/*
 *  linux/kernel/sched.c
 *
 *  Copyright (C) 1991, 1992  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 extract a field from
 * current-task
 */

#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/kernel.h>
#include <linux/kernel_stat.h>
#include <linux/fdreg.h>
#include <linux/errno.h>
#include <linux/time.h>
#include <linux/ptrace.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/tqueue.h>
#include <linux/resource.h>
#include <linux/mm.h>
#include <linux/smp.h>

#include <asm/system.h>
#include <asm/io.h>
#include <asm/segment.h>
#include <asm/pgtable.h>
#include <asm/mmu_context.h>

#include <linux/timex.h>

/*
 * kernel variables
 */

int securelevel = 0;			/* system security level */

long tick = 1000000 / HZ;		/* timer interrupt period */
volatile struct timeval xtime;		/* The current time */
int tickadj = 500/HZ;			/* microsecs */

DECLARE_TASK_QUEUE(tq_timer);
DECLARE_TASK_QUEUE(tq_immediate);
DECLARE_TASK_QUEUE(tq_scheduler);

/*
 * phase-lock loop variables
 */
int time_state = TIME_BAD;	/* clock synchronization status */
int time_status = STA_UNSYNC | STA_PLL;	/* clock status bits */
long time_offset = 0;		/* time adjustment (us) */
long time_constant = 2;		/* pll time constant */
long time_tolerance = MAXFREQ;	/* frequency tolerance (ppm) */
long time_precision = 1;	/* clock precision (us) */
long time_maxerror = 0x70000000;/* maximum error */
long time_esterror = 0x70000000;/* estimated error */
long time_phase = 0;		/* phase offset (scaled us) */
long time_freq = 0;		/* frequency offset (scaled ppm) */
long time_adj = 0;		/* tick adjust (scaled 1 / HZ) */
long time_reftime = 0;		/* time at last adjustment (s) */

long time_adjust = 0;
long time_adjust_step = 0;

int need_resched = 0;
unsigned long event = 0;

extern int _setitimer(int, struct itimerval *, struct itimerval *);
unsigned int * prof_buffer = NULL;
unsigned long prof_len = 0;
unsigned long prof_shift = 0;

#define _S(nr) (1<<((nr)-1))

extern void mem_use(void);

static unsigned long init_kernel_stack[1024] = { STACK_MAGIC, };
unsigned long init_user_stack[1024] = { STACK_MAGIC, };
static struct vm_area_struct init_mmap = INIT_MMAP;
static struct fs_struct init_fs = INIT_FS;
static struct files_struct init_files = INIT_FILES;
static struct signal_struct init_signals = INIT_SIGNALS;

struct mm_struct init_mm = INIT_MM;
struct task_struct init_task = INIT_TASK;

unsigned long volatile jiffies=0;

struct task_struct *current_set[NR_CPUS];
struct task_struct *last_task_used_math = NULL;

struct task_struct * task[NR_TASKS] = {&init_task, };

struct kernel_stat kstat = { 0 };

static inline void add_to_runqueue(struct task_struct * p)
{
#ifdef __SMP__
	int cpu=smp_processor_id();
#endif	
#if 1	/* sanity tests */
	if (p->next_run || p->prev_run) {
		printk("task already on run-queue\n");
		return;
	}
#endif
	if (p->counter > current->counter + 3)
		need_resched = 1;
	nr_running++;
	(p->prev_run = init_task.prev_run)->next_run = p;
	p->next_run = &init_task;
	init_task.prev_run = p;
#ifdef __SMP__
	/* this is safe only if called with cli()*/
	while(set_bit(31,&smp_process_available));
#if 0	
	{
		while(test_bit(31,&smp_process_available))
		{
			if(clear_bit(cpu,&smp_invalidate_needed))
			{
				local_flush_tlb();
				set_bit(cpu,&cpu_callin_map[0]);
			}
		}
	}
#endif	
	smp_process_available++;
	clear_bit(31,&smp_process_available);
	if ((0!=p->pid) && smp_threads_ready)
	{
		int i;
		for (i=0;i<smp_num_cpus;i++)
		{
			if (0==current_set[cpu_logical_map[i]]->pid) 
			{
				smp_message_pass(cpu_logical_map[i], MSG_RESCHEDULE, 0L, 0);
				break;
			}
		}
	}
#endif
}

static inline void del_from_runqueue(struct task_struct * p)
{
	struct task_struct *next = p->next_run;
	struct task_struct *prev = p->prev_run;

#if 1	/* sanity tests */
	if (!next || !prev) {
		printk("task not on run-queue\n");
		return;
	}
#endif
	if (p == &init_task) {
		static int nr = 0;
		if (nr < 5) {
			nr++;
			printk("idle task may not sleep\n");
		}
		return;
	}
	nr_running--;
	next->prev_run = prev;
	prev->next_run = next;
	p->next_run = NULL;
	p->prev_run = NULL;
}

static inline void move_last_runqueue(struct task_struct * p)
{
	struct task_struct *next = p->next_run;
	struct task_struct *prev = p->prev_run;

