kernel/sched.c

/* */
This source file includes following definitions.
add_to_runqueue
del_from_runqueue
wake_up_process
process_timeout
schedule
sys_pause
wake_up
wake_up_interruptible
__down
__sleep_on
interruptible_sleep_on
sleep_on
add_timer
del_timer
count_active_tasks
calc_load
second_overflow
timer_bh
tqueue_bh
immediate_bh
do_timer
sys_alarm
sys_getpid
sys_getppid
sys_getuid
sys_geteuid
sys_getgid
sys_getegid
sys_nice
show_task
show_state
sched_init
   1 /*
   2  *  linux/kernel/sched.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6 
   7 /*
   8  * 'sched.c' is the main kernel file. It contains scheduling primitives
   9  * (sleep_on, wakeup, schedule etc) as well as a number of simple system
  10  * call functions (type getpid(), which just extracts a field from
  11  * current-task
  12  */
  13 
  14 #include <linux/config.h>
  15 #include <linux/signal.h>
  16 #include <linux/sched.h>
  17 #include <linux/timer.h>
  18 #include <linux/kernel.h>
  19 #include <linux/kernel_stat.h>
  20 #include <linux/fdreg.h>
  21 #include <linux/errno.h>
  22 #include <linux/time.h>
  23 #include <linux/ptrace.h>
  24 #include <linux/delay.h>
  25 #include <linux/interrupt.h>
  26 #include <linux/tqueue.h>
  27 #include <linux/resource.h>
  28 #include <linux/mm.h>
  29 
  30 #include <asm/system.h>
  31 #include <asm/io.h>
  32 #include <asm/segment.h>
  33 #include <asm/pgtable.h>
  34 
  35 #define TIMER_IRQ 0
  36 
  37 #include <linux/timex.h>
  38 
  39 /*
  40  * kernel variables
  41  */
  42 long tick = 1000000 / HZ;               /* timer interrupt period */
  43 volatile struct timeval xtime;          /* The current time */
  44 int tickadj = 500/HZ;                   /* microsecs */
  45 
  46 DECLARE_TASK_QUEUE(tq_timer);
  47 DECLARE_TASK_QUEUE(tq_immediate);
  48 DECLARE_TASK_QUEUE(tq_scheduler);
  49 
  50 /*
  51  * phase-lock loop variables
  52  */
  53 int time_status = TIME_BAD;     /* clock synchronization status */
  54 long time_offset = 0;           /* time adjustment (us) */
  55 long time_constant = 0;         /* pll time constant */
  56 long time_tolerance = MAXFREQ;  /* frequency tolerance (ppm) */
  57 long time_precision = 1;        /* clock precision (us) */
  58 long time_maxerror = 0x70000000;/* maximum error */
  59 long time_esterror = 0x70000000;/* estimated error */
  60 long time_phase = 0;            /* phase offset (scaled us) */
  61 long time_freq = 0;             /* frequency offset (scaled ppm) */
  62 long time_adj = 0;              /* tick adjust (scaled 1 / HZ) */
  63 long time_reftime = 0;          /* time at last adjustment (s) */
  64 
  65 long time_adjust = 0;
  66 long time_adjust_step = 0;
  67 
  68 int need_resched = 0;
  69 unsigned long event = 0;
  70 
  71 extern int _setitimer(int, struct itimerval *, struct itimerval *);
  72 unsigned long * prof_buffer = NULL;
  73 unsigned long prof_len = 0;
  74 
  75 #define _S(nr) (1<<((nr)-1))
  76 
  77 extern void mem_use(void);
  78 
  79 extern int timer_interrupt(void);
  80  
  81 static unsigned long init_kernel_stack[1024] = { STACK_MAGIC, };
  82 unsigned long init_user_stack[1024] = { STACK_MAGIC, };
  83 static struct vm_area_struct init_mmap = INIT_MMAP;
  84 static struct mm_struct init_mm = INIT_MM;
  85 static struct fs_struct init_fs = INIT_FS;
  86 static struct files_struct init_files = INIT_FILES;
  87 static struct sigaction init_sigaction[32] = { {0,}, };
  88 struct task_struct init_task = INIT_TASK;
  89 
  90 unsigned long volatile jiffies=0;
  91 
  92 struct task_struct *current = &init_task;
  93 struct task_struct *last_task_used_math = NULL;
  94 
  95 struct task_struct * task[NR_TASKS] = {&init_task, };
  96 
  97 struct kernel_stat kstat = { 0 };
  98 
  99 static inline void add_to_runqueue(struct task_struct * p)
     /*  */
 100 {
 101 #if 1   /* sanity tests */
 102         if (p->next_run || p->prev_run) {
 103                 printk("task already on run-queue\n");
 104                 return;
 105         }
