root/kernel/sched.c

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DEFINITIONS

This source file includes following definitions.
  1. sys_ni_syscall
  2. math_state_restore
  3. math_emulate
  4. schedule
  5. sys_pause
  6. wake_up
  7. wake_up_interruptible
  8. __sleep_on
  9. interruptible_sleep_on
  10. sleep_on
  11. add_timer
  12. del_timer
  13. count_active_tasks
  14. calc_load
  15. second_overflow
  16. timer_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/sys.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 
  28 #include <asm/system.h>
  29 #include <asm/io.h>
  30 #include <asm/segment.h>
  31 
  32 #define TIMER_IRQ 0
  33 
  34 #include <linux/timex.h>
  35 
  36 /*
  37  * kernel variables
  38  */
  39 long tick = 1000000 / HZ;               /* timer interrupt period */
  40 volatile struct timeval xtime;          /* The current time */
  41 int tickadj = 500/HZ;                   /* microsecs */
  42 
  43 /*
  44  * phase-lock loop variables
  45  */
  46 int time_status = TIME_BAD;     /* clock synchronization status */
  47 long time_offset = 0;           /* time adjustment (us) */
  48 long time_constant = 0;         /* pll time constant */
  49 long time_tolerance = MAXFREQ;  /* frequency tolerance (ppm) */
  50 long time_precision = 1;        /* clock precision (us) */
  51 long time_maxerror = 0x70000000;/* maximum error */
  52 long time_esterror = 0x70000000;/* estimated error */
  53 long time_phase = 0;            /* phase offset (scaled us) */
  54 long time_freq = 0;             /* frequency offset (scaled ppm) */
  55 long time_adj = 0;              /* tick adjust (scaled 1 / HZ) */
  56 long time_reftime = 0;          /* time at last adjustment (s) */
  57 
  58 long time_adjust = 0;
  59 
  60 int need_resched = 0;
  61 
  62 /*
  63  * Tell us the machine setup..
  64  */
  65 int hard_math = 0;              /* set by boot/head.S */
  66 int x86 = 0;                    /* set by boot/head.S to 3 or 4 */
  67 int ignore_irq13 = 0;           /* set if exception 16 works */
  68 int wp_works_ok = 0;            /* set if paging hardware honours WP */ 
  69 
  70 /*
  71  * Bus types ..
  72  */
  73 int EISA_bus = 0;
  74 
  75 extern int _setitimer(int, struct itimerval *, struct itimerval *);
  76 unsigned long * prof_buffer = NULL;
  77 unsigned long prof_len = 0;
  78 
  79 #define _S(nr) (1<<((nr)-1))
  80 
  81 extern void mem_use(void);
  82 
  83 extern int timer_interrupt(void);
  84 asmlinkage int system_call(void);
  85 
  86 static unsigned long init_kernel_stack[1024];
  87 struct task_struct init_task = INIT_TASK;
  88 
  89 unsigned long volatile jiffies=0;
  90 
  91 struct task_struct *current = &init_task;
  92 struct task_struct *last_task_used_math = NULL;
  93 
  94 struct task_struct * task[NR_TASKS] = {&init_task, };
  95 
  96 long user_stack [ PAGE_SIZE>>2 ] ;
  97 
  98 struct {
  99         long * a;
 100         short b;
 101         } stack_start = { & user_stack [PAGE_SIZE>>2] , KERNEL_DS };
 102 
 103 /*
 104  * int 0x80 entry points.. Moved away from the header file, as
 105  * iBCS2 may also want to use the '<linux/sys.h>' headers..
