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 fs_struct init_fs = INIT_FS;
  85 static struct files_struct init_files = INIT_FILES;
  86 static struct sigaction init_sigaction[32] = { {0,}, };
  87 
  88 struct mm_struct init_mm = INIT_MM;
  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 struct kernel_stat kstat = { 0 };
  99 
 100 static inline void add_to_runqueue(struct task_struct * p)
     /*  */
 101 {
 102 #if 1   /* sanity tests */
 103         if (p->next_run || p->prev_run) {
 104                 printk("task already on run-queue\n");
 105                 return;
 106         }
 107 #endif
 108         if (p->counter > current->counter + 3)
 109                 need_resched = 1;
 110         nr_running++;
 111         (p->next_run = init_task.next_run)->prev_run = p;
 112         p->prev_run = &init_task;
 113         init_task.next_run = p;
 114 }
 115 
 116 static inline void del_from_runqueue(struct task_struct * p)
     /*  */
 117 {
 118         struct task_struct *next = p->next_run;
 119         struct task_struct *prev = p->prev_run;
 120 
 121 #if 1   /* sanity tests */
 122         if (!next || !prev) {
 123                 printk("task not on run-queue\n");
 124                 return;
 125         }
 126 #endif
 127         if (p == &init_task) {
 128                 static int nr = 0;
 129                 if (nr < 5) {
 130                         nr++;
 131                         printk("idle task may not sleep\n");
 132                 }
 133                 return;
 134         }
 135         nr_running--;
 136         next->prev_run = prev;
 137         prev->next_run = next;
 138         p->next_run = NULL;
 139         p->prev_run = NULL;
 140 }
 141 
 142 /*
 143  * Wake up a process. Put it on the run-queue if it's not
 144  * already there.  The "current" process is always on the
 145  * run-queue (except when the actual re-schedule is in
 146  * progress), and as such you're allowed to do the simpler
 147  * "current->state = TASK_RUNNING" to mark yourself runnable
 148  * without the overhead of this.
 149  */
 150 inline void wake_up_process(struct task_struct * p)
     /*  */
 151 {
 152         unsigned long flags;
 153 
 154         save_flags(flags);
 155         cli();
 156         p->state = TASK_RUNNING;
 157         if (!p->next_run)
 158                 add_to_runqueue(p);
 159         restore_flags(flags);
 160 }
 161 
 162 static void process_timeout(unsigned long __data)
     /*  */
 163 {
 164         struct task_struct * p = (struct task_struct *) __data;
 165 
 166         p->timeout = 0;
 167         wake_up_process(p);
 168 }
 169 
 170 /*
 171  *  'schedule()' is the scheduler function. It's a very simple and nice
 172  * scheduler: it's not perfect, but certainly works for most things.
 173  *
 174  * The goto is "interesting".
 175  *
 176  *   NOTE!!  Task 0 is the 'idle' task, which gets called when no other
 177  * tasks can run. It can not be killed, and it cannot sleep. The 'state'
 178  * information in task[0] is never used.
 179  */
 180 asmlinkage void schedule(void)
     /*  */
 181 {
 182         int c;
 183         struct task_struct * p;
 184         struct task_struct * next;
 185         unsigned long timeout = 0;
 186 
 187 /* check alarm, wake up any interruptible tasks that have got a signal */
 188 
 189         if (intr_count) {
 190                 printk("Aiee: scheduling in interrupt\n");
 191                 return;
 192         }
 193         run_task_queue(&tq_scheduler);
 194 
 195         need_resched = 0;
 196         cli();
 197         switch (current->state) {
 198                 case TASK_INTERRUPTIBLE:
 199                         if (current->signal & ~current->blocked)
 200                                 goto makerunnable;
 201                         timeout = current->timeout;
 202                         if (timeout && (timeout <= jiffies)) {
 203                                 current->timeout = 0;
 204                                 timeout = 0;
 205                 makerunnable:
 206                                 current->state = TASK_RUNNING;
 207                                 break;
 208                         }
 209                 default:
 210                         del_from_runqueue(current);
 211                 case TASK_RUNNING:
 212         }
 213         p = init_task.next_run;
 214         sti();
 215 
 216 /*
 217  * Note! there may appear new tasks on the run-queue during this, as
 218  * interrupts are enabled. However, they will be put on front of the
 219  * list, so our list starting at "p" is essentially fixed.