	/* remove from list */
	next->prev_run = prev;
	prev->next_run = next;
	/* add back to list */
	p->next_run = &init_task;
	prev = init_task.prev_run;
	init_task.prev_run = p;
	p->prev_run = prev;
	prev->next_run = p;
}

/*
 * Wake up a process. Put it on the run-queue if it's not
 * already there.  The "current" process is always on the
 * run-queue (except when the actual re-schedule is in
 * progress), and as such you're allowed to do the simpler
 * "current->state = TASK_RUNNING" to mark yourself runnable
 * without the overhead of this.
 */
inline void wake_up_process(struct task_struct * p)
{
	unsigned long flags;

	save_flags(flags);
	cli();
	p->state = TASK_RUNNING;
	if (!p->next_run)
		add_to_runqueue(p);
	restore_flags(flags);
}

static void process_timeout(unsigned long __data)
{
	struct task_struct * p = (struct task_struct *) __data;

	p->timeout = 0;
	wake_up_process(p);
}

/*
 * This is the function that decides how desirable a process is..
 * You can weigh different processes against each other depending
 * on what CPU they've run on lately etc to try to handle cache
 * and TLB miss penalties.
 *
 * Return values:
 *	 -1000: never select this
 *	     0: out of time, recalculate counters (but it might still be
 *		selected)
 *	   +ve: "goodness" value (the larger, the better)
 *	 +1000: realtime process, select this.
 */
static inline int goodness(struct task_struct * p, struct task_struct * prev, int this_cpu)
{
	int weight;

#ifdef __SMP__	
	/* We are not permitted to run a task someone else is running */
	if (p->processor != NO_PROC_ID)
		return -1000;
#endif

	/*
	 * Realtime process, select the first one on the
	 * runqueue (taking priorities within processes
	 * into account).
	 */
	if (p->policy != SCHED_OTHER)
		return 1000 + p->rt_priority;

	/*
	 * Give the process a first-approximation goodness value
	 * according to the number of clock-ticks it has left.
	 *
	 * Don't do any other calculations if the time slice is
	 * over..
	 */
	weight = p->counter;
	if (weight) {
			
#ifdef __SMP__
		/* Give a largish advantage to the same processor...   */
		/* (this is equivalent to penalizing other processors) */
		if (p->last_processor == this_cpu)
			weight += PROC_CHANGE_PENALTY;
#endif

		/* .. and a slight advantage to the current process */
		if (p == prev)
			weight += 1;
	}

	return weight;
}

/*
 *  'schedule()' is the scheduler function. It's a very simple and nice
 * scheduler: it's not perfect, but certainly works for most things.
 *
 * The goto is "interesting".
 *
 *   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.
 */
asmlinkage void schedule(void)
{
	int c;
	struct task_struct * p;
	struct task_struct * prev, * next;
	unsigned long timeout = 0;
	int this_cpu=smp_processor_id();

/* check alarm, wake up any interruptible tasks that have got a signal */

	if (intr_count)
		goto scheduling_in_interrupt;

	if (bh_active & bh_mask) {
		intr_count = 1;
		do_bottom_half();
		intr_count = 0;
	}

	run_task_queue(&tq_scheduler);

	need_resched = 0;
	prev = current;
	cli();
	/* move an exhausted RR process to be last.. */
	if (!prev->counter && prev->policy == SCHED_RR) {
		prev->counter = prev->priority;
		move_last_runqueue(prev);
	}
	switch (prev->state) {
		case TASK_INTERRUPTIBLE:
			if (prev->signal & ~prev->blocked)
				goto makerunnable;
			timeout = prev->timeout;
			if (timeout && (timeout <= jiffies)) {
				prev->timeout = 0;
				timeout = 0;
		makerunnable:
				prev->state = TASK_RUNNING;
				break;
			}
		default:
			del_from_runqueue(prev);
		case TASK_RUNNING:
	}
	p = init_task.next_run;
	sti();
	
#ifdef __SMP__
	/*
	 *	This is safe as we do not permit re-entry of schedule()
	 */
	prev->processor = NO_PROC_ID;
#define idle_task (task[this_cpu])
#else
#define idle_task (&init_task)
#endif	

/*
 * Note! there may appear new tasks on the run-queue during this, as
 * interrupts are enabled. However, they will be put on front of the
 * list, so our list starting at "p" is essentially fixed.
 */
/* this is the scheduler proper: */
	c = -1000;
	next = idle_task;
	while (p != &init_task) {
		int weight = goodness(p, prev, this_cpu);
		if (weight > c)
			c = weight, next = p;
		p = p->next_run;
	}