 106  */
 107 #ifdef __cplusplus
 108 extern "C" {
 109 #endif
 110 
 111 int sys_ni_syscall(void)
     /* [previous][next][first][last][top][bottom][index][help] */
 112 {
 113         return -EINVAL;
 114 }
 115 
 116 fn_ptr sys_call_table[] = { sys_setup, sys_exit, sys_fork, sys_read,
 117 sys_write, sys_open, sys_close, sys_waitpid, sys_creat, sys_link,
 118 sys_unlink, sys_execve, sys_chdir, sys_time, sys_mknod, sys_chmod,
 119 sys_chown, sys_break, sys_stat, sys_lseek, sys_getpid, sys_mount,
 120 sys_umount, sys_setuid, sys_getuid, sys_stime, sys_ptrace, sys_alarm,
 121 sys_fstat, sys_pause, sys_utime, sys_stty, sys_gtty, sys_access,
 122 sys_nice, sys_ftime, sys_sync, sys_kill, sys_rename, sys_mkdir,
 123 sys_rmdir, sys_dup, sys_pipe, sys_times, sys_prof, sys_brk, sys_setgid,
 124 sys_getgid, sys_signal, sys_geteuid, sys_getegid, sys_acct, sys_phys,
 125 sys_lock, sys_ioctl, sys_fcntl, sys_mpx, sys_setpgid, sys_ulimit,
 126 sys_olduname, sys_umask, sys_chroot, sys_ustat, sys_dup2, sys_getppid,
 127 sys_getpgrp, sys_setsid, sys_sigaction, sys_sgetmask, sys_ssetmask,
 128 sys_setreuid,sys_setregid, sys_sigsuspend, sys_sigpending,
 129 sys_sethostname, sys_setrlimit, sys_getrlimit, sys_getrusage,
 130 sys_gettimeofday, sys_settimeofday, sys_getgroups, sys_setgroups,
 131 sys_select, sys_symlink, sys_lstat, sys_readlink, sys_uselib,
 132 sys_swapon, sys_reboot, sys_readdir, sys_mmap, sys_munmap, sys_truncate,
 133 sys_ftruncate, sys_fchmod, sys_fchown, sys_getpriority, sys_setpriority,
 134 sys_profil, sys_statfs, sys_fstatfs, sys_ioperm, sys_socketcall,
 135 sys_syslog, sys_setitimer, sys_getitimer, sys_newstat, sys_newlstat,
 136 sys_newfstat, sys_uname, sys_iopl, sys_vhangup, sys_idle, sys_vm86,
 137 sys_wait4, sys_swapoff, sys_sysinfo, sys_ipc, sys_fsync, sys_sigreturn,
 138 sys_clone, sys_setdomainname, sys_newuname, sys_modify_ldt,
 139 sys_adjtimex, sys_mprotect, sys_sigprocmask, sys_create_module,
 140 sys_init_module, sys_delete_module, sys_get_kernel_syms, sys_quotactl,
 141 sys_getpgid, sys_fchdir };
 142 
 143 /* So we don't have to do any more manual updating.... */
 144 int NR_syscalls = sizeof(sys_call_table)/sizeof(fn_ptr);
 145 
 146 #ifdef __cplusplus
 147 }
 148 #endif
 149 
 150 /*
 151  *  'math_state_restore()' saves the current math information in the
 152  * old math state array, and gets the new ones from the current task
 153  *
 154  * Careful.. There are problems with IBM-designed IRQ13 behaviour.
 155  * Don't touch unless you *really* know how it works.
 156  */
 157 asmlinkage void math_state_restore(void)
     /* [previous][next][first][last][top][bottom][index][help] */
 158 {
 159         __asm__ __volatile__("clts");
 160         if (last_task_used_math == current)
 161                 return;
 162         timer_table[COPRO_TIMER].expires = jiffies+50;
 163         timer_active |= 1<<COPRO_TIMER; 
 164         if (last_task_used_math)
 165                 __asm__("fnsave %0":"=m" (last_task_used_math->tss.i387));
 166         else
 167                 __asm__("fnclex");
 168         last_task_used_math = current;
 169         if (current->used_math) {
 170                 __asm__("frstor %0": :"m" (current->tss.i387));
 171         } else {
 172                 __asm__("fninit");
 173                 current->used_math=1;
 174         }
 175         timer_active &= ~(1<<COPRO_TIMER);
 176 }
 177 
 178 #ifndef CONFIG_MATH_EMULATION
 179 
 180 asmlinkage void math_emulate(long arg)
     /* [previous][next][first][last][top][bottom][index][help] */
 181 {
 182   printk("math-emulation not enabled and no coprocessor found.\n");
 183   printk("killing %s.\n",current->comm);
 184   send_sig(SIGFPE,current,1);
 185   schedule();
 186 }
 187 
 188 #endif /* CONFIG_MATH_EMULATION */
 189 
 190 static unsigned long itimer_ticks = 0;
 191 static unsigned long itimer_next = ~0;
 192 static unsigned long lost_ticks = 0;
 193 
 194 /*
 195  *  'schedule()' is the scheduler function. It's a very simple and nice
 196  * scheduler: it's not perfect, but certainly works for most things.
