/*
* linux/kernel/sched.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*
* 1996-04-21 Modified by Ulrich Windl to make NTP work
* 1996-12-23 Modified by Dave Grothe to fix bugs in semaphores and
* make semaphores SMP safe
* 1997-01-28 Modified by Finn Arne Gangstad to make timers scale better.
*/
/*
* '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 <linux/smp_lock.h>
#include <linux/init.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/mmu_context.h>
#include <asm/spinlock.h>
#include <linux/timex.h>
/*
* kernel variables
*/
unsigned securebits = SECUREBITS_DEFAULT; /* systemwide security settings */
long tick = (1000000 + HZ/2) / HZ; /* timer interrupt period */
/* The current time */
volatile struct timeval xtime __attribute__ ((aligned (16)));
/* Don't completely fail for HZ > 500. */
int tickadj = 500/HZ ? : 1; /* microsecs */
DECLARE_TASK_QUEUE(tq_timer);
DECLARE_TASK_QUEUE(tq_immediate);
DECLARE_TASK_QUEUE(tq_scheduler);
/*
* phase-lock loop variables
*/
/* TIME_ERROR prevents overwriting the CMOS clock */
int time_state = TIME_ERROR; /* clock synchronization status */
int time_status = STA_UNSYNC; /* 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 = MAXPHASE; /* maximum error (us) */
long time_esterror = MAXPHASE; /* estimated error (us) */
long time_phase = 0; /* phase offset (scaled us) */
long time_freq = ((1000000 + HZ/2) % HZ - HZ/2) << SHIFT_USEC; /* 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;
unsigned long event = 0;
extern int do_setitimer(int, struct itimerval *, struct itimerval *);
unsigned int * prof_buffer = NULL;
unsigned long prof_len = 0;
unsigned long prof_shift = 0;
extern void mem_use(void);
unsigned long volatile jiffies=0;
/*
* Init task must be ok at boot for the ix86 as we will check its signals
* via the SMP irq return path.
*/
struct task_struct * task[NR_TASKS] = {&init_task, };
struct kernel_stat kstat = { 0 };
void scheduling_functions_start_here(void) { }
static inline void reschedule_idle(struct task_struct * p)
{
/*
* For SMP, we try to see if the CPU the task used
* to run on is idle..
*/
#if 0
/*
* Disable this for now. Ingo has some interesting
* code that looks too complex, and I have some ideas,
* but in the meantime.. One problem is that "wakeup()"
* can be (and is) called before we've even initialized
* SMP completely, so..
*/
#ifdef __SMP__
int want_cpu = p->processor;
/*
* Don't even try to find another CPU for us if the task
* ran on this one before..
*/
if (want_cpu != smp_processor_id()) {
struct task_struct **idle = task;
int i = smp_num_cpus;
do {
struct task_struct *tsk = *idle;
idle++;
/* Something like this.. */
if (tsk->has_cpu && tsk->processor == want_cpu) {
tsk->need_resched = 1;
smp_send_reschedule(want_cpu);
return;
}
} while (--i > 0);
}
#endif
#endif
if (p->policy != SCHED_OTHER || p->counter > current->counter + 3)
current->need_resched = 1;
}
/*
* Careful!
*
* This has to add the process to the _beginning_ of the
* run-queue, not the end. See the comment about "This is
* subtle" in the scheduler proper..
*/
static inline void add_to_runqueue(struct task_struct * p)
{
struct task_struct *next = init_task.next_run;
p->prev_run = &init_task;
init_task.next_run = p;
p->next_run = next;
next->prev_run = p;
}
static inline void del_from_runqueue(struct task_struct * p)
{
struct task_struct *next = p->next_run;
struct task_struct *prev = p->prev_run;
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;
}
static inline void move_first_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->prev_run = &init_task;
next = init_task.next_run;
init_task.next_run = p;
p->next_run = next;
next->prev_run = p;
}
/*
* The tasklist_lock protects the linked list of processes.
*
* The scheduler lock is protecting against multiple entry
* into the scheduling code, and doesn't need to worry
* about interrupts (because interrupts cannot call the
* scheduler).
*
* The run-queue lock locks the parts that actually access
* and change the run-queues, and have to be interrupt-safe.
