kernel/sched.c

/* */
This source file includes following definitions.
math_state_restore
math_emulate
schedule
sys_pause
wake_up
wake_up_interruptible
__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/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 extern int _setitimer(int, struct itimerval *, struct itimerval *);
  71 unsigned long * prof_buffer = NULL;
  72 unsigned long prof_len = 0;
  73 
  74 #define _S(nr) (1<<((nr)-1))
  75 
  76 extern void mem_use(void);
  77 
  78 extern int timer_interrupt(void);
  79 asmlinkage int system_call(void);
  80 
  81 static unsigned long init_kernel_stack[1024];
  82 struct task_struct init_task = INIT_TASK;
  83 
  84 unsigned long volatile jiffies=0;
  85 
  86 struct task_struct *current = &init_task;
  87 struct task_struct *last_task_used_math = NULL;
  88 
  89 struct task_struct * task[NR_TASKS] = {&init_task, };
  90 
  91 long user_stack [ PAGE_SIZE>>2 ] ;
  92 
  93 struct {
  94         long * a;
  95         short b;
  96         } stack_start = { & user_stack [PAGE_SIZE>>2] , KERNEL_DS };
  97 
  98 /*
  99  * int 0x80 entry points.. Moved away from the header file, as
 100  * iBCS2 may also want to use the '<linux/sys.h>' headers..
 101  */
 102 #ifdef __cplusplus
 103 extern "C" {
 104 #endif
 105 
 106 fn_ptr sys_call_table[] = { sys_setup, sys_exit, sys_fork, sys_read,
 107 sys_write, sys_open, sys_close, sys_waitpid, sys_creat, sys_link,
 108 sys_unlink, sys_execve, sys_chdir, sys_time, sys_mknod, sys_chmod,
 109 sys_chown, sys_break, sys_stat, sys_lseek, sys_getpid, sys_mount,
 110 sys_umount, sys_setuid, sys_getuid, sys_stime, sys_ptrace, sys_alarm,
 111 sys_fstat, sys_pause, sys_utime, sys_stty, sys_gtty, sys_access,
 112 sys_nice, sys_ftime, sys_sync, sys_kill, sys_rename, sys_mkdir,
 113 sys_rmdir, sys_dup, sys_pipe, sys_times, sys_prof, sys_brk, sys_setgid,
 114 sys_getgid, sys_signal, sys_geteuid, sys_getegid, sys_acct, sys_phys,
 115 sys_lock, sys_ioctl, sys_fcntl, sys_mpx, sys_setpgid, sys_ulimit,
 116 sys_olduname, sys_umask, sys_chroot, sys_ustat, sys_dup2, sys_getppid,
 117 sys_getpgrp, sys_setsid, sys_sigaction, sys_sgetmask, sys_ssetmask,
 118 sys_setreuid,sys_setregid, sys_sigsuspend, sys_sigpending,
 119 sys_sethostname, sys_setrlimit, sys_getrlimit, sys_getrusage,
 120 sys_gettimeofday, sys_settimeofday, sys_getgroups, sys_setgroups,
 121 sys_select, sys_symlink, sys_lstat, sys_readlink, sys_uselib,
 122 sys_swapon, sys_reboot, sys_readdir, sys_mmap, sys_munmap, sys_truncate,
 123 sys_ftruncate, sys_fchmod, sys_fchown, sys_getpriority, sys_setpriority,
 124 sys_profil, sys_statfs, sys_fstatfs, sys_ioperm, sys_socketcall,
 125 sys_syslog, sys_setitimer, sys_getitimer, sys_newstat, sys_newlstat,
 126 sys_newfstat, sys_uname, sys_iopl, sys_vhangup, sys_idle, sys_vm86,
 127 sys_wait4, sys_swapoff, sys_sysinfo, sys_ipc, sys_fsync, sys_sigreturn,
 128 sys_clone, sys_setdomainname, sys_newuname, sys_modify_ldt,
 129 sys_adjtimex, sys_mprotect, sys_sigprocmask,
 130 sys_create_module, sys_init_module, sys_delete_module, sys_get_kernel_syms };
 131 
 132 /* So we don't have to do any more manual updating.... */
 133 int NR_syscalls = sizeof(sys_call_table)/sizeof(fn_ptr);
 134 
 135 #ifdef __cplusplus
 136 }
 137 #endif
 138 
 139 /*
 140  *  'math_state_restore()' saves the current math information in the
 141  * old math state array, and gets the new ones from the current task
 142  *
 143  * Careful.. There are problems with IBM-designed IRQ13 behaviour.