	/* if all runnable processes have "counter == 0", re-calculate counters */
	if (!c) {
		for_each_task(p)
			p->counter = (p->counter >> 1) + p->priority;
	}
#ifdef __SMP__
	/*
	 *	Allocate process to CPU
	 */
	 
	 next->processor = this_cpu;
	 next->last_processor = this_cpu;
#endif	 
#ifdef __SMP_PROF__ 
	/* mark processor running an idle thread */
	if (0==next->pid)
		set_bit(this_cpu,&smp_idle_map);
	else
		clear_bit(this_cpu,&smp_idle_map);
#endif
	if (prev != next) {
		struct timer_list timer;

		kstat.context_swtch++;
		if (timeout) {
			init_timer(&timer);
			timer.expires = timeout;
			timer.data = (unsigned long) prev;
			timer.function = process_timeout;
			add_timer(&timer);
		}
		get_mmu_context(next);
		switch_to(prev,next);
		if (timeout)
			del_timer(&timer);
	}
	return;

scheduling_in_interrupt:
	printk("Aiee: scheduling in interrupt\n");
}

#ifndef __alpha__

/*
 * For backwards compatibility?  This can be done in libc so Alpha
 * and all newer ports shouldn't need it.
 */
asmlinkage int sys_pause(void)
{
	current->state = TASK_INTERRUPTIBLE;
	schedule();
	return -ERESTARTNOHAND;
}

#endif

/*
 * wake_up doesn't wake up stopped processes - they have to be awakened
 * with signals or similar.
 *
 * Note that this doesn't need cli-sti pairs: interrupts may not change
 * the wait-queue structures directly, but only call wake_up() to wake
 * a process. The process itself must remove the queue once it has woken.
 */
void wake_up(struct wait_queue **q)
{
	struct wait_queue *tmp;
	struct task_struct * p;

	if (!q || !(tmp = *q))
		return;
	do {
		if ((p = tmp->task) != NULL) {
			if ((p->state == TASK_UNINTERRUPTIBLE) ||
			    (p->state == TASK_INTERRUPTIBLE))
				wake_up_process(p);
		}
		if (!tmp->next) {
			printk("wait_queue is bad (eip = %p)\n",
				__builtin_return_address(0));
			printk("        q = %p\n",q);
			printk("       *q = %p\n",*q);
			printk("      tmp = %p\n",tmp);
			break;
		}
		tmp = tmp->next;
	} while (tmp != *q);
}

void wake_up_interruptible(struct wait_queue **q)
{
	struct wait_queue *tmp;
	struct task_struct * p;

	if (!q || !(tmp = *q))
		return;
	do {
		if ((p = tmp->task) != NULL) {
			if (p->state == TASK_INTERRUPTIBLE)
				wake_up_process(p);
		}
		if (!tmp->next) {
			printk("wait_queue is bad (eip = %p)\n",
				__builtin_return_address(0));
			printk("        q = %p\n",q);
			printk("       *q = %p\n",*q);
			printk("      tmp = %p\n",tmp);
			break;
		}
		tmp = tmp->next;
	} while (tmp != *q);
}

void __down(struct semaphore * sem)
{
	struct wait_queue wait = { current, NULL };
	add_wait_queue(&sem->wait, &wait);
	current->state = TASK_UNINTERRUPTIBLE;
	while (sem->count <= 0) {
		schedule();
		current->state = TASK_UNINTERRUPTIBLE;
	}
	current->state = TASK_RUNNING;
	remove_wait_queue(&sem->wait, &wait);
}

static inline void __sleep_on(struct wait_queue **p, int state)
{
	unsigned long flags;
	struct wait_queue wait = { current, NULL };

	if (!p)
		return;
	if (current == task[0])
		panic("task[0] trying to sleep");
	current->state = state;
	add_wait_queue(p, &wait);
	save_flags(flags);
	sti();
	schedule();
	remove_wait_queue(p, &wait);
	restore_flags(flags);
}

void interruptible_sleep_on(struct wait_queue **p)
{
	__sleep_on(p,TASK_INTERRUPTIBLE);
}

void sleep_on(struct wait_queue **p)
{
	__sleep_on(p,TASK_UNINTERRUPTIBLE);
}

/*
 * The head for the timer-list has a "expires" field of MAX_UINT,
 * and the sorting routine counts on this..
 */
static struct timer_list timer_head = { &timer_head, &timer_head, ~0, 0, NULL };
#define SLOW_BUT_DEBUGGING_TIMERS 0

void add_timer(struct timer_list * timer)
{
	unsigned long flags;
	struct timer_list *p;

