kernel/sched.c

/* */
This source file includes following definitions.
math_state_restore
math_emulate
schedule
sys_pause
wake_up
wake_up_interruptible
__down
__sleep_on
interruptible_sleep_on
sleep_on
add_timer
del_timer
count_active_tasks
calc_load
second_overflow
timer_bh
tqueue_bh
do_timer
sys_alarm
sys_getpid
sys_getppid
sys_getuid
sys_geteuid
sys_getgid
sys_getegid
sys_nice
show_task
show_state
sched_init
   1 /*
   2  *  linux/kernel/sched.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6 
   7 /*
   8  * 'sched.c' is the main kernel file. It contains scheduling primitives
   9  * (sleep_on, wakeup, schedule etc) as well as a number of simple system
  10  * call functions (type getpid(), which just extracts a field from
  11  * current-task
  12  */
  13 
  14 #include <linux/config.h>
  15 #include <linux/signal.h>
  16 #include <linux/sched.h>
  17 #include <linux/timer.h>
  18 #include <linux/kernel.h>
  19 #include <linux/kernel_stat.h>
  20 #include <linux/fdreg.h>
  21 #include <linux/errno.h>
  22 #include <linux/time.h>
  23 #include <linux/ptrace.h>
  24 #include <linux/segment.h>
  25 #include <linux/delay.h>
  26 #include <linux/interrupt.h>
  27 #include <linux/tqueue.h>
  28 
  29 #include <asm/system.h>
  30 #include <asm/io.h>
  31 #include <asm/segment.h>
  32 
  33 #define TIMER_IRQ 0
  34 
  35 #include <linux/timex.h>
  36 
  37 /*
  38  * kernel variables
  39  */
  40 long tick = 1000000 / HZ;               /* timer interrupt period */
  41 volatile struct timeval xtime;          /* The current time */
  42 int tickadj = 500/HZ;                   /* microsecs */
  43 
  44 DECLARE_TASK_QUEUE(tq_timer);
  45 
  46 /*
  47  * phase-lock loop variables
  48  */
  49 int time_status = TIME_BAD;     /* clock synchronization status */
  50 long time_offset = 0;           /* time adjustment (us) */
  51 long time_constant = 0;         /* pll time constant */
  52 long time_tolerance = MAXFREQ;  /* frequency tolerance (ppm) */
  53 long time_precision = 1;        /* clock precision (us) */
  54 long time_maxerror = 0x70000000;/* maximum error */
  55 long time_esterror = 0x70000000;/* estimated error */
  56 long time_phase = 0;            /* phase offset (scaled us) */
  57 long time_freq = 0;             /* frequency offset (scaled ppm) */
  58 long time_adj = 0;              /* tick adjust (scaled 1 / HZ) */
  59 long time_reftime = 0;          /* time at last adjustment (s) */
  60 
  61 long time_adjust = 0;
  62 long time_adjust_step = 0;
  63 
  64 int need_resched = 0;
  65 unsigned long event = 0;
  66 
  67 /*
  68  * Tell us the machine setup..
  69  */
  70 int hard_math = 0;              /* set by boot/head.S */
  71 int x86 = 0;                    /* set by boot/head.S to 3 or 4 */
  72 int ignore_irq13 = 0;           /* set if exception 16 works */
  73 int wp_works_ok = 0;            /* set if paging hardware honours WP */ 
  74 
  75 /*
  76  * Bus types ..
