root/kernel/sched.c

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DEFINITIONS

This source file includes following definitions.
  1. schedule
  2. sys_pause
  3. wake_up
  4. wake_up_interruptible
  5. __down
  6. __sleep_on
  7. interruptible_sleep_on
  8. sleep_on
  9. add_timer
  10. del_timer
  11. count_active_tasks
  12. calc_load
  13. second_overflow
  14. timer_bh
  15. tqueue_bh
  16. immediate_bh
  17. do_timer
  18. sys_alarm
  19. sys_getpid
  20. sys_getppid
  21. sys_getuid
  22. sys_geteuid
  23. sys_getgid
  24. sys_getegid
  25. sys_nice
  26. show_task
  27. show_state
  28. 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/delay.h>
  25 #include <linux/interrupt.h>
  26 #include <linux/tqueue.h>
  27 #include <linux/resource.h>
  28 #include <linux/mm.h>
  29 
  30 #include <asm/system.h>
  31 #include <asm/io.h>
  32 #include <asm/segment.h>
  33 
  34 #define TIMER_IRQ 0
  35 
  36 #include <linux/timex.h>
  37 
  38 /*
  39  * kernel variables
  40  */
  41 long tick = 1000000 / HZ;               /* timer interrupt period */
  42 volatile struct timeval xtime;          /* The current time */
  43 int tickadj = 500/HZ;                   /* microsecs */
  44 
  45 DECLARE_TASK_QUEUE(tq_timer);
  46 DECLARE_TASK_QUEUE(tq_immediate);
  47 
  48 /*
  49  * phase-lock loop variables
  50  */
  51 int time_status = TIME_BAD;     /* clock synchronization status */
  52 long time_offset = 0;           /* time adjustment (us) */
  53 long time_constant = 0;         /* pll time constant */
  54 long time_tolerance = MAXFREQ;  /* frequency tolerance (ppm) */
  55 long time_precision = 1;        /* clock precision (us) */
  56 long time_maxerror = 0x70000000;/* maximum error */
  57 long time_esterror = 0x70000000;/* estimated error */
  58 long time_phase = 0;            /* phase offset (scaled us) */
  59 long time_freq = 0;             /* frequency offset (scaled ppm) */
  60 long time_adj = 0;              /* tick adjust (scaled 1 / HZ) */
  61 long time_reftime = 0;          /* time at last adjustment (s) */
  62 
  63 long time_adjust = 0;
  64 long time_adjust_step = 0;
  65 
  66 int need_resched = 0;
  67 unsigned long event = 0;
  68 
  69 extern int _setitimer(int, struct itimerval *, struct itimerval *);
  70 unsigned long * prof_buffer = NULL;
  71 unsigned long prof_len = 0;
  72 
  73 #define _S(nr) (1<<((nr)-1))
  74 
  75 extern void mem_use(void);
  76 
  77 extern int timer_interrupt(void);
  78  
  79 static unsigned long init_kernel_stack[1024] = { STACK_MAGIC, };
  80 unsigned long init_user_stack[1024] = { STACK_MAGIC, };
  81 static struct vm_area_struct init_mmap = INIT_MMAP;
  82 struct task_struct init_task = INIT_TASK;
  83 
  84 unsigned long volatile jiffies=0;
  85 
  86 struct task_struct *current = &init_task;
  87 struct task_struct *last_task_used_math = NULL;
  88 
  89 struct task_struct * task[NR_TASKS] = {&init_task, };
  90 
  91 struct kernel_stat kstat = { 0 };
  92 
  93 unsigned long itimer_ticks = 0;
  94 unsigned long itimer_next = ~0;
  95 
  96 /*
  97  *  'schedule()' is the scheduler function. It's a very simple and nice
  98  * scheduler: it's not perfect, but certainly works for most things.
  99  * The one thing you might take a look at is the signal-handler code here.
 100  *
 101  *   NOTE!!  Task 0 is the 'idle' task, which gets called when no other
 102  * tasks can run. It can not be killed, and it cannot sleep. The 'state'
 103  * information in task[0] is never used.
 104  *
 105  * The "confuse_gcc" goto is used only to get better assembly code..
 106  * Dijkstra probably hates me.