#if SLOW_BUT_DEBUGGING_TIMERS
	if (timer->next || timer->prev) {
		printk("add_timer() called with non-zero list from %p\n",
			__builtin_return_address(0));
		return;
	}
#endif
	p = &timer_head;
	save_flags(flags);
	cli();
	do {
		p = p->next;
	} while (timer->expires > p->expires);
	timer->next = p;
	timer->prev = p->prev;
	p->prev = timer;
	timer->prev->next = timer;
	restore_flags(flags);
}

int del_timer(struct timer_list * timer)
{
	int ret = 0;
	if (timer->next) {
		unsigned long flags;
		struct timer_list * next;
		save_flags(flags);
		cli();
		if ((next = timer->next) != NULL) {
			(next->prev = timer->prev)->next = next;
			timer->next = timer->prev = NULL;
			ret = 1;
		}
		restore_flags(flags);
	}
	return ret;
}

static inline void run_timer_list(void)
{
	struct timer_list * timer;

	while ((timer = timer_head.next) != &timer_head && timer->expires <= jiffies) {
		void (*fn)(unsigned long) = timer->function;
		unsigned long data = timer->data;
		timer->next->prev = timer->prev;
		timer->prev->next = timer->next;
		timer->next = timer->prev = NULL;
		sti();
		fn(data);
		cli();
	}
}

static inline void run_old_timers(void)
{
	struct timer_struct *tp;
	unsigned long mask;

	for (mask = 1, tp = timer_table+0 ; mask ; tp++,mask += mask) {
		if (mask > timer_active)
			break;
		if (!(mask & timer_active))
			continue;
		if (tp->expires > jiffies)
			continue;
		timer_active &= ~mask;
		tp->fn();
		sti();
	}
}

void tqueue_bh(void)
{
	run_task_queue(&tq_timer);
}

void immediate_bh(void)
{
	run_task_queue(&tq_immediate);
}

unsigned long timer_active = 0;
struct timer_struct timer_table[32];

/*
 * Hmm.. Changed this, as the GNU make sources (load.c) seems to
 * imply that avenrun[] is the standard name for this kind of thing.
 * Nothing else seems to be standardized: the fractional size etc
 * all seem to differ on different machines.
 */
unsigned long avenrun[3] = { 0,0,0 };

/*
 * Nr of active tasks - counted in fixed-point numbers
 */
static unsigned long count_active_tasks(void)
{
	struct task_struct **p;
	unsigned long nr = 0;

	for(p = &LAST_TASK; p > &FIRST_TASK; --p)
		if (*p && ((*p)->state == TASK_RUNNING ||
			   (*p)->state == TASK_UNINTERRUPTIBLE ||
			   (*p)->state == TASK_SWAPPING))
			nr += FIXED_1;
#ifdef __SMP__
	nr-=(smp_num_cpus-1)*FIXED_1;
#endif			
	return nr;
}

static inline void calc_load(unsigned long ticks)
{
	unsigned long active_tasks; /* fixed-point */
	static int count = LOAD_FREQ;

	count -= ticks;
	if (count < 0) {
		count += LOAD_FREQ;
		active_tasks = count_active_tasks();
		CALC_LOAD(avenrun[0], EXP_1, active_tasks);
		CALC_LOAD(avenrun[1], EXP_5, active_tasks);
		CALC_LOAD(avenrun[2], EXP_15, active_tasks);
	}
}

/*
 * this routine handles the overflow of the microsecond field
 *
 * The tricky bits of code to handle the accurate clock support
 * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
 * They were originally developed for SUN and DEC kernels.
 * All the kudos should go to Dave for this stuff.
 *
 */
static void second_overflow(void)
{
    long ltemp;

    /* Bump the maxerror field */
    time_maxerror = (0x70000000-time_maxerror <
		     time_tolerance >> SHIFT_USEC) ?
	0x70000000 : (time_maxerror + (time_tolerance >> SHIFT_USEC));

    /*
     * Leap second processing. If in leap-insert state at
     * the end of the day, the system clock is set back one
     * second; if in leap-delete state, the system clock is
     * set ahead one second. The microtime() routine or
     * external clock driver will insure that reported time
     * is always monotonic. The ugly divides should be
     * replaced.
     */
    switch (time_state) {

    case TIME_OK:
	if (time_status & STA_INS)
	    time_state = TIME_INS;
	else if (time_status & STA_DEL)
	    time_state = TIME_DEL;
	break;

    case TIME_INS:
	if (xtime.tv_sec % 86400 == 0) {
	    xtime.tv_sec--;
	    time_state = TIME_OOP;
	    printk("Clock: inserting leap second 23:59:60 UTC\n");
	}
	break;

    case TIME_DEL:
	if ((xtime.tv_sec + 1) % 86400 == 0) {
	    xtime.tv_sec++;
	    time_state = TIME_WAIT;
	    printk("Clock: deleting leap second 23:59:59 UTC\n");
	}
	break;

    case TIME_OOP:

	time_state = TIME_WAIT;
	break;

    case TIME_WAIT:
	if (!(time_status & (STA_INS | STA_DEL)))
	    time_state = TIME_OK;
    }

