kernel/sched.c

/* */
This source file includes following definitions.
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
immediate_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/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 #include <asm/pgtable.h>
  34 
  35 #define TIMER_IRQ 0
  36 
  37 #include <linux/timex.h>
  38 
  39 /*
  40  * kernel variables
  41  */
  42 long tick = 1000000 / HZ;               /* timer interrupt period */
  43 volatile struct timeval xtime;          /* The current time */
  44 int tickadj = 500/HZ;                   /* microsecs */
  45 
  46 DECLARE_TASK_QUEUE(tq_timer);
  47 DECLARE_TASK_QUEUE(tq_immediate);
  48 
  49 /*
  50  * phase-lock loop variables
  51  */
  52 int time_status = TIME_BAD;     /* clock synchronization status */
  53 long time_offset = 0;           /* time adjustment (us) */
  54 long time_constant = 0;         /* pll time constant */
  55 long time_tolerance = MAXFREQ;  /* frequency tolerance (ppm) */
  56 long time_precision = 1;        /* clock precision (us) */
  57 long time_maxerror = 0x70000000;/* maximum error */
  58 long time_esterror = 0x70000000;/* estimated error */
  59 long time_phase = 0;            /* phase offset (scaled us) */
  60 long time_freq = 0;             /* frequency offset (scaled ppm) */
  61 long time_adj = 0;              /* tick adjust (scaled 1 / HZ) */
  62 long time_reftime = 0;          /* time at last adjustment (s) */
  63 
  64 long time_adjust = 0;
  65 long time_adjust_step = 0;
  66 
  67 int need_resched = 0;
  68 unsigned long event = 0;
  69 
  70 extern int _setitimer(int, struct itimerval *, struct itimerval *);
  71 unsigned long * prof_buffer = NULL;
  72 unsigned long prof_len = 0;
  73 
  74 #define _S(nr) (1<<((nr)-1))
  75 
  76 extern void mem_use(void);
  77 
  78 extern int timer_interrupt(void);
  79  
  80 static unsigned long init_kernel_stack[1024] = { STACK_MAGIC, };
  81 unsigned long init_user_stack[1024] = { STACK_MAGIC, };
  82 static struct vm_area_struct init_mmap = INIT_MMAP;
  83 struct task_struct init_task = INIT_TASK;
  84 
  85 unsigned long volatile jiffies=0;
  86 
  87 struct task_struct *current = &init_task;
  88 struct task_struct *last_task_used_math = NULL;
  89 
  90 struct task_struct * task[NR_TASKS] = {&init_task, };
  91 
  92 struct kernel_stat kstat = { 0 };
  93 
  94 unsigned long itimer_ticks = 0;
  95 unsigned long itimer_next = ~0;
  96 
  97 /*
  98  *  'schedule()' is the scheduler function. It's a very simple and nice
  99  * scheduler: it's not perfect, but certainly works for most things.
 100  * The one thing you might take a look at is the signal-handler code here.
 101  *
 102  *   NOTE!!  Task 0 is the 'idle' task, which gets called when no other
 103  * tasks can run. It can not be killed, and it cannot sleep. The 'state'
 104  * information in task[0] is never used.
 105  *
 106  * The "confuse_gcc" goto is used only to get better assembly code..
 107  * Dijkstra probably hates me.