*/
spinlock_t scheduler_lock = SPIN_LOCK_UNLOCKED; /* should be acquired first */
spinlock_t runqueue_lock = SPIN_LOCK_UNLOCKED; /* second */
rwlock_t tasklist_lock = RW_LOCK_UNLOCKED; /* third */
/*
* 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;
spin_lock_irqsave(&runqueue_lock, flags);
p->state = TASK_RUNNING;
if (!p->next_run) {
add_to_runqueue(p);
reschedule_idle(p);
nr_running++;
}
spin_unlock_irqrestore(&runqueue_lock, 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 policy = p->policy;
int weight;
if (policy & SCHED_YIELD) {
p->policy = policy & ~SCHED_YIELD;
return 0;
}
/*
* Realtime process, select the first one on the
* runqueue (taking priorities within processes
* into account).
*/
if (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->processor == this_cpu)
weight += PROC_CHANGE_PENALTY;
#endif
/* .. and a slight advantage to the current thread */
if (p->mm == prev->mm)
weight += 1;
weight += p->priority;
}
return weight;
}
/*
* Event timer code
*/
#define TVN_BITS 6
#define TVR_BITS 8
#define TVN_SIZE (1 << TVN_BITS)
#define TVR_SIZE (1 << TVR_BITS)
#define TVN_MASK (TVN_SIZE - 1)
#define TVR_MASK (TVR_SIZE - 1)
struct timer_vec {
int index;
struct timer_list *vec[TVN_SIZE];
};
struct timer_vec_root {
int index;
struct timer_list *vec[TVR_SIZE];
};
static struct timer_vec tv5 = { 0 };
static struct timer_vec tv4 = { 0 };
static struct timer_vec tv3 = { 0 };
static struct timer_vec tv2 = { 0 };
static struct timer_vec_root tv1 = { 0 };
static struct timer_vec * const tvecs[] = {
(struct timer_vec *)&tv1, &tv2, &tv3, &tv4, &tv5
};
#define NOOF_TVECS (sizeof(tvecs) / sizeof(tvecs[0]))
static unsigned long timer_jiffies = 0;
static inline void insert_timer(struct timer_list *timer,
struct timer_list **vec, int idx)
{
if ((timer->next = vec[idx]))
vec[idx]->prev = timer;
vec[idx] = timer;
timer->prev = (struct timer_list *)&vec[idx];
}
static inline void internal_add_timer(struct timer_list *timer)
{
/*
* must be cli-ed when calling this
*/
unsigned long expires = timer->expires;
unsigned long idx = expires - timer_jiffies;
if (idx < TVR_SIZE) {
int i = expires & TVR_MASK;
insert_timer(timer, tv1.vec, i);
} else if (idx < 1 << (TVR_BITS + TVN_BITS)) {
int i = (expires >> TVR_BITS) & TVN_MASK;
insert_timer(timer, tv2.vec, i);
} else if (idx < 1 << (TVR_BITS + 2 * TVN_BITS)) {
int i = (expires >> (TVR_BITS + TVN_BITS)) & TVN_MASK;
insert_timer(timer, tv3.vec, i);
} else if (idx < 1 << (TVR_BITS + 3 * TVN_BITS)) {
int i = (expires >> (TVR_BITS + 2 * TVN_BITS)) & TVN_MASK;
insert_timer(timer, tv4.vec, i);
} else if (expires < timer_jiffies) {
/* can happen if you add a timer with expires == jiffies,
* or you set a timer to go off in the past
*/
insert_timer(timer, tv1.vec, tv1.index);
} else if (idx < 0xffffffffUL) {
int i = (expires >> (TVR_BITS + 3 * TVN_BITS)) & TVN_MASK;
insert_timer(timer, tv5.vec, i);
} else {
/* Can only get here on architectures with 64-bit jiffies */
timer->next = timer->prev = timer;
}
}
spinlock_t timerlist_lock = SPIN_LOCK_UNLOCKED;
void add_timer(struct timer_list *timer)
{
unsigned long flags;
spin_lock_irqsave(&timerlist_lock, flags);
internal_add_timer(timer);
spin_unlock_irqrestore(&timerlist_lock, flags);
}
static inline int detach_timer(struct timer_list *timer)
{
struct timer_list *prev = timer->prev;
if (prev) {
struct timer_list *next = timer->next;
prev->next = next;
if (next)
next->prev = prev;
return 1;
}
return 0;
}
void mod_timer(struct timer_list *timer, unsigned long expires)
{
unsigned long flags;
spin_lock_irqsave(&timerlist_lock, flags);
timer->expires = expires;
detach_timer(timer);
internal_add_timer(timer);
spin_unlock_irqrestore(&timerlist_lock, flags);
}
int del_timer(struct timer_list * timer)