  77  */
  78 int EISA_bus = 0;
  79 
  80 extern int _setitimer(int, struct itimerval *, struct itimerval *);
  81 unsigned long * prof_buffer = NULL;
  82 unsigned long prof_len = 0;
  83 
  84 #define _S(nr) (1<<((nr)-1))
  85 
  86 extern void mem_use(void);
  87 
  88 extern int timer_interrupt(void);
  89 asmlinkage int system_call(void);
  90 
  91 static unsigned long init_kernel_stack[1024] = { STACK_MAGIC, };
  92 struct task_struct init_task = INIT_TASK;
  93 
  94 unsigned long volatile jiffies=0;
  95 
  96 struct task_struct *current = &init_task;
  97 struct task_struct *last_task_used_math = NULL;
  98 
  99 struct task_struct * task[NR_TASKS] = {&init_task, };
 100 
 101 long user_stack [ PAGE_SIZE>>2 ] = { STACK_MAGIC, };
 102 
 103 struct {
 104         long * a;
 105         short b;
 106         } stack_start = { & user_stack [PAGE_SIZE>>2] , KERNEL_DS };
 107 
 108 struct kernel_stat kstat = { 0 };
 109 
 110 /*
 111  *  'math_state_restore()' saves the current math information in the
 112  * old math state array, and gets the new ones from the current task
 113  *
 114  * Careful.. There are problems with IBM-designed IRQ13 behaviour.
 115  * Don't touch unless you *really* know how it works.
 116  */
 117 asmlinkage void math_state_restore(void)
     /*  */
 118 {
 119         __asm__ __volatile__("clts");
 120         if (last_task_used_math == current)
 121                 return;
 122         timer_table[COPRO_TIMER].expires = jiffies+50;
 123         timer_active |= 1<<COPRO_TIMER; 
 124         if (last_task_used_math)
 125                 __asm__("fnsave %0":"=m" (last_task_used_math->tss.i387));
 126         else
 127                 __asm__("fnclex");
 128         last_task_used_math = current;
 129         if (current->used_math) {
 130                 __asm__("frstor %0": :"m" (current->tss.i387));
 131         } else {
 132                 __asm__("fninit");
 133                 current->used_math=1;
 134         }
 135         timer_active &= ~(1<<COPRO_TIMER);
 136 }
 137 
 138 #ifndef CONFIG_MATH_EMULATION
 139 
 140 asmlinkage void math_emulate(long arg)
     /*  */
 141 {
 142   printk("math-emulation not enabled and no coprocessor found.\n");
 143   printk("killing %s.\n",current->comm);
 144   send_sig(SIGFPE,current,1);
 145   schedule();
 146 }
 147 
 148 #endif /* CONFIG_MATH_EMULATION */
 149 
 150 unsigned long itimer_ticks = 0;
 151 unsigned long itimer_next = ~0;
 152 
 153 /*
 154  *  'schedule()' is the scheduler function. It's a very simple and nice
 155  * scheduler: it's not perfect, but certainly works for most things.
 156  * The one thing you might take a look at is the signal-handler code here.
 157  *
 158  *   NOTE!!  Task 0 is the 'idle' task, which gets called when no other
 159  * tasks can run. It can not be killed, and it cannot sleep. The 'state'
 160  * information in task[0] is never used.
 161  *
 162  * The "confuse_gcc" goto is used only to get better assembly code..
 163  * Djikstra probably hates me.