 108  */
 109 asmlinkage void schedule(void)
     /*  */
 110 {
 111         int c;
 112         struct task_struct * p;
 113         struct task_struct * next;
 114         unsigned long ticks;
 115 
 116 /* check alarm, wake up any interruptible tasks that have got a signal */
 117 
 118         if (intr_count) {
 119                 printk("Aiee: scheduling in interrupt\n");
 120                 intr_count = 0;
 121         }
 122         cli();
 123         ticks = itimer_ticks;
 124         itimer_ticks = 0;
 125         itimer_next = ~0;
 126         sti();
 127         need_resched = 0;
 128         nr_running = 0;
 129         p = &init_task;
 130         for (;;) {
 131                 if ((p = p->next_task) == &init_task)
 132                         goto confuse_gcc1;
 133                 if (ticks && p->it_real_value) {
 134                         if (p->it_real_value <= ticks) {
 135                                 send_sig(SIGALRM, p, 1);
 136                                 if (!p->it_real_incr) {
 137                                         p->it_real_value = 0;
 138                                         goto end_itimer;
 139                                 }
 140                                 do {
 141                                         p->it_real_value += p->it_real_incr;
 142                                 } while (p->it_real_value <= ticks);
 143                         }
 144                         p->it_real_value -= ticks;
 145                         if (p->it_real_value < itimer_next)
 146                                 itimer_next = p->it_real_value;
 147                 }
 148 end_itimer:
 149                 if (p->state != TASK_INTERRUPTIBLE)
 150                         continue;
 151                 if (p->signal & ~p->blocked) {
 152                         p->state = TASK_RUNNING;
 153                         continue;
 154                 }
 155                 if (p->timeout && p->timeout <= jiffies) {
 156                         p->timeout = 0;
 157                         p->state = TASK_RUNNING;
 158                 }
 159         }
 160 confuse_gcc1:
 161 
 162 /* this is the scheduler proper: */
 163 #if 0
 164         /* give processes that go to sleep a bit higher priority.. */
 165         /* This depends on the values for TASK_XXX */
 166         /* This gives smoother scheduling for some things, but */
 167         /* can be very unfair under some circumstances, so.. */
 168         if (TASK_UNINTERRUPTIBLE >= (unsigned) current->state &&
 169             current->counter < current->priority*2) {
 170                 ++current->counter;
 171         }
 172 #endif
 173         c = -1000;
 174         next = p = &init_task;
 175         for (;;) {
 176                 if ((p = p->next_task) == &init_task)
 177                         goto confuse_gcc2;
 178                 if (p->state == TASK_RUNNING) {
 179                         nr_running++;
 180                         if (p->counter > c)
 181                                 c = p->counter, next = p;
 182                 }
 183         }
 184 confuse_gcc2:
 185         if (!c) {
 186                 for_each_task(p)
 187                         p->counter = (p->counter >> 1) + p->priority;
 188         }
 189         if (current == next)
 190                 return;
 191         kstat.context_swtch++;
 192         switch_to(next);
 193 }
 194 
 195 asmlinkage int sys_pause(void)
     /*  */
 196 {
 197         current->state = TASK_INTERRUPTIBLE;
 198         schedule();
 199         return -ERESTARTNOHAND;
 200 }
 201 
 202 /*
 203  * wake_up doesn't wake up stopped processes - they have to be awakened
 204  * with signals or similar.
 205  *
 206  * Note that this doesn't need cli-sti pairs: interrupts may not change
 207  * the wait-queue structures directly, but only call wake_up() to wake
 208  * a process. The process itself must remove the queue once it has woken.
 209  */
 210 void wake_up(struct wait_queue **q)
     /*  */
 211 {
 212         struct wait_queue *tmp;
 213         struct task_struct * p;
 214 
 215         if (!q || !(tmp = *q))
 216                 return;
 217         do {
 218                 if ((p = tmp->task) != NULL) {
 219                         if ((p->state == TASK_UNINTERRUPTIBLE) ||
 220                             (p->state == TASK_INTERRUPTIBLE)) {
 221                                 p->state = TASK_RUNNING;
 222                                 if (p->counter > current->counter + 3)
 223                                         need_resched = 1;
 224                         }
 225                 }
 226                 if (!tmp->next) {
 227                         printk("wait_queue is bad (eip = %p)\n",
 228                                 __builtin_return_address(0));
 229                         printk("        q = %p\n",q);
 230                         printk("       *q = %p\n",*q);
 231                         printk("      tmp = %p\n",tmp);
 232                         break;
 233                 }
 234                 tmp = tmp->next;
 235         } while (tmp != *q);
 236 }
 237 
 238 void wake_up_interruptible(struct wait_queue **q)
     /*  */
 239 {