 220  */
 221 /* this is the scheduler proper: */
 222         c = -1000;
 223         next = &init_task;
 224         while (p != &init_task) {
 225                 if (p->counter > c)
 226                         c = p->counter, next = p;
 227                 p = p->next_run;
 228         }
 229 
 230         /* if all runnable processes have "counter == 0", re-calculate counters */
 231         if (!c) {
 232                 for_each_task(p)
 233                         p->counter = (p->counter >> 1) + p->priority;
 234         }
 235         if (current != next) {
 236                 struct timer_list timer;
 237 
 238                 kstat.context_swtch++;
 239                 if (timeout) {
 240                         init_timer(&timer);
 241                         timer.expires = timeout;
 242                         timer.data = (unsigned long) current;
 243                         timer.function = process_timeout;
 244                         add_timer(&timer);
 245                 }
 246                 switch_to(next);
 247                 if (timeout)
 248                         del_timer(&timer);
 249         }
 250 }
 251 
 252 asmlinkage int sys_pause(void)
     /*  */
 253 {
 254         current->state = TASK_INTERRUPTIBLE;
 255         schedule();
 256         return -ERESTARTNOHAND;
 257 }
 258 
 259 /*
 260  * wake_up doesn't wake up stopped processes - they have to be awakened
 261  * with signals or similar.
 262  *
 263  * Note that this doesn't need cli-sti pairs: interrupts may not change
 264  * the wait-queue structures directly, but only call wake_up() to wake
 265  * a process. The process itself must remove the queue once it has woken.
 266  */
 267 void wake_up(struct wait_queue **q)
     /*  */
 268 {
 269         struct wait_queue *tmp;
 270         struct task_struct * p;
 271 
 272         if (!q || !(tmp = *q))
 273                 return;
 274         do {
 275                 if ((p = tmp->task) != NULL) {
 276                         if ((p->state == TASK_UNINTERRUPTIBLE) ||
 277                             (p->state == TASK_INTERRUPTIBLE))
 278                                 wake_up_process(p);
 279                 }
 280                 if (!tmp->next) {
 281                         printk("wait_queue is bad (eip = %p)\n",
 282                                 __builtin_return_address(0));
 283                         printk("        q = %p\n",q);
 284                         printk("       *q = %p\n",*q);
 285                         printk("      tmp = %p\n",tmp);
 286                         break;
 287                 }
 288                 tmp = tmp->next;
 289         } while (tmp != *q);
 290 }
 291 
 292 void wake_up_interruptible(struct wait_queue **q)
     /*  */
 293 {
 294         struct wait_queue *tmp;
 295         struct task_struct * p;
 296 
 297         if (!q || !(tmp = *q))
 298                 return;
 299         do {
 300                 if ((p = tmp->task) != NULL) {
 301                         if (p->state == TASK_INTERRUPTIBLE)
 302                                 wake_up_process(p);
 303                 }
 304                 if (!tmp->next) {
 305                         printk("wait_queue is bad (eip = %p)\n",
 306                                 __builtin_return_address(0));
 307                         printk("        q = %p\n",q);
 308                         printk("       *q = %p\n",*q);
 309                         printk("      tmp = %p\n",tmp);
 310                         break;
 311                 }
 312                 tmp = tmp->next;
 313         } while (tmp != *q);
 314 }
 315 
 316 void __down(struct semaphore * sem)
     /*  */
 317 {
 318         struct wait_queue wait = { current, NULL };
 319         add_wait_queue(&sem->wait, &wait);
 320         current->state = TASK_UNINTERRUPTIBLE;
 321         while (sem->count <= 0) {
 322                 schedule();
 323                 current->state = TASK_UNINTERRUPTIBLE;
 324         }
 325         current->state = TASK_RUNNING;
 326         remove_wait_queue(&sem->wait, &wait);
 327 }
 328 
 329 static inline void __sleep_on(struct wait_queue **p, int state)
     /*  */
 330 {
 331         unsigned long flags;
 332         struct wait_queue wait = { current, NULL };
 333 
 334         if (!p)
 335                 return;
 336         if (current == task[0])
 337                 panic("task[0] trying to sleep");
 338         current->state = state;
 339         add_wait_queue(p, &wait);
 340         save_flags(flags);
 341         sti();
 342         schedule();
 343         remove_wait_queue(p, &wait);
 344         restore_flags(flags);
 345 }
 346 
 347 void interruptible_sleep_on(struct wait_queue **p)
     /*  */
 348 {
 349         __sleep_on(p,TASK_INTERRUPTIBLE);
 350 }
 351 
 352 void sleep_on(struct wait_queue **p)
     /*  */
 353 {
 354         __sleep_on(p,TASK_UNINTERRUPTIBLE);
 355 }
 356 
 357 /*
 358  * The head for the timer-list has a "expires" field of MAX_UINT,
 359  * and the sorting routine counts on this..
