kernel/exit.c

   1 /*
   2  *  linux/kernel/exit.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 #include <linux/config.h>
   8 #include <linux/mm.h>
   9 #include <linux/slab.h>
  10 #include <linux/interrupt.h>
  11 #include <linux/smp_lock.h>
  12 #include <linux/module.h>
  13 #include <linux/completion.h>
  14 #include <linux/personality.h>
  15 #include <linux/tty.h>
  16 #include <linux/namespace.h>
  17 #include <linux/key.h>
  18 #include <linux/security.h>
  19 #include <linux/cpu.h>
  20 #include <linux/acct.h>
  21 #include <linux/file.h>
  22 #include <linux/binfmts.h>
  23 #include <linux/ptrace.h>
  24 #include <linux/profile.h>
  25 #include <linux/mount.h>
  26 #include <linux/proc_fs.h>
  27 #include <linux/mempolicy.h>
  28 #include <linux/cpuset.h>
  29 #include <linux/syscalls.h>
  30 #include <linux/signal.h>
  31
  32 #include <asm/uaccess.h>
  33 #include <asm/unistd.h>
  34 #include <asm/pgtable.h>
  35 #include <asm/mmu_context.h>
  36
  37 extern void sem_exit (void);
  38 extern struct task_struct *child_reaper;
  39
  40 int getrusage(struct task_struct *, int, struct rusage __user *);
  41
  42 static void exit_mm(struct task_struct * tsk);
  43
  44 static void __unhash_process(struct task_struct *p)
  45 {
  46         nr_threads--;
  47         detach_pid(p, PIDTYPE_PID);
  48         detach_pid(p, PIDTYPE_TGID);
  49         if (thread_group_leader(p)) {
  50                 detach_pid(p, PIDTYPE_PGID);
  51                 detach_pid(p, PIDTYPE_SID);
  52                 if (p->pid)
  53                         __get_cpu_var(process_counts)--;
  54         }
  55
  56         REMOVE_LINKS(p);
  57 }
  58
  59 void release_task(struct task_struct * p)
  60 {
  61         int zap_leader;
  62         task_t *leader;
  63         struct dentry *proc_dentry;
  64
  65 repeat:
  66         atomic_dec(&p->user->processes);
  67         spin_lock(&p->proc_lock);
  68         proc_dentry = proc_pid_unhash(p);
  69         write_lock_irq(&tasklist_lock);
  70         if (unlikely(p->ptrace))
  71                 __ptrace_unlink(p);
  72         BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
  73         __exit_signal(p);
  74         __exit_sighand(p);
  75         /*
  76          * Note that the fastpath in sys_times depends on __exit_signal having
  77          * updated the counters before a task is removed from the tasklist of
  78          * the process by __unhash_process.
  79          */
  80         __unhash_process(p);
  81
  82         /*
  83          * If we are the last non-leader member of the thread
  84          * group, and the leader is zombie, then notify the
  85          * group leader's parent process. (if it wants notification.)
  86          */
  87         zap_leader = 0;
  88         leader = p->group_leader;
  89         if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
  90                 BUG_ON(leader->exit_signal == -1);
  91                 do_notify_parent(leader, leader->exit_signal);
  92                 /*
  93                  * If we were the last child thread and the leader has
  94                  * exited already, and the leader's parent ignores SIGCHLD,
  95                  * then we are the one who should release the leader.
  96                  *
  97                  * do_notify_parent() will have marked it self-reaping in
  98                  * that case.
  99                  */
 100                 zap_leader = (leader->exit_signal == -1);
 101         }
 102
 103         sched_exit(p);
 104         write_unlock_irq(&tasklist_lock);
 105         spin_unlock(&p->proc_lock);
 106         proc_pid_flush(proc_dentry);
 107         release_thread(p);
 108         put_task_struct(p);
 109
 110         p = leader;
 111         if (unlikely(zap_leader))
 112                 goto repeat;
 113 }
 114
 115 /* we are using it only for SMP init */
 116
 117 void unhash_process(struct task_struct *p)
 118 {
 119         struct dentry *proc_dentry;
 120
 121         spin_lock(&p->proc_lock);
 122         proc_dentry = proc_pid_unhash(p);
 123         write_lock_irq(&tasklist_lock);
 124         __unhash_process(p);
 125         write_unlock_irq(&tasklist_lock);
 126         spin_unlock(&p->proc_lock);
 127         proc_pid_flush(proc_dentry);
 128 }
 129
 130 /*
 131  * This checks not only the pgrp, but falls back on the pid if no
 132  * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
 133  * without this...
 134  */
 135 int session_of_pgrp(int pgrp)
 136 {
 137         struct task_struct *p;
 138         int sid = -1;
 139
 140         read_lock(&tasklist_lock);
 141         do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
 142                 if (p->signal->session > 0) {
 143                         sid = p->signal->session;
 144                         goto out;
 145                 }
 146         } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
 147         p = find_task_by_pid(pgrp);
 148         if (p)
 149                 sid = p->signal->session;
 150 out:
 151         read_unlock(&tasklist_lock);
 152
 153         return sid;
 154 }
 155
 156 /*
 157  * Determine if a process group is "orphaned", according to the POSIX
 158  * definition in 2.2.2.52.  Orphaned process groups are not to be affected
 159  * by terminal-generated stop signals.  Newly orphaned process groups are
 160  * to receive a SIGHUP and a SIGCONT.
 161  *
 162  * "I ask you, have you ever known what it is to be an orphan?"
 163  */
 164 static int will_become_orphaned_pgrp(int pgrp, task_t *ignored_task)
 165 {
 166         struct task_struct *p;
 167         int ret = 1;
 168
 169         do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
 170                 if (p == ignored_task
 171                                 || p->exit_state
 172                                 || p->real_parent->pid == 1)
 173                         continue;
 174                 if (process_group(p->real_parent) != pgrp
 175                             && p->real_parent->signal->session == p->signal->session) {
 176                         ret = 0;
 177                         break;
 178                 }
 179         } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
 180         return ret;     /* (sighing) "Often!" */
 181 }
 182
 183 int is_orphaned_pgrp(int pgrp)
 184 {
 185         int retval;
 186
 187         read_lock(&tasklist_lock);
 188         retval = will_become_orphaned_pgrp(pgrp, NULL);
 189         read_unlock(&tasklist_lock);
 190
 191         return retval;
 192 }
 193
 194 static inline int has_stopped_jobs(int pgrp)
 195 {
 196         int retval = 0;
 197         struct task_struct *p;
 198
 199         do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
 200                 if (p->state != TASK_STOPPED)
 201                         continue;
 202
 203                 /* If p is stopped by a debugger on a signal that won't
 204                    stop it, then don't count p as stopped.  This isn't
 205                    perfect but it's a good approximation.  */
 206                 if (unlikely (p->ptrace)
 207                     && p->exit_code != SIGSTOP
 208                     && p->exit_code != SIGTSTP
 209                     && p->exit_code != SIGTTOU
 210                     && p->exit_code != SIGTTIN)
 211                         continue;
 212
 213                 retval = 1;
 214                 break;
 215         } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
 216         return retval;
 217 }
 218
 219 /**
 220  * reparent_to_init - Reparent the calling kernel thread to the init task.