 106 #endif
 107         if (p->counter > current->counter + 3)
 108                 need_resched = 1;
 109         nr_running++;
 110         (p->next_run = init_task.next_run)->prev_run = p;
 111         p->prev_run = &init_task;
 112         init_task.next_run = p;
 113 }
 114 
 115 static inline void del_from_runqueue(struct task_struct * p)
     /*  */
 116 {
 117         struct task_struct *next = p->next_run;
 118         struct task_struct *prev = p->prev_run;
 119 
 120 #if 1   /* sanity tests */
 121         if (!next || !prev) {
 122                 printk("task not on run-queue\n");
 123                 return;
 124         }
 125 #endif
 126         if (p == &init_task) {
 127                 static int nr = 0;
 128                 if (nr < 5) {
 129                         nr++;
 130                         printk("idle task may not sleep\n");
 131                 }
 132                 return;
 133         }
 134         nr_running--;
 135         next->prev_run = prev;
 136         prev->next_run = next;
 137         p->next_run = NULL;
 138         p->prev_run = NULL;
 139 }
 140 
 141 /*
 142  * Wake up a process. Put it on the run-queue if it's not
 143  * already there.  The "current" process is always on the
 144  * run-queue (except when the actual re-schedule is in
 145  * progress), and as such you're allowed to do the simpler
 146  * "current->state = TASK_RUNNING" to mark yourself runnable
 147  * without the overhead of this.
 148  */
 149 inline void wake_up_process(struct task_struct * p)
     /*  */
 150 {
 151         unsigned long flags;
 152 
 153         save_flags(flags);
 154         cli();
 155         p->state = TASK_RUNNING;
 156         if (!p->next_run)
 157                 add_to_runqueue(p);
 158         restore_flags(flags);
 159 }
 160 
 161 static void process_timeout(unsigned long __data)
     /*  */
 162 {
 163         struct task_struct * p = (struct task_struct *) __data;
 164 
 165         p->timeout = 0;
 166         wake_up_process(p);
 167 }
 168 
 169 /*
 170  *  'schedule()' is the scheduler function. It's a very simple and nice
 171  * scheduler: it's not perfect, but certainly works for most things.
 172  *
 173  * The goto is "interesting".
 174  *
 175  *   NOTE!!  Task 0 is the 'idle' task, which gets called when no other
 176  * tasks can run. It can not be killed, and it cannot sleep. The 'state'
 177  * information in task[0] is never used.
 178  */
 179 asmlinkage void schedule(void)
     /*  */
 180 {
 181         int c;
 182         struct task_struct * p;
 183         struct task_struct * next;
 184         unsigned long timeout = 0;
 185 
 186 /* check alarm, wake up any interruptible tasks that have got a signal */
 187 
 188         if (intr_count) {
 189                 printk("Aiee: scheduling in interrupt\n");
 190                 return;
 191         }
 192         run_task_queue(&tq_scheduler);
 193 
 194         need_resched = 0;
 195         cli();
 196         switch (current->state) {
 197                 case TASK_INTERRUPTIBLE:
 198                         if (current->signal & ~current->blocked)
 199                                 goto makerunnable;
 200                         timeout = current->timeout;
 201                         if (timeout && (timeout <= jiffies)) {
 202                                 current->timeout = 0;
 203                                 timeout = 0;
 204                 makerunnable:
 205                                 current->state = TASK_RUNNING;
 206                                 break;
 207                         }
 208                 default:
 209                         del_from_runqueue(current);
 210                 case TASK_RUNNING:
 211         }
 212         p = init_task.next_run;
 213         sti();
 214 
 215 /*
 216  * Note! there may appear new tasks on the run-queue during this, as
 217  * interrupts are enabled. However, they will be put on front of the
 218  * list, so our list starting at "p" is essentially fixed.