{
int ret;
unsigned long flags;
spin_lock_irqsave(&timerlist_lock, flags);
ret = detach_timer(timer);
timer->next = timer->prev = 0;
spin_unlock_irqrestore(&timerlist_lock, flags);
return ret;
}
#ifdef __SMP__
#define idle_task (task[cpu_number_map[this_cpu]])
#define can_schedule(p) (!(p)->has_cpu)
#else
#define idle_task (&init_task)
#define can_schedule(p) (1)
#endif
/*
* '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)
{
struct task_struct * prev, * next;
unsigned long timeout;
int this_cpu;
prev = current;
this_cpu = prev->processor;
if (in_interrupt())
goto scheduling_in_interrupt;
release_kernel_lock(prev, this_cpu);
/* Do "administrative" work here while we don't hold any locks */
if (bh_active & bh_mask)
do_bottom_half();
run_task_queue(&tq_scheduler);
spin_lock(&scheduler_lock);
spin_lock_irq(&runqueue_lock);
/* move an exhausted RR process to be last.. */
prev->need_resched = 0;
if (!prev->counter && prev->policy == SCHED_RR) {
prev->counter = prev->priority;
move_last_runqueue(prev);
}
timeout = 0;
switch (prev->state) {
case TASK_INTERRUPTIBLE:
if (signal_pending(prev))
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:
}
{
struct task_struct * p = init_task.next_run;
/*
* This is subtle.
* Note how we can enable interrupts here, even
* though interrupts can add processes to the run-
* queue. This is because any new processes will
* be added to the front of the queue, so "p" above
* is a safe starting point.
* run-queue deletion and re-ordering is protected by
* the scheduler lock
*/
spin_unlock_irq(&runqueue_lock);
#ifdef __SMP__
prev->has_cpu = 0;
#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: */
{
int c = -1000;
next = idle_task;
while (p != &init_task) {
if (can_schedule(p)) {
int weight = goodness(p, prev, this_cpu);
if (weight > c)
c = weight, next = p;
}
p = p->next_run;
}
/* Do we need to re-calculate counters? */
if (!c) {
struct task_struct *p;
read_lock(&tasklist_lock);
for_each_task(p)
p->counter = (p->counter >> 1) + p->priority;
read_unlock(&tasklist_lock);
}
}
}
#ifdef __SMP__
next->has_cpu = 1;
next->processor = this_cpu;
#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);
}
spin_unlock(&scheduler_lock);
/*
* At this point "prev" is "current", as we just
* switched into it (from an even more "previous"
* prev)
*/
reacquire_kernel_lock(prev);
return;
scheduling_in_interrupt:
printk("Scheduling in interrupt\n");
*(int *)0 = 0;
}
rwlock_t waitqueue_lock = RW_LOCK_UNLOCKED;
/*
* wake_up doesn't wake up stopped processes - they have to be awakened
* with signals or similar.
*
* Note that we only need a read lock for the wait queue (and thus do not
* have to protect against interrupts), as the actual removal from the
* queue is handled by the process itself.
*/
void __wake_up(struct wait_queue **q, unsigned int mode)
{
struct wait_queue *next;
read_lock(&waitqueue_lock);
if (q && (next = *q)) {
struct wait_queue *head;
head = WAIT_QUEUE_HEAD(q);
while (next != head) {
struct task_struct *p = next->task;
next = next->next;
if (p->state & mode)
wake_up_process(p);
}
}
read_unlock(&waitqueue_lock);
}
/*
* Semaphores are implemented using a two-way counter:
* The "count" variable is decremented for each process
* that tries to sleep, while the "waking" variable is
* incremented when the "up()" code goes to wake up waiting
* processes.
*
* Notably, the inline "up()" and "down()" functions can
* efficiently test if they need to do any extra work (up
* needs to do something only if count was negative before
* the increment operation.
*
* waking_non_zero() (from asm/semaphore.h) must execute
* atomically.
*
* When __up() is called, the count was negative before
* incrementing it, and we need to wake up somebody.