    /*
     * Compute the phase adjustment for the next second. In
     * PLL mode, the offset is reduced by a fixed factor
     * times the time constant. In FLL mode the offset is
     * used directly. In either mode, the maximum phase
     * adjustment for each second is clamped so as to spread
     * the adjustment over not more than the number of
     * seconds between updates.
     */
    if (time_offset < 0) {
	ltemp = -time_offset;
	if (!(time_status & STA_FLL))
	    ltemp >>= SHIFT_KG + time_constant;
	if (ltemp > (MAXPHASE / MINSEC) << SHIFT_UPDATE)
	    ltemp = (MAXPHASE / MINSEC) <<
		SHIFT_UPDATE;
	time_offset += ltemp;
	time_adj = -ltemp << (SHIFT_SCALE - SHIFT_HZ -
			      SHIFT_UPDATE);
    } else {
	ltemp = time_offset;
	if (!(time_status & STA_FLL))
	    ltemp >>= SHIFT_KG + time_constant;
	if (ltemp > (MAXPHASE / MINSEC) << SHIFT_UPDATE)
	    ltemp = (MAXPHASE / MINSEC) <<
		SHIFT_UPDATE;
	time_offset -= ltemp;
	time_adj = ltemp << (SHIFT_SCALE - SHIFT_HZ -
			     SHIFT_UPDATE);
    }

    /*
     * Compute the frequency estimate and additional phase
     * adjustment due to frequency error for the next
     * second. When the PPS signal is engaged, gnaw on the
     * watchdog counter and update the frequency computed by
     * the pll and the PPS signal.
     */
    pps_valid++;
    if (pps_valid == PPS_VALID) {
	pps_jitter = MAXTIME;
	pps_stabil = MAXFREQ;
	time_status &= ~(STA_PPSSIGNAL | STA_PPSJITTER |
			 STA_PPSWANDER | STA_PPSERROR);
    }
    ltemp = time_freq + pps_freq;
    if (ltemp < 0)
	time_adj -= -ltemp >>
	    (SHIFT_USEC + SHIFT_HZ - SHIFT_SCALE);
    else
	time_adj += ltemp >>
	    (SHIFT_USEC + SHIFT_HZ - SHIFT_SCALE);

#if HZ == 100
    /* compensate for (HZ==100) != 128. Add 25% to get 125; => only 3% error */
    if (time_adj < 0)
	time_adj -= -time_adj >> 2;
    else
	time_adj += time_adj >> 2;
#endif
}

static void update_wall_time_one_tick(void)
{
	/*
	 * Advance the phase, once it gets to one microsecond, then
	 * advance the tick more.
	 */
	time_phase += time_adj;
	if (time_phase <= -FINEUSEC) {
		long ltemp = -time_phase >> SHIFT_SCALE;
		time_phase += ltemp << SHIFT_SCALE;
		xtime.tv_usec += tick + time_adjust_step - ltemp;
	}
	else if (time_phase >= FINEUSEC) {
		long ltemp = time_phase >> SHIFT_SCALE;
		time_phase -= ltemp << SHIFT_SCALE;
		xtime.tv_usec += tick + time_adjust_step + ltemp;
	} else
		xtime.tv_usec += tick + time_adjust_step;

	if (time_adjust) {
	    /* We are doing an adjtime thing. 
	     *
	     * Modify the value of the tick for next time.
	     * Note that a positive delta means we want the clock
	     * to run fast. This means that the tick should be bigger
	     *
	     * Limit the amount of the step for *next* tick to be
	     * in the range -tickadj .. +tickadj
	     */
	     if (time_adjust > tickadj)
		time_adjust_step = tickadj;
	     else if (time_adjust < -tickadj)
		time_adjust_step = -tickadj;
	     else
		time_adjust_step = time_adjust;
	     
	    /* Reduce by this step the amount of time left  */
	    time_adjust -= time_adjust_step;
	}
	else
	    time_adjust_step = 0;
}

/*
 * Using a loop looks inefficient, but "ticks" is
 * usually just one (we shouldn't be losing ticks,
 * we're doing this this way mainly for interrupt
 * latency reasons, not because we think we'll
 * have lots of lost timer ticks
 */
static void update_wall_time(unsigned long ticks)
{
	do {
		ticks--;
		update_wall_time_one_tick();
	} while (ticks);

	if (xtime.tv_usec >= 1000000) {
	    xtime.tv_usec -= 1000000;
	    xtime.tv_sec++;
	    second_overflow();
	}
}

static inline void do_process_times(struct task_struct *p,
	unsigned long user, unsigned long system)
{
	long psecs;

	p->utime += user;
	p->stime += system;

	psecs = (p->stime + p->utime) / HZ;
	if (psecs > p->rlim[RLIMIT_CPU].rlim_cur) {
		/* Send SIGXCPU every second.. */
		if (psecs * HZ == p->stime + p->utime)
			send_sig(SIGXCPU, p, 1);
		/* and SIGKILL when we go over max.. */
		if (psecs > p->rlim[RLIMIT_CPU].rlim_max)
			send_sig(SIGKILL, p, 1);
	}
}

static inline void do_it_virt(struct task_struct * p, unsigned long ticks)
{
	unsigned long it_virt = p->it_virt_value;

	if (it_virt) {
		if (it_virt <= ticks) {
			it_virt = ticks + p->it_virt_incr;
			send_sig(SIGVTALRM, p, 1);
		}
		p->it_virt_value = it_virt - ticks;
	}
}