 164  */
 165 asmlinkage void schedule(void)
     /*  */
 166 {
 167         int c;
 168         struct task_struct * p;
 169         struct task_struct * next;
 170         unsigned long ticks;
 171 
 172 /* check alarm, wake up any interruptible tasks that have got a signal */
 173 
 174         if (intr_count) {
 175                 printk("Aiee: scheduling in interrupt\n");
 176                 intr_count = 0;
 177         }
 178         cli();
 179         ticks = itimer_ticks;
 180         itimer_ticks = 0;
 181         itimer_next = ~0;
 182         sti();
 183         need_resched = 0;
 184         p = &init_task;
 185         for (;;) {
 186                 if ((p = p->next_task) == &init_task)
 187                         goto confuse_gcc1;
 188                 if (ticks && p->it_real_value) {
 189                         if (p->it_real_value <= ticks) {
 190                                 send_sig(SIGALRM, p, 1);
 191                                 if (!p->it_real_incr) {
 192                                         p->it_real_value = 0;
 193                                         goto end_itimer;
 194                                 }
 195                                 do {
 196                                         p->it_real_value += p->it_real_incr;
 197                                 } while (p->it_real_value <= ticks);
 198                         }
 199                         p->it_real_value -= ticks;
 200                         if (p->it_real_value < itimer_next)
 201                                 itimer_next = p->it_real_value;
 202                 }
 203 end_itimer:
 204                 if (p->state != TASK_INTERRUPTIBLE)
 205                         continue;
 206                 if (p->signal & ~p->blocked) {
 207                         p->state = TASK_RUNNING;
 208                         continue;
 209                 }
 210                 if (p->timeout && p->timeout <= jiffies) {
 211                         p->timeout = 0;
 212                         p->state = TASK_RUNNING;
 213                 }
 214         }
 215 confuse_gcc1:
 216 
 217 /* this is the scheduler proper: */
 218 #if 0
 219         /* give processes that go to sleep a bit higher priority.. */
 220         /* This depends on the values for TASK_XXX */
 221         /* This gives smoother scheduling for some things, but */
 222         /* can be very unfair under some circumstances, so.. */
 223         if (TASK_UNINTERRUPTIBLE >= (unsigned) current->state &&
 224             current->counter < current->priority*2) {
 225                 ++current->counter;
 226         }
 227 #endif
 228         c = -1000;
 229         next = p = &init_task;
 230         for (;;) {
 231                 if ((p = p->next_task) == &init_task)
 232                         goto confuse_gcc2;
 233                 if (p->state == TASK_RUNNING && p->counter > c)
 234                         c = p->counter, next = p;
 235         }
 236 confuse_gcc2:
 237         if (!c) {
 238                 for_each_task(p)
 239                         p->counter = (p->counter >> 1) + p->priority;
 240         }
 241         if (current == next)
 242                 return;
 243         kstat.context_swtch++;
 244         switch_to(next);
 245         /* Now maybe reload the debug registers */
 246         if(current->debugreg[7]){
 247                 loaddebug(0);
 248                 loaddebug(1);
 249                 loaddebug(2);
 250                 loaddebug(3);
 251                 loaddebug(6);
 252         };
 253 }
 254 
 255 asmlinkage int sys_pause(void)
     /*  */
 256 {
 257         current->state = TASK_INTERRUPTIBLE;
 258         schedule();
 259         return -ERESTARTNOHAND;
 260 }
 261 
 262 /*
 263  * wake_up doesn't wake up stopped processes - they have to be awakened
 264  * with signals or similar.
 265  *
 266  * Note that this doesn't need cli-sti pairs: interrupts may not change
 267  * the wait-queue structures directly, but only call wake_up() to wake
 268  * a process. The process itself must remove the queue once it has woken.
 269  */
 270 void wake_up(struct wait_queue **q)
     /*  */
 271 {
 272         struct wait_queue *tmp;
 273         struct task_struct * p;
 274 
 275         if (!q || !(tmp = *q))
 276                 return;
 277         do {
 278                 if ((p = tmp->task) != NULL) {
 279                         if ((p->state == TASK_UNINTERRUPTIBLE) ||
 280                             (p->state == TASK_INTERRUPTIBLE)) {
 281                                 p->state = TASK_RUNNING;
 282                                 if (p->counter > current->counter + 3)
 283                                         need_resched = 1;
 284                         }
 285                 }
 286                 if (!tmp->next) {
 287                         printk("wait_queue is bad (eip = %08lx)\n",((unsigned long *) q)[-1]);
 288                         printk("        q = %p\n",q);
 289                         printk("       *q = %p\n",*q);
 290                         printk("      tmp = %p\n",tmp);
 291                         break;
 292                 }
 293                 tmp = tmp->next;