*
* This routine adds one to the count of processes that need to
* wake up and exit. ALL waiting processes actually wake up but
* only the one that gets to the "waking" field first will gate
* through and acquire the semaphore. The others will go back
* to sleep.
*
* Note that these functions are only called when there is
* contention on the lock, and as such all this is the
* "non-critical" part of the whole semaphore business. The
* critical part is the inline stuff in <asm/semaphore.h>
* where we want to avoid any extra jumps and calls.
*/
void __up(struct semaphore *sem)
{
wake_one_more(sem);
wake_up(&sem->wait);
}
/*
* Perform the "down" function. Return zero for semaphore acquired,
* return negative for signalled out of the function.
*
* If called from __down, the return is ignored and the wait loop is
* not interruptible. This means that a task waiting on a semaphore
* using "down()" cannot be killed until someone does an "up()" on
* the semaphore.
*
* If called from __down_interruptible, the return value gets checked
* upon return. If the return value is negative then the task continues
* with the negative value in the return register (it can be tested by
* the caller).
*
* Either form may be used in conjunction with "up()".
*
*/
static inline int __do_down(struct semaphore * sem, int task_state)
{
struct task_struct *tsk = current;
struct wait_queue wait = { tsk, NULL };
int ret = 0;
tsk->state = task_state;
add_wait_queue(&sem->wait, &wait);
/*
* Ok, we're set up. sem->count is known to be less than zero
* so we must wait.
*
* We can let go the lock for purposes of waiting.
* We re-acquire it after awaking so as to protect
* all semaphore operations.
*
* If "up()" is called before we call waking_non_zero() then
* we will catch it right away. If it is called later then
* we will have to go through a wakeup cycle to catch it.
*
* Multiple waiters contend for the semaphore lock to see
* who gets to gate through and who has to wait some more.
*/
for (;;) {
if (waking_non_zero(sem)) /* are we waking up? */
break; /* yes, exit loop */
if (task_state == TASK_INTERRUPTIBLE && signal_pending(tsk)) {
ret = -EINTR; /* interrupted */
atomic_inc(&sem->count); /* give up on down operation */
break;
}
schedule();
tsk->state = task_state;
}
tsk->state = TASK_RUNNING;
remove_wait_queue(&sem->wait, &wait);
return ret;
}
void __down(struct semaphore * sem)
{
__do_down(sem,TASK_UNINTERRUPTIBLE);
}
int __down_interruptible(struct semaphore * sem)
{
return __do_down(sem,TASK_INTERRUPTIBLE);
}
static void FASTCALL(__sleep_on(struct wait_queue **p, int state));
static void __sleep_on(struct wait_queue **p, int state)
{
unsigned long flags;
struct wait_queue wait;
current->state = state;
wait.task = current;
write_lock_irqsave(&waitqueue_lock, flags);
__add_wait_queue(p, &wait);
write_unlock(&waitqueue_lock);
schedule();
write_lock_irq(&waitqueue_lock);
__remove_wait_queue(p, &wait);
write_unlock_irqrestore(&waitqueue_lock, 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);
}
void scheduling_functions_end_here(void) { }
static inline void cascade_timers(struct timer_vec *tv)
{
/* cascade all the timers from tv up one level */
struct timer_list *timer;
timer = tv->vec[tv->index];
/*
* We are removing _all_ timers from the list, so we don't have to
* detach them individually, just clear the list afterwards.