 144  * Don't touch unless you *really* know how it works.
 145  */
 146 asmlinkage void math_state_restore(void)
     /*  */
 147 {
 148         __asm__ __volatile__("clts");
 149         if (last_task_used_math == current)
 150                 return;
 151         timer_table[COPRO_TIMER].expires = jiffies+50;
 152         timer_active |= 1<<COPRO_TIMER; 
 153         if (last_task_used_math)
 154                 __asm__("fnsave %0":"=m" (last_task_used_math->tss.i387));
 155         else
 156                 __asm__("fnclex");
 157         last_task_used_math = current;
 158         if (current->used_math) {
 159                 __asm__("frstor %0": :"m" (current->tss.i387));
 160         } else {
 161                 __asm__("fninit");
 162                 current->used_math=1;
 163         }
 164         timer_active &= ~(1<<COPRO_TIMER);
 165 }
 166 
 167 #ifndef CONFIG_MATH_EMULATION
 168 
 169 asmlinkage void math_emulate(long arg)
     /*  */
 170 {
 171   printk("math-emulation not enabled and no coprocessor found.\n");
 172   printk("killing %s.\n",current->comm);
 173   send_sig(SIGFPE,current,1);
 174   schedule();
 175 }
 176 
 177 #endif /* CONFIG_MATH_EMULATION */
 178 
 179 static unsigned long itimer_ticks = 0;
 180 static unsigned long itimer_next = ~0;
 181 static unsigned long lost_ticks = 0;
 182 
 183 /*
 184  *  'schedule()' is the scheduler function. It's a very simple and nice
 185  * scheduler: it's not perfect, but certainly works for most things.
 186  * The one thing you might take a look at is the signal-handler code here.
 187  *
 188  *   NOTE!!  Task 0 is the 'idle' task, which gets called when no other
 189  * tasks can run. It can not be killed, and it cannot sleep. The 'state'
 190  * information in task[0] is never used.
 191  *
 192  * The "confuse_gcc" goto is used only to get better assembly code..
 193  * Djikstra probably hates me.
 194  */
 195 asmlinkage void schedule(void)
     /*  */
 196 {
 197         int c;
 198         struct task_struct * p;
 199         struct task_struct * next;
 200         unsigned long ticks;
 201 
 202 /* check alarm, wake up any interruptible tasks that have got a signal */
 203 
 204         cli();
 205         ticks = itimer_ticks;
 206         itimer_ticks = 0;
 207         itimer_next = ~0;
 208         sti();
 209         need_resched = 0;
 210         p = &init_task;
 211         for (;;) {
 212                 if ((p = p->next_task) == &init_task)
 213                         goto confuse_gcc1;
 214                 if (ticks && p->it_real_value) {
 215                         if (p->it_real_value <= ticks) {
 216                                 send_sig(SIGALRM, p, 1);
 217                                 if (!p->it_real_incr) {
 218                                         p->it_real_value = 0;
 219                                         goto end_itimer;
 220                                 }
 221                                 do {
 222                                         p->it_real_value += p->it_real_incr;
 223                                 } while (p->it_real_value <= ticks);
 224                         }
 225                         p->it_real_value -= ticks;
 226                         if (p->it_real_value < itimer_next)
 227                                 itimer_next = p->it_real_value;
 228                 }
 229 end_itimer:
 230                 if (p->state != TASK_INTERRUPTIBLE)
 231                         continue;
 232                 if (p->signal & ~p->blocked) {
 233                         p->state = TASK_RUNNING;
 234                         continue;
 235                 }
 236                 if (p->timeout && p->timeout <= jiffies) {
 237                         p->timeout = 0;
 238                         p->state = TASK_RUNNING;
 239                 }
 240         }
 241 confuse_gcc1:
 242 
 243 /* this is the scheduler proper: */
 244 #if 0
 245         /* give processes that go to sleep a bit higher priority.. */
 246         /* This depends on the values for TASK_XXX */
 247         /* This gives smoother scheduling for some things, but */
 248         /* can be very unfair under some circumstances, so.. */
 249         if (TASK_UNINTERRUPTIBLE >= (unsigned) current->state &&