 360  */
 361 static struct timer_list timer_head = { &timer_head, &timer_head, ~0, 0, NULL };
 362 #define SLOW_BUT_DEBUGGING_TIMERS 1
 363 
 364 void add_timer(struct timer_list * timer)
     /*  */
 365 {
 366         unsigned long flags;
 367         struct timer_list *p;
 368 
 369 #if SLOW_BUT_DEBUGGING_TIMERS
 370         if (timer->next || timer->prev) {
 371                 printk("add_timer() called with non-zero list from %p\n",
 372                         __builtin_return_address(0));
 373                 return;
 374         }
 375 #endif
 376         p = &timer_head;
 377         save_flags(flags);
 378         cli();
 379         do {
 380                 p = p->next;
 381         } while (timer->expires > p->expires);
 382         timer->next = p;
 383         timer->prev = p->prev;
 384         p->prev = timer;
 385         timer->prev->next = timer;
 386         restore_flags(flags);
 387 }
 388 
 389 int del_timer(struct timer_list * timer)
     /*  */
 390 {
 391         unsigned long flags;
 392 #if SLOW_BUT_DEBUGGING_TIMERS
 393         struct timer_list * p;
 394 
 395         p = &timer_head;
 396         save_flags(flags);
 397         cli();
 398         while ((p = p->next) != &timer_head) {
 399                 if (p == timer) {
 400                         timer->next->prev = timer->prev;
 401                         timer->prev->next = timer->next;
 402                         timer->next = timer->prev = NULL;
 403                         restore_flags(flags);
 404                         return 1;
 405                 }
 406         }
 407         if (timer->next || timer->prev)
 408                 printk("del_timer() called from %p with timer not initialized\n",
 409                         __builtin_return_address(0));
 410         restore_flags(flags);
 411         return 0;
 412 #else   
 413         save_flags(flags);
 414         cli();
 415         if (timer->next) {
 416                 timer->next->prev = timer->prev;
 417                 timer->prev->next = timer->next;
 418                 timer->next = timer->prev = NULL;
 419                 restore_flags(flags);
 420                 return 1;
 421         }
 422         restore_flags(flags);
 423         return 0;
 424 #endif
 425 }
 426 
 427 unsigned long timer_active = 0;
 428 struct timer_struct timer_table[32];
 429 
 430 /*
 431  * Hmm.. Changed this, as the GNU make sources (load.c) seems to
 432  * imply that avenrun[] is the standard name for this kind of thing.
 433  * Nothing else seems to be standardized: the fractional size etc
 434  * all seem to differ on different machines.
 435  */
 436 unsigned long avenrun[3] = { 0,0,0 };
 437 
 438 /*
 439  * Nr of active tasks - counted in fixed-point numbers
 440  */
 441 static unsigned long count_active_tasks(void)
     /*  */
 442 {
 443         struct task_struct **p;
 444         unsigned long nr = 0;
 445 
 446         for(p = &LAST_TASK; p > &FIRST_TASK; --p)
 447                 if (*p && ((*p)->state == TASK_RUNNING ||
 448                            (*p)->state == TASK_UNINTERRUPTIBLE ||
 449                            (*p)->state == TASK_SWAPPING))
 450                         nr += FIXED_1;
 451         return nr;
 452 }
 453 
 454 static inline void calc_load(void)
     /*  */
 455 {
 456         unsigned long active_tasks; /* fixed-point */
 457         static int count = LOAD_FREQ;
 458 
 459         if (count-- > 0)
 460                 return;
 461         count = LOAD_FREQ;
 462         active_tasks = count_active_tasks();
 463         CALC_LOAD(avenrun[0], EXP_1, active_tasks);
 464         CALC_LOAD(avenrun[1], EXP_5, active_tasks);
 465         CALC_LOAD(avenrun[2], EXP_15, active_tasks);
 466 }
 467 
 468 /*
 469  * this routine handles the overflow of the microsecond field
 470  *
 471  * The tricky bits of code to handle the accurate clock support
 472  * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
 473  * They were originally developed for SUN and DEC kernels.