static inline void do_it_prof(struct task_struct * p, unsigned long ticks)
{
	unsigned long it_prof = p->it_prof_value;

	if (it_prof) {
		if (it_prof <= ticks) {
			it_prof = ticks + p->it_prof_incr;
			send_sig(SIGPROF, p, 1);
		}
		p->it_prof_value = it_prof - ticks;
	}
}

static __inline__ void update_one_process(struct task_struct *p,
	unsigned long ticks, unsigned long user, unsigned long system)
{
	do_process_times(p, user, system);
	do_it_virt(p, user);
	do_it_prof(p, ticks);
}	

static void update_process_times(unsigned long ticks, unsigned long system)
{
#ifndef  __SMP__
	struct task_struct * p = current;
	unsigned long user = ticks - system;
	if (p->pid) {
		p->counter -= ticks;
		if (p->counter < 0) {
			p->counter = 0;
			need_resched = 1;
		}
		if (p->priority < DEF_PRIORITY)
			kstat.cpu_nice += user;
		else
			kstat.cpu_user += user;
		kstat.cpu_system += system;
	}
	update_one_process(p, ticks, user, system);
#else
	int cpu,j;
	cpu = smp_processor_id();
	for (j=0;j<smp_num_cpus;j++)
	{
		int i = cpu_logical_map[j];
		struct task_struct *p;
		
#ifdef __SMP_PROF__
		if (test_bit(i,&smp_idle_map)) 
			smp_idle_count[i]++;
#endif
		p = current_set[i];
		/*
		 * Do we have a real process?
		 */
		if (p->pid) {
			/* assume user-mode process */
			unsigned long utime = ticks;
			unsigned long stime = 0;
			if (cpu == i) {
				utime = ticks-system;
				stime = system;
			} else if (smp_proc_in_lock[i]) {
				utime = 0;
				stime = ticks;
			}
			update_one_process(p, ticks, utime, stime);

			p->counter -= ticks;
			if (p->counter >= 0)
				continue;
			p->counter = 0;
		} else {
			/*
			 * Idle processor found, do we have anything
			 * we could run?
			 */
			if (!(0x7fffffff & smp_process_available))
				continue;
		}
		/* Ok, we should reschedule, do the magic */
		if (i==cpu)
			need_resched = 1;
		else
			smp_message_pass(i, MSG_RESCHEDULE, 0L, 0);
	}
#endif
}

static unsigned long lost_ticks = 0;
static unsigned long lost_ticks_system = 0;

static void timer_bh(void)
{
	unsigned long ticks, system;

	run_old_timers();

	cli();
	run_timer_list();
	ticks = lost_ticks;
	lost_ticks = 0;
	system = lost_ticks_system;
	lost_ticks_system = 0;
	sti();

	if (ticks) {
		calc_load(ticks);
		update_wall_time(ticks);
		update_process_times(ticks, system);
	}
}

/*
 * Run the bottom half stuff only about 100 times a second,
 * we'd just use up unnecessary CPU time for timer handling
 * otherwise
 */
#if HZ > 100
#define should_run_timers(x) ((x) >= HZ/100)
#else
#define should_run_timers(x) (1)
#endif

void do_timer(struct pt_regs * regs)
{
	(*(unsigned long *)&jiffies)++;
	lost_ticks++;
	if (should_run_timers(lost_ticks))
		mark_bh(TIMER_BH);
	if (!user_mode(regs)) {
		lost_ticks_system++;
		if (prof_buffer && current->pid) {
			extern int _stext;
			unsigned long ip = instruction_pointer(regs);
			ip -= (unsigned long) &_stext;
			ip >>= prof_shift;
			if (ip < prof_len)
				prof_buffer[ip]++;
		}
	}
	if (tq_timer)
		mark_bh(TQUEUE_BH);
}

#ifndef __alpha__

/*
 * For backwards compatibility?  This can be done in libc so Alpha
 * and all newer ports shouldn't need it.
 */
asmlinkage unsigned int sys_alarm(unsigned int seconds)
{
	struct itimerval it_new, it_old;
	unsigned int oldalarm;

	it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
	it_new.it_value.tv_sec = seconds;
	it_new.it_value.tv_usec = 0;
	_setitimer(ITIMER_REAL, &it_new, &it_old);
	oldalarm = it_old.it_value.tv_sec;
	/* ehhh.. We can't return 0 if we have an alarm pending.. */
	/* And we'd better return too much than too little anyway */
	if (it_old.it_value.tv_usec)
		oldalarm++;
	return oldalarm;
}