 294         } while (tmp != *q);
 295 }
 296 
 297 void wake_up_interruptible(struct wait_queue **q)
     /*  */
 298 {
 299         struct wait_queue *tmp;
 300         struct task_struct * p;
 301 
 302         if (!q || !(tmp = *q))
 303                 return;
 304         do {
 305                 if ((p = tmp->task) != NULL) {
 306                         if (p->state == TASK_INTERRUPTIBLE) {
 307                                 p->state = TASK_RUNNING;
 308                                 if (p->counter > current->counter + 3)
 309                                         need_resched = 1;
 310                         }
 311                 }
 312                 if (!tmp->next) {
 313                         printk("wait_queue is bad (eip = %08lx)\n",((unsigned long *) q)[-1]);
 314                         printk("        q = %p\n",q);
 315                         printk("       *q = %p\n",*q);
 316                         printk("      tmp = %p\n",tmp);
 317                         break;
 318                 }
 319                 tmp = tmp->next;
 320         } while (tmp != *q);
 321 }
 322 
 323 void __down(struct semaphore * sem)
     /*  */
 324 {
 325         struct wait_queue wait = { current, NULL };
 326         add_wait_queue(&sem->wait, &wait);
 327         current->state = TASK_UNINTERRUPTIBLE;
 328         while (sem->count <= 0) {
 329                 schedule();
 330                 current->state = TASK_UNINTERRUPTIBLE;
 331         }
 332         current->state = TASK_RUNNING;
 333         remove_wait_queue(&sem->wait, &wait);
 334 }
 335 
 336 static inline void __sleep_on(struct wait_queue **p, int state)
     /*  */
 337 {
 338         unsigned long flags;
 339         struct wait_queue wait = { current, NULL };
 340 
 341         if (!p)
 342                 return;
 343         if (current == task[0])
 344                 panic("task[0] trying to sleep");
 345         current->state = state;
 346         add_wait_queue(p, &wait);
 347         save_flags(flags);
 348         sti();
 349         schedule();
 350         remove_wait_queue(p, &wait);
 351         restore_flags(flags);
 352 }
 353 
 354 void interruptible_sleep_on(struct wait_queue **p)
     /*  */
 355 {
 356         __sleep_on(p,TASK_INTERRUPTIBLE);
 357 }
 358 
 359 void sleep_on(struct wait_queue **p)
     /*  */
 360 {
 361         __sleep_on(p,TASK_UNINTERRUPTIBLE);
 362 }
 363 
 364 /*
 365  * The head for the timer-list has a "expires" field of MAX_UINT,
 366  * and the sorting routine counts on this..
 367  */
 368 static struct timer_list timer_head = { &timer_head, &timer_head, ~0, 0, NULL };
 369 #define SLOW_BUT_DEBUGGING_TIMERS 1
 370 
 371 void add_timer(struct timer_list * timer)
     /*  */
 372 {
 373         unsigned long flags;
 374         struct timer_list *p;
 375 
 376 #if SLOW_BUT_DEBUGGING_TIMERS
 377         if (timer->next || timer->prev) {
 378                 printk("add_timer() called with non-zero list from %08lx\n",
 379                         ((unsigned long *) &timer)[-1]);
 380                 return;
 381         }
 382 #endif
 383         p = &timer_head;
 384         timer->expires += jiffies;
 385         save_flags(flags);
 386         cli();
 387         do {
 388                 p = p->next;
 389         } while (timer->expires > p->expires);
 390         timer->next = p;
 391         timer->prev = p->prev;
 392         p->prev = timer;
 393         timer->prev->next = timer;
 394         restore_flags(flags);
 395 }
 396 
 397 int del_timer(struct timer_list * timer)
     /*  */
 398 {
 399         unsigned long flags;
 400 #if SLOW_BUT_DEBUGGING_TIMERS
 401         struct timer_list * p;
 402 
 403         p = &timer_head;
 404         save_flags(flags);
 405         cli();
 406         while ((p = p->next) != &timer_head) {
 407                 if (p == timer) {
 408                         timer->next->prev = timer->prev;
 409                         timer->prev->next = timer->next;
 410                         timer->next = timer->prev = NULL;
 411                         restore_flags(flags);
 412                         timer->expires -= jiffies;
 413                         return 1;
 414                 }
 415         }
 416         if (timer->next || timer->prev)
 417                 printk("del_timer() called from %08lx with timer not initialized\n",
 418                         ((unsigned long *) &timer)[-1]);
 419         restore_flags(flags);
 420         return 0;
 421 #else   
 422         save_flags(flags);
 423         cli();
 424         if (timer->next) {
 425                 timer->next->prev = timer->prev;
 426                 timer->prev->next = timer->next;
 427                 timer->next = timer->prev = NULL;
 428                 restore_flags(flags);
 429                 timer->expires -= jiffies;
 430                 return 1;
 431         }
 432         restore_flags(flags);
 433         return 0;
 434 #endif
 435 }
 436 
 437 unsigned long timer_active = 0;
 438 struct timer_struct timer_table[32];
 439 
 440 /*
 441  * Hmm.. Changed this, as the GNU make sources (load.c) seems to
 442  * imply that avenrun[] is the standard name for this kind of thing.