*/
while (timer) {
struct timer_list *tmp = timer;
timer = timer->next;
internal_add_timer(tmp);
}
tv->vec[tv->index] = NULL;
tv->index = (tv->index + 1) & TVN_MASK;
}
static inline void run_timer_list(void)
{
spin_lock_irq(&timerlist_lock);
while ((long)(jiffies - timer_jiffies) >= 0) {
struct timer_list *timer;
if (!tv1.index) {
int n = 1;
do {
cascade_timers(tvecs[n]);
} while (tvecs[n]->index == 1 && ++n < NOOF_TVECS);
}
while ((timer = tv1.vec[tv1.index])) {
void (*fn)(unsigned long) = timer->function;
unsigned long data = timer->data;
detach_timer(timer);
timer->next = timer->prev = NULL;
spin_unlock_irq(&timerlist_lock);
fn(data);
spin_lock_irq(&timerlist_lock);
}
++timer_jiffies;
tv1.index = (tv1.index + 1) & TVR_MASK;
}
spin_unlock_irq(&timerlist_lock);
}
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();
}
}
spinlock_t tqueue_lock;
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;
read_lock(&tasklist_lock);
for_each_task(p) {
if (p->pid &&
(p->state == TASK_RUNNING ||
p->state == TASK_UNINTERRUPTIBLE ||
p->state == TASK_SWAPPING))
nr += FIXED_1;
}
read_unlock(&tasklist_lock);
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 += time_tolerance >> SHIFT_USEC;
if ( time_maxerror > MAXPHASE )
time_maxerror = MAXPHASE;
/*
* 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
}
/* in the NTP reference this is called "hardclock()" */
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;
psecs = (p->times.tms_utime += user);
psecs += (p->times.tms_stime += system);
if (psecs / HZ > p->rlim[RLIMIT_CPU].rlim_cur) {
/* Send SIGXCPU every second.. */
if (!(psecs % HZ))
send_sig(SIGXCPU, p, 1);
/* and SIGKILL when we go over max.. */
if (psecs / HZ > 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;
}
}
void update_one_process(struct task_struct *p,
unsigned long ticks, unsigned long user, unsigned long system, int cpu)
{
p->per_cpu_utime[cpu] += user;
p->per_cpu_stime[cpu] += 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)
{
/*
* SMP does this on a per-CPU basis elsewhere
*/
#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;
p->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, 0);
#endif
}
volatile unsigned long lost_ticks = 0;
static unsigned long lost_ticks_system = 0;
static inline void update_times(void)
{
unsigned long ticks;
unsigned long flags;
save_flags(flags);
cli();
ticks = lost_ticks;
lost_ticks = 0;
if (ticks) {
unsigned long system;
system = xchg(&lost_ticks_system, 0);
calc_load(ticks);
update_wall_time(ticks);
restore_flags(flags);
update_process_times(ticks, system);
} else
restore_flags(flags);
}
static void timer_bh(void)
{
update_times();
run_old_timers();
run_timer_list();
}
void do_timer(struct pt_regs * regs)
{
(*(unsigned long *)&jiffies)++;
lost_ticks++;
mark_bh(TIMER_BH);
if (!user_mode(regs))
lost_ticks_system++;
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;
do_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)
{
/* This is SMP safe - current->pid doesn't change */
return current->pid;
}
/*
* This is not strictly SMP safe: p_opptr could change
* from under us. However, rather than getting any lock
* we can use an optimistic algorithm: get the parent
* pid, and go back and check that the parent is still
* the same. If it has changed (which is extremely unlikely
* indeed), we just try again..
*
* NOTE! This depends on the fact that even if we _do_
* get an old value of "parent", we can happily dereference
* the pointer: we just can't necessarily trust the result
* until we know that the parent pointer is valid.
*
* The "mb()" macro is a memory barrier - a synchronizing
* event. It also makes sure that gcc doesn't optimize
* away the necessary memory references.. The barrier doesn't
* have to have all that strong semantics: on x86 we don't
* really require a synchronizing instruction, for example.
* The barrier is more important for code generation than
* for any real memory ordering semantics (even if there is
* a small window for a race, using the old pointer is
* harmless for a while).
*/
asmlinkage int sys_getppid(void)
{
int pid;
struct task_struct * me = current;
struct task_struct * parent;
parent = me->p_opptr;
for (;;) {
pid = parent->pid;
#if __SMP__
{
struct task_struct *old = parent;
mb();
parent = me->p_opptr;
if (old != parent)
continue;
}
#endif
break;
}
return pid;
}
asmlinkage int sys_getuid(void)
{
/* Only we change this so SMP safe */
return current->uid;
}
asmlinkage int sys_geteuid(void)
{
/* Only we change this so SMP safe */
return current->euid;
}
asmlinkage int sys_getgid(void)
{
/* Only we change this so SMP safe */
return current->gid;
}
asmlinkage int sys_getegid(void)
{
/* Only we change this so SMP safe */
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;
/*
* Setpriority might change our priority at the same moment.
* We don't have to worry. Conceptually one call occurs first
* and we have a single winner.
