kernel/sched.c

/* */
This source file includes following definitions.
sys_ni_syscall
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
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/sys.h>
  21 #include <linux/fdreg.h>
  22 #include <linux/errno.h>
  23 #include <linux/time.h>
  24 #include <linux/ptrace.h>
  25 #include <linux/segment.h>
  26 #include <linux/delay.h>
  27 #include <linux/interrupt.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 /*
  45  * phase-lock loop variables
  46  */
  47 int time_status = TIME_BAD;     /* clock synchronization status */
  48 long time_offset = 0;           /* time adjustment (us) */
  49 long time_constant = 0;         /* pll time constant */
  50 long time_tolerance = MAXFREQ;  /* frequency tolerance (ppm) */
  51 long time_precision = 1;        /* clock precision (us) */
  52 long time_maxerror = 0x70000000;/* maximum error */
  53 long time_esterror = 0x70000000;/* estimated error */
  54 long time_phase = 0;            /* phase offset (scaled us) */
  55 long time_freq = 0;             /* frequency offset (scaled ppm) */
  56 long time_adj = 0;              /* tick adjust (scaled 1 / HZ) */
  57 long time_reftime = 0;          /* time at last adjustment (s) */
  58 
  59 long time_adjust = 0;
  60 long time_adjust_step = 0;
  61 
  62 int need_resched = 0;
  63 
  64 /*
  65  * Tell us the machine setup..
  66  */
  67 int hard_math = 0;              /* set by boot/head.S */
  68 int x86 = 0;                    /* set by boot/head.S to 3 or 4 */
  69 int ignore_irq13 = 0;           /* set if exception 16 works */
  70 int wp_works_ok = 0;            /* set if paging hardware honours WP */ 
  71 
  72 /*
  73  * Bus types ..
  74  */
  75 int EISA_bus = 0;
  76 
  77 extern int _setitimer(int, struct itimerval *, struct itimerval *);
  78 unsigned long * prof_buffer = NULL;
  79 unsigned long prof_len = 0;
  80 
  81 #define _S(nr) (1<<((nr)-1))
  82 
  83 extern void mem_use(void);
  84 
  85 extern int timer_interrupt(void);
  86 asmlinkage int system_call(void);
  87 
  88 static unsigned long init_kernel_stack[1024] = { STACK_MAGIC, };
  89 struct task_struct init_task = INIT_TASK;
  90 
  91 unsigned long volatile jiffies=0;
  92 
  93 struct task_struct *current = &init_task;
  94 struct task_struct *last_task_used_math = NULL;
  95 
  96 struct task_struct * task[NR_TASKS] = {&init_task, };
  97 
  98 long user_stack [ PAGE_SIZE>>2 ] = { STACK_MAGIC, };
  99 
 100 struct {
 101         long * a;
 102         short b;
 103         } stack_start = { & user_stack [PAGE_SIZE>>2] , KERNEL_DS };
 104 
 105 struct kernel_stat kstat =
 106         { 0, 0, 0, { 0, 0, 0, 0 }, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
 107 
 108 /*
 109  * int 0x80 entry points.. Moved away from the header file, as
 110  * iBCS2 may also want to use the '<linux/sys.h>' headers..