 240         struct wait_queue *tmp;
 241         struct task_struct * p;
 242 
 243         if (!q || !(tmp = *q))
 244                 return;
 245         do {
 246                 if ((p = tmp->task) != NULL) {
 247                         if (p->state == TASK_INTERRUPTIBLE) {
 248                                 p->state = TASK_RUNNING;
 249                                 if (p->counter > current->counter + 3)
 250                                         need_resched = 1;
 251                         }
 252                 }
 253                 if (!tmp->next) {
 254                         printk("wait_queue is bad (eip = %p)\n",
 255                                 __builtin_return_address(0));
 256                         printk("        q = %p\n",q);
 257                         printk("       *q = %p\n",*q);
 258                         printk("      tmp = %p\n",tmp);
 259                         break;
 260                 }
 261                 tmp = tmp->next;
 262         } while (tmp != *q);
 263 }
 264 
 265 void __down(struct semaphore * sem)
     /*  */
 266 {
 267         struct wait_queue wait = { current, NULL };
 268         add_wait_queue(&sem->wait, &wait);
 269         current->state = TASK_UNINTERRUPTIBLE;
 270         while (sem->count <= 0) {
 271                 schedule();
 272                 current->state = TASK_UNINTERRUPTIBLE;
 273         }
 274         current->state = TASK_RUNNING;
 275         remove_wait_queue(&sem->wait, &wait);
 276 }
 277 
 278 static inline void __sleep_on(struct wait_queue **p, int state)
     /*  */
 279 {
 280         unsigned long flags;
 281         struct wait_queue wait = { current, NULL };
 282 
 283         if (!p)
 284                 return;
 285         if (current == task[0])
 286                 panic("task[0] trying to sleep");
 287         current->state = state;
 288         add_wait_queue(p, &wait);
 289         save_flags(flags);
 290         sti();
 291         schedule();
 292         remove_wait_queue(p, &wait);
 293         restore_flags(flags);
 294 }
 295 
 296 void interruptible_sleep_on(struct wait_queue **p)
     /*  */
 297 {
 298         __sleep_on(p,TASK_INTERRUPTIBLE);
 299 }
 300 
 301 void sleep_on(struct wait_queue **p)
     /*  */
 302 {
 303         __sleep_on(p,TASK_UNINTERRUPTIBLE);
 304 }
 305 
 306 /*
 307  * The head for the timer-list has a "expires" field of MAX_UINT,
 308  * and the sorting routine counts on this..
 309  */
 310 static struct timer_list timer_head = { &timer_head, &timer_head, ~0, 0, NULL };
 311 #define SLOW_BUT_DEBUGGING_TIMERS 1
 312 
 313 void add_timer(struct timer_list * timer)
     /*  */
 314 {
 315         unsigned long flags;
 316         struct timer_list *p;
 317 
 318 #if SLOW_BUT_DEBUGGING_TIMERS
 319         if (timer->next || timer->prev) {
 320                 printk("add_timer() called with non-zero list from %p\n",
 321                         __builtin_return_address(0));
 322                 return;
 323         }
 324 #endif
 325         p = &timer_head;
 326         timer->expires += jiffies;
 327         save_flags(flags);
 328         cli();
 329         do {
 330                 p = p->next;
 331         } while (timer->expires > p->expires);
 332         timer->next = p;
 333         timer->prev = p->prev;
 334         p->prev = timer;
 335         timer->prev->next = timer;
 336         restore_flags(flags);
 337 }
 338 
 339 int del_timer(struct timer_list * timer)
     /*  */
 340 {
 341         unsigned long flags;
 342 #if SLOW_BUT_DEBUGGING_TIMERS
 343         struct timer_list * p;
 344 
 345         p = &timer_head;
 346         save_flags(flags);
 347         cli();
 348         while ((p = p->next) != &timer_head) {
 349                 if (p == timer) {
 350                         timer->next->prev = timer->prev;
 351                         timer->prev->next = timer->next;
 352                         timer->next = timer->prev = NULL;
 353                         restore_flags(flags);
 354                         timer->expires -= jiffies;
 355                         return 1;
 356                 }
 357         }
 358         if (timer->next || timer->prev)
 359                 printk("del_timer() called from %p with timer not initialized\n",
 360                         __builtin_return_address(0));
 361         restore_flags(flags);
 362         return 0;
 363 #else   
 364         save_flags(flags);
 365         cli();
 366         if (timer->next) {
 367                 timer->next->prev = timer->prev;
 368                 timer->prev->next = timer->next;
 369                 timer->next = timer->prev = NULL;
 370                 restore_flags(flags);
 371                 timer->expires -= jiffies;
 372                 return 1;
 373         }
 374         restore_flags(flags);
 375         return 0;
 376 #endif
 377 }
 378 
 379 unsigned long timer_active = 0;
 380 struct timer_struct timer_table[32];
 381 
 382 /*
 383  * Hmm.. Changed this, as the GNU make sources (load.c) seems to
 384  * imply that avenrun[] is the standard name for this kind of thing.
 385  * Nothing else seems to be standardized: the fractional size etc
 386  * all seem to differ on different machines.