 474  * All the kudos should go to Dave for this stuff.
 475  *
 476  * These were ported to Linux by Philip Gladstone.
 477  */
 478 static void second_overflow(void)
     /*  */
 479 {
 480         long ltemp;
 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 UTC\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 UTC\n");
 520                 }
 521                 break;
 522 
 523                 case TIME_OOP:
 524                 time_status = TIME_OK;
 525                 break;
 526         }
 527 }
 528 
 529 /*
 530  * disregard lost ticks for now.. We don't care enough.
 531  */
 532 static void timer_bh(void * unused)
     /*  */
 533 {
 534         unsigned long mask;
 535         struct timer_struct *tp;
 536         struct timer_list * timer;
 537 
 538         cli();
 539         while ((timer = timer_head.next) != &timer_head && timer->expires < jiffies) {
 540                 void (*fn)(unsigned long) = timer->function;
 541                 unsigned long data = timer->data;
 542                 timer->next->prev = timer->prev;
 543                 timer->prev->next = timer->next;
 544                 timer->next = timer->prev = NULL;
 545                 sti();
 546                 fn(data);
 547                 cli();
 548         }
 549         sti();
 550         
 551         for (mask = 1, tp = timer_table+0 ; mask ; tp++,mask += mask) {
 552                 if (mask > timer_active)
 553                         break;
 554                 if (!(mask & timer_active))
 555                         continue;
 556                 if (tp->expires > jiffies)
 557                         continue;
 558                 timer_active &= ~mask;
 559                 tp->fn();
 560                 sti();
 561         }
 562 }
 563 
 564 void tqueue_bh(void * unused)
     /*  */
 565 {
 566         run_task_queue(&tq_timer);
 567 }
 568 
 569 void immediate_bh(void * unused)
     /*  */
 570 {
 571         run_task_queue(&tq_immediate);
 572 }
 573 
 574 /*
 575  * The int argument is really a (struct pt_regs *), in case the
 576  * interrupt wants to know from where it was called. The timer
 577  * irq uses this to decide if it should update the user or system
 578  * times.
 579  */
 580 static void do_timer(int irq, struct pt_regs * regs)
     /*  */
 581 {
 582         unsigned long mask;
 583         struct timer_struct *tp;
 584         /* last time the cmos clock got updated */
 585         static long last_rtc_update=0;
 586         extern int set_rtc_mmss(unsigned long);
 587 
 588         long ltemp, psecs;
 589 
 590         /* Advance the phase, once it gets to one microsecond, then
 591          * advance the tick more.
 592          */
 593         time_phase += time_adj;
 594         if (time_phase < -FINEUSEC) {
 595                 ltemp = -time_phase >> SHIFT_SCALE;
 596                 time_phase += ltemp << SHIFT_SCALE;
 597                 xtime.tv_usec += tick + time_adjust_step - ltemp;
 598         }
 599         else if (time_phase > FINEUSEC) {
 600                 ltemp = time_phase >> SHIFT_SCALE;
 601                 time_phase -= ltemp << SHIFT_SCALE;
 602                 xtime.tv_usec += tick + time_adjust_step + ltemp;
 603         } else
 604                 xtime.tv_usec += tick + time_adjust_step;
 605 
 606         if (time_adjust)
 607         {
 608             /* We are doing an adjtime thing. 
 609              *
 610              * Modify the value of the tick for next time.
 611              * Note that a positive delta means we want the clock
 612              * to run fast. This means that the tick should be bigger
 613              *
 614              * Limit the amount of the step for *next* tick to be
 615              * in the range -tickadj .. +tickadj
 616              */
 617              if (time_adjust > tickadj)
 618                time_adjust_step = tickadj;
 619              else if (time_adjust < -tickadj)
 620                time_adjust_step = -tickadj;
 621              else
 622                time_adjust_step = time_adjust;
 623              
 624             /* Reduce by this step the amount of time left  */
 625             time_adjust -= time_adjust_step;
 626         }
 627         else
 628             time_adjust_step = 0;
 629 
 630         if (xtime.tv_usec >= 1000000) {
 631             xtime.tv_usec -= 1000000;
 632             xtime.tv_sec++;
 633             second_overflow();
 634         }
 635 
 636         /* If we have an externally synchronized Linux clock, then update
 637          * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
 638          * called as close as possible to 500 ms before the new second starts.