 111  */
 112 #ifdef __cplusplus
 113 extern "C" {
 114 #endif
 115 
 116 int sys_ni_syscall(void)
     /*  */
 117 {
 118         return -EINVAL;
 119 }
 120 
 121 fn_ptr sys_call_table[] = { sys_setup, sys_exit, sys_fork, sys_read,
 122 sys_write, sys_open, sys_close, sys_waitpid, sys_creat, sys_link,
 123 sys_unlink, sys_execve, sys_chdir, sys_time, sys_mknod, sys_chmod,
 124 sys_chown, sys_break, sys_stat, sys_lseek, sys_getpid, sys_mount,
 125 sys_umount, sys_setuid, sys_getuid, sys_stime, sys_ptrace, sys_alarm,
 126 sys_fstat, sys_pause, sys_utime, sys_stty, sys_gtty, sys_access,
 127 sys_nice, sys_ftime, sys_sync, sys_kill, sys_rename, sys_mkdir,
 128 sys_rmdir, sys_dup, sys_pipe, sys_times, sys_prof, sys_brk, sys_setgid,
 129 sys_getgid, sys_signal, sys_geteuid, sys_getegid, sys_acct, sys_phys,
 130 sys_lock, sys_ioctl, sys_fcntl, sys_mpx, sys_setpgid, sys_ulimit,
 131 sys_olduname, sys_umask, sys_chroot, sys_ustat, sys_dup2, sys_getppid,
 132 sys_getpgrp, sys_setsid, sys_sigaction, sys_sgetmask, sys_ssetmask,
 133 sys_setreuid,sys_setregid, sys_sigsuspend, sys_sigpending,
 134 sys_sethostname, sys_setrlimit, sys_getrlimit, sys_getrusage,
 135 sys_gettimeofday, sys_settimeofday, sys_getgroups, sys_setgroups,
 136 sys_select, sys_symlink, sys_lstat, sys_readlink, sys_uselib,
 137 sys_swapon, sys_reboot, sys_readdir, sys_mmap, sys_munmap, sys_truncate,
 138 sys_ftruncate, sys_fchmod, sys_fchown, sys_getpriority, sys_setpriority,
 139 sys_profil, sys_statfs, sys_fstatfs, sys_ioperm, sys_socketcall,
 140 sys_syslog, sys_setitimer, sys_getitimer, sys_newstat, sys_newlstat,
 141 sys_newfstat, sys_uname, sys_iopl, sys_vhangup, sys_idle, sys_vm86,
 142 sys_wait4, sys_swapoff, sys_sysinfo, sys_ipc, sys_fsync, sys_sigreturn,
 143 sys_clone, sys_setdomainname, sys_newuname, sys_modify_ldt,
 144 sys_adjtimex, sys_mprotect, sys_sigprocmask, sys_create_module,
 145 sys_init_module, sys_delete_module, sys_get_kernel_syms, sys_quotactl,
 146 sys_getpgid, sys_fchdir, sys_bdflush };
 147 
 148 /* So we don't have to do any more manual updating.... */
 149 int NR_syscalls = sizeof(sys_call_table)/sizeof(fn_ptr);
 150 
 151 #ifdef __cplusplus
 152 }
 153 #endif
 154 
 155 /*
 156  *  'math_state_restore()' saves the current math information in the
 157  * old math state array, and gets the new ones from the current task
 158  *
 159  * Careful.. There are problems with IBM-designed IRQ13 behaviour.
 160  * Don't touch unless you *really* know how it works.
 161  */
 162 asmlinkage void math_state_restore(void)
     /*  */
 163 {
 164         __asm__ __volatile__("clts");
 165         if (last_task_used_math == current)
 166                 return;
 167         timer_table[COPRO_TIMER].expires = jiffies+50;
 168         timer_active |= 1<<COPRO_TIMER; 
 169         if (last_task_used_math)
 170                 __asm__("fnsave %0":"=m" (last_task_used_math->tss.i387));
 171         else
 172                 __asm__("fnclex");
 173         last_task_used_math = current;
 174         if (current->used_math) {
 175                 __asm__("frstor %0": :"m" (current->tss.i387));
 176         } else {
 177                 __asm__("fninit");
 178                 current->used_math=1;
 179         }
 180         timer_active &= ~(1<<COPRO_TIMER);
 181 }
 182 
 183 #ifndef CONFIG_MATH_EMULATION
 184 
 185 asmlinkage void math_emulate(long arg)
     /*  */
 186 {
 187   printk("math-emulation not enabled and no coprocessor found.\n");
 188   printk("killing %s.\n",current->comm);
 189   send_sig(SIGFPE,current,1);
 190   schedule();
 191 }
 192 
 193 #endif /* CONFIG_MATH_EMULATION */
 194 
 195 unsigned long itimer_ticks = 0;
 196 unsigned long itimer_next = ~0;
 197 static unsigned long lost_ticks = 0;
 198 
 199 /*
 200  *  'schedule()' is the scheduler function. It's a very simple and nice
 201  * scheduler: it's not perfect, but certainly works for most things.
