/*
* linux/kernel/sched.c
*
* (C) 1991 Linus Torvalds
*/
/*
* 'sched.c' is the main kernel file. It contains scheduling primitives
* (sleep_on, wakeup, schedule etc) as well as a number of simple system
* call functions (type getpid(), which just extracts a field from
* current-task
*/
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/sys.h>
#include <linux/fdreg.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/segment.h>
#include <signal.h>
#define _S(nr) (1<<((nr)-1))
#define _BLOCKABLE (~(_S(SIGKILL) | _S(SIGSTOP)))
void show_task(int nr,struct task_struct * p)
{
int i,j = 4096-sizeof(struct task_struct);
printk("%d: pid=%d, state=%d, ",nr,p->pid,p->state);
i=0;
while (i<j && !((char *)(p+1))[i])
i++;
printk("%d (of %d) chars free in kernel stack\n\r",i,j);
}
void show_stat(void)
{
int i;
for (i=0;i<NR_TASKS;i++)
if (task[i])
show_task(i,task[i]);
}
#define LATCH (1193180/HZ)
extern void mem_use(void);
extern int timer_interrupt(void);
extern int system_call(void);
union task_union {
struct task_struct task;
char stack[PAGE_SIZE];
};
static union task_union init_task = {INIT_TASK,};
long volatile jiffies=0;
long startup_time=0;
struct task_struct *current = &(init_task.task);
struct task_struct *last_task_used_math = NULL;
struct task_struct * task[NR_TASKS] = {&(init_task.task), };
long user_stack [ PAGE_SIZE>>2 ] ;
struct {
long * a;
short b;
} stack_start = { & user_stack [PAGE_SIZE>>2] , 0x10 };
/*
* 'math_state_restore()' saves the current math information in the
* old math state array, and gets the new ones from the current task
*/
void math_state_restore()
{
if (last_task_used_math == current)
return;
__asm__("fwait");
if (last_task_used_math) {
__asm__("fnsave %0"::"m" (last_task_used_math->tss.i387));
}
last_task_used_math=current;
if (current->used_math) {
__asm__("frstor %0"::"m" (current->tss.i387));
} else {
__asm__("fninit"::);
current->used_math=1;
}
}
/*
* 'schedule()' is the scheduler function. This is GOOD CODE! There
* probably won't be any reason to change this, as it should work well
* in all circumstances (ie gives IO-bound processes good response etc).
* The one thing you might take a look at is the signal-handler code here.
*
* NOTE!! Task 0 is the 'idle' task, which gets called when no other
* tasks can run. It can not be killed, and it cannot sleep. The 'state'
* information in task[0] is never used.
*/
void schedule(void)
{
int i,next,c;
struct task_struct ** p;
/* check alarm, wake up any interruptible tasks that have got a signal */
for(p = &LAST_TASK ; p > &FIRST_TASK ; --p)
if (*p) {
if ((*p)->alarm && (*p)->alarm < jiffies) {
(*p)->signal |= (1<<(SIGALRM-1));
(*p)->alarm = 0;
}
if (((*p)->signal & ~(_BLOCKABLE & (*p)->blocked)) &&
(*p)->state==TASK_INTERRUPTIBLE)
{
(*p)->state=TASK_RUNNING;
fprintk(3, "%ld\t%c\t%ld\n", (*p)->pid, 'J', jiffies);
}
}
/* this is the scheduler proper: */
while (1) {
c = -1;
next = 0;
i = NR_TASKS;
p = &task[NR_TASKS];
while (--i) {
if (!*--p)
continue;
if ((*p)->state == TASK_RUNNING && (*p)->counter > c)
c = (*p)->counter, next = i;
}
if (c) break;
for(p = &LAST_TASK ; p > &FIRST_TASK ; --p)
if (*p)
(*p)->counter = ((*p)->counter >> 1) +
(*p)->priority;
}
if(current->state == TASK_RUNNING && current != task[next])
{
fprintk(3, "%ld\t%c\t%ld\n", current->pid, 'J', jiffies);
}
if(current != task[next])
{
fprintk(3, "%ld\t%c\t%ld\n", task[next]->pid, 'R', jiffies);
}
switch_to(next);
}
int sys_pause(void)
{
current->state = TASK_INTERRUPTIBLE;
if(current->pid != 0)
{
fprintk(3, "%ld\t%c\t%ld\n", current->pid, 'W', jiffies);
}
schedule();
return 0;
}
void sleep_on(struct task_struct **p)
{
struct task_struct *tmp;
if (!p)
return;
if (current == &(init_task.task))
panic("task[0] trying to sleep");
tmp = *p;
*p = current;
current->state = TASK_UNINTERRUPTIBLE;
if(current->pid != 0)
{
fprintk(3, "%ld\t%c\t%ld\n", current->pid, 'W', jiffies);
}
schedule();
if (tmp)
{
tmp->state=0;
fprintk(3, "%ld\t%c\t%ld\n", tmp->pid, 'J', jiffies);
}
}
void interruptible_sleep_on(struct task_struct **p)
{
struct task_struct *tmp;
if (!p)
return;
if (current == &(init_task.task))
panic("task[0] trying to sleep");
tmp=*p;
*p=current;
repeat: current->state = TASK_INTERRUPTIBLE;
if(current->pid != 0)
{
fprintk(3, "%ld\t%c\t%ld\n", current->pid, 'W', jiffies);
}
schedule();
if (*p && *p != current) {
(**p).state=0;
fprintk(3, "%ld\t%c\t%ld\n", (**p).pid, 'J', jiffies);
goto repeat;
}
*p=NULL;
if (tmp)
{
tmp->state=0;
fprintk(3, "%ld\t%c\t%ld\n", tmp->pid, 'J', jiffies);
}
}
void wake_up(struct task_struct **p)
{
if (p && *p) {
(**p).state=0;
fprintk(3, "%ld\t%c\t%ld\n", (**p).pid, 'J', jiffies);
*p=NULL;
}
}
/*
* OK, here are some floppy things that shouldn't be in the kernel
* proper. They are here because the floppy needs a timer, and this
* was the easiest way of doing it.