 387  */
 388 unsigned long avenrun[3] = { 0,0,0 };
 389 
 390 /*
 391  * Nr of active tasks - counted in fixed-point numbers
 392  */
 393 static unsigned long count_active_tasks(void)
     /*  */
 394 {
 395         struct task_struct **p;
 396         unsigned long nr = 0;
 397 
 398         for(p = &LAST_TASK; p > &FIRST_TASK; --p)
 399                 if (*p && ((*p)->state == TASK_RUNNING ||
 400                            (*p)->state == TASK_UNINTERRUPTIBLE ||
 401                            (*p)->state == TASK_SWAPPING))
 402                         nr += FIXED_1;
 403         return nr;
 404 }
 405 
 406 static inline void calc_load(void)
     /*  */
 407 {
 408         unsigned long active_tasks; /* fixed-point */
 409         static int count = LOAD_FREQ;
 410 
 411         if (count-- > 0)
 412                 return;
 413         count = LOAD_FREQ;
 414         active_tasks = count_active_tasks();
 415         CALC_LOAD(avenrun[0], EXP_1, active_tasks);
 416         CALC_LOAD(avenrun[1], EXP_5, active_tasks);
 417         CALC_LOAD(avenrun[2], EXP_15, active_tasks);
 418 }
 419 
 420 /*
 421  * this routine handles the overflow of the microsecond field
 422  *
 423  * The tricky bits of code to handle the accurate clock support
 424  * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
 425  * They were originally developed for SUN and DEC kernels.
 426  * All the kudos should go to Dave for this stuff.
 427  *
 428  * These were ported to Linux by Philip Gladstone.
 429  */
 430 static void second_overflow(void)
     /*  */
 431 {
 432         long ltemp;
 433 
 434         /* Bump the maxerror field */
 435         time_maxerror = (0x70000000-time_maxerror < time_tolerance) ?
 436           0x70000000 : (time_maxerror + time_tolerance);
 437 
 438         /* Run the PLL */
 439         if (time_offset < 0) {
 440                 ltemp = (-(time_offset+1) >> (SHIFT_KG + time_constant)) + 1;
 441                 time_adj = ltemp << (SHIFT_SCALE - SHIFT_HZ - SHIFT_UPDATE);
 442                 time_offset += (time_adj * HZ) >> (SHIFT_SCALE - SHIFT_UPDATE);
 443                 time_adj = - time_adj;
 444         } else if (time_offset > 0) {
 445                 ltemp = ((time_offset-1) >> (SHIFT_KG + time_constant)) + 1;
 446                 time_adj = ltemp << (SHIFT_SCALE - SHIFT_HZ - SHIFT_UPDATE);
 447                 time_offset -= (time_adj * HZ) >> (SHIFT_SCALE - SHIFT_UPDATE);
 448         } else {
 449                 time_adj = 0;
 450         }
 451 
 452         time_adj += (time_freq >> (SHIFT_KF + SHIFT_HZ - SHIFT_SCALE))
 453             + FINETUNE;
 454 
 455         /* Handle the leap second stuff */
 456         switch (time_status) {
 457                 case TIME_INS:
 458                 /* ugly divide should be replaced */
 459                 if (xtime.tv_sec % 86400 == 0) {
 460                         xtime.tv_sec--; /* !! */
 461                         time_status = TIME_OOP;
 462                         printk("Clock: inserting leap second 23:59:60 UTC\n");
 463                 }
 464                 break;
 465 
 466                 case TIME_DEL:
 467                 /* ugly divide should be replaced */
 468                 if (xtime.tv_sec % 86400 == 86399) {
 469                         xtime.tv_sec++;
 470                         time_status = TIME_OK;
 471                         printk("Clock: deleting leap second 23:59:59 UTC\n");
 472                 }
 473                 break;
 474 
 475                 case TIME_OOP:
 476                 time_status = TIME_OK;
 477                 break;
 478         }
 479 }
 480 
 481 /*
 482  * disregard lost ticks for now.. We don't care enough.