 202  * The one thing you might take a look at is the signal-handler code here.
 203  *
 204  *   NOTE!!  Task 0 is the 'idle' task, which gets called when no other
 205  * tasks can run. It can not be killed, and it cannot sleep. The 'state'
 206  * information in task[0] is never used.
 207  *
 208  * The "confuse_gcc" goto is used only to get better assembly code..
 209  * Djikstra probably hates me.
 210  */
 211 asmlinkage void schedule(void)
     /*  */
 212 {
 213         int c;
 214         struct task_struct * p;
 215         struct task_struct * next;
 216         unsigned long ticks;
 217 
 218 /* check alarm, wake up any interruptible tasks that have got a signal */
 219 
 220         if (intr_count) {
 221                 printk("Aiee: scheduling in interrupt\n");
 222                 intr_count = 0;
 223         }
 224         cli();
 225         ticks = itimer_ticks;
 226         itimer_ticks = 0;
 227         itimer_next = ~0;
 228         sti();
 229         need_resched = 0;
 230         p = &init_task;
 231         for (;;) {
 232                 if ((p = p->next_task) == &init_task)
 233                         goto confuse_gcc1;
 234                 if (ticks && p->it_real_value) {
 235                         if (p->it_real_value <= ticks) {
 236                                 send_sig(SIGALRM, p, 1);
 237                                 if (!p->it_real_incr) {
 238                                         p->it_real_value = 0;
 239                                         goto end_itimer;
 240                                 }
 241                                 do {
 242                                         p->it_real_value += p->it_real_incr;
 243                                 } while (p->it_real_value <= ticks);
 244                         }
 245                         p->it_real_value -= ticks;
 246                         if (p->it_real_value < itimer_next)
 247                                 itimer_next = p->it_real_value;
 248                 }
 249 end_itimer:
 250                 if (p->state != TASK_INTERRUPTIBLE)
 251                         continue;
 252                 if (p->signal & ~p->blocked) {
 253                         p->state = TASK_RUNNING;
 254                         continue;
 255                 }
 256                 if (p->timeout && p->timeout <= jiffies) {
 257                         p->timeout = 0;
 258                         p->state = TASK_RUNNING;
 259                 }
 260         }
 261 confuse_gcc1:
 262 
 263 /* this is the scheduler proper: */
 264 #if 0
 265         /* give processes that go to sleep a bit higher priority.. */
 266         /* This depends on the values for TASK_XXX */
 267         /* This gives smoother scheduling for some things, but */
 268         /* can be very unfair under some circumstances, so.. */
 269         if (TASK_UNINTERRUPTIBLE >= (unsigned) current->state &&
 270             current->counter < current->priority*2) {
 271                 ++current->counter;
 272         }
 273 #endif
 274         c = -1;
 275         next = p = &init_task;
 276         for (;;) {
 277                 if ((p = p->next_task) == &init_task)
 278                         goto confuse_gcc2;
 279                 if (p->state == TASK_RUNNING && p->counter > c)
 280                         c = p->counter, next = p;
 281         }
 282 confuse_gcc2:
 283         if (!c) {
 284                 for_each_task(p)
 285                         p->counter = (p->counter >> 1) + p->priority;
 286         }
 287         if(current != next)
 288                 kstat.context_swtch++;
 289         switch_to(next);
 290         /* Now maybe reload the debug registers */
 291         if(current->debugreg[7]){
 292                 loaddebug(0);
 293                 loaddebug(1);
 294                 loaddebug(2);
 295                 loaddebug(3);
 296                 loaddebug(6);
 297         };
 298 }
 299 
 300 asmlinkage int sys_pause(void)
     /*  */
 301 {
 302         current->state = TASK_INTERRUPTIBLE;
 303         schedule();
 304         return -ERESTARTNOHAND;
 305 }
 306 
 307 /*
 308  * wake_up doesn't wake up stopped processes - they have to be awakened
 309  * with signals or similar.