 639          */
 640         if (time_status != TIME_BAD && xtime.tv_sec > last_rtc_update + 660 &&
 641             xtime.tv_usec > 500000 - (tick >> 1) &&
 642             xtime.tv_usec < 500000 + (tick >> 1))
 643           if (set_rtc_mmss(xtime.tv_sec) == 0)
 644             last_rtc_update = xtime.tv_sec;
 645           else
 646             last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */
 647 
 648         jiffies++;
 649         calc_load();
 650         if (user_mode(regs)) {
 651                 current->utime++;
 652                 if (current != task[0]) {
 653                         if (current->priority < 15)
 654                                 kstat.cpu_nice++;
 655                         else
 656                                 kstat.cpu_user++;
 657                 }
 658                 /* Update ITIMER_VIRT for current task if not in a system call */
 659                 if (current->it_virt_value && !(--current->it_virt_value)) {
 660                         current->it_virt_value = current->it_virt_incr;
 661                         send_sig(SIGVTALRM,current,1);
 662                 }
 663         } else {
 664                 current->stime++;
 665                 if(current != task[0])
 666                         kstat.cpu_system++;
 667 #ifdef CONFIG_PROFILE
 668                 if (prof_buffer && current != task[0]) {
 669                         extern int _stext;
 670                         unsigned long eip = regs->eip - (unsigned long) &_stext;
 671                         eip >>= CONFIG_PROFILE_SHIFT;
 672                         if (eip < prof_len)
 673                                 prof_buffer[eip]++;
 674                 }
 675 #endif
 676         }
 677         /*
 678          * check the cpu time limit on the process.
 679          */
 680         if ((current->rlim[RLIMIT_CPU].rlim_max != RLIM_INFINITY) &&
 681             (((current->stime + current->utime) / HZ) >= current->rlim[RLIMIT_CPU].rlim_max))
 682                 send_sig(SIGKILL, current, 1);
 683         if ((current->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) &&
 684             (((current->stime + current->utime) % HZ) == 0)) {
 685                 psecs = (current->stime + current->utime) / HZ;
 686                 /* send when equal */
 687                 if (psecs == current->rlim[RLIMIT_CPU].rlim_cur)
 688                         send_sig(SIGXCPU, current, 1);
 689                 /* and every five seconds thereafter. */
 690                 else if ((psecs > current->rlim[RLIMIT_CPU].rlim_cur) &&
 691                         ((psecs - current->rlim[RLIMIT_CPU].rlim_cur) % 5) == 0)
 692                         send_sig(SIGXCPU, current, 1);
 693         }
 694 
 695         if (current != task[0] && 0 > --current->counter) {
 696                 current->counter = 0;
 697                 need_resched = 1;
 698         }
 699         /* Update ITIMER_PROF for the current task */
 700         if (current->it_prof_value && !(--current->it_prof_value)) {
 701                 current->it_prof_value = current->it_prof_incr;
 702                 send_sig(SIGPROF,current,1);
 703         }
 704         for (mask = 1, tp = timer_table+0 ; mask ; tp++,mask += mask) {
 705                 if (mask > timer_active)
 706                         break;
 707                 if (!(mask & timer_active))
 708                         continue;
 709                 if (tp->expires > jiffies)
 710                         continue;
 711                 mark_bh(TIMER_BH);
 712         }
 713         cli();
 714         if (timer_head.next->expires < jiffies)
 715                 mark_bh(TIMER_BH);
 716         if (tq_timer != &tq_last)
 717                 mark_bh(TQUEUE_BH);
 718         sti();
 719 }
 720 
 721 asmlinkage unsigned int sys_alarm(unsigned int seconds)
     /*  */
 722 {
 723         struct itimerval it_new, it_old;
 724         unsigned int oldalarm;
 725 
 726         it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
 727         it_new.it_value.tv_sec = seconds;
 728         it_new.it_value.tv_usec = 0;