 443  * Nothing else seems to be standardized: the fractional size etc
 444  * all seem to differ on different machines.
 445  */
 446 unsigned long avenrun[3] = { 0,0,0 };
 447 
 448 /*
 449  * Nr of active tasks - counted in fixed-point numbers
 450  */
 451 static unsigned long count_active_tasks(void)
     /*  */
 452 {
 453         struct task_struct **p;
 454         unsigned long nr = 0;
 455 
 456         for(p = &LAST_TASK; p > &FIRST_TASK; --p)
 457                 if (*p && ((*p)->state == TASK_RUNNING ||
 458                            (*p)->state == TASK_UNINTERRUPTIBLE ||
 459                            (*p)->state == TASK_SWAPPING))
 460                         nr += FIXED_1;
 461         return nr;
 462 }
 463 
 464 static inline void calc_load(void)
     /*  */
 465 {
 466         unsigned long active_tasks; /* fixed-point */
 467         static int count = LOAD_FREQ;
 468 
 469         if (count-- > 0)
 470                 return;
 471         count = LOAD_FREQ;
 472         active_tasks = count_active_tasks();
 473         CALC_LOAD(avenrun[0], EXP_1, active_tasks);
 474         CALC_LOAD(avenrun[1], EXP_5, active_tasks);
 475         CALC_LOAD(avenrun[2], EXP_15, active_tasks);
 476 }
 477 
 478 /*
 479  * this routine handles the overflow of the microsecond field
 480  *
 481  * The tricky bits of code to handle the accurate clock support
 482  * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
 483  * They were originally developed for SUN and DEC kernels.
 484  * All the kudos should go to Dave for this stuff.
 485  *
 486  * These were ported to Linux by Philip Gladstone.
 487  */
 488 static void second_overflow(void)
     /*  */
 489 {
 490         long ltemp;
 491         /* last time the cmos clock got updated */
 492         static long last_rtc_update=0;
 493         extern int set_rtc_mmss(unsigned long);
 494 
 495         /* Bump the maxerror field */
 496         time_maxerror = (0x70000000-time_maxerror < time_tolerance) ?