 197  * The one thing you might take a look at is the signal-handler code here.
 198  *
 199  *   NOTE!!  Task 0 is the 'idle' task, which gets called when no other
 200  * tasks can run. It can not be killed, and it cannot sleep. The 'state'
 201  * information in task[0] is never used.
 202  *
 203  * The "confuse_gcc" goto is used only to get better assembly code..
 204  * Djikstra probably hates me.
 205  */
 206 asmlinkage void schedule(void)
     /* [previous][next][first][last][top][bottom][index][help] */
 207 {
 208         int c;
 209         struct task_struct * p;
 210         struct task_struct * next;
 211         unsigned long ticks;
 212 
 213 /* check alarm, wake up any interruptible tasks that have got a signal */
 214 
 215         cli();
 216         ticks = itimer_ticks;
 217         itimer_ticks = 0;
 218         itimer_next = ~0;
 219         sti();
 220         need_resched = 0;
 221         p = &init_task;
 222         for (;;) {
 223                 if ((p = p->next_task) == &init_task)
 224                         goto confuse_gcc1;
 225                 if (ticks && p->it_real_value) {
 226                         if (p->it_real_value <= ticks) {
 227                                 send_sig(SIGALRM, p, 1);
 228                                 if (!p->it_real_incr) {
 229                                         p->it_real_value = 0;
 230                                         goto end_itimer;
 231                                 }
 232                                 do {
 233                                         p->it_real_value += p->it_real_incr;
 234                                 } while (p->it_real_value <= ticks);
 235                         }
 236                         p->it_real_value -= ticks;
 237                         if (p->it_real_value < itimer_next)
 238                                 itimer_next = p->it_real_value;
 239                 }
 240 end_itimer:
 241                 if (p->state != TASK_INTERRUPTIBLE)
 242                         continue;
 243                 if (p->signal & ~p->blocked) {
 244                         p->state = TASK_RUNNING;
 245                         continue;
 246                 }
 247                 if (p->timeout && p->timeout <= jiffies) {
 248                         p->timeout = 0;
 249                         p->state = TASK_RUNNING;
 250                 }
 251         }
 252 confuse_gcc1:
 253 
 254 /* this is the scheduler proper: */
 255 #if 0
 256         /* give processes that go to sleep a bit higher priority.. */
 257         /* This depends on the values for TASK_XXX */
 258         /* This gives smoother scheduling for some things, but */
 259         /* can be very unfair under some circumstances, so.. */
 260         if (TASK_UNINTERRUPTIBLE >= (unsigned) current->state &&
 261             current->counter < current->priority*2) {
 262                 ++current->counter;
 263         }
 264 #endif
 265         c = -1;
 266         next = p = &init_task;
 267         for (;;) {
 268                 if ((p = p->next_task) == &init_task)
 269                         goto confuse_gcc2;
 270                 if (p->state == TASK_RUNNING && p->counter > c)
 271                         c = p->counter, next = p;
 272         }
 273 confuse_gcc2:
 274         if (!c) {
 275                 for_each_task(p)
 276                         p->counter = (p->counter >> 1) + p->priority;
 277         }
 278         switch_to(next);
 279         /* Now maybe reload the debug registers */
 280         if(current->debugreg[7]){
 281                 loaddebug(0);
 282                 loaddebug(1);
 283                 loaddebug(2);
 284                 loaddebug(3);
 285                 loaddebug(6);
 286         };
 287 }
 288 
 289 asmlinkage int sys_pause(void)
     /* [previous][next][first][last][top][bottom][index][help] */
 290 {
 291         current->state = TASK_INTERRUPTIBLE;
 292         schedule();
 293         return -ERESTARTNOHAND;
 294 }
 295 
 296 /*
 297  * wake_up doesn't wake up stopped processes - they have to be awakened
 298  * with signals or similar.