 221  *
 222  * If a kernel thread is launched as a result of a system call, or if
 223  * it ever exits, it should generally reparent itself to init so that
 224  * it is correctly cleaned up on exit.
 225  *
 226  * The various task state such as scheduling policy and priority may have
 227  * been inherited from a user process, so we reset them to sane values here.
 228  *
 229  * NOTE that reparent_to_init() gives the caller full capabilities.
 230  */
 231 static inline void reparent_to_init(void)
 232 {
 233         write_lock_irq(&tasklist_lock);
 234
 235         ptrace_unlink(current);
 236         /* Reparent to init */
 237         REMOVE_LINKS(current);
 238         current->parent = child_reaper;
 239         current->real_parent = child_reaper;
 240         SET_LINKS(current);
 241
 242         /* Set the exit signal to SIGCHLD so we signal init on exit */
 243         current->exit_signal = SIGCHLD;
 244
 245         if ((current->policy == SCHED_NORMAL) && (task_nice(current) < 0))
 246                 set_user_nice(current, 0);
 247         /* cpus_allowed? */
 248         /* rt_priority? */
 249         /* signals? */
 250         security_task_reparent_to_init(current);
 251         memcpy(current->signal->rlim, init_task.signal->rlim,
 252                sizeof(current->signal->rlim));
 253         atomic_inc(&(INIT_USER->__count));
 254         write_unlock_irq(&tasklist_lock);
 255         switch_uid(INIT_USER);
 256 }
 257
 258 void __set_special_pids(pid_t session, pid_t pgrp)
 259 {
 260         struct task_struct *curr = current;
 261
 262         if (curr->signal->session != session) {
 263                 detach_pid(curr, PIDTYPE_SID);
 264                 curr->signal->session = session;
 265                 attach_pid(curr, PIDTYPE_SID, session);
 266         }
 267         if (process_group(curr) != pgrp) {
 268                 detach_pid(curr, PIDTYPE_PGID);
 269                 curr->signal->pgrp = pgrp;
 270                 attach_pid(curr, PIDTYPE_PGID, pgrp);
 271         }
 272 }
 273
 274 void set_special_pids(pid_t session, pid_t pgrp)
 275 {
 276         write_lock_irq(&tasklist_lock);
 277         __set_special_pids(session, pgrp);
 278         write_unlock_irq(&tasklist_lock);
 279 }
 280
 281 /*
 282  * Let kernel threads use this to say that they
 283  * allow a certain signal (since daemonize() will
 284  * have disabled all of them by default).
 285  */
 286 int allow_signal(int sig)
 287 {
 288         if (!valid_signal(sig) || sig < 1)
 289                 return -EINVAL;
 290
 291         spin_lock_irq(&current->sighand->siglock);
 292         sigdelset(&current->blocked, sig);
 293         if (!current->mm) {
 294                 /* Kernel threads handle their own signals.
 295                    Let the signal code know it'll be handled, so
 296                    that they don't get converted to SIGKILL or
 297                    just silently dropped */
 298                 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
 299         }
 300         recalc_sigpending();
 301         spin_unlock_irq(&current->sighand->siglock);
 302         return 0;
 303 }
 304
 305 EXPORT_SYMBOL(allow_signal);
 306
 307 int disallow_signal(int sig)
 308 {
 309         if (!valid_signal(sig) || sig < 1)
 310                 return -EINVAL;
 311
 312         spin_lock_irq(&current->sighand->siglock);
 313         sigaddset(&current->blocked, sig);
 314         recalc_sigpending();
 315         spin_unlock_irq(&current->sighand->siglock);
 316         return 0;
 317 }
 318
 319 EXPORT_SYMBOL(disallow_signal);
 320
 321 /*
 322  *      Put all the gunge required to become a kernel thread without
 323  *      attached user resources in one place where it belongs.
 324  */
 325
 326 void daemonize(const char *name, ...)
 327 {
 328         va_list args;
 329         struct fs_struct *fs;
 330         sigset_t blocked;
 331
 332         va_start(args, name);
 333         vsnprintf(current->comm, sizeof(current->comm), name, args);
 334         va_end(args);
 335
 336         /*
 337          * If we were started as result of loading a module, close all of the
 338          * user space pages.  We don't need them, and if we didn't close them
 339          * they would be locked into memory.
 340          */
 341         exit_mm(current);
 342
 343         set_special_pids(1, 1);
 344         down(&tty_sem);
 345         current->signal->tty = NULL;
 346         up(&tty_sem);
 347
 348         /* Block and flush all signals */
 349         sigfillset(&blocked);
 350         sigprocmask(SIG_BLOCK, &blocked, NULL);
 351         flush_signals(current);
 352
 353         /* Become as one with the init task */
 354
 355         exit_fs(current);       /* current->fs->count--; */
 356         fs = init_task.fs;
 357         current->fs = fs;
 358         atomic_inc(&fs->count);
 359         exit_files(current);
 360         current->files = init_task.files;
 361         atomic_inc(&current->files->count);
 362
 363         reparent_to_init();
 364 }
 365
 366 EXPORT_SYMBOL(daemonize);
 367
 368 static inline void close_files(struct files_struct * files)
 369 {
 370         int i, j;
 371         struct fdtable *fdt;
 372
 373         j = 0;
 374         fdt = files_fdtable(files);
 375         for (;;) {
 376                 unsigned long set;
 377                 i = j * __NFDBITS;
 378                 if (i >= fdt->max_fdset || i >= fdt->max_fds)
 379                         break;
 380                 set = fdt->open_fds->fds_bits[j++];
 381                 while (set) {
 382                         if (set & 1) {
 383                                 struct file * file = xchg(&fdt->fd[i], NULL);
 384                                 if (file)
 385                                         filp_close(file, files);
 386                         }
 387                         i++;
 388                         set >>= 1;
 389                 }
 390         }
 391 }
 392
 393 struct files_struct *get_files_struct(struct task_struct *task)
 394 {
 395         struct files_struct *files;
 396
 397         task_lock(task);
 398         files = task->files;
 399         if (files)
 400                 atomic_inc(&files->count);
 401         task_unlock(task);
 402
 403         return files;
 404 }
 405
 406 void fastcall put_files_struct(struct files_struct *files)
 407 {
 408         struct fdtable *fdt;
 409
 410         if (atomic_dec_and_test(&files->count)) {
 411                 close_files(files);
 412                 /*
 413                  * Free the fd and fdset arrays if we expanded them.