 729         _setitimer(ITIMER_REAL, &it_new, &it_old);
 730         oldalarm = it_old.it_value.tv_sec;
 731         /* ehhh.. We can't return 0 if we have an alarm pending.. */
 732         /* And we'd better return too much than too little anyway */
 733         if (it_old.it_value.tv_usec)
 734                 oldalarm++;
 735         return oldalarm;
 736 }
 737 
 738 asmlinkage int sys_getpid(void)
     /*  */
 739 {
 740         return current->pid;
 741 }
 742 
 743 asmlinkage int sys_getppid(void)
     /*  */
 744 {
 745         return current->p_opptr->pid;
 746 }
 747 
 748 asmlinkage int sys_getuid(void)
     /*  */
 749 {
 750         return current->uid;
 751 }
 752 
 753 asmlinkage int sys_geteuid(void)
     /*  */
 754 {
 755         return current->euid;
 756 }
 757 
 758 asmlinkage int sys_getgid(void)
     /*  */
 759 {
 760         return current->gid;
 761 }
 762 
 763 asmlinkage int sys_getegid(void)
     /*  */
 764 {
 765         return current->egid;
 766 }
 767 
 768 asmlinkage int sys_nice(long increment)
     /*  */
 769 {
 770         int newprio;
 771 
 772         if (increment < 0 && !suser())
 773                 return -EPERM;
 774         newprio = current->priority - increment;
 775         if (newprio < 1)
 776                 newprio = 1;
 777         if (newprio > 35)
 778                 newprio = 35;
 779         current->priority = newprio;
 780         return 0;
 781 }
 782 
 783 static void show_task(int nr,struct task_struct * p)
     /*  */
 784 {
 785         unsigned long free;
 786         static const char * stat_nam[] = { "R", "S", "D", "Z", "T", "W" };
 787 
 788         printk("%-8s %3d ", p->comm, (p == current) ? -nr : nr);
 789         if (((unsigned) p->state) < sizeof(stat_nam)/sizeof(char *))
 790                 printk(stat_nam[p->state]);
 791         else
 792                 printk(" ");
 793 #if ((~0UL) == 0xffffffff)
 794         if (p == current)
 795                 printk(" current  ");
 796         else
 797                 printk(" %08lX ", thread_saved_pc(&p->tss));
 798 #else
 799         if (p == current)
 800                 printk("   current task   ");
 801         else
 802                 printk(" %016lx ", thread_saved_pc(&p->tss));
 803 #endif
 804         for (free = 1; free < PAGE_SIZE/sizeof(long) ; free++) {
 805                 if (((unsigned long *)p->kernel_stack_page)[free])
 806                         break;
 807         }
 808         printk("%5lu %5d %6d ", free*sizeof(long), p->pid, p->p_pptr->pid);
 809         if (p->p_cptr)
 810                 printk("%5d ", p->p_cptr->pid);
 811         else
 812                 printk("      ");
 813         if (p->p_ysptr)
 814                 printk("%7d", p->p_ysptr->pid);
 815         else
 816                 printk("       ");
 817         if (p->p_osptr)
 818                 printk(" %5d\n", p->p_osptr->pid);
 819         else
 820                 printk("\n");
 821 }
 822 
 823 void show_state(void)
     /*  */
 824 {
 825         int i;
 826 
 827 #if ((~0UL) == 0xffffffff)
 828         printk("\n"
 829                "                         free                        sibling\n");
 830         printk("  task             PC    stack   pid father child younger older\n");
 831 #else
 832         printk("\n"
 833                "                                 free                        sibling\n");
 834         printk("  task                 PC        stack   pid father child younger older\n");
 835 #endif
 836         for (i=0 ; i<NR_TASKS ; i++)
 837                 if (task[i])
 838                         show_task(i,task[i]);
 839 }
 840 
 841 void sched_init(void)
     /*  */
 842 {
 843         bh_base[TIMER_BH].routine = timer_bh;
 844         bh_base[TQUEUE_BH].routine = tqueue_bh;
 845         bh_base[IMMEDIATE_BH].routine = immediate_bh;
 846         if (request_irq(TIMER_IRQ, do_timer, 0, "timer") != 0)
 847                 panic("Could not allocate timer IRQ!");
 848         enable_bh(TIMER_BH);
 849         enable_bh(TQUEUE_BH);
 850         enable_bh(IMMEDIATE_BH);
 851 }
/* */
root/kernel/sched.c

DEFINITIONS