*/
newprio = increment;
if (increment < 0) {
if (!capable(CAP_SYS_NICE))
return -EPERM;
newprio = -increment;
increase = 1;
}
if (newprio > 40)
newprio = 40;
/*
* do a "normalization" of the priority (traditionally
* Unix nice values are -20 to 20; Linux doesn't really
* use that kind of thing, but uses the length of the
* timeslice instead (default 150 ms). The rounding is
* why we want to avoid negative values.
*/
newprio = (newprio * DEF_PRIORITY + 10) / 20;
increment = newprio;
if (increase)
increment = -increment;
/*
* Current->priority can change between this point
* and the assignment. We are assigning not doing add/subs
* so thats ok. Conceptually a process might just instantaneously
* read the value we stomp over. I don't think that is an issue
* unless posix makes it one. If so we can loop on changes
* to current->priority.
*/
newprio = current->priority - increment;
if ((signed) newprio < 1)
newprio = 1;
if (newprio > DEF_PRIORITY*2)
newprio = DEF_PRIORITY*2;
current->priority = newprio;
return 0;
}
#endif
static inline struct task_struct *find_process_by_pid(pid_t pid)
{
struct task_struct *tsk = current;
if (pid)
tsk = find_task_by_pid(pid);
return tsk;
}
static int setscheduler(pid_t pid, int policy,
struct sched_param *param)
{
struct sched_param lp;
struct task_struct *p;
int retval;
retval = -EINVAL;
if (!param || pid < 0)
goto out_nounlock;
retval = -EFAULT;
if (copy_from_user(&lp, param, sizeof(struct sched_param)))
goto out_nounlock;
/*
* We play safe to avoid deadlocks.
*/
spin_lock(&scheduler_lock);
spin_lock_irq(&runqueue_lock);
read_lock(&tasklist_lock);
p = find_process_by_pid(pid);
retval = -ESRCH;
if (!p)
goto out_unlock;
if (policy < 0)
policy = p->policy;
else {
retval = -EINVAL;
if (policy != SCHED_FIFO && policy != SCHED_RR &&
policy != SCHED_OTHER)
goto out_unlock;
}
/*
* Valid priorities for SCHED_FIFO and SCHED_RR are 1..99, valid
* priority for SCHED_OTHER is 0.
*/
retval = -EINVAL;
if (lp.sched_priority < 0 || lp.sched_priority > 99)
goto out_unlock;
if ((policy == SCHED_OTHER) != (lp.sched_priority == 0))
goto out_unlock;
retval = -EPERM;
if ((policy == SCHED_FIFO || policy == SCHED_RR) &&
!capable(CAP_SYS_NICE))
goto out_unlock;
if ((current->euid != p->euid) && (current->euid != p->uid) &&
!capable(CAP_SYS_NICE))
goto out_unlock;
retval = 0;
p->policy = policy;
p->rt_priority = lp.sched_priority;
if (p->next_run)
move_first_runqueue(p);
current->need_resched = 1;
out_unlock:
read_unlock(&tasklist_lock);
spin_unlock_irq(&runqueue_lock);
spin_unlock(&scheduler_lock);
out_nounlock:
return retval;
}
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;
int retval;
retval = -EINVAL;
if (pid < 0)
goto out_nounlock;
read_lock(&tasklist_lock);
retval = -ESRCH;
p = find_process_by_pid(pid);
if (!p)
goto out_unlock;
retval = p->policy;
out_unlock:
read_unlock(&tasklist_lock);
out_nounlock:
return retval;
}
asmlinkage int sys_sched_getparam(pid_t pid, struct sched_param *param)
{
struct task_struct *p;
struct sched_param lp;
int retval;
retval = -EINVAL;
if (!param || pid < 0)
goto out_nounlock;
read_lock(&tasklist_lock);
p = find_process_by_pid(pid);
retval = -ESRCH;
if (!p)
goto out_unlock;
lp.sched_priority = p->rt_priority;
read_unlock(&tasklist_lock);
/*
* This one might sleep, we cannot do it with a spinlock held ...