 414                  * If the fdtable was embedded, pass files for freeing
 415                  * at the end of the RCU grace period. Otherwise,
 416                  * you can free files immediately.
 417                  */
 418                 fdt = files_fdtable(files);
 419                 if (fdt == &files->fdtab)
 420                         fdt->free_files = files;
 421                 else
 422                         kmem_cache_free(files_cachep, files);
 423                 free_fdtable(fdt);
 424         }
 425 }
 426
 427 EXPORT_SYMBOL(put_files_struct);
 428
 429 static inline void __exit_files(struct task_struct *tsk)
 430 {
 431         struct files_struct * files = tsk->files;
 432
 433         if (files) {
 434                 task_lock(tsk);
 435                 tsk->files = NULL;
 436                 task_unlock(tsk);
 437                 put_files_struct(files);
 438         }
 439 }
 440
 441 void exit_files(struct task_struct *tsk)
 442 {
 443         __exit_files(tsk);
 444 }
 445
 446 static inline void __put_fs_struct(struct fs_struct *fs)
 447 {
 448         /* No need to hold fs->lock if we are killing it */
 449         if (atomic_dec_and_test(&fs->count)) {
 450                 dput(fs->root);
 451                 mntput(fs->rootmnt);
 452                 dput(fs->pwd);
 453                 mntput(fs->pwdmnt);
 454                 if (fs->altroot) {
 455                         dput(fs->altroot);
 456                         mntput(fs->altrootmnt);
 457                 }
 458                 kmem_cache_free(fs_cachep, fs);
 459         }
 460 }
 461
 462 void put_fs_struct(struct fs_struct *fs)
 463 {
 464         __put_fs_struct(fs);
 465 }
 466
 467 static inline void __exit_fs(struct task_struct *tsk)
 468 {
 469         struct fs_struct * fs = tsk->fs;
 470
 471         if (fs) {
 472                 task_lock(tsk);
 473                 tsk->fs = NULL;
 474                 task_unlock(tsk);
 475                 __put_fs_struct(fs);
 476         }
 477 }
 478
 479 void exit_fs(struct task_struct *tsk)
 480 {
 481         __exit_fs(tsk);
 482 }
 483
 484 EXPORT_SYMBOL_GPL(exit_fs);
 485
 486 /*
 487  * Turn us into a lazy TLB process if we
 488  * aren't already..
 489  */
 490 static void exit_mm(struct task_struct * tsk)
 491 {
 492         struct mm_struct *mm = tsk->mm;
 493
 494         mm_release(tsk, mm);
 495         if (!mm)
 496                 return;
 497         /*
 498          * Serialize with any possible pending coredump.
 499          * We must hold mmap_sem around checking core_waiters
 500          * and clearing tsk->mm.  The core-inducing thread
 501          * will increment core_waiters for each thread in the
 502          * group with ->mm != NULL.
 503          */
 504         down_read(&mm->mmap_sem);
 505         if (mm->core_waiters) {
 506                 up_read(&mm->mmap_sem);
 507                 down_write(&mm->mmap_sem);
 508                 if (!--mm->core_waiters)
 509                         complete(mm->core_startup_done);
 510                 up_write(&mm->mmap_sem);
 511
 512                 wait_for_completion(&mm->core_done);
 513                 down_read(&mm->mmap_sem);
 514         }
 515         atomic_inc(&mm->mm_count);
 516         if (mm != tsk->active_mm) BUG();
 517         /* more a memory barrier than a real lock */
 518         task_lock(tsk);
 519         tsk->mm = NULL;
 520         up_read(&mm->mmap_sem);
 521         enter_lazy_tlb(mm, current);
 522         task_unlock(tsk);
 523         mmput(mm);
 524 }
 525
 526 static inline void choose_new_parent(task_t *p, task_t *reaper, task_t *child_reaper)
 527 {
 528         /*
 529          * Make sure we're not reparenting to ourselves and that
 530          * the parent is not a zombie.
 531          */
 532         BUG_ON(p == reaper || reaper->exit_state >= EXIT_ZOMBIE);
 533         p->real_parent = reaper;
 534 }
 535
 536 static inline void reparent_thread(task_t *p, task_t *father, int traced)
 537 {
 538         /* We don't want people slaying init.  */
 539         if (p->exit_signal != -1)
 540                 p->exit_signal = SIGCHLD;
 541
 542         if (p->pdeath_signal)
 543                 /* We already hold the tasklist_lock here.  */
 544                 group_send_sig_info(p->pdeath_signal, (void *) 0, p);
 545
 546         /* Move the child from its dying parent to the new one.  */
 547         if (unlikely(traced)) {
 548                 /* Preserve ptrace links if someone else is tracing this child.  */
 549                 list_del_init(&p->ptrace_list);
 550                 if (p->parent != p->real_parent)
 551                         list_add(&p->ptrace_list, &p->real_parent->ptrace_children);
 552         } else {
 553                 /* If this child is being traced, then we're the one tracing it
 554                  * anyway, so let go of it.
 555                  */
 556                 p->ptrace = 0;
 557                 list_del_init(&p->sibling);
 558                 p->parent = p->real_parent;
 559                 list_add_tail(&p->sibling, &p->parent->children);
 560
 561                 /* If we'd notified the old parent about this child's death,
 562                  * also notify the new parent.
 563                  */
 564                 if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
 565                     thread_group_empty(p))
 566                         do_notify_parent(p, p->exit_signal);
 567                 else if (p->state == TASK_TRACED) {
 568                         /*
 569                          * If it was at a trace stop, turn it into
 570                          * a normal stop since it's no longer being
 571                          * traced.
 572                          */
 573                         ptrace_untrace(p);
 574                 }
 575         }
 576
 577         /*
 578          * process group orphan check
 579          * Case ii: Our child is in a different pgrp
 580          * than we are, and it was the only connection
 581          * outside, so the child pgrp is now orphaned.
 582          */
 583         if ((process_group(p) != process_group(father)) &&
 584             (p->signal->session == father->signal->session)) {
 585                 int pgrp = process_group(p);
 586
 587                 if (will_become_orphaned_pgrp(pgrp, NULL) && has_stopped_jobs(pgrp)) {
 588                         __kill_pg_info(SIGHUP, (void *)1, pgrp);
 589                         __kill_pg_info(SIGCONT, (void *)1, pgrp);
 590                 }
 591         }
 592 }
 593
 594 /*
 595  * When we die, we re-parent all our children.