 310  *
 311  * Note that this doesn't need cli-sti pairs: interrupts may not change
 312  * the wait-queue structures directly, but only call wake_up() to wake
 313  * a process. The process itself must remove the queue once it has woken.
 314  */
 315 void wake_up(struct wait_queue **q)
     /*  */
 316 {
 317         struct wait_queue *tmp;
 318         struct task_struct * p;
 319 
 320         if (!q || !(tmp = *q))
 321                 return;
 322         do {
 323                 if ((p = tmp->task) != NULL) {
 324                         if ((p->state == TASK_UNINTERRUPTIBLE) ||
 325                             (p->state == TASK_INTERRUPTIBLE)) {
 326                                 p->state = TASK_RUNNING;
 327                                 if (p->counter > current->counter)
 328                                         need_resched = 1;
 329                         }
 330                 }
 331                 if (!tmp->next) {
 332                         printk("wait_queue is bad (eip = %08lx)\n",((unsigned long *) q)[-1]);
 333                         printk("        q = %p\n",q);
 334                         printk("       *q = %p\n",*q);
 335                         printk("      tmp = %p\n",tmp);
 336                         break;
 337                 }
 338                 tmp = tmp->next;
 339         } while (tmp != *q);
 340 }
 341 
 342 void wake_up_interruptible(struct wait_queue **q)
     /*  */
 343 {
 344         struct wait_queue *tmp;
 345         struct task_struct * p;
 346 
 347         if (!q || !(tmp = *q))
 348                 return;
 349         do {
 350                 if ((p = tmp->task) != NULL) {
 351                         if (p->state == TASK_INTERRUPTIBLE) {
 352                                 p->state = TASK_RUNNING;
 353                                 if (p->counter > current->counter)
 354                                         need_resched = 1;
 355                         }
 356                 }
 357                 if (!tmp->next) {
 358                         printk("wait_queue is bad (eip = %08lx)\n",((unsigned long *) q)[-1]);
 359                         printk("        q = %p\n",q);
 360                         printk("       *q = %p\n",*q);
 361                         printk("      tmp = %p\n",tmp);
 362                         break;
 363                 }
 364                 tmp = tmp->next;
 365         } while (tmp != *q);
 366 }
 367 
 368 void __down(struct semaphore * sem)
     /*  */
 369 {
 370         struct wait_queue wait = { current, NULL };
 371         add_wait_queue(&sem->wait, &wait);
 372         current->state = TASK_UNINTERRUPTIBLE;
 373         while (sem->count <= 0) {
 374                 schedule();
 375                 current->state = TASK_UNINTERRUPTIBLE;
 376         }
 377         current->state = TASK_RUNNING;
 378         remove_wait_queue(&sem->wait, &wait);
 379 }
 380 
 381 static inline void __sleep_on(struct wait_queue **p, int state)
     /*  */
 382 {
 383         unsigned long flags;
 384         struct wait_queue wait = { current, NULL };
 385 
 386         if (!p)
 387                 return;
 388         if (current == task[0])
 389                 panic("task[0] trying to sleep");
 390         current->state = state;
 391         add_wait_queue(p, &wait);
 392         save_flags(flags);
 393         sti();
 394         schedule();
 395         remove_wait_queue(p, &wait);
 396         restore_flags(flags);
 397 }
 398 
 399 void interruptible_sleep_on(struct wait_queue **p)
     /*  */
 400 {
 401         __sleep_on(p,TASK_INTERRUPTIBLE);
 402 }
 403 
 404 void sleep_on(struct wait_queue **p)
     /*  */
 405 {
 406         __sleep_on(p,TASK_UNINTERRUPTIBLE);
 407 }
 408 
 409 static struct timer_list * next_timer = NULL;