 299  *
 300  * Note that this doesn't need cli-sti pairs: interrupts may not change
 301  * the wait-queue structures directly, but only call wake_up() to wake
 302  * a process. The process itself must remove the queue once it has woken.
 303  */
 304 void wake_up(struct wait_queue **q)
     /* [previous][next][first][last][top][bottom][index][help] */
 305 {
 306         struct wait_queue *tmp;
 307         struct task_struct * p;
 308 
 309         if (!q || !(tmp = *q))
 310                 return;
 311         do {
 312                 if ((p = tmp->task) != NULL) {
 313                         if ((p->state == TASK_UNINTERRUPTIBLE) ||
 314                             (p->state == TASK_INTERRUPTIBLE)) {
 315                                 p->state = TASK_RUNNING;
 316                                 if (p->counter > current->counter)
 317                                         need_resched = 1;
 318                         }
 319                 }
 320                 if (!tmp->next) {
 321                         printk("wait_queue is bad (eip = %08lx)\n",((unsigned long *) q)[-1]);
 322                         printk("        q = %p\n",q);
 323                         printk("       *q = %p\n",*q);
 324                         printk("      tmp = %p\n",tmp);
 325                         break;
 326                 }
 327                 tmp = tmp->next;
 328         } while (tmp != *q);
 329 }
 330 
 331 void wake_up_interruptible(struct wait_queue **q)
     /* [previous][next][first][last][top][bottom][index][help] */
 332 {
 333         struct wait_queue *tmp;
 334         struct task_struct * p;
 335 
 336         if (!q || !(tmp = *q))
 337                 return;
 338         do {
 339                 if ((p = tmp->task) != NULL) {
 340                         if (p->state == TASK_INTERRUPTIBLE) {
 341                                 p->state = TASK_RUNNING;
 342                                 if (p->counter > current->counter)
 343                                         need_resched = 1;
 344                         }
 345                 }
 346                 if (!tmp->next) {
 347                         printk("wait_queue is bad (eip = %08lx)\n",((unsigned long *) q)[-1]);
 348                         printk("        q = %p\n",q);
 349                         printk("       *q = %p\n",*q);
 350                         printk("      tmp = %p\n",tmp);
 351                         break;
 352                 }
 353                 tmp = tmp->next;
 354         } while (tmp != *q);
 355 }
 356 
 357 static inline void __sleep_on(struct wait_queue **p, int state)
     /* [previous][next][first][last][top][bottom][index][help] */
 358 {
 359         unsigned long flags;
 360         struct wait_queue wait = { current, NULL };
 361 
 362         if (!p)
 363                 return;
 364         if (current == task[0])
 365                 panic("task[0] trying to sleep");
 366         current->state = state;
 367         add_wait_queue(p, &wait);
 368         save_flags(flags);
 369         sti();
 370         schedule();
 371         remove_wait_queue(p, &wait);
 372         restore_flags(flags);
 373 }
 374 
 375 void interruptible_sleep_on(struct wait_queue **p)
     /* [previous][next][first][last][top][bottom][index][help] */
 376 {
 377         __sleep_on(p,TASK_INTERRUPTIBLE);
 378 }
 379 
 380 void sleep_on(struct wait_queue **p)
     /* [previous][next][first][last][top][bottom][index][help] */
 381 {
 382         __sleep_on(p,TASK_UNINTERRUPTIBLE);
 383 }
 384 
 385 static struct timer_list * next_timer = NULL;
 386 
 387 void add_timer(struct timer_list * timer)
     /* [previous][next][first][last][top][bottom][index][help] */
 388 {
 389         unsigned long flags;
 390         struct timer_list ** p;
 391 
 392         if (!timer)