 219  */
 220 /* this is the scheduler proper: */
 221         c = -1000;
 222         next = &init_task;
 223         while (p != &init_task) {
 224                 if (p->counter > c)
 225                         c = p->counter, next = p;
 226                 p = p->next_run;
 227         }
 228 
 229         /* if all runnable processes have "counter == 0", re-calculate counters */
 230         if (!c) {
 231                 for_each_task(p)
 232                         p->counter = (p->counter >> 1) + p->priority;
 233         }
 234         if (current != next) {
 235                 struct timer_list timer;
 236 
 237                 kstat.context_swtch++;
 238                 if (timeout) {
 239                         init_timer(&timer);
 240                         timer.expires = timeout;
 241                         timer.data = (unsigned long) current;
 242                         timer.function = process_timeout;
 243                         add_timer(&timer);
 244                 }
 245                 switch_to(next);
 246                 if (timeout)
 247                         del_timer(&timer);
 248         }
 249 }
 250 
 251 asmlinkage int sys_pause(void)
     /*  */
 252 {
 253         current->state = TASK_INTERRUPTIBLE;
 254         schedule();
 255         return -ERESTARTNOHAND;
 256 }
 257 
 258 /*
 259  * wake_up doesn't wake up stopped processes - they have to be awakened
 260  * with signals or similar.
 261  *
 262  * Note that this doesn't need cli-sti pairs: interrupts may not change
 263  * the wait-queue structures directly, but only call wake_up() to wake
 264  * a process. The process itself must remove the queue once it has woken.
 265  */
 266 void wake_up(struct wait_queue **q)
     /*  */
 267 {
 268         struct wait_queue *tmp;
 269         struct task_struct * p;
 270 
 271         if (!q || !(tmp = *q))
 272                 return;
 273         do {
 274                 if ((p = tmp->task) != NULL) {
 275                         if ((p->state == TASK_UNINTERRUPTIBLE) ||
 276                             (p->state == TASK_INTERRUPTIBLE))
 277                                 wake_up_process(p);
 278                 }
 279                 if (!tmp->next) {
 280                         printk("wait_queue is bad (eip = %p)\n",
 281                                 __builtin_return_address(0));
 282                         printk("        q = %p\n",q);
 283                         printk("       *q = %p\n",*q);
 284                         printk("      tmp = %p\n",tmp);
 285                         break;
 286                 }
 287                 tmp = tmp->next;
 288         } while (tmp != *q);
 289 }
 290 
 291 void wake_up_interruptible(struct wait_queue **q)
     /*  */
 292 {
 293         struct wait_queue *tmp;
 294         struct task_struct * p;
 295 
 296         if (!q || !(tmp = *q))
 297                 return;
 298         do {
 299                 if ((p = tmp->task) != NULL) {
 300                         if (p->state == TASK_INTERRUPTIBLE)
 301                                 wake_up_process(p);
 302                 }
 303                 if (!tmp->next) {
 304                         printk("wait_queue is bad (eip = %p)\n",
 305                                 __builtin_return_address(0));
 306                         printk("        q = %p\n",q);
 307                         printk("       *q = %p\n",*q);
 308                         printk("      tmp = %p\n",tmp);
 309                         break;
 310                 }
 311                 tmp = tmp->next;
 312         } while (tmp != *q);
 313 }
 314 
 315 void __down(struct semaphore * sem)
     /*  */
 316 {
 317         struct wait_queue wait = { current, NULL };
 318         add_wait_queue(&sem->wait, &wait);
 319         current->state = TASK_UNINTERRUPTIBLE;