 410 
 411 void add_timer(struct timer_list * timer)
     /*  */
 412 {
 413         unsigned long flags;
 414         struct timer_list ** p;
 415 
 416         if (!timer)
 417                 return;
 418         timer->next = NULL;
 419         p = &next_timer;
 420         save_flags(flags);
 421         cli();
 422         while (*p) {
 423                 if ((*p)->expires > timer->expires) {
 424                         (*p)->expires -= timer->expires;
 425                         timer->next = *p;
 426                         break;
 427                 }
 428                 timer->expires -= (*p)->expires;
 429                 p = &(*p)->next;
 430         }
 431         *p = timer;
 432         restore_flags(flags);
 433 }
 434 
 435 int del_timer(struct timer_list * timer)
     /*  */
 436 {
 437         unsigned long flags;
 438         unsigned long expires = 0;
 439         struct timer_list **p;
 440 
 441         p = &next_timer;
 442         save_flags(flags);
 443         cli();
 444         while (*p) {
 445                 if (*p == timer) {
 446                         if ((*p = timer->next) != NULL)
 447                                 (*p)->expires += timer->expires;
 448                         timer->expires += expires;
 449                         restore_flags(flags);
 450                         return 1;
 451                 }
 452                 expires += (*p)->expires;
 453                 p = &(*p)->next;
 454         }
 455         restore_flags(flags);
 456         return 0;
 457 }
 458 
 459 unsigned long timer_active = 0;
 460 struct timer_struct timer_table[32];
 461 
 462 /*
 463  * Hmm.. Changed this, as the GNU make sources (load.c) seems to
 464  * imply that avenrun[] is the standard name for this kind of thing.
 465  * Nothing else seems to be standardized: the fractional size etc
 466  * all seem to differ on different machines.
 467  */
 468 unsigned long avenrun[3] = { 0,0,0 };
 469 
 470 /*
 471  * Nr of active tasks - counted in fixed-point numbers
 472  */
 473 static unsigned long count_active_tasks(void)
     /*  */
 474 {
 475         struct task_struct **p;
 476         unsigned long nr = 0;
 477 
 478         for(p = &LAST_TASK; p > &FIRST_TASK; --p)
 479                 if (*p && ((*p)->state == TASK_RUNNING ||
 480                            (*p)->state == TASK_UNINTERRUPTIBLE ||
 481                            (*p)->state == TASK_SWAPPING))
 482                         nr += FIXED_1;
 483         return nr;
 484 }
 485 
 486 static inline void calc_load(void)
     /*  */
 487 {
 488         unsigned long active_tasks; /* fixed-point */
 489         static int count = LOAD_FREQ;
 490 
 491         if (count-- > 0)
 492                 return;
 493         count = LOAD_FREQ;
 494         active_tasks = count_active_tasks();
 495         CALC_LOAD(avenrun[0], EXP_1, active_tasks);
 496         CALC_LOAD(avenrun[1], EXP_5, active_tasks);
 497         CALC_LOAD(avenrun[2], EXP_15, active_tasks);
 498 }
 499 
 500 /*
 501  * this routine handles the overflow of the microsecond field
 502  *
 503  * The tricky bits of code to handle the accurate clock support
 504  * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
 505  * They were originally developed for SUN and DEC kernels.
 506  * All the kudos should go to Dave for this stuff.
 507  *
 508  * These were ported to Linux by Philip Gladstone.
 509  */
 510 static void second_overflow(void)
     /*  */
 511 {
 512         long ltemp;
 513         /* last time the cmos clock got updated */
 514         static long last_rtc_update=0;
 515         extern int set_rtc_mmss(unsigned long);
 516 
 517         /* Bump the maxerror field */
 518         time_maxerror = (0x70000000-time_maxerror < time_tolerance) ?