 250             current->counter < current->priority*2) {
 251                 ++current->counter;
 252         }
 253 #endif
 254         c = -1;
 255         next = p = &init_task;
 256         for (;;) {
 257                 if ((p = p->next_task) == &init_task)
 258                         goto confuse_gcc2;
 259                 if (p->state == TASK_RUNNING && p->counter > c)
 260                         c = p->counter, next = p;
 261         }
 262 confuse_gcc2:
 263         if (!c) {
 264                 for_each_task(p)
 265                         p->counter = (p->counter >> 1) + p->priority;
 266         }
 267         switch_to(next);
 268         /* Now maybe reload the debug registers */
 269         if(current->debugreg[7]){
 270                 loaddebug(0);
 271                 loaddebug(1);
 272                 loaddebug(2);
 273                 loaddebug(3);
 274                 loaddebug(6);
 275         };
 276 }
 277 
 278 asmlinkage int sys_pause(void)
     /*  */
 279 {
 280         current->state = TASK_INTERRUPTIBLE;
 281         schedule();
 282         return -ERESTARTNOHAND;
 283 }
 284 
 285 /*
 286  * wake_up doesn't wake up stopped processes - they have to be awakened
 287  * with signals or similar.
 288  *
 289  * Note that this doesn't need cli-sti pairs: interrupts may not change
 290  * the wait-queue structures directly, but only call wake_up() to wake
 291  * a process. The process itself must remove the queue once it has woken.
 292  */
 293 void wake_up(struct wait_queue **q)
     /*  */
 294 {
 295         struct wait_queue *tmp;
 296         struct task_struct * p;
 297 
 298         if (!q || !(tmp = *q))
 299                 return;
 300         do {
 301                 if ((p = tmp->task) != NULL) {
 302                         if ((p->state == TASK_UNINTERRUPTIBLE) ||
 303                             (p->state == TASK_INTERRUPTIBLE)) {
 304                                 p->state = TASK_RUNNING;
 305                                 if (p->counter > current->counter)
 306                                         need_resched = 1;
 307                         }
 308                 }
 309                 if (!tmp->next) {
 310                         printk("wait_queue is bad (eip = %08lx)\n",((unsigned long *) q)[-1]);
 311                         printk("        q = %p\n",q);
 312                         printk("       *q = %p\n",*q);
 313                         printk("      tmp = %p\n",tmp);
 314                         break;
 315                 }
 316                 tmp = tmp->next;
 317         } while (tmp != *q);
 318 }
 319 
 320 void wake_up_interruptible(struct wait_queue **q)
     /*  */
 321 {
 322         struct wait_queue *tmp;
 323         struct task_struct * p;
 324 
 325         if (!q || !(tmp = *q))
 326                 return;
 327         do {
 328                 if ((p = tmp->task) != NULL) {
 329                         if (p->state == TASK_INTERRUPTIBLE) {
 330                                 p->state = TASK_RUNNING;
 331                                 if (p->counter > current->counter)
 332                                         need_resched = 1;
 333                         }
 334                 }
 335                 if (!tmp->next) {
 336                         printk("wait_queue is bad (eip = %08lx)\n",((unsigned long *) q)[-1]);
 337                         printk("        q = %p\n",q);
 338                         printk("       *q = %p\n",*q);
 339                         printk("      tmp = %p\n",tmp);
 340                         break;
 341                 }
 342                 tmp = tmp->next;
 343         } while (tmp != *q);
 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 /*
 565  * The int argument is really a (struct pt_regs *), in case the
 566  * interrupt wants to know from where it was called. The timer
 567  * irq uses this to decide if it should update the user or system
 568  * times.
 569  */
 570 static void do_timer(struct pt_regs * regs)
     /*  */
 571 {
 572         unsigned long mask;
 573         struct timer_struct *tp;
 574 
 575         long ltemp;
 576 
 577         /* Advance the phase, once it gets to one microsecond, then
 578          * advance the tick more.
