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

DEFINITIONS