 483  */
 484 static void timer_bh(void * unused)
     /*  */
 485 {
 486         unsigned long mask;
 487         struct timer_struct *tp;
 488         struct timer_list * timer;
 489 
 490         cli();
 491         while ((timer = timer_head.next) != &timer_head && timer->expires < jiffies) {
 492                 void (*fn)(unsigned long) = timer->function;
 493                 unsigned long data = timer->data;
 494                 timer->next->prev = timer->prev;
 495                 timer->prev->next = timer->next;
 496                 timer->next = timer->prev = NULL;
 497                 sti();
 498                 fn(data);
 499                 cli();
 500         }
 501         sti();
 502         
 503         for (mask = 1, tp = timer_table+0 ; mask ; tp++,mask += mask) {
 504                 if (mask > timer_active)
 505                         break;
 506                 if (!(mask & timer_active))
 507                         continue;
 508                 if (tp->expires > jiffies)
 509                         continue;
 510                 timer_active &= ~mask;
 511                 tp->fn();
 512                 sti();
 513         }
 514 }
 515 
 516 void tqueue_bh(void * unused)
     /*  */
 517 {
 518         run_task_queue(&tq_timer);
 519 }
 520 
 521 void immediate_bh(void * unused)
     /*  */
 522 {
 523         run_task_queue(&tq_immediate);
 524 }
 525 
 526 /*
 527  * The int argument is really a (struct pt_regs *), in case the
 528  * interrupt wants to know from where it was called. The timer
 529  * irq uses this to decide if it should update the user or system
 530  * times.
 531  */
 532 static void do_timer(int irq, struct pt_regs * regs)
     /*  */
 533 {
 534         unsigned long mask;
 535         struct timer_struct *tp;
 536         /* last time the cmos clock got updated */
 537         static long last_rtc_update=0;
 538         extern int set_rtc_mmss(unsigned long);
 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         /* If we have an externally synchronized Linux clock, then update
 589          * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
 590          * called as close as possible to 500 ms before the new second starts.
 591          */
 592         if (time_status != TIME_BAD && xtime.tv_sec > last_rtc_update + 660 &&
 593             xtime.tv_usec > 500000 - (tick >> 1) &&
 594             xtime.tv_usec < 500000 + (tick >> 1))
 595           if (set_rtc_mmss(xtime.tv_sec) == 0)
 596             last_rtc_update = xtime.tv_sec;
 597           else
 598             last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */
 599 
 600         jiffies++;
 601         calc_load();
 602         if (user_mode(regs)) {
 603                 current->utime++;
 604                 if (current != task[0]) {
 605                         if (current->priority < 15)
 606                                 kstat.cpu_nice++;
 607                         else
 608                                 kstat.cpu_user++;
 609                 }
 610                 /* Update ITIMER_VIRT for current task if not in a system call */
 611                 if (current->it_virt_value && !(--current->it_virt_value)) {
 612                         current->it_virt_value = current->it_virt_incr;
 613                         send_sig(SIGVTALRM,current,1);
 614                 }
 615         } else {
 616                 current->stime++;
 617                 if(current != task[0])
 618                         kstat.cpu_system++;
 619 #ifdef CONFIG_PROFILE
 620                 if (prof_buffer && current != task[0]) {
 621                         unsigned long eip = regs->eip;
 622                         eip >>= CONFIG_PROFILE_SHIFT;
 623                         if (eip < prof_len)
 624                                 prof_buffer[eip]++;
 625                 }
 626 #endif
 627         }
 628         /*
 629          * check the cpu time limit on the process.
 630          */
 631         if ((current->rlim[RLIMIT_CPU].rlim_max != RLIM_INFINITY) &&
 632             (((current->stime + current->utime) / HZ) >= current->rlim[RLIMIT_CPU].rlim_max))
 633                 send_sig(SIGKILL, current, 1);
 634         if ((current->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) &&
 635             (((current->stime + current->utime) % HZ) == 0)) {
 636                 psecs = (current->stime + current->utime) / HZ;
 637                 /* send when equal */
 638                 if (psecs == current->rlim[RLIMIT_CPU].rlim_cur)
 639                         send_sig(SIGXCPU, current, 1);
 640                 /* and every five seconds thereafter. */
 641                 else if ((psecs > current->rlim[RLIMIT_CPU].rlim_cur) &&
 642                         ((psecs - current->rlim[RLIMIT_CPU].rlim_cur) % 5) == 0)
 643                         send_sig(SIGXCPU, current, 1);