 596  * Try to give them to another thread in our thread
 597  * group, and if no such member exists, give it to
 598  * the global child reaper process (ie "init")
 599  */
 600 static inline void forget_original_parent(struct task_struct * father,
 601                                           struct list_head *to_release)
 602 {
 603         struct task_struct *p, *reaper = father;
 604         struct list_head *_p, *_n;
 605
 606         do {
 607                 reaper = next_thread(reaper);
 608                 if (reaper == father) {
 609                         reaper = child_reaper;
 610                         break;
 611                 }
 612         } while (reaper->exit_state);
 613
 614         /*
 615          * There are only two places where our children can be:
 616          *
 617          * - in our child list
 618          * - in our ptraced child list
 619          *
 620          * Search them and reparent children.
 621          */
 622         list_for_each_safe(_p, _n, &father->children) {
 623                 int ptrace;
 624                 p = list_entry(_p,struct task_struct,sibling);
 625
 626                 ptrace = p->ptrace;
 627
 628                 /* if father isn't the real parent, then ptrace must be enabled */
 629                 BUG_ON(father != p->real_parent && !ptrace);
 630
 631                 if (father == p->real_parent) {
 632                         /* reparent with a reaper, real father it's us */
 633                         choose_new_parent(p, reaper, child_reaper);
 634                         reparent_thread(p, father, 0);
 635                 } else {
 636                         /* reparent ptraced task to its real parent */
 637                         __ptrace_unlink (p);
 638                         if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
 639                             thread_group_empty(p))
 640                                 do_notify_parent(p, p->exit_signal);
 641                 }
 642
 643                 /*
 644                  * if the ptraced child is a zombie with exit_signal == -1
 645                  * we must collect it before we exit, or it will remain
 646                  * zombie forever since we prevented it from self-reap itself
 647                  * while it was being traced by us, to be able to see it in wait4.
 648                  */
 649                 if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && p->exit_signal == -1))
 650                         list_add(&p->ptrace_list, to_release);
 651         }
 652         list_for_each_safe(_p, _n, &father->ptrace_children) {
 653                 p = list_entry(_p,struct task_struct,ptrace_list);
 654                 choose_new_parent(p, reaper, child_reaper);
 655                 reparent_thread(p, father, 1);
 656         }
 657 }
 658
 659 /*
 660  * Send signals to all our closest relatives so that they know
 661  * to properly mourn us..
 662  */
 663 static void exit_notify(struct task_struct *tsk)
 664 {
 665         int state;
 666         struct task_struct *t;
 667         struct list_head ptrace_dead, *_p, *_n;
 668
 669         if (signal_pending(tsk) && !(tsk->signal->flags & SIGNAL_GROUP_EXIT)
 670             && !thread_group_empty(tsk)) {
 671                 /*
 672                  * This occurs when there was a race between our exit
 673                  * syscall and a group signal choosing us as the one to
 674                  * wake up.  It could be that we are the only thread
 675                  * alerted to check for pending signals, but another thread
 676                  * should be woken now to take the signal since we will not.
 677                  * Now we'll wake all the threads in the group just to make
 678                  * sure someone gets all the pending signals.
 679                  */
 680                 read_lock(&tasklist_lock);
 681                 spin_lock_irq(&tsk->sighand->siglock);
 682                 for (t = next_thread(tsk); t != tsk; t = next_thread(t))
 683                         if (!signal_pending(t) && !(t->flags & PF_EXITING)) {
 684                                 recalc_sigpending_tsk(t);
 685                                 if (signal_pending(t))
 686                                         signal_wake_up(t, 0);
 687                         }
 688                 spin_unlock_irq(&tsk->sighand->siglock);
 689                 read_unlock(&tasklist_lock);
 690         }
 691
 692         write_lock_irq(&tasklist_lock);
 693
 694         /*
 695          * This does two things:
 696          *
 697          * A.  Make init inherit all the child processes
 698          * B.  Check to see if any process groups have become orphaned
 699          *      as a result of our exiting, and if they have any stopped
 700          *      jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
 701          */
 702
 703         INIT_LIST_HEAD(&ptrace_dead);
 704         forget_original_parent(tsk, &ptrace_dead);
 705         BUG_ON(!list_empty(&tsk->children));
 706         BUG_ON(!list_empty(&tsk->ptrace_children));
 707
 708         /*
 709          * Check to see if any process groups have become orphaned
 710          * as a result of our exiting, and if they have any stopped
 711          * jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
 712          *
 713          * Case i: Our father is in a different pgrp than we are
 714          * and we were the only connection outside, so our pgrp
 715          * is about to become orphaned.
 716          */
 717
 718         t = tsk->real_parent;
 719
 720         if ((process_group(t) != process_group(tsk)) &&
 721             (t->signal->session == tsk->signal->session) &&
 722             will_become_orphaned_pgrp(process_group(tsk), tsk) &&
 723             has_stopped_jobs(process_group(tsk))) {
 724                 __kill_pg_info(SIGHUP, (void *)1, process_group(tsk));
 725                 __kill_pg_info(SIGCONT, (void *)1, process_group(tsk));
 726         }
 727
 728         /* Let father know we died
 729          *
 730          * Thread signals are configurable, but you aren't going to use
 731          * that to send signals to arbitary processes.
 732          * That stops right now.
 733          *
 734          * If the parent exec id doesn't match the exec id we saved
 735          * when we started then we know the parent has changed security
 736          * domain.
 737          *
 738          * If our self_exec id doesn't match our parent_exec_id then
 739          * we have changed execution domain as these two values started
 740          * the same after a fork.
 741          *
 742          */
 743
 744         if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 &&
 745             ( tsk->parent_exec_id != t->self_exec_id  ||
 746               tsk->self_exec_id != tsk->parent_exec_id)
 747             && !capable(CAP_KILL))
 748                 tsk->exit_signal = SIGCHLD;
 749
 750
 751         /* If something other than our normal parent is ptracing us, then
 752          * send it a SIGCHLD instead of honoring exit_signal.  exit_signal
 753          * only has special meaning to our real parent.
 754          */
 755         if (tsk->exit_signal != -1 && thread_group_empty(tsk)) {
 756                 int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD;
 757                 do_notify_parent(tsk, signal);
 758         } else if (tsk->ptrace) {
 759                 do_notify_parent(tsk, SIGCHLD);
 760         }
 761
 762         state = EXIT_ZOMBIE;
 763         if (tsk->exit_signal == -1 &&
 764             (likely(tsk->ptrace == 0) ||
 765              unlikely(tsk->parent->signal->flags & SIGNAL_GROUP_EXIT)))
 766                 state = EXIT_DEAD;
 767         tsk->exit_state = state;
 768
 769         write_unlock_irq(&tasklist_lock);
 770
 771         list_for_each_safe(_p, _n, &ptrace_dead) {
 772                 list_del_init(_p);
 773                 t = list_entry(_p,struct task_struct,ptrace_list);
 774                 release_task(t);
 775         }
 776
 777         /* If the process is dead, release it - nobody will wait for it */
 778         if (state == EXIT_DEAD)
 779                 release_task(tsk);
 780
 781         /* PF_DEAD causes final put_task_struct after we schedule. */
 782         preempt_disable();
 783         tsk->flags |= PF_DEAD;
 784 }
 785
 786 fastcall NORET_TYPE void do_exit(long code)
 787 {
 788         struct task_struct *tsk = current;
 789         int group_dead;
 790
 791         profile_task_exit(tsk);
 792
 793         WARN_ON(atomic_read(&tsk->fs_excl));
 794
 795         if (unlikely(in_interrupt()))
 796                 panic("Aiee, killing interrupt handler!");
 797         if (unlikely(!tsk->pid))
 798                 panic("Attempted to kill the idle task!");
 799         if (unlikely(tsk->pid == 1))
 800                 panic("Attempted to kill init!");
 801         if (tsk->io_context)
 802                 exit_io_context();
 803
 804         if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
 805                 current->ptrace_message = code;
 806                 ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP);
 807         }
 808
 809         /*
 810          * We're taking recursive faults here in do_exit. Safest is to just
 811          * leave this task alone and wait for reboot.