/*
 * The Alpha uses getxpid, getxuid, and getxgid instead.  Maybe this
 * should be moved into arch/i386 instead?
 */
asmlinkage int sys_getpid(void)
{
	return current->pid;
}

asmlinkage int sys_getppid(void)
{
	return current->p_opptr->pid;
}

asmlinkage int sys_getuid(void)
{
	return current->uid;
}

asmlinkage int sys_geteuid(void)
{
	return current->euid;
}

asmlinkage int sys_getgid(void)
{
	return current->gid;
}

asmlinkage int sys_getegid(void)
{
	return current->egid;
}

/*
 * This has been replaced by sys_setpriority.  Maybe it should be
 * moved into the arch dependent tree for those ports that require
 * it for backward compatibility?
 */
asmlinkage int sys_nice(int increment)
{
	unsigned long newprio;
	int increase = 0;

	newprio = increment;
	if (increment < 0) {
		if (!suser())
			return -EPERM;
		newprio = -increment;
		increase = 1;
	}
	if (newprio > 40)
		newprio = 40;
	/*
	 * do a "normalization" of the priority (traditionally
	 * unix nice values are -20..20, linux doesn't really
	 * use that kind of thing, but uses the length of the
	 * timeslice instead (default 150 msec). The rounding is
	 * why we want to avoid negative values.
	 */
	newprio = (newprio * DEF_PRIORITY + 10) / 20;
	increment = newprio;
	if (increase)
		increment = -increment;
	newprio = current->priority - increment;
	if (newprio < 1)
		newprio = 1;
	if (newprio > DEF_PRIORITY*2)
		newprio = DEF_PRIORITY*2;
	current->priority = newprio;
	return 0;
}

#endif

static struct task_struct *find_process_by_pid(pid_t pid) {
	struct task_struct *p, *q;

	if (pid == 0)
		p = current;
	else {
		p = 0;
		for_each_task(q) {
			if (q && q->pid == pid) {
				p = q;
				break;
			}
		}
	}
	return p;
}

static int setscheduler(pid_t pid, int policy, 
			struct sched_param *param)
{
	int error;
	struct sched_param lp;
	struct task_struct *p;

	if (!param || pid < 0)
		return -EINVAL;

	error = verify_area(VERIFY_READ, param, sizeof(struct sched_param));
	if (error)
		return error;
	memcpy_fromfs(&lp, param, sizeof(struct sched_param));

	p = find_process_by_pid(pid);
	if (!p)
		return -ESRCH;
			
	if (policy < 0)
		policy = p->policy;
	else if (policy != SCHED_FIFO && policy != SCHED_RR &&
		 policy != SCHED_OTHER)
		return -EINVAL;
	
	/*
	 * Valid priorities for SCHED_FIFO and SCHED_RR are 1..99, valid
	 * priority for SCHED_OTHER is 0.
	 */
	if (lp.sched_priority < 0 || lp.sched_priority > 99)
		return -EINVAL;
	if ((policy == SCHED_OTHER) != (lp.sched_priority == 0))
		return -EINVAL;

	if ((policy == SCHED_FIFO || policy == SCHED_RR) && !suser())
		return -EPERM;
	if ((current->euid != p->euid) && (current->euid != p->uid) &&
	    !suser())
		return -EPERM;

	p->policy = policy;
	p->rt_priority = lp.sched_priority;
	if (p->next_run)
		move_last_runqueue(p);
	schedule();

	return 0;
}

asmlinkage int sys_sched_setscheduler(pid_t pid, int policy, 
				      struct sched_param *param)
{
	return setscheduler(pid, policy, param);
}

asmlinkage int sys_sched_setparam(pid_t pid, struct sched_param *param)
{
	return setscheduler(pid, -1, param);
}

asmlinkage int sys_sched_getscheduler(pid_t pid)
{
	struct task_struct *p;

	if (pid < 0)
		return -EINVAL;

	p = find_process_by_pid(pid);
	if (!p)
		return -ESRCH;
			
	return p->policy;
}

asmlinkage int sys_sched_getparam(pid_t pid, struct sched_param *param)
{
	int error;
	struct task_struct *p;
	struct sched_param lp;

	if (!param || pid < 0)
		return -EINVAL;

	error = verify_area(VERIFY_WRITE, param, sizeof(struct sched_param));
	if (error)
		return error;

	p = find_process_by_pid(pid);
	if (!p)
		return -ESRCH;

	lp.sched_priority = p->rt_priority;
	memcpy_tofs(param, &lp, sizeof(struct sched_param));

	return 0;
}

asmlinkage int sys_sched_yield(void)
{
	move_last_runqueue(current);

	return 0;
}

asmlinkage int sys_sched_get_priority_max(int policy)
{
	switch (policy) {
	      case SCHED_FIFO:
	      case SCHED_RR:
		return 99;
	      case SCHED_OTHER:
		return 0;
	}

	return -EINVAL;
}

asmlinkage int sys_sched_get_priority_min(int policy)
{
	switch (policy) {
	      case SCHED_FIFO:
	      case SCHED_RR:
		return 1;
	      case SCHED_OTHER:
		return 0;
	}

	return -EINVAL;
}

asmlinkage int sys_sched_rr_get_interval(pid_t pid, struct timespec *interval)
{
	int error;
	struct timespec t;