 519           0x70000000 : (time_maxerror + time_tolerance);
 520 
 521         /* Run the PLL */
 522         if (time_offset < 0) {
 523                 ltemp = (-(time_offset+1) >> (SHIFT_KG + time_constant)) + 1;
 524                 time_adj = ltemp << (SHIFT_SCALE - SHIFT_HZ - SHIFT_UPDATE);
 525                 time_offset += (time_adj * HZ) >> (SHIFT_SCALE - SHIFT_UPDATE);
 526                 time_adj = - time_adj;
 527         } else if (time_offset > 0) {
 528                 ltemp = ((time_offset-1) >> (SHIFT_KG + time_constant)) + 1;
 529                 time_adj = ltemp << (SHIFT_SCALE - SHIFT_HZ - SHIFT_UPDATE);
 530                 time_offset -= (time_adj * HZ) >> (SHIFT_SCALE - SHIFT_UPDATE);
 531         } else {
 532                 time_adj = 0;
 533         }
 534 
 535         time_adj += (time_freq >> (SHIFT_KF + SHIFT_HZ - SHIFT_SCALE))
 536             + FINETUNE;
 537 
 538         /* Handle the leap second stuff */
 539         switch (time_status) {
 540                 case TIME_INS:
 541                 /* ugly divide should be replaced */
 542                 if (xtime.tv_sec % 86400 == 0) {
 543                         xtime.tv_sec--; /* !! */
 544                         time_status = TIME_OOP;
 545                         printk("Clock: inserting leap second 23:59:60 GMT\n");
 546                 }
 547                 break;
 548 
 549                 case TIME_DEL:
 550                 /* ugly divide should be replaced */
 551                 if (xtime.tv_sec % 86400 == 86399) {
 552                         xtime.tv_sec++;
 553                         time_status = TIME_OK;
 554                         printk("Clock: deleting leap second 23:59:59 GMT\n");
 555                 }
 556                 break;
 557 
 558                 case TIME_OOP:
 559                 time_status = TIME_OK;
 560                 break;
 561         }
 562         if (xtime.tv_sec > last_rtc_update + 660)
 563           if (set_rtc_mmss(xtime.tv_sec) == 0)
 564             last_rtc_update = xtime.tv_sec;
 565 }
 566 
 567 /*
 568  * disregard lost ticks for now.. We don't care enough.
 569  */
 570 static void timer_bh(void * unused)
     /*  */
 571 {
 572         unsigned long mask;
 573         struct timer_struct *tp;
 574 
 575         cli();
 576         while (next_timer && next_timer->expires == 0) {
 577                 void (*fn)(unsigned long) = next_timer->function;
 578                 unsigned long data = next_timer->data;
 579                 next_timer = next_timer->next;
 580                 sti();
 581                 fn(data);
 582                 cli();
 583         }
 584         sti();
 585         
 586         for (mask = 1, tp = timer_table+0 ; mask ; tp++,mask += mask) {
 587                 if (mask > timer_active)
 588                         break;
 589                 if (!(mask & timer_active))
 590                         continue;
 591                 if (tp->expires > jiffies)
 592                         continue;
 593                 timer_active &= ~mask;
 594                 tp->fn();
 595                 sti();
 596         }
 597 }
 598 
 599 /*
 600  * The int argument is really a (struct pt_regs *), in case the
 601  * interrupt wants to know from where it was called. The timer
 602  * irq uses this to decide if it should update the user or system
 603  * times.
 604  */
 605 static void do_timer(struct pt_regs * regs)
     /*  */
 606 {
 607         unsigned long mask;
 608         struct timer_struct *tp;
 609 
 610         long ltemp;
 611 
 612         /* Advance the phase, once it gets to one microsecond, then
 613          * advance the tick more.
 614          */
 615         time_phase += time_adj;
 616         if (time_phase < -FINEUSEC) {
 617                 ltemp = -time_phase >> SHIFT_SCALE;
 618                 time_phase += ltemp << SHIFT_SCALE;
 619                 xtime.tv_usec += tick + time_adjust_step - ltemp;
 620         }
 621         else if (time_phase > FINEUSEC) {
 622                 ltemp = time_phase >> SHIFT_SCALE;
 623                 time_phase -= ltemp << SHIFT_SCALE;
 624                 xtime.tv_usec += tick + time_adjust_step + ltemp;
 625         } else
 626                 xtime.tv_usec += tick + time_adjust_step;
 627 
 628         if (time_adjust)
 629         {
 630             /* We are doing an adjtime thing. 
 631              *
 632              * Modify the value of the tick for next time.
