138 lines
3.8 KiB
C
138 lines
3.8 KiB
C
/*
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* Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA.
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*
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* You can also choose to distribute this program under the terms of
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* the Unmodified Binary Distribution Licence (as given in the file
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* COPYING.UBDL), provided that you have satisfied its requirements.
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*/
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FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
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#include <ipxe/list.h>
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#include <ipxe/init.h>
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#include <ipxe/process.h>
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/** @file
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*
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* Processes
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*
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* We implement a trivial form of cooperative multitasking, in which
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* all processes share a single stack and address space.
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*/
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/** Process run queue */
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static LIST_HEAD ( run_queue );
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/**
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* Get pointer to object containing process
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*
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* @v process Process
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* @ret object Containing object
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*/
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void * process_object ( struct process *process ) {
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return ( ( ( void * ) process ) - process->desc->offset );
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}
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/**
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* Add process to process list
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*
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* @v process Process
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*
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* It is safe to call process_add() multiple times; further calls will
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* have no effect.
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*/
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void process_add ( struct process *process ) {
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if ( ! process_running ( process ) ) {
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DBGC ( PROC_COL ( process ), "PROCESS " PROC_FMT
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" starting\n", PROC_DBG ( process ) );
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ref_get ( process->refcnt );
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list_add_tail ( &process->list, &run_queue );
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} else {
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DBGC ( PROC_COL ( process ), "PROCESS " PROC_FMT
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" already started\n", PROC_DBG ( process ) );
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}
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}
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/**
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* Remove process from process list
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*
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* @v process Process
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*
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* It is safe to call process_del() multiple times; further calls will
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* have no effect.
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*/
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void process_del ( struct process *process ) {
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if ( process_running ( process ) ) {
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DBGC ( PROC_COL ( process ), "PROCESS " PROC_FMT
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" stopping\n", PROC_DBG ( process ) );
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list_del ( &process->list );
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INIT_LIST_HEAD ( &process->list );
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ref_put ( process->refcnt );
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} else {
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DBGC ( PROC_COL ( process ), "PROCESS " PROC_FMT
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" already stopped\n", PROC_DBG ( process ) );
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}
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}
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/**
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* Single-step a single process
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*
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* This executes a single step of the first process in the run queue,
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* and moves the process to the end of the run queue.
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*/
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void step ( void ) {
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struct process *process;
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struct process_descriptor *desc;
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void *object;
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if ( ( process = list_first_entry ( &run_queue, struct process,
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list ) ) ) {
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ref_get ( process->refcnt ); /* Inhibit destruction mid-step */
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desc = process->desc;
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object = process_object ( process );
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if ( desc->reschedule ) {
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list_del ( &process->list );
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list_add_tail ( &process->list, &run_queue );
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} else {
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process_del ( process );
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}
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DBGC2 ( PROC_COL ( process ), "PROCESS " PROC_FMT
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" executing\n", PROC_DBG ( process ) );
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desc->step ( object );
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DBGC2 ( PROC_COL ( process ), "PROCESS " PROC_FMT
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" finished executing\n", PROC_DBG ( process ) );
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ref_put ( process->refcnt ); /* Allow destruction */
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}
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}
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/**
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* Initialise processes
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*
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*/
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static void init_processes ( void ) {
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struct process *process;
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for_each_table_entry ( process, PERMANENT_PROCESSES )
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process_add ( process );
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}
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/** Process initialiser */
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struct init_fn process_init_fn __init_fn ( INIT_NORMAL ) = {
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.initialise = init_processes,
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};
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