 107  */
 108 asmlinkage void schedule(void)
     /* [previous][next][first][last][top][bottom][index][help] */
 109 {
 110         int c;
 111         struct task_struct * p;
 112         struct task_struct * next;
 113         unsigned long ticks;
 114 
 115 /* check alarm, wake up any interruptible tasks that have got a signal */
 116 
 117         if (intr_count) {
 118                 printk("Aiee: scheduling in interrupt\n");
 119                 intr_count = 0;
 120         }
 121         cli();
 122         ticks = itimer_ticks;
 123         itimer_ticks = 0;
 124         itimer_next = ~0;
 125         sti();
 126         need_resched = 0;
 127         p = &init_task;
 128         for (;;) {
 129                 if ((p = p->next_task) == &init_task)
 130                         goto confuse_gcc1;
 131                 if (ticks && p->it_real_value) {
 132                         if (p->it_real_value <= ticks) {
 133                                 send_sig(SIGALRM, p, 1);
 134                                 if (!p->it_real_incr) {
 135                                         p->it_real_value = 0;
 136                                         goto end_itimer;
 137                                 }
 138                                 do {
 139                                         p->it_real_value += p->it_real_incr;
 140                                 } while (p->it_real_value <= ticks);
 141                         }
 142                         p->it_real_value -= ticks;
 143                         if (p->it_real_value < itimer_next)
 144                                 itimer_next = p->it_real_value;
 145                 }
 146 end_itimer:
 147                 if (p->state != TASK_INTERRUPTIBLE)
 148                         continue;
 149                 if (p->signal & ~p->blocked) {
 150                         p->state = TASK_RUNNING;
 151                         continue;
 152                 }
 153                 if (p->timeout && p->timeout <= jiffies) {
 154                         p->timeout = 0;
 155                         p->state = TASK_RUNNING;
 156                 }
 157         }
 158 confuse_gcc1:
 159 
 160 /* this is the scheduler proper: */
 161 #if 0
 162         /* give processes that go to sleep a bit higher priority.. */
 163         /* This depends on the values for TASK_XXX */
 164         /* This gives smoother scheduling for some things, but */
 165         /* can be very unfair under some circumstances, so.. */
 166         if (TASK_UNINTERRUPTIBLE >= (unsigned) current->state &&
 167             current->counter < current->priority*2) {
 168                 ++current->counter;
 169         }
 170 #endif
 171         c = -1000;
 172         next = p = &init_task;
 173         for (;;) {
 174                 if ((p = p->next_task) == &init_task)
 175                         goto confuse_gcc2;
 176                 if (p->state == TASK_RUNNING && p->counter > c)
 177                         c = p->counter, next = p;
 178         }
 179 confuse_gcc2:
 180         if (!c) {
 181                 for_each_task(p)
 182                         p->counter = (p->counter >> 1) + p->priority;
 183         }
 184         if (current == next)
 185                 return;
 186         kstat.context_swtch++;
 187         switch_to(next);
 188 }
 189 
 190 asmlinkage int sys_pause(void)
     /* [previous][next][first][last][top][bottom][index][help] */
 191 {
 192         current->state = TASK_INTERRUPTIBLE;
 193         schedule();
 194         return -ERESTARTNOHAND;
 195 }
 196 
 197 /*
 198  * wake_up doesn't wake up stopped processes - they have to be awakened
 199  * with signals or similar.
 200  *
 201  * Note that this doesn't need cli-sti pairs: interrupts may not change
 202  * the wait-queue structures directly, but only call wake_up() to wake
 203  * a process. The process itself must remove the queue once it has woken.