 812          */
 813         if (unlikely(tsk->flags & PF_EXITING)) {
 814                 printk(KERN_ALERT
 815                         "Fixing recursive fault but reboot is needed!\n");
 816                 set_current_state(TASK_UNINTERRUPTIBLE);
 817                 schedule();
 818         }
 819
 820         tsk->flags |= PF_EXITING;
 821
 822         /*
 823          * Make sure we don't try to process any timer firings
 824          * while we are already exiting.
 825          */
 826         tsk->it_virt_expires = cputime_zero;
 827         tsk->it_prof_expires = cputime_zero;
 828         tsk->it_sched_expires = 0;
 829
 830         if (unlikely(in_atomic()))
 831                 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
 832                                 current->comm, current->pid,
 833                                 preempt_count());
 834
 835         acct_update_integrals(tsk);
 836         update_mem_hiwater(tsk);
 837         group_dead = atomic_dec_and_test(&tsk->signal->live);
 838         if (group_dead) {
 839                 del_timer_sync(&tsk->signal->real_timer);
 840                 acct_process(code);
 841         }
 842         exit_mm(tsk);
 843
 844         exit_sem(tsk);
 845         __exit_files(tsk);
 846         __exit_fs(tsk);
 847         exit_namespace(tsk);
 848         exit_thread();
 849         cpuset_exit(tsk);
 850         exit_keys(tsk);
 851
 852         if (group_dead && tsk->signal->leader)
 853                 disassociate_ctty(1);
 854
 855         module_put(tsk->thread_info->exec_domain->module);
 856         if (tsk->binfmt)
 857                 module_put(tsk->binfmt->module);
 858
 859         tsk->exit_code = code;
 860         exit_notify(tsk);
 861 #ifdef CONFIG_NUMA
 862         mpol_free(tsk->mempolicy);
 863         tsk->mempolicy = NULL;
 864 #endif
 865
 866         BUG_ON(!(current->flags & PF_DEAD));
 867         schedule();
 868         BUG();
 869         /* Avoid "noreturn function does return".  */
 870         for (;;) ;
 871 }
 872
 873 EXPORT_SYMBOL_GPL(do_exit);
 874
 875 NORET_TYPE void complete_and_exit(struct completion *comp, long code)
 876 {
 877         if (comp)
 878                 complete(comp);
 879
 880         do_exit(code);
 881 }
 882
 883 EXPORT_SYMBOL(complete_and_exit);
 884
 885 asmlinkage long sys_exit(int error_code)
 886 {
 887         do_exit((error_code&0xff)<<8);
 888 }
 889
 890 task_t fastcall *next_thread(const task_t *p)
 891 {
 892         return pid_task(p->pids[PIDTYPE_TGID].pid_list.next, PIDTYPE_TGID);
 893 }
 894
 895 EXPORT_SYMBOL(next_thread);
 896
 897 /*
 898  * Take down every thread in the group.  This is called by fatal signals
 899  * as well as by sys_exit_group (below).
 900  */
 901 NORET_TYPE void
 902 do_group_exit(int exit_code)
 903 {
 904         BUG_ON(exit_code & 0x80); /* core dumps don't get here */
 905
 906         if (current->signal->flags & SIGNAL_GROUP_EXIT)
 907                 exit_code = current->signal->group_exit_code;
 908         else if (!thread_group_empty(current)) {
 909                 struct signal_struct *const sig = current->signal;
 910                 struct sighand_struct *const sighand = current->sighand;
 911                 read_lock(&tasklist_lock);
 912                 spin_lock_irq(&sighand->siglock);
 913                 if (sig->flags & SIGNAL_GROUP_EXIT)
 914                         /* Another thread got here before we took the lock.  */
 915                         exit_code = sig->group_exit_code;
 916                 else {
 917                         sig->flags = SIGNAL_GROUP_EXIT;
 918                         sig->group_exit_code = exit_code;
 919                         zap_other_threads(current);
 920                 }
 921                 spin_unlock_irq(&sighand->siglock);
 922                 read_unlock(&tasklist_lock);
 923         }
 924
 925         do_exit(exit_code);
 926         /* NOTREACHED */
 927 }
 928
 929 /*
 930  * this kills every thread in the thread group. Note that any externally
 931  * wait4()-ing process will get the correct exit code - even if this
 932  * thread is not the thread group leader.
 933  */
 934 asmlinkage void sys_exit_group(int error_code)
 935 {
 936         do_group_exit((error_code & 0xff) << 8);
 937 }
 938
 939 static int eligible_child(pid_t pid, int options, task_t *p)
 940 {
 941         if (pid > 0) {
 942                 if (p->pid != pid)
 943                         return 0;
 944         } else if (!pid) {
 945                 if (process_group(p) != process_group(current))
 946                         return 0;
 947         } else if (pid != -1) {
 948                 if (process_group(p) != -pid)
 949                         return 0;
 950         }
 951
 952         /*
 953          * Do not consider detached threads that are
 954          * not ptraced:
 955          */
 956         if (p->exit_signal == -1 && !p->ptrace)
 957                 return 0;
 958
 959         /* Wait for all children (clone and not) if __WALL is set;
 960          * otherwise, wait for clone children *only* if __WCLONE is
 961          * set; otherwise, wait for non-clone children *only*.  (Note:
 962          * A "clone" child here is one that reports to its parent
 963          * using a signal other than SIGCHLD.) */
 964         if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
 965             && !(options & __WALL))
 966                 return 0;
 967         /*
 968          * Do not consider thread group leaders that are
 969          * in a non-empty thread group:
 970          */
 971         if (current->tgid != p->tgid && delay_group_leader(p))
 972                 return 2;
 973
 974         if (security_task_wait(p))
 975                 return 0;
 976
 977         return 1;
 978 }
 979
 980 static int wait_noreap_copyout(task_t *p, pid_t pid, uid_t uid,
 981                                int why, int status,
 982                                struct siginfo __user *infop,
 983                                struct rusage __user *rusagep)
 984 {
 985         int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
 986         put_task_struct(p);
 987         if (!retval)
 988                 retval = put_user(SIGCHLD, &infop->si_signo);
 989         if (!retval)
 990                 retval = put_user(0, &infop->si_errno);
 991         if (!retval)
 992                 retval = put_user((short)why, &infop->si_code);
 993         if (!retval)
 994                 retval = put_user(pid, &infop->si_pid);
 995         if (!retval)
 996                 retval = put_user(uid, &infop->si_uid);
 997         if (!retval)
 998                 retval = put_user(status, &infop->si_status);
 999         if (!retval)
1000                 retval = pid;
1001         return retval;
1002 }
1003
1004 /*
1005  * Handle sys_wait4 work for one task in state EXIT_ZOMBIE.  We hold
1006  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1007  * the lock and this task is uninteresting.  If we return nonzero, we have
1008  * released the lock and the system call should return.