 393                 return;
 394         timer->next = NULL;
 395         p = &next_timer;
 396         save_flags(flags);
 397         cli();
 398         while (*p) {
 399                 if ((*p)->expires > timer->expires) {
 400                         (*p)->expires -= timer->expires;
 401                         timer->next = *p;
 402                         break;
 403                 }
 404                 timer->expires -= (*p)->expires;
 405                 p = &(*p)->next;
 406         }
 407         *p = timer;
 408         restore_flags(flags);
 409 }
 410 
 411 int del_timer(struct timer_list * timer)
     /* [previous][next][first][last][top][bottom][index][help] */
 412 {
 413         unsigned long flags;
 414         unsigned long expires = 0;
 415         struct timer_list **p;
 416 
 417         p = &next_timer;
 418         save_flags(flags);
 419         cli();
 420         while (*p) {
 421                 if (*p == timer) {
 422                         if ((*p = timer->next) != NULL)
 423                                 (*p)->expires += timer->expires;
 424                         timer->expires += expires;
 425                         restore_flags(flags);
 426                         return 1;
 427                 }
 428                 expires += (*p)->expires;
 429                 p = &(*p)->next;
 430         }
 431         restore_flags(flags);
 432         return 0;
 433 }
 434 
 435 unsigned long timer_active = 0;
 436 struct timer_struct timer_table[32];
 437 
 438 /*
 439  * Hmm.. Changed this, as the GNU make sources (load.c) seems to
 440  * imply that avenrun[] is the standard name for this kind of thing.
 441  * Nothing else seems to be standardized: the fractional size etc
 442  * all seem to differ on different machines.
 443  */
 444 unsigned long avenrun[3] = { 0,0,0 };
 445 
 446 /*
 447  * Nr of active tasks - counted in fixed-point numbers
 448  */
 449 static unsigned long count_active_tasks(void)
     /* [previous][next][first][last][top][bottom][index][help] */
 450 {
 451         struct task_struct **p;
 452         unsigned long nr = 0;
 453 
 454         for(p = &LAST_TASK; p > &FIRST_TASK; --p)
 455                 if (*p && ((*p)->state == TASK_RUNNING ||
 456                            (*p)->state == TASK_UNINTERRUPTIBLE ||
 457                            (*p)->state == TASK_SWAPPING))
 458                         nr += FIXED_1;
 459         return nr;
 460 }
 461 
 462 static inline void calc_load(void)
     /* [previous][next][first][last][top][bottom][index][help] */
 463 {
 464         unsigned long active_tasks; /* fixed-point */
 465         static int count = LOAD_FREQ;
 466 
 467         if (count-- > 0)
 468                 return;
 469         count = LOAD_FREQ;
 470         active_tasks = count_active_tasks();
 471         CALC_LOAD(avenrun[0], EXP_1, active_tasks);
 472         CALC_LOAD(avenrun[1], EXP_5, active_tasks);
 473         CALC_LOAD(avenrun[2], EXP_15, active_tasks);
 474 }
 475 
 476 /*
 477  * this routine handles the overflow of the microsecond field
 478  *
 479  * The tricky bits of code to handle the accurate clock support
 480  * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
 481  * They were originally developed for SUN and DEC kernels.
 482  * All the kudos should go to Dave for this stuff.
 483  *
 484  * These were ported to Linux by Philip Gladstone.
 485  */
 486 static void second_overflow(void)
     /* [previous][next][first][last][top][bottom][index][help] */
 487 {
 488         long ltemp;
 489         /* last time the cmos clock got updated */
 490         static long last_rtc_update=0;
 491         extern int set_rtc_mmss(unsigned long);
 492 
 493         /* Bump the maxerror field */
 494         time_maxerror = (0x70000000-time_maxerror < time_tolerance) ?