 204  */
 205 void wake_up(struct wait_queue **q)
     /* [previous][next][first][last][top][bottom][index][help] */
 206 {
 207         struct wait_queue *tmp;
 208         struct task_struct * p;
 209 
 210         if (!q || !(tmp = *q))
 211                 return;
 212         do {
 213                 if ((p = tmp->task) != NULL) {
 214                         if ((p->state == TASK_UNINTERRUPTIBLE) ||
 215                             (p->state == TASK_INTERRUPTIBLE)) {
 216                                 p->state = TASK_RUNNING;
 217                                 if (p->counter > current->counter + 3)
 218                                         need_resched = 1;
 219                         }
 220                 }
 221                 if (!tmp->next) {
 222                         printk("wait_queue is bad (eip = %p)\n",
 223                                 __builtin_return_address(0));
 224                         printk("        q = %p\n",q);
 225                         printk("       *q = %p\n",*q);
 226                         printk("      tmp = %p\n",tmp);
 227                         break;
 228                 }
 229                 tmp = tmp->next;
 230         } while (tmp != *q);
 231 }
 232 
 233 void wake_up_interruptible(struct wait_queue **q)
     /* [previous][next][first][last][top][bottom][index][help] */
 234 {
 235         struct wait_queue *tmp;
 236         struct task_struct * p;
 237 
 238         if (!q || !(tmp = *q))
 239                 return;
 240         do {
 241                 if ((p = tmp->task) != NULL) {
 242                         if (p->state == TASK_INTERRUPTIBLE) {
 243                                 p->state = TASK_RUNNING;
 244                                 if (p->counter > current->counter + 3)
 245                                         need_resched = 1;
 246                         }
 247                 }
 248                 if (!tmp->next) {
 249                         printk("wait_queue is bad (eip = %p)\n",
 250                                 __builtin_return_address(0));
 251                         printk("        q = %p\n",q);
 252                         printk("       *q = %p\n",*q);
 253                         printk("      tmp = %p\n",tmp);
 254                         break;
 255                 }
 256                 tmp = tmp->next;
 257         } while (tmp != *q);
 258 }
 259 
 260 void __down(struct semaphore * sem)
     /* [previous][next][first][last][top][bottom][index][help] */
 261 {
 262         struct wait_queue wait = { current, NULL };
 263         add_wait_queue(&sem->wait, &wait);
 264         current->state = TASK_UNINTERRUPTIBLE;
 265         while (sem->count <= 0) {
 266                 schedule();
 267                 current->state = TASK_UNINTERRUPTIBLE;
 268         }
 269         current->state = TASK_RUNNING;
 270         remove_wait_queue(&sem->wait, &wait);
 271 }
 272 
 273 static inline void __sleep_on(struct wait_queue **p, int state)
     /* [previous][next][first][last][top][bottom][index][help] */
 274 {
 275         unsigned long flags;
 276         struct wait_queue wait = { current, NULL };
 277 
 278         if (!p)
 279                 return;
 280         if (current == task[0])
 281                 panic("task[0] trying to sleep");
 282         current->state = state;
 283         add_wait_queue(p, &wait);
 284         save_flags(flags);
 285         sti();
 286         schedule();
 287         remove_wait_queue(p, &wait);
 288         restore_flags(flags);
 289 }
 290 
 291 void interruptible_sleep_on(struct wait_queue **p)
     /* [previous][next][first][last][top][bottom][index][help] */
 292 {
 293         __sleep_on(p,TASK_INTERRUPTIBLE);
 294 }
 295 
 296 void sleep_on(struct wait_queue **p)
     /* [previous][next][first][last][top][bottom][index][help] */
 297 {
 298         __sleep_on(p,TASK_UNINTERRUPTIBLE);
 299 }
 300 
 301 /*
 302  * The head for the timer-list has a "expires" field of MAX_UINT,
 303  * and the sorting routine counts on this..