1009  */
1010 static int wait_task_zombie(task_t *p, int noreap,
1011                             struct siginfo __user *infop,
1012                             int __user *stat_addr, struct rusage __user *ru)
1013 {
1014         unsigned long state;
1015         int retval;
1016         int status;
1017
1018         if (unlikely(noreap)) {
1019                 pid_t pid = p->pid;
1020                 uid_t uid = p->uid;
1021                 int exit_code = p->exit_code;
1022                 int why, status;
1023
1024                 if (unlikely(p->exit_state != EXIT_ZOMBIE))
1025                         return 0;
1026                 if (unlikely(p->exit_signal == -1 && p->ptrace == 0))
1027                         return 0;
1028                 get_task_struct(p);
1029                 read_unlock(&tasklist_lock);
1030                 if ((exit_code & 0x7f) == 0) {
1031                         why = CLD_EXITED;
1032                         status = exit_code >> 8;
1033                 } else {
1034                         why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1035                         status = exit_code & 0x7f;
1036                 }
1037                 return wait_noreap_copyout(p, pid, uid, why,
1038                                            status, infop, ru);
1039         }
1040
1041         /*
1042          * Try to move the task's state to DEAD
1043          * only one thread is allowed to do this:
1044          */
1045         state = xchg(&p->exit_state, EXIT_DEAD);
1046         if (state != EXIT_ZOMBIE) {
1047                 BUG_ON(state != EXIT_DEAD);
1048                 return 0;
1049         }
1050         if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) {
1051                 /*
1052                  * This can only happen in a race with a ptraced thread
1053                  * dying on another processor.
1054                  */
1055                 return 0;
1056         }
1057
1058         if (likely(p->real_parent == p->parent) && likely(p->signal)) {
1059                 /*
1060                  * The resource counters for the group leader are in its
1061                  * own task_struct.  Those for dead threads in the group
1062                  * are in its signal_struct, as are those for the child
1063                  * processes it has previously reaped.  All these
1064                  * accumulate in the parent's signal_struct c* fields.
1065                  *
1066                  * We don't bother to take a lock here to protect these
1067                  * p->signal fields, because they are only touched by
1068                  * __exit_signal, which runs with tasklist_lock
1069                  * write-locked anyway, and so is excluded here.  We do
1070                  * need to protect the access to p->parent->signal fields,
1071                  * as other threads in the parent group can be right
1072                  * here reaping other children at the same time.
1073                  */
1074                 spin_lock_irq(&p->parent->sighand->siglock);
1075                 p->parent->signal->cutime =
1076                         cputime_add(p->parent->signal->cutime,
1077                         cputime_add(p->utime,
1078                         cputime_add(p->signal->utime,
1079                                     p->signal->cutime)));
1080                 p->parent->signal->cstime =
1081                         cputime_add(p->parent->signal->cstime,
1082                         cputime_add(p->stime,
1083                         cputime_add(p->signal->stime,
1084                                     p->signal->cstime)));
1085                 p->parent->signal->cmin_flt +=
1086                         p->min_flt + p->signal->min_flt + p->signal->cmin_flt;
1087                 p->parent->signal->cmaj_flt +=
1088                         p->maj_flt + p->signal->maj_flt + p->signal->cmaj_flt;
1089                 p->parent->signal->cnvcsw +=
1090                         p->nvcsw + p->signal->nvcsw + p->signal->cnvcsw;
1091                 p->parent->signal->cnivcsw +=
1092                         p->nivcsw + p->signal->nivcsw + p->signal->cnivcsw;
1093                 spin_unlock_irq(&p->parent->sighand->siglock);
1094         }
1095
1096         /*
1097          * Now we are sure this task is interesting, and no other
1098          * thread can reap it because we set its state to EXIT_DEAD.
1099          */
1100         read_unlock(&tasklist_lock);
1101
1102         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1103         status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1104                 ? p->signal->group_exit_code : p->exit_code;
1105         if (!retval && stat_addr)
1106                 retval = put_user(status, stat_addr);
1107         if (!retval && infop)
1108                 retval = put_user(SIGCHLD, &infop->si_signo);
1109         if (!retval && infop)
1110                 retval = put_user(0, &infop->si_errno);
1111         if (!retval && infop) {
1112                 int why;
1113
1114                 if ((status & 0x7f) == 0) {
1115                         why = CLD_EXITED;
1116                         status >>= 8;
1117                 } else {
1118                         why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1119                         status &= 0x7f;
1120                 }
1121                 retval = put_user((short)why, &infop->si_code);
1122                 if (!retval)
1123                         retval = put_user(status, &infop->si_status);
1124         }
1125         if (!retval && infop)
1126                 retval = put_user(p->pid, &infop->si_pid);
1127         if (!retval && infop)
1128                 retval = put_user(p->uid, &infop->si_uid);
1129         if (retval) {
1130                 // TODO: is this safe?
1131                 p->exit_state = EXIT_ZOMBIE;
1132                 return retval;
1133         }
1134         retval = p->pid;
1135         if (p->real_parent != p->parent) {
1136                 write_lock_irq(&tasklist_lock);
1137                 /* Double-check with lock held.  */
1138                 if (p->real_parent != p->parent) {
1139                         __ptrace_unlink(p);
1140                         // TODO: is this safe?
1141                         p->exit_state = EXIT_ZOMBIE;
1142                         /*
1143                          * If this is not a detached task, notify the parent.
1144                          * If it's still not detached after that, don't release
1145                          * it now.
1146                          */
1147                         if (p->exit_signal != -1) {
1148                                 do_notify_parent(p, p->exit_signal);
1149                                 if (p->exit_signal != -1)
1150                                         p = NULL;
1151                         }
1152                 }
1153                 write_unlock_irq(&tasklist_lock);
1154         }
1155         if (p != NULL)
1156                 release_task(p);
1157         BUG_ON(!retval);
1158         return retval;
1159 }
1160
1161 /*
1162  * Handle sys_wait4 work for one task in state TASK_STOPPED.  We hold
1163  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1164  * the lock and this task is uninteresting.  If we return nonzero, we have
1165  * released the lock and the system call should return.