 497           0x70000000 : (time_maxerror + time_tolerance);
 498 
 499         /* Run the PLL */
 500         if (time_offset < 0) {
 501                 ltemp = (-(time_offset+1) >> (SHIFT_KG + time_constant)) + 1;
 502                 time_adj = ltemp << (SHIFT_SCALE - SHIFT_HZ - SHIFT_UPDATE);
 503                 time_offset += (time_adj * HZ) >> (SHIFT_SCALE - SHIFT_UPDATE);
 504                 time_adj = - time_adj;
 505         } else if (time_offset > 0) {
 506                 ltemp = ((time_offset-1) >> (SHIFT_KG + time_constant)) + 1;
 507                 time_adj = ltemp << (SHIFT_SCALE - SHIFT_HZ - SHIFT_UPDATE);
 508                 time_offset -= (time_adj * HZ) >> (SHIFT_SCALE - SHIFT_UPDATE);
 509         } else {
 510                 time_adj = 0;
 511         }
 512 
 513         time_adj += (time_freq >> (SHIFT_KF + SHIFT_HZ - SHIFT_SCALE))
 514             + FINETUNE;
 515 
 516         /* Handle the leap second stuff */
 517         switch (time_status) {
 518                 case TIME_INS:
 519                 /* ugly divide should be replaced */
 520                 if (xtime.tv_sec % 86400 == 0) {
 521                         xtime.tv_sec--; /* !! */
 522                         time_status = TIME_OOP;
 523                         printk("Clock: inserting leap second 23:59:60 GMT\n");
 524                 }
 525                 break;
 526 
 527                 case TIME_DEL:
 528                 /* ugly divide should be replaced */
 529                 if (xtime.tv_sec % 86400 == 86399) {
 530                         xtime.tv_sec++;
 531                         time_status = TIME_OK;
 532                         printk("Clock: deleting leap second 23:59:59 GMT\n");
 533                 }
 534                 break;
 535 
 536                 case TIME_OOP:
 537                 time_status = TIME_OK;
 538                 break;
 539         }
 540         if (xtime.tv_sec > last_rtc_update + 660)
 541           if (set_rtc_mmss(xtime.tv_sec) == 0)
 542             last_rtc_update = xtime.tv_sec;
 543           else
 544             last_rtc_update = xtime.tv_sec - 600; /* do it again in one min */
 545 }
 546 
 547 /*
 548  * disregard lost ticks for now.. We don't care enough.
 549  */
 550 static void timer_bh(void * unused)
     /*  */
 551 {
 552         unsigned long mask;
 553         struct timer_struct *tp;
 554         struct timer_list * timer;
 555 
 556         cli();
 557         while ((timer = timer_head.next) != &timer_head && timer->expires < jiffies) {
 558                 void (*fn)(unsigned long) = timer->function;
 559                 unsigned long data = timer->data;
 560                 timer->next->prev = timer->prev;
 561                 timer->prev->next = timer->next;
 562                 timer->next = timer->prev = NULL;
 563                 sti();
 564                 fn(data);
 565                 cli();
 566         }
 567         sti();
 568         
 569         for (mask = 1, tp = timer_table+0 ; mask ; tp++,mask += mask) {
 570                 if (mask > timer_active)
 571                         break;
 572                 if (!(mask & timer_active))
 573                         continue;
 574                 if (tp->expires > jiffies)
 575                         continue;
 576                 timer_active &= ~mask;
 577                 tp->fn();
 578                 sti();
 579         }
 580 }
 581 
 582 void tqueue_bh(void * unused)
     /*  */
 583 {
 584         run_task_queue(&tq_timer);
 585 }
 586 
 587 /*
 588  * The int argument is really a (struct pt_regs *), in case the
 589  * interrupt wants to know from where it was called. The timer
 590  * irq uses this to decide if it should update the user or system
 591  * times.
 592  */
 593 static void do_timer(struct pt_regs * regs)
     /*  */
 594 {
 595         unsigned long mask;
 596         struct timer_struct *tp;
 597 
 598         long ltemp;
 599 
 600         /* Advance the phase, once it gets to one microsecond, then
 601          * advance the tick more.
 602          */
 603         time_phase += time_adj;
 604         if (time_phase < -FINEUSEC) {
 605                 ltemp = -time_phase >> SHIFT_SCALE;
 606                 time_phase += ltemp << SHIFT_SCALE;
 607                 xtime.tv_usec += tick + time_adjust_step - ltemp;
 608         }
 609         else if (time_phase > FINEUSEC) {
 610                 ltemp = time_phase >> SHIFT_SCALE;
 611                 time_phase -= ltemp << SHIFT_SCALE;
 612                 xtime.tv_usec += tick + time_adjust_step + ltemp;
 613         } else
 614                 xtime.tv_usec += tick + time_adjust_step;
 615 
 616         if (time_adjust)
 617         {
 618             /* We are doing an adjtime thing. 
 619              *
 620              * Modify the value of the tick for next time.