 304  */
 305 static struct timer_list timer_head = { &timer_head, &timer_head, ~0, 0, NULL };
 306 #define SLOW_BUT_DEBUGGING_TIMERS 1
 307 
 308 void add_timer(struct timer_list * timer)
     /* [previous][next][first][last][top][bottom][index][help] */
 309 {
 310         unsigned long flags;
 311         struct timer_list *p;
 312 
 313 #if SLOW_BUT_DEBUGGING_TIMERS
 314         if (timer->next || timer->prev) {
 315                 printk("add_timer() called with non-zero list from %p\n",
 316                         __builtin_return_address(0));
 317                 return;
 318         }
 319 #endif
 320         p = &timer_head;
 321         timer->expires += jiffies;
 322         save_flags(flags);
 323         cli();
 324         do {
 325                 p = p->next;
 326         } while (timer->expires > p->expires);
 327         timer->next = p;
 328         timer->prev = p->prev;
 329         p->prev = timer;
 330         timer->prev->next = timer;
 331         restore_flags(flags);
 332 }
 333 
 334 int del_timer(struct timer_list * timer)
     /* [previous][next][first][last][top][bottom][index][help] */
 335 {
 336         unsigned long flags;
 337 #if SLOW_BUT_DEBUGGING_TIMERS
 338         struct timer_list * p;
 339 
 340         p = &timer_head;
 341         save_flags(flags);
 342         cli();
 343         while ((p = p->next) != &timer_head) {
 344                 if (p == timer) {
 345                         timer->next->prev = timer->prev;
 346                         timer->prev->next = timer->next;
 347                         timer->next = timer->prev = NULL;
 348                         restore_flags(flags);
 349                         timer->expires -= jiffies;
 350                         return 1;
 351                 }
 352         }
 353         if (timer->next || timer->prev)
 354                 printk("del_timer() called from %p with timer not initialized\n",
 355                         __builtin_return_address(0));
 356         restore_flags(flags);
 357         return 0;
 358 #else   
 359         save_flags(flags);
 360         cli();
 361         if (timer->next) {
 362                 timer->next->prev = timer->prev;
 363                 timer->prev->next = timer->next;
 364                 timer->next = timer->prev = NULL;
 365                 restore_flags(flags);
 366                 timer->expires -= jiffies;
 367                 return 1;
 368         }
 369         restore_flags(flags);
 370         return 0;
 371 #endif
 372 }
 373 
 374 unsigned long timer_active = 0;
 375 struct timer_struct timer_table[32];
 376 
 377 /*
 378  * Hmm.. Changed this, as the GNU make sources (load.c) seems to
 379  * imply that avenrun[] is the standard name for this kind of thing.
 380  * Nothing else seems to be standardized: the fractional size etc
 381  * all seem to differ on different machines.
 382  */
 383 unsigned long avenrun[3] = { 0,0,0 };
 384 
 385 /*
 386  * Nr of active tasks - counted in fixed-point numbers
 387  */
 388 static unsigned long count_active_tasks(void)
     /* [previous][next][first][last][top][bottom][index][help] */
 389 {
 390         struct task_struct **p;
 391         unsigned long nr = 0;
 392 
 393         for(p = &LAST_TASK; p > &FIRST_TASK; --p)
 394                 if (*p && ((*p)->state == TASK_RUNNING ||
 395                            (*p)->state == TASK_UNINTERRUPTIBLE ||
 396                            (*p)->state == TASK_SWAPPING))
 397                         nr += FIXED_1;
 398         return nr;
 399 }
 400 
 401 static inline void calc_load(void)
     /* [previous][next][first][last][top][bottom][index][help] */
 402 {
 403         unsigned long active_tasks; /* fixed-point */
 404         static int count = LOAD_FREQ;
 405 
 406         if (count-- > 0)
 407                 return;
 408         count = LOAD_FREQ;
 409         active_tasks = count_active_tasks();
 410         CALC_LOAD(avenrun[0], EXP_1, active_tasks);
 411         CALC_LOAD(avenrun[1], EXP_5, active_tasks);
 412         CALC_LOAD(avenrun[2], EXP_15, active_tasks);
 413 }
 414 
 415 /*
 416  * this routine handles the overflow of the microsecond field
 417  *
 418  * The tricky bits of code to handle the accurate clock support
 419  * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
 420  * They were originally developed for SUN and DEC kernels.
 421  * All the kudos should go to Dave for this stuff.
 422  *
 423  * These were ported to Linux by Philip Gladstone.
 424  */
 425 static void second_overflow(void)
     /* [previous][next][first][last][top][bottom][index][help] */
 426 {
 427         long ltemp;
 428         /* last time the cmos clock got updated */
 429         static long last_rtc_update=0;
 430         extern int set_rtc_mmss(unsigned long);
 431 
 432         /* Bump the maxerror field */
 433         time_maxerror = (0x70000000-time_maxerror < time_tolerance) ?