 495           0x70000000 : (time_maxerror + time_tolerance);
 496 
 497         /* Run the PLL */
 498         if (time_offset < 0) {
 499                 ltemp = (-(time_offset+1) >> (SHIFT_KG + time_constant)) + 1;
 500                 time_adj = ltemp << (SHIFT_SCALE - SHIFT_HZ - SHIFT_UPDATE);
 501                 time_offset += (time_adj * HZ) >> (SHIFT_SCALE - SHIFT_UPDATE);
 502                 time_adj = - time_adj;
 503         } else if (time_offset > 0) {
 504                 ltemp = ((time_offset-1) >> (SHIFT_KG + time_constant)) + 1;
 505                 time_adj = ltemp << (SHIFT_SCALE - SHIFT_HZ - SHIFT_UPDATE);
 506                 time_offset -= (time_adj * HZ) >> (SHIFT_SCALE - SHIFT_UPDATE);
 507         } else {
 508                 time_adj = 0;
 509         }
 510 
 511         time_adj += (time_freq >> (SHIFT_KF + SHIFT_HZ - SHIFT_SCALE))
 512             + FINETUNE;
 513 
 514         /* Handle the leap second stuff */
 515         switch (time_status) {
 516                 case TIME_INS:
 517                 /* ugly divide should be replaced */
 518                 if (xtime.tv_sec % 86400 == 0) {
 519                         xtime.tv_sec--; /* !! */
 520                         time_status = TIME_OOP;
 521                         printk("Clock: inserting leap second 23:59:60 GMT\n");
 522                 }
 523                 break;
 524 
 525                 case TIME_DEL:
 526                 /* ugly divide should be replaced */
 527                 if (xtime.tv_sec % 86400 == 86399) {
 528                         xtime.tv_sec++;
 529                         time_status = TIME_OK;
 530                         printk("Clock: deleting leap second 23:59:59 GMT\n");
 531                 }
 532                 break;
 533 
 534                 case TIME_OOP:
 535                 time_status = TIME_OK;
 536                 break;
 537         }
 538         if (xtime.tv_sec > last_rtc_update + 660)
 539           if (set_rtc_mmss(xtime.tv_sec) == 0)
 540             last_rtc_update = xtime.tv_sec;
 541 }
 542 
 543 /*
 544  * disregard lost ticks for now.. We don't care enough.
 545  */
 546 static void timer_bh(void * unused)
     /* [previous][next][first][last][top][bottom][index][help] */
 547 {
 548         unsigned long mask;
 549         struct timer_struct *tp;
 550 
 551         cli();
 552         while (next_timer && next_timer->expires == 0) {
 553                 void (*fn)(unsigned long) = next_timer->function;
 554                 unsigned long data = next_timer->data;
 555                 next_timer = next_timer->next;
 556                 sti();
 557                 fn(data);
 558                 cli();
 559         }
 560         sti();
 561         
 562         for (mask = 1, tp = timer_table+0 ; mask ; tp++,mask += mask) {
 563                 if (mask > timer_active)
 564                         break;
 565                 if (!(mask & timer_active))
 566                         continue;
 567                 if (tp->expires > jiffies)
 568                         continue;
 569                 timer_active &= ~mask;
 570                 tp->fn();
 571                 sti();
 572         }
 573 }
 574 
 575 /*
 576  * The int argument is really a (struct pt_regs *), in case the
 577  * interrupt wants to know from where it was called. The timer
 578  * irq uses this to decide if it should update the user or system
 579  * times.
 580  */
 581 static void do_timer(struct pt_regs * regs)
     /* [previous][next][first][last][top][bottom][index][help] */
 582 {
 583         unsigned long mask;
 584         struct timer_struct *tp;
 585 
 586         long ltemp;
 587 
 588         /* Advance the phase, once it gets to one microsecond, then
 589          * advance the tick more.
 590          */
 591         time_phase += time_adj;
 592         if (time_phase < -FINEUSEC) {
 593                 ltemp = -time_phase >> SHIFT_SCALE;
 594                 time_phase += ltemp << SHIFT_SCALE;
 595                 xtime.tv_usec += tick - ltemp;
 596         }
 597         else if (time_phase > FINEUSEC) {
 598                 ltemp = time_phase >> SHIFT_SCALE;
 599                 time_phase -= ltemp << SHIFT_SCALE;
 600                 xtime.tv_usec += tick + ltemp;
 601         } else
 602                 xtime.tv_usec += tick;
 603 
 604         if (time_adjust)
 605         {
 606             /* We are doing an adjtime thing. 