 320         while (sem->count <= 0) {
 321                 schedule();
 322                 current->state = TASK_UNINTERRUPTIBLE;
 323         }
 324         current->state = TASK_RUNNING;
 325         remove_wait_queue(&sem->wait, &wait);
 326 }
 327 
 328 static inline void __sleep_on(struct wait_queue **p, int state)
     /*  */
 329 {
 330         unsigned long flags;
 331         struct wait_queue wait = { current, NULL };
 332 
 333         if (!p)
 334                 return;
 335         if (current == task[0])
 336                 panic("task[0] trying to sleep");
 337         current->state = state;
 338         add_wait_queue(p, &wait);
 339         save_flags(flags);
 340         sti();
 341         schedule();
 342         remove_wait_queue(p, &wait);
 343         restore_flags(flags);
 344 }
 345 
 346 void interruptible_sleep_on(struct wait_queue **p)
     /*  */
 347 {
 348         __sleep_on(p,TASK_INTERRUPTIBLE);
 349 }
 350 
 351 void sleep_on(struct wait_queue **p)
     /*  */
 352 {
 353         __sleep_on(p,TASK_UNINTERRUPTIBLE);
 354 }
 355 
 356 /*
 357  * The head for the timer-list has a "expires" field of MAX_UINT,
 358  * and the sorting routine counts on this..
 359  */
 360 static struct timer_list timer_head = { &timer_head, &timer_head, ~0, 0, NULL };
 361 #define SLOW_BUT_DEBUGGING_TIMERS 1
 362 
 363 void add_timer(struct timer_list * timer)
     /*  */
 364 {
 365         unsigned long flags;
 366         struct timer_list *p;
 367 
 368 #if SLOW_BUT_DEBUGGING_TIMERS
 369         if (timer->next || timer->prev) {
 370                 printk("add_timer() called with non-zero list from %p\n",
 371                         __builtin_return_address(0));
 372                 return;
 373         }
 374 #endif
 375         p = &timer_head;
 376         save_flags(flags);
 377         cli();
 378         do {
 379                 p = p->next;
 380         } while (timer->expires > p->expires);
 381         timer->next = p;
 382         timer->prev = p->prev;
 383         p->prev = timer;
 384         timer->prev->next = timer;
 385         restore_flags(flags);
 386 }
 387 
 388 int del_timer(struct timer_list * timer)
     /*  */
 389 {
 390         unsigned long flags;
 391 #if SLOW_BUT_DEBUGGING_TIMERS
 392         struct timer_list * p;
 393 
 394         p = &timer_head;
 395         save_flags(flags);
 396         cli();
 397         while ((p = p->next) != &timer_head) {
 398                 if (p == timer) {
 399                         timer->next->prev = timer->prev;
 400                         timer->prev->next = timer->next;
 401                         timer->next = timer->prev = NULL;
 402                         restore_flags(flags);
 403                         return 1;
 404                 }
 405         }
 406         if (timer->next || timer->prev)
 407                 printk("del_timer() called from %p with timer not initialized\n",
 408                         __builtin_return_address(0));
 409         restore_flags(flags);
 410         return 0;
 411 #else   
 412         save_flags(flags);
 413         cli();
 414         if (timer->next) {
 415                 timer->next->prev = timer->prev;
 416                 timer->prev->next = timer->next;
 417                 timer->next = timer->prev = NULL;
 418                 restore_flags(flags);
 419                 return 1;
 420         }
 421         restore_flags(flags);
 422         return 0;
 423 #endif
 424 }
 425 
 426 unsigned long timer_active = 0;
 427 struct timer_struct timer_table[32];
 428 
 429 /*
 430  * Hmm.. Changed this, as the GNU make sources (load.c) seems to
 431  * imply that avenrun[] is the standard name for this kind of thing.
 432  * Nothing else seems to be standardized: the fractional size etc
 433  * all seem to differ on different machines.