 434           0x70000000 : (time_maxerror + time_tolerance);
 435 
 436         /* Run the PLL */
 437         if (time_offset < 0) {
 438                 ltemp = (-(time_offset+1) >> (SHIFT_KG + time_constant)) + 1;
 439                 time_adj = ltemp << (SHIFT_SCALE - SHIFT_HZ - SHIFT_UPDATE);
 440                 time_offset += (time_adj * HZ) >> (SHIFT_SCALE - SHIFT_UPDATE);
 441                 time_adj = - time_adj;
 442         } else if (time_offset > 0) {
 443                 ltemp = ((time_offset-1) >> (SHIFT_KG + time_constant)) + 1;
 444                 time_adj = ltemp << (SHIFT_SCALE - SHIFT_HZ - SHIFT_UPDATE);
 445                 time_offset -= (time_adj * HZ) >> (SHIFT_SCALE - SHIFT_UPDATE);
 446         } else {
 447                 time_adj = 0;
 448         }
 449 
 450         time_adj += (time_freq >> (SHIFT_KF + SHIFT_HZ - SHIFT_SCALE))
 451             + FINETUNE;
 452 
 453         /* Handle the leap second stuff */
 454         switch (time_status) {
 455                 case TIME_INS:
 456                 /* ugly divide should be replaced */
 457                 if (xtime.tv_sec % 86400 == 0) {
 458                         xtime.tv_sec--; /* !! */
 459                         time_status = TIME_OOP;
 460                         printk("Clock: inserting leap second 23:59:60 GMT\n");
 461                 }
 462                 break;
 463 
 464                 case TIME_DEL:
 465                 /* ugly divide should be replaced */
 466                 if (xtime.tv_sec % 86400 == 86399) {
 467                         xtime.tv_sec++;
 468                         time_status = TIME_OK;
 469                         printk("Clock: deleting leap second 23:59:59 GMT\n");
 470                 }
 471                 break;
 472 
 473                 case TIME_OOP:
 474                 time_status = TIME_OK;
 475                 break;
 476         }
 477         if (time_status != TIME_BAD && xtime.tv_sec > last_rtc_update + 660)
 478           if (set_rtc_mmss(xtime.tv_sec) == 0)
 479             last_rtc_update = xtime.tv_sec;
 480           else
 481             last_rtc_update = xtime.tv_sec - 600; /* do it again in one min */
 482 }
 483 
 484 /*
 485  * disregard lost ticks for now.. We don't care enough.
 486  */
 487 static void timer_bh(void * unused)
     /* [previous][next][first][last][top][bottom][index][help] */
 488 {
 489         unsigned long mask;
 490         struct timer_struct *tp;
 491         struct timer_list * timer;
 492 
 493         cli();
 494         while ((timer = timer_head.next) != &timer_head && timer->expires < jiffies) {
 495                 void (*fn)(unsigned long) = timer->function;
 496                 unsigned long data = timer->data;
 497                 timer->next->prev = timer->prev;
 498                 timer->prev->next = timer->next;
 499                 timer->next = timer->prev = NULL;
 500                 sti();
 501                 fn(data);
 502                 cli();
 503         }
 504         sti();
 505         
 506         for (mask = 1, tp = timer_table+0 ; mask ; tp++,mask += mask) {
 507                 if (mask > timer_active)
 508                         break;
 509                 if (!(mask & timer_active))
 510                         continue;
 511                 if (tp->expires > jiffies)
 512                         continue;
 513                 timer_active &= ~mask;
 514                 tp->fn();
 515                 sti();
 516         }
 517 }
 518 
 519 void tqueue_bh(void * unused)
     /* [previous][next][first][last][top][bottom][index][help] */
 520 {
 521         run_task_queue(&tq_timer);
 522 }
 523 
 524 void immediate_bh(void * unused)
     /* [previous][next][first][last][top][bottom][index][help] */
 525 {
 526         run_task_queue(&tq_immediate);
 527 }
 528 
 529 /*
 530  * The int argument is really a (struct pt_regs *), in case the
 531  * interrupt wants to know from where it was called. The timer
 532  * irq uses this to decide if it should update the user or system
 533  * times.
 534  */
 535 static void do_timer(int irq, struct pt_regs * regs)
     /* [previous][next][first][last][top][bottom][index][help] */
 536 {
 537         unsigned long mask;
 538         struct timer_struct *tp;
 539 
 540         long ltemp, psecs;
 541 
 542         /* Advance the phase, once it gets to one microsecond, then
 543          * advance the tick more.
