel/types.h>
#ifdef __cplusplus
extern "C"
{
#endif
/** @fn task_yield
* @brief Defer task if there are other ready-tasks available
*
* See POSIX sched_yield.
*/
void task_yield();
/** @fn task_create
* @brief Create a new task.
*
* @param[in] start_routine - Function pointer to start execution at.
* @param[in] arg - Pointer to pass to task as argument.
*
* @return The task ID of the child.
*
* See POSIX pthread_create.
*/
tid_t task_create(void*(*start_routine)(void*), void* arg);
/** @fn task_end
* @brief End the calling task.
*
* See POSIX pthread_exit.
*
* @note A task could call task_end when it wishes to exit. But it will likely
* cause a memory leak. It is better for a task to
* simply return from its entry point function, the kernel sets up
* the initial task structure with the link-register pointing to this
* function. The "NO_RETURN" does not call the destructors to clean up.
* Might be used in case of task needing to be terminated due to
* unknown cause.
*/
void task_end() NO_RETURN;
/** @fn task_end2
* @brief End the calling task with a return value.
* Will likely cause a memory leak. Better to return the value on the
* return to the entry point. See comments on task_end.
*
* See POSIX pthread_exit.
*
* @param[in] retval - A pointer to return to the task performing task_join /
* task_wait on this task.
*/
void task_end2(void* retval) NO_RETURN;
/** @define task_crash
* @brief End the calling task as if it crashed.
*
*/
#define task_crash() ((*(volatile char*)NULL) = 'F')
/** @fn task_gettid
* @brief Get task ID of calling task.
*
* See Linux gettid.
*/
tid_t task_gettid();
/** @fn task_getcpuid
* @brief Get the CPU ID of the CPU currently executing this task.
*
* This function is simply for debug / tracing purposes. At the time this
* function call returns, or any time afterwards, a pre-emptive context
* switch could occur and the task could be migrated to another CPU when
* execution resumes. Therefore there is no guarentee that the return
* value is valid at anytime after this function returns.
*/
cpuid_t task_getcpuid();
/** @fn task_exec
* @brief Requests the VFS to create a new task from a path string.
*
* Calls the VFS process and looks up the module referenced in path and
* creates a new task from the _start function in that module.
*
* @param[in] path - The module desired to start.
* @param[in] arg - A pointer passed to the child task as argument.
*
* @return Task ID of the child task.
*
* See POSIX fork + exec.
*/
tid_t task_exec(const char* path, void* arg);
/** @fn task_affinity_pin
* @brief Pins a task onto the CPU it is currently executing on.
*
* This function may be called any number of times and each should be paired
* with a task_affinity_unpin call. This is so that callers do not need to
* be concerned with affinity pinning desires of functions above and below in
* a call stack.
*
* See Linux sched_setaffinity.
*/
void task_affinity_pin();
/** @fn task_affinity_unpin
* @brief Unpins a task from the CPU it is currently executing on.
*
* This function should be called after a task_affinity_pin call to allow a
* task to migrate freely between CPUs.
*
* See Linux sched_setaffinity.
*/
void task_affinity_unpin();
/** @fn task_affinity_migrate_to_master
* @brief Moves a task from the CPU it is on to the master core/thread.
*
* Unless the affinity is pinned, the task could be migrated to another
* core at any point in time. Suggestion is to use task_affinity_pin
* prior to this call.
*/
void task_affinity_migrate_to_master();
/** @enum task_status
* @brief Status of how a task exited.
*/
enum task_status
{
/** Task called task_end cleanly. */
TASK_STATUS_EXITED_CLEAN,
/** Task crashed. Ended by the kernel due to error. */
TASK_STATUS_CRASHED,
};
/** @fn task_detach
* @brief Sets the calling task to the 'detached' state, meaning no parent
* may task_wait_tid on it.
*/
void task_detach();
/** @fn task_wait_tid
* @brief Block calling task until a requested child process exits.
*
* See also: POSIX 'waitid' / Linux 'waitpid'.
*
* @param[in] tid - Task to wait for completion.
*
* @param[out] status - Optional address to write child status.
* @param[out] retval - Optional address to write return-value.
*
* Status values come from task_status enumeration.
* Retval values come from child's 'task_end2' parameter.
*
* @note All non-detached tasks must be waited on by their parent to ensure
* there are not kernel memory-leaks.
*
* @note If a parent task ends prior to waiting on its children, the children
* become parented by their grand-parents, who must do the wait.
*
* @return tid of child waited on or negative number on error.
*
* @retval EDEADLK - Performing this wait would deadlock the caller such as
* when it has no children.
* @retval EFAULT - Bad memory address given for status or retval parameter.
*/
tid_t task_wait_tid(tid_t tid, int* status, void** retval);
/** @fn task_wait
* @brief Block calling task until any child process exits.
*
* See also: Linux 'wait'.
*
* @param[out] status - Optional address to write child status.
* @param[out] retval - Optional address to write return-value.
*
* Status values come from task_status enumeration.
* Retval values come from child's 'task_end2' parameter.
*
* @note All non-detached tasks must be waited on by their parent to ensure
* there are not kernel memory-leaks.
*
* @note If a parent task ends prior to waiting on its children, the children
* become parented by their grand-parents, who must do the wait.
*
* @return tid of child waited on or negative number on error.
*
* @retval EDEADLK - Performing this wait would deadlock the caller such as
* when it has no children.
* @retval EFAULT - Bad memory address given for status or retval parameter.
*/
tid_t task_wait(int* status, void** retval);
#ifdef __cplusplus
}
#endif
#endif
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