 434  */
 435 unsigned long avenrun[3] = { 0,0,0 };
 436 
 437 /*
 438  * Nr of active tasks - counted in fixed-point numbers
 439  */
 440 static unsigned long count_active_tasks(void)
     /*  */
 441 {
 442         struct task_struct **p;
 443         unsigned long nr = 0;
 444 
 445         for(p = &LAST_TASK; p > &FIRST_TASK; --p)
 446                 if (*p && ((*p)->state == TASK_RUNNING ||
 447                            (*p)->state == TASK_UNINTERRUPTIBLE ||
 448                            (*p)->state == TASK_SWAPPING))
 449                         nr += FIXED_1;
 450         return nr;
 451 }
 452 
 453 static inline void calc_load(void)
     /*  */
 454 {
 455         unsigned long active_tasks; /* fixed-point */
 456         static int count = LOAD_FREQ;
 457 
 458         if (count-- > 0)
 459                 return;
 460         count = LOAD_FREQ;
 461         active_tasks = count_active_tasks();
 462         CALC_LOAD(avenrun[0], EXP_1, active_tasks);
 463         CALC_LOAD(avenrun[1], EXP_5, active_tasks);
 464         CALC_LOAD(avenrun[2], EXP_15, active_tasks);
 465 }
 466 
 467 /*
 468  * this routine handles the overflow of the microsecond field
 469  *
 470  * The tricky bits of code to handle the accurate clock support
 471  * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
 472  * They were originally developed for SUN and DEC kernels.
 473  * All the kudos should go to Dave for this stuff.
 474  *
 475  * These were ported to Linux by Philip Gladstone.
 476  */
 477 static void second_overflow(void)
     /*  */
 478 {
 479         long ltemp;
 480 
 481         /* Bump the maxerror field */
 482         time_maxerror = (0x70000000-time_maxerror < time_tolerance) ?
 483           0x70000000 : (time_maxerror + time_tolerance);
 484 
 485         /* Run the PLL */
 486         if (time_offset < 0) {
 487                 ltemp = (-(time_offset+1) >> (SHIFT_KG + time_constant)) + 1;
 488                 time_adj = ltemp << (SHIFT_SCALE - SHIFT_HZ - SHIFT_UPDATE);
 489                 time_offset += (time_adj * HZ) >> (SHIFT_SCALE - SHIFT_UPDATE);
 490                 time_adj = - time_adj;
 491         } else if (time_offset > 0) {
 492                 ltemp = ((time_offset-1) >> (SHIFT_KG + time_constant)) + 1;
 493                 time_adj = ltemp << (SHIFT_SCALE - SHIFT_HZ - SHIFT_UPDATE);
 494                 time_offset -= (time_adj * HZ) >> (SHIFT_SCALE - SHIFT_UPDATE);
 495         } else {
 496                 time_adj = 0;
 497         }
 498 
 499         time_adj += (time_freq >> (SHIFT_KF + SHIFT_HZ - SHIFT_SCALE))
 500             + FINETUNE;
 501 
 502         /* Handle the leap second stuff */
 503         switch (time_status) {
 504                 case TIME_INS:
 505                 /* ugly divide should be replaced */
 506                 if (xtime.tv_sec % 86400 == 0) {
 507                         xtime.tv_sec--; /* !! */
 508                         time_status = TIME_OOP;
 509                         printk("Clock: inserting leap second 23:59:60 UTC\n");
 510                 }
 511                 break;
 512 
 513                 case TIME_DEL:
 514                 /* ugly divide should be replaced */
 515                 if (xtime.tv_sec % 86400 == 86399) {
 516                         xtime.tv_sec++;
 517                         time_status = TIME_OK;
 518                         printk("Clock: deleting leap second 23:59:59 UTC\n");
 519                 }
 520                 break;
 521 
 522                 case TIME_OOP:
 523                 time_status = TIME_OK;
 524                 break;
 525         }
 526 }
 527 
 528 /*
 529  * disregard lost ticks for now.. We don't care enough.