 621              * Note that a positive delta means we want the clock
 622              * to run fast. This means that the tick should be bigger
 623              *
 624              * Limit the amount of the step for *next* tick to be
 625              * in the range -tickadj .. +tickadj
 626              */
 627              if (time_adjust > tickadj)
 628                time_adjust_step = tickadj;
 629              else if (time_adjust < -tickadj)
 630                time_adjust_step = -tickadj;
 631              else
 632                time_adjust_step = time_adjust;
 633              
 634             /* Reduce by this step the amount of time left  */
 635             time_adjust -= time_adjust_step;
 636         }
 637         else
 638             time_adjust_step = 0;
 639 
 640         if (xtime.tv_usec >= 1000000) {
 641             xtime.tv_usec -= 1000000;
 642             xtime.tv_sec++;
 643             second_overflow();
 644         }
 645 
 646         jiffies++;
 647         calc_load();
 648         if ((VM_MASK & regs->eflags) || (3 & regs->cs)) {
 649                 current->utime++;
 650                 if (current != task[0]) {
 651                         if (current->priority < 15)
 652                                 kstat.cpu_nice++;
 653                         else
 654                                 kstat.cpu_user++;
 655                 }
 656                 /* Update ITIMER_VIRT for current task if not in a system call */
 657                 if (current->it_virt_value && !(--current->it_virt_value)) {
 658                         current->it_virt_value = current->it_virt_incr;
 659                         send_sig(SIGVTALRM,current,1);
 660                 }
 661         } else {
 662                 current->stime++;
 663                 if(current != task[0])
 664                         kstat.cpu_system++;
 665 #ifdef CONFIG_PROFILE
 666                 if (prof_buffer && current != task[0]) {
 667                         unsigned long eip = regs->eip;
 668                         eip >>= 2;
 669                         if (eip < prof_len)
 670                                 prof_buffer[eip]++;
 671                 }
 672 #endif
 673         }
 674         if (current != task[0] && 0 > --current->counter) {
 675                 current->counter = 0;
 676                 need_resched = 1;
 677         }
 678         /* Update ITIMER_PROF for the current task */
 679         if (current->it_prof_value && !(--current->it_prof_value)) {
 680                 current->it_prof_value = current->it_prof_incr;
 681                 send_sig(SIGPROF,current,1);
 682         }
 683         for (mask = 1, tp = timer_table+0 ; mask ; tp++,mask += mask) {
 684                 if (mask > timer_active)
 685                         break;
 686                 if (!(mask & timer_active))
 687                         continue;
 688                 if (tp->expires > jiffies)
 689                         continue;
 690                 mark_bh(TIMER_BH);
 691         }
 692         cli();
 693         itimer_ticks++;
 694         if (itimer_ticks > itimer_next)
 695                 need_resched = 1;
 696         if (timer_head.next->expires < jiffies)
 697                 mark_bh(TIMER_BH);
 698         if (tq_timer != &tq_last)
 699                 mark_bh(TQUEUE_BH);
 700         sti();
 701 }
 702 
 703 asmlinkage int sys_alarm(long seconds)
     /*  */
 704 {
 705         struct itimerval it_new, it_old;
 706 
 707         it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
 708         it_new.it_value.tv_sec = seconds;
 709         it_new.it_value.tv_usec = 0;
 710         _setitimer(ITIMER_REAL, &it_new, &it_old);
 711         return(it_old.it_value.tv_sec + (it_old.it_value.tv_usec / 1000000));
 712 }
 713 
 714 asmlinkage int sys_getpid(void)
     /*  */
 715 {
 716         return current->pid;
 717 }
 718 