 579          */
 580         time_phase += time_adj;
 581         if (time_phase < -FINEUSEC) {
 582                 ltemp = -time_phase >> SHIFT_SCALE;
 583                 time_phase += ltemp << SHIFT_SCALE;
 584                 xtime.tv_usec += tick - ltemp;
 585         }
 586         else if (time_phase > FINEUSEC) {
 587                 ltemp = time_phase >> SHIFT_SCALE;
 588                 time_phase -= ltemp << SHIFT_SCALE;
 589                 xtime.tv_usec += tick + ltemp;
 590         } else
 591                 xtime.tv_usec += tick;
 592 
 593         if (time_adjust)
 594         {
 595             /* We are doing an adjtime thing. 
 596              */
 597 
 598             /* Limit the amount of the step for *next* tick to be
 599              * in the range -tickadj .. +tickadj
 600              */
 601              if (time_adjust > tickadj)
 602                ltemp = tickadj;
 603              else if (time_adjust < -tickadj)
 604                ltemp = -tickadj;
 605              else
 606                ltemp = time_adjust;
 607              
 608             /* Reduce the amount of time left by this step */
 609             time_adjust -= ltemp;
 610 
 611             /* Modify the value of the tick for next time.
 612              * Note that a positive delta means we want the clock
 613              * to run fast. This means that the tick should be bigger
 614              */
 615             tick = 1000000/HZ + ltemp;
 616         }
 617         else
 618             tick = 1000000/HZ;
 619 
 620         if (xtime.tv_usec >= 1000000) {
 621             xtime.tv_usec -= 1000000;
 622             xtime.tv_sec++;
 623             second_overflow();
 624         }
 625 
 626         jiffies++;
 627         calc_load();
 628         if ((VM_MASK & regs->eflags) || (3 & regs->cs)) {
 629                 current->utime++;
 630                 /* Update ITIMER_VIRT for current task if not in a system call */
 631                 if (current->it_virt_value && !(--current->it_virt_value)) {
 632                         current->it_virt_value = current->it_virt_incr;
 633                         send_sig(SIGVTALRM,current,1);
 634                 }
 635         } else {
 636                 current->stime++;
 637 #ifdef CONFIG_PROFILE
 638                 if (prof_buffer && current != task[0]) {
 639                         unsigned long eip = regs->eip;
 640                         eip >>= 2;
 641                         if (eip < prof_len)
 642                                 prof_buffer[eip]++;
 643                 }
 644 #endif
 645         }
 646         if (current == task[0] || (--current->counter)<=0) {
 647                 current->counter=0;
 648                 need_resched = 1;
 649         }
 650         /* Update ITIMER_PROF for the current task */
 651         if (current->it_prof_value && !(--current->it_prof_value)) {
 652                 current->it_prof_value = current->it_prof_incr;
 653                 send_sig(SIGPROF,current,1);
 654         }
 655         for (mask = 1, tp = timer_table+0 ; mask ; tp++,mask += mask) {
 656                 if (mask > timer_active)
 657                         break;
 658                 if (!(mask & timer_active))
 659                         continue;
 660                 if (tp->expires > jiffies)
 661                         continue;
 662                 mark_bh(TIMER_BH);
 663         }
 664         cli();
 665         itimer_ticks++;
 666         if (itimer_ticks > itimer_next)
 667                 need_resched = 1;
 668         if (next_timer) {
 669                 if (next_timer->expires) {
 670                         next_timer->expires--;
 671                         if (!next_timer->expires)
 672                                 mark_bh(TIMER_BH);
 673                 } else {
 674                         lost_ticks++;
 675                         mark_bh(TIMER_BH);
 676                 }
 677         }
 678         sti();
 679 }
 680 
 681 asmlinkage int sys_alarm(long seconds)
     /*  */
 682 {
 683         struct itimerval it_new, it_old;
 684 