 633              * Note that a positive delta means we want the clock
 634              * to run fast. This means that the tick should be bigger
 635              *
 636              * Limit the amount of the step for *next* tick to be
 637              * in the range -tickadj .. +tickadj
 638              */
 639              if (time_adjust > tickadj)
 640                time_adjust_step = tickadj;
 641              else if (time_adjust < -tickadj)
 642                time_adjust_step = -tickadj;
 643              else
 644                time_adjust_step = time_adjust;
 645              
 646             /* Reduce by this step the amount of time left  */
 647             time_adjust -= time_adjust_step;
 648         }
 649         else
 650             time_adjust_step = 0;
 651 
 652         if (xtime.tv_usec >= 1000000) {
 653             xtime.tv_usec -= 1000000;
 654             xtime.tv_sec++;
 655             second_overflow();
 656         }
 657 
 658         jiffies++;
 659         calc_load();
 660         if ((VM_MASK & regs->eflags) || (3 & regs->cs)) {
 661                 current->utime++;
 662                 if (current != task[0]) {
 663                         if (current->priority < 15)
 664                                 kstat.cpu_nice++;
 665                         else
 666                                 kstat.cpu_user++;
 667                 }
 668                 /* Update ITIMER_VIRT for current task if not in a system call */
 669                 if (current->it_virt_value && !(--current->it_virt_value)) {
 670                         current->it_virt_value = current->it_virt_incr;
 671                         send_sig(SIGVTALRM,current,1);
 672                 }
 673         } else {
 674                 current->stime++;
 675                 if(current != task[0])
 676                         kstat.cpu_system++;
 677 #ifdef CONFIG_PROFILE
 678                 if (prof_buffer && current != task[0]) {
 679                         unsigned long eip = regs->eip;
 680                         eip >>= 2;
 681                         if (eip < prof_len)
 682                                 prof_buffer[eip]++;
 683                 }
 684 #endif
 685         }
 686         if (current == task[0] || (--current->counter)<=0) {
 687                 current->counter=0;
 688                 need_resched = 1;
 689         }
 690         /* Update ITIMER_PROF for the current task */
 691         if (current->it_prof_value && !(--current->it_prof_value)) {
 692                 current->it_prof_value = current->it_prof_incr;
 693                 send_sig(SIGPROF,current,1);
 694         }
 695         for (mask = 1, tp = timer_table+0 ; mask ; tp++,mask += mask) {
 696                 if (mask > timer_active)
 697                         break;
 698                 if (!(mask & timer_active))
 699                         continue;
 700                 if (tp->expires > jiffies)
 701                         continue;
 702                 mark_bh(TIMER_BH);
 703         }
 704         cli();
 705         itimer_ticks++;
 706         if (itimer_ticks > itimer_next)
 707                 need_resched = 1;
 708         if (next_timer) {
 709                 if (next_timer->expires) {
 710                         next_timer->expires--;
 711                         if (!next_timer->expires)
 712                                 mark_bh(TIMER_BH);
 713                 } else {
 714                         lost_ticks++;
 715                         mark_bh(TIMER_BH);
 716                 }
 717         }
 718         sti();
 719 }
 720 
 721 asmlinkage int sys_alarm(long seconds)
     /*  */
 722 {
 723         struct itimerval it_new, it_old;
 724 
 725         it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
 726         it_new.it_value.tv_sec = seconds;
 727         it_new.it_value.tv_usec = 0;
 728         _setitimer(ITIMER_REAL, &it_new, &it_old);
 729         return(it_old.it_value.tv_sec + (it_old.it_value.tv_usec / 1000000));