 719 asmlinkage int sys_getppid(void)
     /*  */
 720 {
 721         return current->p_opptr->pid;
 722 }
 723 
 724 asmlinkage int sys_getuid(void)
     /*  */
 725 {
 726         return current->uid;
 727 }
 728 
 729 asmlinkage int sys_geteuid(void)
     /*  */
 730 {
 731         return current->euid;
 732 }
 733 
 734 asmlinkage int sys_getgid(void)
     /*  */
 735 {
 736         return current->gid;
 737 }
 738 
 739 asmlinkage int sys_getegid(void)
     /*  */
 740 {
 741         return current->egid;
 742 }
 743 
 744 asmlinkage int sys_nice(long increment)
     /*  */
 745 {
 746         int newprio;
 747 
 748         if (increment < 0 && !suser())
 749                 return -EPERM;
 750         newprio = current->priority - increment;
 751         if (newprio < 1)
 752                 newprio = 1;
 753         if (newprio > 35)
 754                 newprio = 35;
 755         current->priority = newprio;
 756         return 0;
 757 }
 758 
 759 static void show_task(int nr,struct task_struct * p)
     /*  */
 760 {
 761         unsigned long free;
 762         static char * stat_nam[] = { "R", "S", "D", "Z", "T", "W" };
 763 
 764         printk("%-8s %3d ", p->comm, (p == current) ? -nr : nr);
 765         if (((unsigned) p->state) < sizeof(stat_nam)/sizeof(char *))
 766                 printk(stat_nam[p->state]);
 767         else
 768                 printk(" ");
 769         if (p == current)
 770                 printk(" current  ");
 771         else
 772                 printk(" %08lX ", ((unsigned long *)p->tss.esp)[3]);
 773         for (free = 1; free < 1024 ; free++) {
 774                 if (((unsigned long *)p->kernel_stack_page)[free])
 775                         break;
 776         }
 777         printk("%5lu %5d %6d ", free << 2, p->pid, p->p_pptr->pid);
 778         if (p->p_cptr)
 779                 printk("%5d ", p->p_cptr->pid);
 780         else
 781                 printk("      ");
 782         if (p->p_ysptr)
 783                 printk("%7d", p->p_ysptr->pid);
 784         else
 785                 printk("       ");
 786         if (p->p_osptr)
 787                 printk(" %5d\n", p->p_osptr->pid);
 788         else
 789                 printk("\n");
 790 }
 791 
 792 void show_state(void)
     /*  */
 793 {
 794         int i;
 795 
 796         printk("                         free                        sibling\n");
 797         printk("  task             PC    stack   pid father child younger older\n");
 798         for (i=0 ; i<NR_TASKS ; i++)
 799                 if (task[i])
 800                         show_task(i,task[i]);
 801 }
 802 
 803 void sched_init(void)
     /*  */
 804 {
 805         int i;
 806         struct desc_struct * p;
 807 
 808         bh_base[TIMER_BH].routine = timer_bh;
 809         bh_base[TQUEUE_BH].routine = tqueue_bh;
 810         if (sizeof(struct sigaction) != 16)
 811                 panic("Struct sigaction MUST be 16 bytes");
 812         set_tss_desc(gdt+FIRST_TSS_ENTRY,&init_task.tss);
 813         set_ldt_desc(gdt+FIRST_LDT_ENTRY,&default_ldt,1);
 814         set_system_gate(0x80,&system_call);
 815         p = gdt+2+FIRST_TSS_ENTRY;
 816         for(i=1 ; i<NR_TASKS ; i++) {
 817                 task[i] = NULL;
 818                 p->a=p->b=0;
 819                 p++;
 820                 p->a=p->b=0;
 821                 p++;
 822         }
 823 /* Clear NT, so that we won't have troubles with that later on */
 824         __asm__("pushfl ; andl $0xffffbfff,(%esp) ; popfl");
 825         load_TR(0);
 826         load_ldt(0);
 827         outb_p(0x34,0x43);              /* binary, mode 2, LSB/MSB, ch 0 */
 828         outb_p(LATCH & 0xff , 0x40);    /* LSB */
 829         outb(LATCH >> 8 , 0x40);        /* MSB */
 830         if (request_irq(TIMER_IRQ,(void (*)(int)) do_timer)!=0)
 831                 panic("Could not allocate timer IRQ!");
 832 }
/* */
root/kernel/sched.c

DEFINITIONS