 530  */
 531 static void timer_bh(void * unused)
     /*  */
 532 {
 533         unsigned long mask;
 534         struct timer_struct *tp;
 535         struct timer_list * timer;
 536 
 537         cli();
 538         while ((timer = timer_head.next) != &timer_head && timer->expires < jiffies) {
 539                 void (*fn)(unsigned long) = timer->function;
 540                 unsigned long data = timer->data;
 541                 timer->next->prev = timer->prev;
 542                 timer->prev->next = timer->next;
 543                 timer->next = timer->prev = NULL;
 544                 sti();
 545                 fn(data);
 546                 cli();
 547         }
 548         sti();
 549         
 550         for (mask = 1, tp = timer_table+0 ; mask ; tp++,mask += mask) {
 551                 if (mask > timer_active)
 552                         break;
 553                 if (!(mask & timer_active))
 554                         continue;
 555                 if (tp->expires > jiffies)
 556                         continue;
 557                 timer_active &= ~mask;
 558                 tp->fn();
 559                 sti();
 560         }
 561 }
 562 
 563 void tqueue_bh(void * unused)
     /*  */
 564 {
 565         run_task_queue(&tq_timer);
 566 }
 567 
 568 void immediate_bh(void * unused)
     /*  */
 569 {
 570         run_task_queue(&tq_immediate);
 571 }
 572 
 573 /*
 574  * The int argument is really a (struct pt_regs *), in case the
 575  * interrupt wants to know from where it was called. The timer
 576  * irq uses this to decide if it should update the user or system
 577  * times.
 578  */
 579 static void do_timer(int irq, struct pt_regs * regs)
     /*  */
 580 {
 581         unsigned long mask;
 582         struct timer_struct *tp;
 583         /* last time the cmos clock got updated */
 584         static long last_rtc_update=0;
 585         extern int set_rtc_mmss(unsigned long);
 586 
 587         long ltemp, psecs;
 588 
 589         /* Advance the phase, once it gets to one microsecond, then
 590          * advance the tick more.
 591          */
 592         time_phase += time_adj;
 593         if (time_phase < -FINEUSEC) {
 594                 ltemp = -time_phase >> SHIFT_SCALE;
 595                 time_phase += ltemp << SHIFT_SCALE;
 596                 xtime.tv_usec += tick + time_adjust_step - ltemp;
 597         }
 598         else if (time_phase > FINEUSEC) {
 599                 ltemp = time_phase >> SHIFT_SCALE;
 600                 time_phase -= ltemp << SHIFT_SCALE;
 601                 xtime.tv_usec += tick + time_adjust_step + ltemp;
 602         } else
 603                 xtime.tv_usec += tick + time_adjust_step;
 604 
 605         if (time_adjust)
 606         {
 607             /* We are doing an adjtime thing. 
 608              *
 609              * Modify the value of the tick for next time.
 610              * Note that a positive delta means we want the clock
 611              * to run fast. This means that the tick should be bigger
 612              *
 613              * Limit the amount of the step for *next* tick to be
 614              * in the range -tickadj .. +tickadj
 615              */
 616              if (time_adjust > tickadj)
 617                time_adjust_step = tickadj;
 618              else if (time_adjust < -tickadj)
 619                time_adjust_step = -tickadj;
 620              else
 621                time_adjust_step = time_adjust;
 622              
 623             /* Reduce by this step the amount of time left  */
 624             time_adjust -= time_adjust_step;
 625         }
 626         else
 627             time_adjust_step = 0;
 628 
 629         if (xtime.tv_usec >= 1000000) {
 630             xtime.tv_usec -= 1000000;
 631             xtime.tv_sec++;
 632             second_overflow();
 633         }
 634 
 635         /* If we have an externally synchronized Linux clock, then update
 636          * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
 637          * called as close as possible to 500 ms before the new second starts.