1166  */
1167 static int wait_task_stopped(task_t *p, int delayed_group_leader, int noreap,
1168                              struct siginfo __user *infop,
1169                              int __user *stat_addr, struct rusage __user *ru)
1170 {
1171         int retval, exit_code;
1172
1173         if (!p->exit_code)
1174                 return 0;
1175         if (delayed_group_leader && !(p->ptrace & PT_PTRACED) &&
1176             p->signal && p->signal->group_stop_count > 0)
1177                 /*
1178                  * A group stop is in progress and this is the group leader.
1179                  * We won't report until all threads have stopped.
1180                  */
1181                 return 0;
1182
1183         /*
1184          * Now we are pretty sure this task is interesting.
1185          * Make sure it doesn't get reaped out from under us while we
1186          * give up the lock and then examine it below.  We don't want to
1187          * keep holding onto the tasklist_lock while we call getrusage and
1188          * possibly take page faults for user memory.
1189          */
1190         get_task_struct(p);
1191         read_unlock(&tasklist_lock);
1192
1193         if (unlikely(noreap)) {
1194                 pid_t pid = p->pid;
1195                 uid_t uid = p->uid;
1196                 int why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
1197
1198                 exit_code = p->exit_code;
1199                 if (unlikely(!exit_code) ||
1200                     unlikely(p->state > TASK_STOPPED))
1201                         goto bail_ref;
1202                 return wait_noreap_copyout(p, pid, uid,
1203                                            why, (exit_code << 8) | 0x7f,
1204                                            infop, ru);
1205         }
1206
1207         write_lock_irq(&tasklist_lock);
1208
1209         /*
1210          * This uses xchg to be atomic with the thread resuming and setting
1211          * it.  It must also be done with the write lock held to prevent a
1212          * race with the EXIT_ZOMBIE case.
1213          */
1214         exit_code = xchg(&p->exit_code, 0);
1215         if (unlikely(p->exit_state)) {
1216                 /*
1217                  * The task resumed and then died.  Let the next iteration
1218                  * catch it in EXIT_ZOMBIE.  Note that exit_code might
1219                  * already be zero here if it resumed and did _exit(0).
1220                  * The task itself is dead and won't touch exit_code again;
1221                  * other processors in this function are locked out.
1222                  */
1223                 p->exit_code = exit_code;
1224                 exit_code = 0;
1225         }
1226         if (unlikely(exit_code == 0)) {
1227                 /*
1228                  * Another thread in this function got to it first, or it
1229                  * resumed, or it resumed and then died.
1230                  */
1231                 write_unlock_irq(&tasklist_lock);
1232 bail_ref:
1233                 put_task_struct(p);
1234                 /*
1235                  * We are returning to the wait loop without having successfully
1236                  * removed the process and having released the lock. We cannot
1237                  * continue, since the "p" task pointer is potentially stale.
1238                  *
1239                  * Return -EAGAIN, and do_wait() will restart the loop from the
1240                  * beginning. Do _not_ re-acquire the lock.
1241                  */
1242                 return -EAGAIN;
1243         }
1244
1245         /* move to end of parent's list to avoid starvation */
1246         remove_parent(p);
1247         add_parent(p, p->parent);
1248
1249         write_unlock_irq(&tasklist_lock);
1250
1251         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1252         if (!retval && stat_addr)
1253                 retval = put_user((exit_code << 8) | 0x7f, stat_addr);
1254         if (!retval && infop)
1255                 retval = put_user(SIGCHLD, &infop->si_signo);
1256         if (!retval && infop)
1257                 retval = put_user(0, &infop->si_errno);
1258         if (!retval && infop)
1259                 retval = put_user((short)((p->ptrace & PT_PTRACED)
1260                                           ? CLD_TRAPPED : CLD_STOPPED),
1261                                   &infop->si_code);
1262         if (!retval && infop)
1263                 retval = put_user(exit_code, &infop->si_status);
1264         if (!retval && infop)
1265                 retval = put_user(p->pid, &infop->si_pid);
1266         if (!retval && infop)
1267                 retval = put_user(p->uid, &infop->si_uid);
1268         if (!retval)
1269                 retval = p->pid;
1270         put_task_struct(p);
1271
1272         BUG_ON(!retval);
1273         return retval;
1274 }
1275
1276 /*
1277  * Handle do_wait work for one task in a live, non-stopped state.
1278  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1279  * the lock and this task is uninteresting.  If we return nonzero, we have
1280  * released the lock and the system call should return.
1281  */
1282 static int wait_task_continued(task_t *p, int noreap,
1283                                struct siginfo __user *infop,
1284                                int __user *stat_addr, struct rusage __user *ru)
1285 {
1286         int retval;
1287         pid_t pid;
1288         uid_t uid;
1289
1290         if (unlikely(!p->signal))
1291                 return 0;
1292
1293         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1294                 return 0;
1295
1296         spin_lock_irq(&p->sighand->siglock);
1297         /* Re-check with the lock held.  */
1298         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1299                 spin_unlock_irq(&p->sighand->siglock);
1300                 return 0;
1301         }
1302         if (!noreap)
1303                 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1304         spin_unlock_irq(&p->sighand->siglock);
1305
1306         pid = p->pid;
1307         uid = p->uid;
1308         get_task_struct(p);
1309         read_unlock(&tasklist_lock);
1310
1311         if (!infop) {
1312                 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1313                 put_task_struct(p);
1314                 if (!retval && stat_addr)
1315                         retval = put_user(0xffff, stat_addr);
1316                 if (!retval)
1317                         retval = p->pid;
1318         } else {
1319                 retval = wait_noreap_copyout(p, pid, uid,
1320                                              CLD_CONTINUED, SIGCONT,
1321                                              infop, ru);
1322                 BUG_ON(retval == 0);
1323         }
1324
1325         return retval;
1326 }
1327
1328
1329 static inline int my_ptrace_child(struct task_struct *p)
1330 {
1331         if (!(p->ptrace & PT_PTRACED))
1332                 return 0;
1333         if (!(p->ptrace & PT_ATTACHED))
1334                 return 1;
1335         /*
1336          * This child was PTRACE_ATTACH'd.  We should be seeing it only if
1337          * we are the attacher.  If we are the real parent, this is a race
1338          * inside ptrace_attach.  It is waiting for the tasklist_lock,
1339          * which we have to switch the parent links, but has already set
1340          * the flags in p->ptrace.