*/
static struct task_struct * wait_motor[4] = {NULL,NULL,NULL,NULL};
static int mon_timer[4]={0,0,0,0};
static int moff_timer[4]={0,0,0,0};
unsigned char current_DOR = 0x0C;
int ticks_to_floppy_on(unsigned int nr)
{
extern unsigned char selected;
unsigned char mask = 0x10 << nr;
if (nr>3)
panic("floppy_on: nr>3");
moff_timer[nr]=10000; /* 100 s = very big :-) */
cli(); /* use floppy_off to turn it off */
mask |= current_DOR;
if (!selected) {
mask &= 0xFC;
mask |= nr;
}
if (mask != current_DOR) {
outb(mask,FD_DOR);
if ((mask ^ current_DOR) & 0xf0)
mon_timer[nr] = HZ/2;
else if (mon_timer[nr] < 2)
mon_timer[nr] = 2;
current_DOR = mask;
}
sti();
return mon_timer[nr];
}
void floppy_on(unsigned int nr)
{
cli();
while (ticks_to_floppy_on(nr))
sleep_on(nr+wait_motor);
sti();
}
void floppy_off(unsigned int nr)
{
moff_timer[nr]=3*HZ;
}
void do_floppy_timer(void)
{
int i;
unsigned char mask = 0x10;
for (i=0 ; i<4 ; i++,mask <<= 1) {
if (!(mask & current_DOR))
continue;
if (mon_timer[i]) {
if (!--mon_timer[i])
wake_up(i+wait_motor);
} else if (!moff_timer[i]) {
current_DOR &= ~mask;
outb(current_DOR,FD_DOR);
} else
moff_timer[i]--;
}
}
#define TIME_REQUESTS 64
static struct timer_list {
long jiffies;
void (*fn)();
struct timer_list * next;
} timer_list[TIME_REQUESTS], * next_timer = NULL;
void add_timer(long jiffies, void (*fn)(void))
{
struct timer_list * p;
if (!fn)
return;
cli();
if (jiffies <= 0)
(fn)();
else {
for (p = timer_list ; p < timer_list + TIME_REQUESTS ; p++)
if (!p->fn)
break;
if (p >= timer_list + TIME_REQUESTS)
panic("No more time requests free");
p->fn = fn;
p->jiffies = jiffies;
p->next = next_timer;
next_timer = p;
while (p->next && p->next->jiffies < p->jiffies) {
p->jiffies -= p->next->jiffies;
fn = p->fn;
p->fn = p->next->fn;
p->next->fn = fn;
jiffies = p->jiffies;
p->jiffies = p->next->jiffies;
p->next->jiffies = jiffies;
p = p->next;
}
}
sti();
}
void do_timer(long cpl)
{
extern int beepcount;
extern void sysbeepstop(void);
if (beepcount)
if (!--beepcount)
sysbeepstop();
if (cpl)
current->utime++;
else
current->stime++;
if (next_timer) {
next_timer->jiffies--;
while (next_timer && next_timer->jiffies <= 0) {
void (*fn)(void);
fn = next_timer->fn;
next_timer->fn = NULL;
next_timer = next_timer->next;
(fn)();
}
}
if (current_DOR & 0xf0)
do_floppy_timer();
if ((--current->counter)>0) return;
current->counter=0;
if (!cpl) return;
schedule();
}
int sys_alarm(long seconds)
{
int old = current->alarm;
if (old)
old = (old - jiffies) / HZ;
current->alarm = (seconds>0)?(jiffies+HZ*seconds):0;
return (old);
}
int sys_getpid(void)
{
return current->pid;
}
int sys_getppid(void)
{
return current->father;
}
int sys_getuid(void)
{
return cur