 638          */
 639         if (time_status != TIME_BAD && xtime.tv_sec > last_rtc_update + 660 &&
 640             xtime.tv_usec > 500000 - (tick >> 1) &&
 641             xtime.tv_usec < 500000 + (tick >> 1))
 642           if (set_rtc_mmss(xtime.tv_sec) == 0)
 643             last_rtc_update = xtime.tv_sec;
 644           else
 645             last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */
 646 
 647         jiffies++;
 648         calc_load();
 649         if (user_mode(regs)) {
 650                 current->utime++;
 651                 if (current != task[0]) {
 652                         if (current->priority < 15)
 653                                 kstat.cpu_nice++;
 654                         else
 655                                 kstat.cpu_user++;
 656                 }
 657                 /* Update ITIMER_VIRT for current task if not in a system call */
 658                 if (current->it_virt_value && !(--current->it_virt_value)) {
 659                         current->it_virt_value = current->it_virt_incr;
 660                         send_sig(SIGVTALRM,current,1);
 661                 }
 662         } else {
 663                 current->stime++;
 664                 if(current != task[0])
 665                         kstat.cpu_system++;
 666 #ifdef CONFIG_PROFILE
 667                 if (prof_buffer && current != task[0]) {
 668                         extern int _stext;
 669                         unsigned long eip = regs->eip - (unsigned long) &_stext;
 670                         eip >>= CONFIG_PROFILE_SHIFT;
 671                         if (eip < prof_len)
 672                                 prof_buffer[eip]++;
 673                 }
 674 #endif
 675         }
 676         /*
 677          * check the cpu time limit on the process.
 678          */
 679         if ((current->rlim[RLIMIT_CPU].rlim_max != RLIM_INFINITY) &&
 680             (((current->stime + current->utime) / HZ) >= current->rlim[RLIMIT_CPU].rlim_max))
 681                 send_sig(SIGKILL, current, 1);
 682         if ((current->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) &&
 683             (((current->stime + current->utime) % HZ) == 0)) {
 684                 psecs = (current->stime + current->utime) / HZ;
 685                 /* send when equal */
 686                 if (psecs == current->rlim[RLIMIT_CPU].rlim_cur)
 687                         send_sig(SIGXCPU, current, 1);
 688                 /* and every five seconds thereafter. */
 689                 else if ((psecs > current->rlim[RLIMIT_CPU].rlim_cur) &&
 690                         ((psecs - current->rlim[RLIMIT_CPU].rlim_cur) % 5) == 0)
 691                         send_sig(SIGXCPU, current, 1);
 692         }
 693 
 694         if (current != task[0] && 0 > --current->counter) {
 695                 current->counter = 0;
 696                 need_resched = 1;
 697         }
 698         /* Update ITIMER_PROF for the current task */
 699         if (current->it_prof_value && !(--current->it_prof_value)) {
 700                 current->it_prof_value = current->it_prof_incr;
 701                 send_sig(SIGPROF,current,1);
 702         }
 703         for (mask = 1, tp = timer_table+0 ; mask ; tp++,mask += mask) {
 704                 if (mask > timer_active)
 705                         break;
 706                 if (!(mask & timer_active))
 707                         continue;
 708                 if (tp->expires > jiffies)
 709                         continue;
 710                 mark_bh(TIMER_BH);
 711         }
 712         cli();
 713         if (timer_head.next->expires < jiffies)
 714                 mark_bh(TIMER_BH);
 715         if (tq_timer != &tq_last)
 716                 mark_bh(TQUEUE_BH);
 717         sti();
 718 }
 719 
 720 asmlinkage unsigned int sys_alarm(unsigned int seconds)
     /*  */
 721 {
 722         struct itimerval it_new, it_old;
 723         unsigned int oldalarm;
 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         oldalarm = it_old.it_value.tv_sec;