 607              */
 608 
 609             /* Limit the amount of the step for *next* tick to be
 610              * in the range -tickadj .. +tickadj
 611              */
 612              if (time_adjust > tickadj)
 613                ltemp = tickadj;
 614              else if (time_adjust < -tickadj)
 615                ltemp = -tickadj;
 616              else
 617                ltemp = time_adjust;
 618              
 619             /* Reduce the amount of time left by this step */
 620             time_adjust -= ltemp;
 621 
 622             /* Modify the value of the tick for next time.
 623              * Note that a positive delta means we want the clock
 624              * to run fast. This means that the tick should be bigger
 625              */
 626             tick = 1000000/HZ + ltemp;
 627         }
 628         else
 629             tick = 1000000/HZ;
 630 
 631         if (xtime.tv_usec >= 1000000) {
 632             xtime.tv_usec -= 1000000;
 633             xtime.tv_sec++;
 634             second_overflow();
 635         }
 636 
 637         jiffies++;
 638         calc_load();
 639         if ((VM_MASK & regs->eflags) || (3 & regs->cs)) {
 640                 current->utime++;
 641                 /* Update ITIMER_VIRT for current task if not in a system call */
 642                 if (current->it_virt_value && !(--current->it_virt_value)) {
 643                         current->it_virt_value = current->it_virt_incr;
 644                         send_sig(SIGVTALRM,current,1);
 645                 }
 646         } else {
 647                 current->stime++;
 648 #ifdef CONFIG_PROFILE
 649                 if (prof_buffer && current != task[0]) {
 650                         unsigned long eip = regs->eip;
 651                         eip >>= 2;
 652                         if (eip < prof_len)
 653                                 prof_buffer[eip]++;
 654                 }
 655 #endif
 656         }
 657         if (current == task[0] || (--current->counter)<=0) {
 658                 current->counter=0;
 659                 need_resched = 1;
 660         }
 661         /* Update ITIMER_PROF for the current task */
 662         if (current->it_prof_value && !(--current->it_prof_value)) {
 663                 current->it_prof_value = current->it_prof_incr;
 664                 send_sig(SIGPROF,current,1);
 665         }
 666         for (mask = 1, tp = timer_table+0 ; mask ; tp++,mask += mask) {
 667                 if (mask > timer_active)
 668                         break;
 669                 if (!(mask & timer_active))
 670                         continue;
 671                 if (tp->expires > jiffies)
 672                         continue;
 673                 mark_bh(TIMER_BH);
 674         }
 675         cli();
 676         itimer_ticks++;
 677         if (itimer_ticks > itimer_next)
 678                 need_resched = 1;
 679         if (next_timer) {
 680                 if (next_timer->expires) {
 681                         next_timer->expires--;
 682                         if (!next_timer->expires)
 683                                 mark_bh(TIMER_BH);
 684                 } else {
 685                         lost_ticks++;
 686                         mark_bh(TIMER_BH);
 687                 }
 688         }
 689         sti();
 690 }
 691 
 692 asmlinkage int sys_alarm(long seconds)
     /* [previous][next][first][last][top][bottom][index][help] */
 693 {
 694         struct itimerval it_new, it_old;
 695 
 696         it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
 697         it_new.it_value.tv_sec = seconds;
 698         it_new.it_value.tv_usec = 0;
 699         _setitimer(ITIMER_REAL, &it_new, &it_old);
 700         return(it_old.it_value.tv_sec + (it_old.it_value.tv_usec / 1000000));
 701 }
 702 
 703 asmlinkage int sys_getpid(void)
     /* [previous][next][first][last][top][bottom][index][help] */
 704 {
 705         return current->pid;
 706 }
 707 
 708 asmlinkage int sys_getppid(void)
     /* [previous][next][first][last][top][bottom][index][help] */
 709 {