 544          */
 545         time_phase += time_adj;
 546         if (time_phase < -FINEUSEC) {
 547                 ltemp = -time_phase >> SHIFT_SCALE;
 548                 time_phase += ltemp << SHIFT_SCALE;
 549                 xtime.tv_usec += tick + time_adjust_step - ltemp;
 550         }
 551         else if (time_phase > FINEUSEC) {
 552                 ltemp = time_phase >> SHIFT_SCALE;
 553                 time_phase -= ltemp << SHIFT_SCALE;
 554                 xtime.tv_usec += tick + time_adjust_step + ltemp;
 555         } else
 556                 xtime.tv_usec += tick + time_adjust_step;
 557 
 558         if (time_adjust)
 559         {
 560             /* We are doing an adjtime thing. 
 561              *
 562              * Modify the value of the tick for next time.
 563              * Note that a positive delta means we want the clock
 564              * to run fast. This means that the tick should be bigger
 565              *
 566              * Limit the amount of the step for *next* tick to be
 567              * in the range -tickadj .. +tickadj
 568              */
 569              if (time_adjust > tickadj)
 570                time_adjust_step = tickadj;
 571              else if (time_adjust < -tickadj)
 572                time_adjust_step = -tickadj;
 573              else
 574                time_adjust_step = time_adjust;
 575              
 576             /* Reduce by this step the amount of time left  */
 577             time_adjust -= time_adjust_step;
 578         }
 579         else
 580             time_adjust_step = 0;
 581 
 582         if (xtime.tv_usec >= 1000000) {
 583             xtime.tv_usec -= 1000000;
 584             xtime.tv_sec++;
 585             second_overflow();
 586         }
 587 
 588         jiffies++;
 589         calc_load();
 590         if (user_mode(regs)) {
 591                 current->utime++;
 592                 if (current != task[0]) {
 593                         if (current->priority < 15)
 594                                 kstat.cpu_nice++;
 595                         else
 596                                 kstat.cpu_user++;
 597                 }
 598                 /* Update ITIMER_VIRT for current task if not in a system call */
 599                 if (current->it_virt_value && !(--current->it_virt_value)) {
 600                         current->it_virt_value = current->it_virt_incr;
 601                         send_sig(SIGVTALRM,current,1);
 602                 }
 603         } else {
 604                 current->stime++;
 605                 if(current != task[0])
 606                         kstat.cpu_system++;
 607 #ifdef CONFIG_PROFILE
 608                 if (prof_buffer && current != task[0]) {
 609                         unsigned long eip = regs->eip;
 610                         eip >>= CONFIG_PROFILE_SHIFT;
 611                         if (eip < prof_len)
 612                                 prof_buffer[eip]++;
 613                 }
 614 #endif
 615         }
 616         /*
 617          * check the cpu time limit on the process.
 618          */
 619         if ((current->rlim[RLIMIT_CPU].rlim_max != RLIM_INFINITY) &&
 620             (((current->stime + current->utime) / HZ) >= current->rlim[RLIMIT_CPU].rlim_max))
 621                 send_sig(SIGKILL, current, 1);
 622         if ((current->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) &&
 623             (((current->stime + current->utime) % HZ) == 0)) {
 624                 psecs = (current->stime + current->utime) / HZ;
 625                 /* send when equal */
 626                 if (psecs == current->rlim[RLIMIT_CPU].rlim_cur)
 627                         send_sig(SIGXCPU, current, 1);
 628                 /* and every five seconds thereafter. */
 629                 else if ((psecs > current->rlim[RLIMIT_CPU].rlim_cur) &&
 630                         ((psecs - current->rlim[RLIMIT_CPU].rlim_cur) % 5) == 0)
 631                         send_sig(SIGXCPU, current, 1);
 632         }
 633 
 634         if (current != task[0] && 0 > --current->counter) {
 635                 current->counter = 0;
 636                 need_resched = 1;
 637         }
 638         /* Update ITIMER_PROF for the current task */
 639         if (current->it_prof_value && !(--current->it_prof_value)) {
 640                 current->it_prof_value = current->it_prof_incr;
 641                 send_sig(SIGPROF,current,1);
 642         }
 643         for (mask = 1, tp = timer_table+0 ; mask ; tp++,mask += mask) {
 644                 if (mask > timer_active)
 645                         break;