1341          */
1342         return (p->parent != p->real_parent);
1343 }
1344
1345 static long do_wait(pid_t pid, int options, struct siginfo __user *infop,
1346                     int __user *stat_addr, struct rusage __user *ru)
1347 {
1348         DECLARE_WAITQUEUE(wait, current);
1349         struct task_struct *tsk;
1350         int flag, retval;
1351
1352         add_wait_queue(&current->signal->wait_chldexit,&wait);
1353 repeat:
1354         /*
1355          * We will set this flag if we see any child that might later
1356          * match our criteria, even if we are not able to reap it yet.
1357          */
1358         flag = 0;
1359         current->state = TASK_INTERRUPTIBLE;
1360         read_lock(&tasklist_lock);
1361         tsk = current;
1362         do {
1363                 struct task_struct *p;
1364                 struct list_head *_p;
1365                 int ret;
1366
1367                 list_for_each(_p,&tsk->children) {
1368                         p = list_entry(_p,struct task_struct,sibling);
1369
1370                         ret = eligible_child(pid, options, p);
1371                         if (!ret)
1372                                 continue;
1373
1374                         switch (p->state) {
1375                         case TASK_TRACED:
1376                                 if (!my_ptrace_child(p))
1377                                         continue;
1378                                 /*FALLTHROUGH*/
1379                         case TASK_STOPPED:
1380                                 /*
1381                                  * It's stopped now, so it might later
1382                                  * continue, exit, or stop again.
1383                                  */
1384                                 flag = 1;
1385                                 if (!(options & WUNTRACED) &&
1386                                     !my_ptrace_child(p))
1387                                         continue;
1388                                 retval = wait_task_stopped(p, ret == 2,
1389                                                            (options & WNOWAIT),
1390                                                            infop,
1391                                                            stat_addr, ru);
1392                                 if (retval == -EAGAIN)
1393                                         goto repeat;
1394                                 if (retval != 0) /* He released the lock.  */
1395                                         goto end;
1396                                 break;
1397                         default:
1398                         // case EXIT_DEAD:
1399                                 if (p->exit_state == EXIT_DEAD)
1400                                         continue;
1401                         // case EXIT_ZOMBIE:
1402                                 if (p->exit_state == EXIT_ZOMBIE) {
1403                                         /*
1404                                          * Eligible but we cannot release
1405                                          * it yet:
1406                                          */
1407                                         if (ret == 2)
1408                                                 goto check_continued;
1409                                         if (!likely(options & WEXITED))
1410                                                 continue;
1411                                         retval = wait_task_zombie(
1412                                                 p, (options & WNOWAIT),
1413                                                 infop, stat_addr, ru);
1414                                         /* He released the lock.  */
1415                                         if (retval != 0)
1416                                                 goto end;
1417                                         break;
1418                                 }
1419 check_continued:
1420                                 /*
1421                                  * It's running now, so it might later
1422                                  * exit, stop, or stop and then continue.
1423                                  */
1424                                 flag = 1;
1425                                 if (!unlikely(options & WCONTINUED))
1426                                         continue;
1427                                 retval = wait_task_continued(
1428                                         p, (options & WNOWAIT),
1429                                         infop, stat_addr, ru);
1430                                 if (retval != 0) /* He released the lock.  */
1431                                         goto end;
1432                                 break;
1433                         }
1434                 }
1435                 if (!flag) {
1436                         list_for_each(_p, &tsk->ptrace_children) {
1437                                 p = list_entry(_p, struct task_struct,
1438                                                 ptrace_list);
1439                                 if (!eligible_child(pid, options, p))
1440                                         continue;
1441                                 flag = 1;
1442                                 break;
1443                         }
1444                 }
1445                 if (options & __WNOTHREAD)
1446                         break;
1447                 tsk = next_thread(tsk);
1448                 if (tsk->signal != current->signal)
1449                         BUG();
1450         } while (tsk != current);
1451
1452         read_unlock(&tasklist_lock);
1453         if (flag) {
1454                 retval = 0;
1455                 if (options & WNOHANG)
1456                         goto end;
1457                 retval = -ERESTARTSYS;
1458                 if (signal_pending(current))
1459                         goto end;
1460                 schedule();
1461                 goto repeat;
1462         }
1463         retval = -ECHILD;
1464 end:
1465         current->state = TASK_RUNNING;
1466         remove_wait_queue(&current->signal->wait_chldexit,&wait);
1467         if (infop) {
1468                 if (retval > 0)
1469                 retval = 0;
1470                 else {
1471                         /*
1472                          * For a WNOHANG return, clear out all the fields
1473                          * we would set so the user can easily tell the
1474                          * difference.
1475                          */
1476                         if (!retval)
1477                                 retval = put_user(0, &infop->si_signo);
1478                         if (!retval)
1479                                 retval = put_user(0, &infop->si_errno);
1480                         if (!retval)
1481                                 retval = put_user(0, &infop->si_code);
1482                         if (!retval)
1483                                 retval = put_user(0, &infop->si_pid);
1484                         if (!retval)
1485                                 retval = put_user(0, &infop->si_uid);
1486                         if (!retval)
1487                                 retval = put_user(0, &infop->si_status);
1488                 }
1489         }
1490         return retval;
1491 }
1492
1493 asmlinkage long sys_waitid(int which, pid_t pid,
1494                            struct siginfo __user *infop, int options,
1495                            struct rusage __user *ru)
1496 {
1497         long ret;
1498
1499         if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1500                 return -EINVAL;
1501         if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1502                 return -EINVAL;
1503
1504         switch (which) {
1505         case P_ALL:
1506                 pid = -1;
1507                 break;
1508         case P_PID:
1509                 if (pid <= 0)
1510                         return -EINVAL;
1511                 break;
1512         case P_PGID:
1513                 if (pid <= 0)
1514                         return -EINVAL;
1515                 pid = -pid;
1516                 break;
1517         default:
1518                 return -EINVAL;
1519         }
1520
1521         ret = do_wait(pid, options, infop, NULL, ru);
1522
1523         /* avoid REGPARM breakage on x86: */
1524         prevent_tail_call(ret);
1525         return ret;
1526 }
1527
1528 asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr,
1529                           int options, struct rusage __user *ru)
1530 {
1531         long ret;
1532
1533         if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1534                         __WNOTHREAD|__WCLONE|__WALL))
1535                 return -EINVAL;
1536         ret = do_wait(pid, options | WEXITED, NULL, stat_addr, ru);
1537
1538         /* avoid REGPARM breakage on x86: */
1539         prevent_tail_call(ret);
1540         return ret;
1541 }
1542
1543 #ifdef __ARCH_WANT_SYS_WAITPID
1544
1545 /*
1546  * sys_waitpid() remains for compatibility. waitpid() should be
1547  * implemented by calling sys_wait4() from libc.a.
1548  */
1549 asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options)
1550 {
1551         return sys_wait4(pid, stat_addr, options, NULL);
1552 }
1553
1554 #endif