 644         }
 645 
 646         if (current != task[0] && 0 > --current->counter) {
 647                 current->counter = 0;
 648                 need_resched = 1;
 649         }
 650         /* Update ITIMER_PROF for the current task */
 651         if (current->it_prof_value && !(--current->it_prof_value)) {
 652                 current->it_prof_value = current->it_prof_incr;
 653                 send_sig(SIGPROF,current,1);
 654         }
 655         for (mask = 1, tp = timer_table+0 ; mask ; tp++,mask += mask) {
 656                 if (mask > timer_active)
 657                         break;
 658                 if (!(mask & timer_active))
 659                         continue;
 660                 if (tp->expires > jiffies)
 661                         continue;
 662                 mark_bh(TIMER_BH);
 663         }
 664         cli();
 665         itimer_ticks++;
 666         if (itimer_ticks > itimer_next)
 667                 need_resched = 1;
 668         if (timer_head.next->expires < jiffies)
 669                 mark_bh(TIMER_BH);
 670         if (tq_timer != &tq_last)
 671                 mark_bh(TQUEUE_BH);
 672         sti();
 673 }
 674 
 675 asmlinkage int sys_alarm(long seconds)
     /*  */
 676 {
 677         struct itimerval it_new, it_old;
 678 
 679         it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
 680         it_new.it_value.tv_sec = seconds;
 681         it_new.it_value.tv_usec = 0;
 682         _setitimer(ITIMER_REAL, &it_new, &it_old);
 683         return(it_old.it_value.tv_sec + (it_old.it_value.tv_usec / 1000000));
 684 }
 685 
 686 asmlinkage int sys_getpid(void)
     /*  */
 687 {
 688         return current->pid;
 689 }
 690 
 691 asmlinkage int sys_getppid(void)
     /*  */
 692 {
 693         return current->p_opptr->pid;
 694 }
 695 
 696 asmlinkage int sys_getuid(void)
     /*  */
 697 {
 698         return current->uid;
 699 }
 700 
 701 asmlinkage int sys_geteuid(void)
     /*  */
 702 {
 703         return current->euid;
 704 }
 705 
 706 asmlinkage int sys_getgid(void)
     /*  */
 707 {
 708         return current->gid;
 709 }
 710 
 711 asmlinkage int sys_getegid(void)
     /*  */
 712 {
 713         return current->egid;
 714 }
 715 
 716 asmlinkage int sys_nice(long increment)
     /*  */
 717 {
 718         int newprio;
 719 
 720         if (increment < 0 && !suser())
 721                 return -EPERM;
 722         newprio = current->priority - increment;
 723         if (newprio < 1)
 724                 newprio = 1;
 725         if (newprio > 35)
 726                 newprio = 35;
 727         current->priority = newprio;
 728         return 0;
 729 }
 730 
 731 static void show_task(int nr,struct task_struct * p)
     /*  */
 732 {
 733         unsigned long free;
 734         static char * stat_nam[] = { "R", "S", "D", "Z", "T", "W" };
 735 
 736         printk("%-8s %3d ", p->comm, (p == current) ? -nr : nr);
 737         if (((unsigned) p->state) < sizeof(stat_nam)/sizeof(char *))
 738                 printk(stat_nam[p->state]);
 739         else
 740                 printk(" ");
 741 #ifdef __i386__
 742         if (p == current)
 743                 printk(" current  ");
 744         else
 745                 printk(" %08lX ", ((unsigned long *)p->tss.esp)[3]);
 746 #endif
 747         for (free = 1; free < 1024 ; free++) {
 748                 if (((unsigned long *)p->kernel_stack_page)[free])
 749                         break;
 750         }
 751         printk("%5lu %5d %6d ", free << 2, p->pid, p->p_pptr->pid);
 752         if (p->p_cptr)
 753                 printk("%5d ", p->p_cptr->pid);
 754         else
 755                 printk("      ");
 756         if (p->p_ysptr)
 757                 printk("%7d", p->p_ysptr->pid);
 758         else
 759                 printk("       ");
 760         if (p->p_osptr)
 761                 printk(" %5d\n", p->p_osptr->pid);
 762         else
 763                 printk("\n");
 764 }
 765 
 766 void show_state(void)
     /*  */
 767 {
 768         int i;
 769 
 770         printk("                         free                        sibling\n");
 771         printk("  task             PC    stack   pid father child younger older\n");
 772         for (i=0 ; i<NR_TASKS ; i++)
 773                 if (task[i])
 774                         show_task(i,task[i]);
 775 }
 776 
 777 void sched_init(void)
     /*  */
 778 {
 779         bh_base[TIMER_BH].routine = timer_bh;
 780         bh_base[TQUEUE_BH].routine = tqueue_bh;
 781         bh_base[IMMEDIATE_BH].routine = immediate_bh;
 782         if (request_irq(TIMER_IRQ, do_timer, 0, "timer") != 0)
 783                 panic("Could not allocate timer IRQ!");
 784         enable_bh(TIMER_BH);
 785         enable_bh(TQUEUE_BH);
 786         enable_bh(IMMEDIATE_BH);
 787 }
/* */
root/kernel/sched.c

DEFINITIONS