 730         /* ehhh.. We can't return 0 if we have an alarm pending.. */
 731         /* And we'd better return too much than too little anyway */
 732         if (it_old.it_value.tv_usec)
 733                 oldalarm++;
 734         return oldalarm;
 735 }
 736 
 737 asmlinkage int sys_getpid(void)
     /*  */
 738 {
 739         return current->pid;
 740 }
 741 
 742 asmlinkage int sys_getppid(void)
     /*  */
 743 {
 744         return current->p_opptr->pid;
 745 }
 746 
 747 asmlinkage int sys_getuid(void)
     /*  */
 748 {
 749         return current->uid;
 750 }
 751 
 752 asmlinkage int sys_geteuid(void)
     /*  */
 753 {
 754         return current->euid;
 755 }
 756 
 757 asmlinkage int sys_getgid(void)
     /*  */
 758 {
 759         return current->gid;
 760 }
 761 
 762 asmlinkage int sys_getegid(void)
     /*  */
 763 {
 764         return current->egid;
 765 }
 766 
 767 asmlinkage int sys_nice(long increment)
     /*  */
 768 {
 769         int newprio;
 770 
 771         if (increment < 0 && !suser())
 772                 return -EPERM;
 773         newprio = current->priority - increment;
 774         if (newprio < 1)
 775                 newprio = 1;
 776         if (newprio > 35)
 777                 newprio = 35;
 778         current->priority = newprio;
 779         return 0;
 780 }
 781 
 782 static void show_task(int nr,struct task_struct * p)
     /*  */
 783 {
 784         unsigned long free;
 785         static const char * stat_nam[] = { "R", "S", "D", "Z", "T", "W" };
 786 
 787         printk("%-8s %3d ", p->comm, (p == current) ? -nr : nr);
 788         if (((unsigned) p->state) < sizeof(stat_nam)/sizeof(char *))
 789                 printk(stat_nam[p->state]);
 790         else
 791                 printk(" ");
 792 #if ((~0UL) == 0xffffffff)
 793         if (p == current)
 794                 printk(" current  ");
 795         else
 796                 printk(" %08lX ", thread_saved_pc(&p->tss));
 797 #else
 798         if (p == current)
 799                 printk("   current task   ");
 800         else
 801                 printk(" %016lx ", thread_saved_pc(&p->tss));
 802 #endif
 803         for (free = 1; free < PAGE_SIZE/sizeof(long) ; free++) {
 804                 if (((unsigned long *)p->kernel_stack_page)[free])
 805                         break;
 806         }
 807         printk("%5lu %5d %6d ", free*sizeof(long), p->pid, p->p_pptr->pid);
 808         if (p->p_cptr)
 809                 printk("%5d ", p->p_cptr->pid);
 810         else
 811                 printk("      ");
 812         if (p->p_ysptr)
 813                 printk("%7d", p->p_ysptr->pid);
 814         else
 815                 printk("       ");
 816         if (p->p_osptr)
 817                 printk(" %5d\n", p->p_osptr->pid);
 818         else
 819                 printk("\n");
 820 }
 821 
 822 void show_state(void)
     /*  */
 823 {
 824         int i;
 825 
 826 #if ((~0UL) == 0xffffffff)
 827         printk("\n"
 828                "                         free                        sibling\n");
 829         printk("  task             PC    stack   pid father child younger older\n");
 830 #else
 831         printk("\n"
 832                "                                 free                        sibling\n");
 833         printk("  task                 PC        stack   pid father child younger older\n");
 834 #endif
 835         for (i=0 ; i<NR_TASKS ; i++)
 836                 if (task[i])
 837                         show_task(i,task[i]);
 838 }
 839 
 840 void sched_init(void)
     /*  */
 841 {
 842         bh_base[TIMER_BH].routine = timer_bh;
 843         bh_base[TQUEUE_BH].routine = tqueue_bh;
 844         bh_base[IMMEDIATE_BH].routine = immediate_bh;
 845         if (request_irq(TIMER_IRQ, do_timer, 0, "timer") != 0)
 846                 panic("Could not allocate timer IRQ!");
 847         enable_bh(TIMER_BH);
 848         enable_bh(TQUEUE_BH);
 849         enable_bh(IMMEDIATE_BH);
 850 }
/* */
root/kernel/sched.c

DEFINITIONS
