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

DEFINITIONS