*/
retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
out_nounlock:
return retval;
out_unlock:
read_unlock(&tasklist_lock);
return retval;
}
asmlinkage int sys_sched_yield(void)
{
spin_lock(&scheduler_lock);
spin_lock_irq(&runqueue_lock);
current->policy |= SCHED_YIELD;
current->need_resched = 1;
move_last_runqueue(current);
spin_unlock_irq(&runqueue_lock);
spin_unlock(&scheduler_lock);
return 0;
}
asmlinkage int sys_sched_get_priority_max(int policy)
{
int ret = -EINVAL;
switch (policy) {
case SCHED_FIFO:
case SCHED_RR:
ret = 99;
break;
case SCHED_OTHER:
ret = 0;
break;
}
return ret;
}
asmlinkage int sys_sched_get_priority_min(int policy)
{
int ret = -EINVAL;
switch (policy) {
case SCHED_FIFO:
case SCHED_RR:
ret = 1;
break;
case SCHED_OTHER:
ret = 0;
}
return ret;
}
asmlinkage int sys_sched_rr_get_interval(pid_t pid, struct timespec *interval)
{
struct timespec t;
t.tv_sec = 0;
t.tv_nsec = 150000;
if (copy_to_user(interval, &t, sizeof(struct timespec)))
return -EFAULT;
return 0;
}
asmlinkage int sys_nanosleep(struct timespec *rqtp, struct timespec *rmtp)
{
struct timespec t;
unsigned long expire;
if(copy_from_user(&t, rqtp, sizeof(struct timespec)))
return -EFAULT;
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.
*
* Its important on SMP not to do this holding locks.
*/
udelay((t.tv_nsec + 999) / 1000);
return 0;
}
expire = timespec_to_jiffies(&t) + (t.tv_sec || t.tv_nsec) + jiffies;
current->timeout = expire;
current->state = TASK_INTERRUPTIBLE;
schedule();
if (expire > jiffies) {
if (rmtp) {
jiffies_to_timespec(expire - jiffies -
(expire > jiffies + 1), &t);
if (copy_to_user(rmtp, &t, sizeof(struct timespec)))
return -EFAULT;
}
return -EINTR;
}
return 0;
}
static void show_task(int nr,struct task_struct * p)
{
unsigned long free = 0;
int state;
static const char * stat_nam[] = { "R", "S", "D", "Z", "T", "W" };
printk("%-8s %3d ", p->comm, (p == current) ? -nr : nr);
state = p->state ? ffz(~p->state) + 1 : 0;
if (((unsigned) state) < sizeof(stat_nam)/sizeof(char *))
printk(stat_nam[state]);
else
printk(" ");
#if (BITS_PER_LONG == 32)
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
{
unsigned long * n = (unsigned long *) (p+1);
while (!*n)
n++;
free = (unsigned long) n - (unsigned long)(p+1);
}
printk("%5lu %5d %6d ", free, 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");
{
struct signal_queue *q;
char s[sizeof(sigset_t)*2+1], b[sizeof(sigset_t)*2+1];
render_sigset_t(&p->signal, s);
render_sigset_t(&p->blocked, b);
printk(" sig: %d %s %s :", signal_pending(p), s, b);
for (q = p->sigqueue; q ; q = q->next)
printk(" %d", q->info.si_signo);
printk(" X\n");
}
}
char * render_sigset_t(sigset_t *set, char *buffer)
{
int i = _NSIG, x;
do {
i -= 4, x = 0;
if (sigismember(set, i+1)) x |= 1;
if (sigismember(set, i+2)) x |= 2;
if (sigismember(set, i+3)) x |= 4;
if (sigismember(set, i+4)) x |= 8;
*buffer++ = (x < 10 ? '0' : 'a' - 10) + x;
} while (i >= 4);
*buffer = 0;
return buffer;
}
void show_state(void)
{
struct task_struct *p;
#if (BITS_PER_LONG == 32)
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
read_lock(&tasklist_lock);
for_each_task(p)
show_task((p->tarray_ptr - &task[0]),p);
read_unlock(&tasklist_lock);
}
void __init sched_init(void)
{
/*
* We have to do a little magic to get the first
* process right in SMP mode.
*/
int cpu=hard_smp_processor_id();
int nr = NR_TASKS;
init_task.processor=cpu;
/* Init task array free list and pidhash table. */
while(--nr > 0)
add_free_taskslot(&task[nr]);
for(nr = 0; nr < PIDHASH_SZ; nr++)
pidhash[nr] = NULL;
init_bh(TIMER_BH, timer_bh);
init_bh(TQUEUE_BH, tqueue_bh);
init_bh(IMMEDIATE_BH, immediate_bh);
}