 646                 if (!(mask & timer_active))
 647                         continue;
 648                 if (tp->expires > jiffies)
 649                         continue;
 650                 mark_bh(TIMER_BH);
 651         }
 652         cli();
 653         itimer_ticks++;
 654         if (itimer_ticks > itimer_next)
 655                 need_resched = 1;
 656         if (timer_head.next->expires < jiffies)
 657                 mark_bh(TIMER_BH);
 658         if (tq_timer != &tq_last)
 659                 mark_bh(TQUEUE_BH);
 660         sti();
 661 }
 662 
 663 asmlinkage int sys_alarm(long seconds)
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 664 {
 665         struct itimerval it_new, it_old;
 666 
 667         it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
 668         it_new.it_value.tv_sec = seconds;
 669         it_new.it_value.tv_usec = 0;
 670         _setitimer(ITIMER_REAL, &it_new, &it_old);
 671         return(it_old.it_value.tv_sec + (it_old.it_value.tv_usec / 1000000));
 672 }
 673 
 674 asmlinkage int sys_getpid(void)
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 675 {
 676         return current->pid;
 677 }
 678 
 679 asmlinkage int sys_getppid(void)
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 680 {
 681         return current->p_opptr->pid;
 682 }
 683 
 684 asmlinkage int sys_getuid(void)
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 685 {
 686         return current->uid;
 687 }
 688 
 689 asmlinkage int sys_geteuid(void)
     /* [previous][next][first][last][top][bottom][index][help] */
 690 {
 691         return current->euid;
 692 }
 693 
 694 asmlinkage int sys_getgid(void)
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 695 {
 696         return current->gid;
 697 }
 698 
 699 asmlinkage int sys_getegid(void)
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 700 {
 701         return current->egid;
 702 }
 703 
 704 asmlinkage int sys_nice(long increment)
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 705 {
 706         int newprio;
 707 
 708         if (increment < 0 && !suser())
 709                 return -EPERM;
 710         newprio = current->priority - increment;
 711         if (newprio < 1)
 712                 newprio = 1;
 713         if (newprio > 35)
 714                 newprio = 35;
 715         current->priority = newprio;
 716         return 0;
 717 }
 718 
 719 static void show_task(int nr,struct task_struct * p)
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 720 {
 721         unsigned long free;
 722         static char * stat_nam[] = { "R", "S", "D", "Z", "T", "W" };
 723 
 724         printk("%-8s %3d ", p->comm, (p == current) ? -nr : nr);
 725         if (((unsigned) p->state) < sizeof(stat_nam)/sizeof(char *))
 726                 printk(stat_nam[p->state]);
 727         else
 728                 printk(" ");
 729 #ifdef __i386__
 730         if (p == current)
 731                 printk(" current  ");
 732         else
 733                 printk(" %08lX ", ((unsigned long *)p->tss.esp)[3]);
 734 #endif
 735         for (free = 1; free < 1024 ; free++) {
 736                 if (((unsigned long *)p->kernel_stack_page)[free])
 737                         break;
 738         }
 739         printk("%5lu %5d %6d ", free << 2, p->pid, p->p_pptr->pid);
 740         if (p->p_cptr)
 741                 printk("%5d ", p->p_cptr->pid);
 742         else
 743                 printk("      ");
 744         if (p->p_ysptr)
 745                 printk("%7d", p->p_ysptr->pid);
 746         else
 747                 printk("       ");
 748         if (p->p_osptr)
 749                 printk(" %5d\n", p->p_osptr->pid);
 750         else
 751                 printk("\n");
 752 }
 753 
 754 void show_state(void)
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 755 {
 756         int i;
 757 
 758         printk("                         free                        sibling\n");
 759         printk("  task             PC    stack   pid father child younger older\n");
 760         for (i=0 ; i<NR_TASKS ; i++)
 761                 if (task[i])
 762                         show_task(i,task[i]);
 763 }
 764 
 765 void sched_init(void)
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 766 {
 767         bh_base[TIMER_BH].routine = timer_bh;
 768         bh_base[TQUEUE_BH].routine = tqueue_bh;
 769         bh_base[IMMEDIATE_BH].routine = immediate_bh;
 770         if (request_irq(TIMER_IRQ, do_timer, 0, "timer") != 0)
 771                 panic("Could not allocate timer IRQ!");
 772 }

/* [previous][next][first][last][top][bottom][index][help] */