 710         return current->p_opptr->pid;
 711 }
 712 
 713 asmlinkage int sys_getuid(void)
     /* [previous][next][first][last][top][bottom][index][help] */
 714 {
 715         return current->uid;
 716 }
 717 
 718 asmlinkage int sys_geteuid(void)
     /* [previous][next][first][last][top][bottom][index][help] */
 719 {
 720         return current->euid;
 721 }
 722 
 723 asmlinkage int sys_getgid(void)
     /* [previous][next][first][last][top][bottom][index][help] */
 724 {
 725         return current->gid;
 726 }
 727 
 728 asmlinkage int sys_getegid(void)
     /* [previous][next][first][last][top][bottom][index][help] */
 729 {
 730         return current->egid;
 731 }
 732 
 733 asmlinkage int sys_nice(long increment)
     /* [previous][next][first][last][top][bottom][index][help] */
 734 {
 735         int newprio;
 736 
 737         if (increment < 0 && !suser())
 738                 return -EPERM;
 739         newprio = current->priority - increment;
 740         if (newprio < 1)
 741                 newprio = 1;
 742         if (newprio > 35)
 743                 newprio = 35;
 744         current->priority = newprio;
 745         return 0;
 746 }
 747 
 748 static void show_task(int nr,struct task_struct * p)
     /* [previous][next][first][last][top][bottom][index][help] */
 749 {
 750         static char * stat_nam[] = { "R", "S", "D", "Z", "T", "W" };
 751 
 752         printk("%-8s %3d ", p->comm, (p == current) ? -nr : nr);
 753         if (((unsigned) p->state) < sizeof(stat_nam)/sizeof(char *))
 754                 printk(stat_nam[p->state]);
 755         else
 756                 printk(" ");
 757         if (p == current)
 758                 printk(" current  ");
 759         else
 760                 printk(" %08lX ", ((unsigned long *)p->tss.esp)[3]);
 761         printk("%5lu %5d %6d ",
 762                 p->tss.esp - p->kernel_stack_page, p->pid, p->p_pptr->pid);
 763         if (p->p_cptr)
 764                 printk("%5d ", p->p_cptr->pid);
 765         else
 766                 printk("      ");
 767         if (p->p_ysptr)
 768                 printk("%7d", p->p_ysptr->pid);
 769         else
 770                 printk("       ");
 771         if (p->p_osptr)
 772                 printk(" %5d\n", p->p_osptr->pid);
 773         else
 774                 printk("\n");
 775 }
 776 
 777 void show_state(void)
     /* [previous][next][first][last][top][bottom][index][help] */
 778 {
 779         int i;
 780 
 781         printk("                         free                        sibling\n");
 782         printk("  task             PC    stack   pid father child younger older\n");
 783         for (i=0 ; i<NR_TASKS ; i++)
 784                 if (task[i])
 785                         show_task(i,task[i]);
 786 }
 787 
 788 void sched_init(void)
     /* [previous][next][first][last][top][bottom][index][help] */
 789 {
 790         int i;
 791         struct desc_struct * p;
 792 
 793         bh_base[TIMER_BH].routine = timer_bh;
 794         if (sizeof(struct sigaction) != 16)
 795                 panic("Struct sigaction MUST be 16 bytes");
 796         set_tss_desc(gdt+FIRST_TSS_ENTRY,&init_task.tss);
 797         set_ldt_desc(gdt+FIRST_LDT_ENTRY,&default_ldt,1);
 798         set_system_gate(0x80,&system_call);
 799         p = gdt+2+FIRST_TSS_ENTRY;
 800         for(i=1 ; i<NR_TASKS ; i++) {
 801                 task[i] = NULL;
 802                 p->a=p->b=0;
 803                 p++;
 804                 p->a=p->b=0;
 805                 p++;
 806         }
 807 /* Clear NT, so that we won't have troubles with that later on */
 808         __asm__("pushfl ; andl $0xffffbfff,(%esp) ; popfl");
 809         load_TR(0);
 810         load_ldt(0);
 811         outb_p(0x34,0x43);              /* binary, mode 2, LSB/MSB, ch 0 */
 812         outb_p(LATCH & 0xff , 0x40);    /* LSB */
 813         outb(LATCH >> 8 , 0x40);        /* MSB */
 814         if (request_irq(TIMER_IRQ,(void (*)(int)) do_timer)!=0)
 815                 panic("Could not allocate timer IRQ!");
 816 }

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