	error = verify_area(VERIFY_WRITE, interval, sizeof(struct timespec));
	if (error)
		return error;
	
	t.tv_sec = 0;
	t.tv_nsec = 0;   /* <-- Linus, please fill correct value in here */
	return -ENOSYS;  /* and then delete this line. Thanks!           */
	memcpy_tofs(interval, &t, sizeof(struct timespec));

	return 0;
}

/*
 * change timeval to jiffies, trying to avoid the 
 * most obvious overflows..
 */
static unsigned long timespectojiffies(struct timespec *value)
{
	unsigned long sec = (unsigned) value->tv_sec;
	long nsec = value->tv_nsec;

	if (sec > (LONG_MAX / HZ))
		return LONG_MAX;
	nsec += 1000000000L / HZ - 1;
	nsec /= 1000000000L / HZ;
	return HZ * sec + nsec;
}

static void jiffiestotimespec(unsigned long jiffies, struct timespec *value)
{
	value->tv_nsec = (jiffies % HZ) * (1000000000L / HZ);
	value->tv_sec = jiffies / HZ;
	return;
}

asmlinkage int sys_nanosleep(struct timespec *rqtp, struct timespec *rmtp)
{
	int error;
	struct timespec t;
	unsigned long expire;

	error = verify_area(VERIFY_READ, rqtp, sizeof(struct timespec));
	if (error)
		return error;
	memcpy_fromfs(&t, rqtp, sizeof(struct timespec));
	if (rmtp) {
		error = verify_area(VERIFY_WRITE, rmtp,
				    sizeof(struct timespec));
		if (error)
			return error;
	}

	if (t.tv_nsec >= 1000000000L || t.tv_nsec < 0 || t.tv_sec < 0)
		return -EINVAL;

	if (t.tv_sec == 0 && t.tv_nsec <= 2000000L &&
	    current->policy != SCHED_OTHER) {
		/*
		 * Short delay requests up to 2 ms will be handled with
		 * high precision by a busy wait for all real-time processes.
		 */
		udelay((t.tv_nsec + 999) / 1000);
		return 0;
	}

	expire = timespectojiffies(&t) + (t.tv_sec || t.tv_nsec) + jiffies;
	current->timeout = expire;
	current->state = TASK_INTERRUPTIBLE;
	schedule();

	if (expire > jiffies) {
		if (rmtp) {
			jiffiestotimespec(expire - jiffies -
					  (expire > jiffies + 1), &t);
			memcpy_tofs(rmtp, &t, sizeof(struct timespec));
		}
		return -EINTR;
	}

	return 0;
}

static void show_task(int nr,struct task_struct * p)
{
	unsigned long free;
	static const char * stat_nam[] = { "R", "S", "D", "Z", "T", "W" };

	printk("%-8s %3d ", p->comm, (p == current) ? -nr : nr);
	if (((unsigned) p->state) < sizeof(stat_nam)/sizeof(char *))
		printk(stat_nam[p->state]);
	else
		printk(" ");
#if ((~0UL) == 0xffffffff)
	if (p == current)
		printk(" current  ");
	else
		printk(" %08lX ", thread_saved_pc(&p->tss));
#else
	if (p == current)
		printk("   current task   ");
	else
		printk(" %016lx ", thread_saved_pc(&p->tss));
#endif
	for (free = 1; free < PAGE_SIZE/sizeof(long) ; free++) {
		if (((unsigned long *)p->kernel_stack_page)[free])
			break;
	}
	printk("%5lu %5d %6d ", free*sizeof(long), p->pid, p->p_pptr->pid);
	if (p->p_cptr)
		printk("%5d ", p->p_cptr->pid);
	else
		printk("      ");
	if (p->p_ysptr)
		printk("%7d", p->p_ysptr->pid);
	else
		printk("       ");
	if (p->p_osptr)
		printk(" %5d\n", p->p_osptr->pid);
	else
		printk("\n");
}

void show_state(void)
{
	int i;

#if ((~0UL) == 0xffffffff)
	printk("\n"
	       "                         free                        sibling\n");
	printk("  task             PC    stack   pid father child younger older\n");
#else
	printk("\n"
	       "                                 free                        sibling\n");
	printk("  task                 PC        stack   pid father child younger older\n");
#endif
	for (i=0 ; i<NR_TASKS ; i++)
		if (task[i])
			show_task(i,task[i]);
}

void sched_init(void)
{
	/*
	 *	We have to do a little magic to get the first
	 *	process right in SMP mode.
	 */
	int cpu=smp_processor_id();
#ifndef __SMP__	
	current_set[cpu]=&init_task;
#else
	init_task.processor=cpu;
	for(cpu = 0; cpu < NR_CPUS; cpu++)
		current_set[cpu] = &init_task;
#endif
	init_bh(TIMER_BH, timer_bh);
	init_bh(TQUEUE_BH, tqueue_bh);
	init_bh(IMMEDIATE_BH, immediate_bh);
}