 730 }
 731 
 732 asmlinkage int sys_getpid(void)
     /*  */
 733 {
 734         return current->pid;
 735 }
 736 
 737 asmlinkage int sys_getppid(void)
     /*  */
 738 {
 739         return current->p_opptr->pid;
 740 }
 741 
 742 asmlinkage int sys_getuid(void)
     /*  */
 743 {
 744         return current->uid;
 745 }
 746 
 747 asmlinkage int sys_geteuid(void)
     /*  */
 748 {
 749         return current->euid;
 750 }
 751 
 752 asmlinkage int sys_getgid(void)
     /*  */
 753 {
 754         return current->gid;
 755 }
 756 
 757 asmlinkage int sys_getegid(void)
     /*  */
 758 {
 759         return current->egid;
 760 }
 761 
 762 asmlinkage int sys_nice(long increment)
     /*  */
 763 {
 764         int newprio;
 765 
 766         if (increment < 0 && !suser())
 767                 return -EPERM;
 768         newprio = current->priority - increment;
 769         if (newprio < 1)
 770                 newprio = 1;
 771         if (newprio > 35)
 772                 newprio = 35;
 773         current->priority = newprio;
 774         return 0;
 775 }
 776 
 777 static void show_task(int nr,struct task_struct * p)
     /*  */
 778 {
 779         unsigned long free;
 780         static char * stat_nam[] = { "R", "S", "D", "Z", "T", "W" };
 781 
 782         printk("%-8s %3d ", p->comm, (p == current) ? -nr : nr);
 783         if (((unsigned) p->state) < sizeof(stat_nam)/sizeof(char *))
 784                 printk(stat_nam[p->state]);
 785         else
 786                 printk(" ");
 787         if (p == current)
 788                 printk(" current  ");
 789         else
 790                 printk(" %08lX ", ((unsigned long *)p->tss.esp)[3]);
 791         for (free = 1; free < 1024 ; free++) {
 792                 if (((unsigned long *)p->kernel_stack_page)[free])
 793                         break;
 794         }
 795         printk("%5lu %5d %6d ", free << 2, p->pid, p->p_pptr->pid);
 796         if (p->p_cptr)
 797                 printk("%5d ", p->p_cptr->pid);
 798         else
 799                 printk("      ");
 800         if (p->p_ysptr)
 801                 printk("%7d", p->p_ysptr->pid);
 802         else
 803                 printk("       ");
 804         if (p->p_osptr)
 805                 printk(" %5d\n", p->p_osptr->pid);
 806         else
 807                 printk("\n");
 808 }
 809 
 810 void show_state(void)
     /*  */
 811 {
 812         int i;
 813 
 814         printk("                         free                        sibling\n");
 815         printk("  task             PC    stack   pid father child younger older\n");
 816         for (i=0 ; i<NR_TASKS ; i++)
 817                 if (task[i])
 818                         show_task(i,task[i]);
 819 }
 820 
 821 void sched_init(void)
     /*  */
 822 {
 823         int i;
 824         struct desc_struct * p;
 825 
 826         bh_base[TIMER_BH].routine = timer_bh;
 827         if (sizeof(struct sigaction) != 16)
 828                 panic("Struct sigaction MUST be 16 bytes");
 829         set_tss_desc(gdt+FIRST_TSS_ENTRY,&init_task.tss);
 830         set_ldt_desc(gdt+FIRST_LDT_ENTRY,&default_ldt,1);
 831         set_system_gate(0x80,&system_call);
 832         p = gdt+2+FIRST_TSS_ENTRY;
 833         for(i=1 ; i<NR_TASKS ; i++) {
 834                 task[i] = NULL;
 835                 p->a=p->b=0;
 836                 p++;
 837                 p->a=p->b=0;
 838                 p++;
 839         }
 840 /* Clear NT, so that we won't have troubles with that later on */
 841         __asm__("pushfl ; andl $0xffffbfff,(%esp) ; popfl");
 842         load_TR(0);
 843         load_ldt(0);
 844         outb_p(0x34,0x43);              /* binary, mode 2, LSB/MSB, ch 0 */
 845         outb_p(LATCH & 0xff , 0x40);    /* LSB */
 846         outb(LATCH >> 8 , 0x40);        /* MSB */
 847         if (request_irq(TIMER_IRQ,(void (*)(int)) do_timer)!=0)
 848                 panic("Could not allocate timer IRQ!");
 849 }
/* */
root/kernel/sched.c

DEFINITIONS