 685         it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
 686         it_new.it_value.tv_sec = seconds;
 687         it_new.it_value.tv_usec = 0;
 688         _setitimer(ITIMER_REAL, &it_new, &it_old);
 689         return(it_old.it_value.tv_sec + (it_old.it_value.tv_usec / 1000000));
 690 }
 691 
 692 asmlinkage int sys_getpid(void)
     /*  */
 693 {
 694         return current->pid;
 695 }
 696 
 697 asmlinkage int sys_getppid(void)
     /*  */
 698 {
 699         return current->p_opptr->pid;
 700 }
 701 
 702 asmlinkage int sys_getuid(void)
     /*  */
 703 {
 704         return current->uid;
 705 }
 706 
 707 asmlinkage int sys_geteuid(void)
     /*  */
 708 {
 709         return current->euid;
 710 }
 711 
 712 asmlinkage int sys_getgid(void)
     /*  */
 713 {
 714         return current->gid;
 715 }
 716 
 717 asmlinkage int sys_getegid(void)
     /*  */
 718 {
 719         return current->egid;
 720 }
 721 
 722 asmlinkage int sys_nice(long increment)
     /*  */
 723 {
 724         int newprio;
 725 
 726         if (increment < 0 && !suser())
 727                 return -EPERM;
 728         newprio = current->priority - increment;
 729         if (newprio < 1)
 730                 newprio = 1;
 731         if (newprio > 35)
 732                 newprio = 35;
 733         current->priority = newprio;
 734         return 0;
 735 }
 736 
 737 static void show_task(int nr,struct task_struct * p)
     /*  */
 738 {
 739         static char * stat_nam[] = { "R", "S", "D", "Z", "T", "W" };
 740 
 741         printk("%-8s %3d ", p->comm, (p == current) ? -nr : nr);
 742         if (((unsigned) p->state) < sizeof(stat_nam)/sizeof(char *))
 743                 printk(stat_nam[p->state]);
 744         else
 745                 printk(" ");
 746         /* this prints bogus values for the current process */
 747         printk(" %08lX ", ((unsigned long *)p->tss.esp)[2]);
 748         printk("%5lu %5d %6d ",
 749                 p->tss.esp - p->kernel_stack_page, p->pid, p->p_pptr->pid);
 750         if (p->p_cptr)
 751                 printk("%5d ", p->p_cptr->pid);
 752         else
 753                 printk("      ");
 754         if (p->p_ysptr)
 755                 printk("%7d", p->p_ysptr->pid);
 756         else
 757                 printk("       ");
 758         if (p->p_osptr)
 759                 printk(" %5d\n", p->p_osptr->pid);
 760         else
 761                 printk("\n");
 762 }
 763 
 764 void show_state(void)
     /*  */
 765 {
 766         int i;
 767 
 768         printk("                         free                        sibling\n");
 769         printk("  task             PC    stack   pid father child younger older\n");
 770         for (i=0 ; i<NR_TASKS ; i++)
 771                 if (task[i])
 772                         show_task(i,task[i]);
 773 }
 774 
 775 void sched_init(void)
     /*  */
 776 {
 777         int i;
 778         struct desc_struct * p;
 779 
 780         bh_base[TIMER_BH].routine = timer_bh;
 781         if (sizeof(struct sigaction) != 16)
 782                 panic("Struct sigaction MUST be 16 bytes");
 783         set_tss_desc(gdt+FIRST_TSS_ENTRY,&init_task.tss);
 784         set_ldt_desc(gdt+FIRST_LDT_ENTRY,&default_ldt,1);
 785         set_system_gate(0x80,&system_call);
 786         p = gdt+2+FIRST_TSS_ENTRY;
 787         for(i=1 ; i<NR_TASKS ; i++) {
 788                 task[i] = NULL;
 789                 p->a=p->b=0;
 790                 p++;
 791                 p->a=p->b=0;
 792                 p++;
 793         }
 794 /* Clear NT, so that we won't have troubles with that later on */
 795         __asm__("pushfl ; andl $0xffffbfff,(%esp) ; popfl");
 796         load_TR(0);
 797         load_ldt(0);
 798         outb_p(0x34,0x43);              /* binary, mode 2, LSB/MSB, ch 0 */
 799         outb_p(LATCH & 0xff , 0x40);    /* LSB */
 800         outb(LATCH >> 8 , 0x40);        /* MSB */
 801         if (request_irq(TIMER_IRQ,(void (*)(int)) do_timer)!=0)
 802                 panic("Could not allocate timer IRQ!");
 803 }
/* */
root/kernel/sched.c

DEFINITIONS
