kernel/exit.c

   1 /*
   2  *  linux/kernel/exit.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 #include <linux/mm.h>
   8 #include <linux/slab.h>
   9 #include <linux/interrupt.h>
  10 #include <linux/smp_lock.h>
  11 #include <linux/module.h>
  12 #include <linux/capability.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/taskstats_kern.h>
  29 #include <linux/delayacct.h>
  30 #include <linux/cpuset.h>
  31 #include <linux/syscalls.h>
  32 #include <linux/signal.h>
  33 #include <linux/posix-timers.h>
  34 #include <linux/cn_proc.h>
  35 #include <linux/mutex.h>
  36 #include <linux/futex.h>
  37 #include <linux/compat.h>
  38 #include <linux/pipe_fs_i.h>
  39 #include <linux/audit.h> /* for audit_free() */
  40 #include <linux/resource.h>
  41
  42 #include <asm/uaccess.h>
  43 #include <asm/unistd.h>
  44 #include <asm/pgtable.h>
  45 #include <asm/mmu_context.h>
  46
  47 extern void sem_exit (void);
  48 extern struct task_struct *child_reaper;
  49
  50 static void exit_mm(struct task_struct * tsk);
  51
  52 static void __unhash_process(struct task_struct *p)
  53 {
  54         nr_threads--;
  55         detach_pid(p, PIDTYPE_PID);
  56         if (thread_group_leader(p)) {
  57                 detach_pid(p, PIDTYPE_PGID);
  58                 detach_pid(p, PIDTYPE_SID);
  59
  60                 list_del_rcu(&p->tasks);
  61                 __get_cpu_var(process_counts)--;
  62         }
  63         list_del_rcu(&p->thread_group);
  64         remove_parent(p);
  65 }
  66
  67 /*
  68  * This function expects the tasklist_lock write-locked.
  69  */
  70 static void __exit_signal(struct task_struct *tsk)
  71 {
  72         struct signal_struct *sig = tsk->signal;
  73         struct sighand_struct *sighand;
  74
  75         BUG_ON(!sig);
  76         BUG_ON(!atomic_read(&sig->count));
  77
  78         rcu_read_lock();
  79         sighand = rcu_dereference(tsk->sighand);
  80         spin_lock(&sighand->siglock);
  81
  82         posix_cpu_timers_exit(tsk);
  83         if (atomic_dec_and_test(&sig->count))
  84                 posix_cpu_timers_exit_group(tsk);
  85         else {
  86                 /*
  87                  * If there is any task waiting for the group exit
  88                  * then notify it:
  89                  */
  90                 if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count) {
  91                         wake_up_process(sig->group_exit_task);
  92                         sig->group_exit_task = NULL;
  93                 }
  94                 if (tsk == sig->curr_target)
  95                         sig->curr_target = next_thread(tsk);
  96                 /*
  97                  * Accumulate here the counters for all threads but the
  98                  * group leader as they die, so they can be added into
  99                  * the process-wide totals when those are taken.
 100                  * The group leader stays around as a zombie as long
 101                  * as there are other threads.  When it gets reaped,
 102                  * the exit.c code will add its counts into these totals.
 103                  * We won't ever get here for the group leader, since it
 104                  * will have been the last reference on the signal_struct.
 105                  */
 106                 sig->utime = cputime_add(sig->utime, tsk->utime);
 107                 sig->stime = cputime_add(sig->stime, tsk->stime);
 108                 sig->min_flt += tsk->min_flt;
 109                 sig->maj_flt += tsk->maj_flt;
 110                 sig->nvcsw += tsk->nvcsw;
 111                 sig->nivcsw += tsk->nivcsw;
 112                 sig->sched_time += tsk->sched_time;
 113                 sig = NULL; /* Marker for below. */
 114         }
 115
 116         __unhash_process(tsk);
 117
 118         tsk->signal = NULL;
 119         tsk->sighand = NULL;
 120         spin_unlock(&sighand->siglock);
 121         rcu_read_unlock();
 122
 123         __cleanup_sighand(sighand);
 124         clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
 125         flush_sigqueue(&tsk->pending);
 126         if (sig) {
 127                 flush_sigqueue(&sig->shared_pending);
 128                 __cleanup_signal(sig);
 129         }
 130 }
 131
 132 static void delayed_put_task_struct(struct rcu_head *rhp)
 133 {
 134         put_task_struct(container_of(rhp, struct task_struct, rcu));
 135 }
 136
 137 void release_task(struct task_struct * p)
 138 {
 139         struct task_struct *leader;
 140         int zap_leader;
 141 repeat:
 142         atomic_dec(&p->user->processes);
 143         write_lock_irq(&tasklist_lock);
 144         ptrace_unlink(p);
 145         BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
 146         __exit_signal(p);
 147
 148         /*
 149          * If we are the last non-leader member of the thread
 150          * group, and the leader is zombie, then notify the
 151          * group leader's parent process. (if it wants notification.)
 152          */
 153         zap_leader = 0;
 154         leader = p->group_leader;
 155         if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
 156                 BUG_ON(leader->exit_signal == -1);
 157                 do_notify_parent(leader, leader->exit_signal);
 158                 /*
 159                  * If we were the last child thread and the leader has
 160                  * exited already, and the leader's parent ignores SIGCHLD,
 161                  * then we are the one who should release the leader.
 162                  *
 163                  * do_notify_parent() will have marked it self-reaping in
 164                  * that case.
 165                  */
 166                 zap_leader = (leader->exit_signal == -1);
 167         }
 168
 169         sched_exit(p);
 170         write_unlock_irq(&tasklist_lock);
 171         proc_flush_task(p);
 172         release_thread(p);
 173         call_rcu(&p->rcu, delayed_put_task_struct);
 174
 175         p = leader;
 176         if (unlikely(zap_leader))
 177                 goto repeat;
 178 }
 179
 180 /*
 181  * This checks not only the pgrp, but falls back on the pid if no
 182  * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
 183  * without this...
 184  */
 185 int session_of_pgrp(int pgrp)
 186 {
 187         struct task_struct *p;
 188         int sid = -1;
 189
 190         read_lock(&tasklist_lock);
 191         do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
 192                 if (p->signal->session > 0) {
 193                         sid = p->signal->session;
 194                         goto out;
 195                 }
 196         } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
 197         p = find_task_by_pid(pgrp);
 198         if (p)
 199                 sid = p->signal->session;
 200 out:
 201         read_unlock(&tasklist_lock);
 202
 203         return sid;
 204 }
 205
 206 /*
 207  * Determine if a process group is "orphaned", according to the POSIX
 208  * definition in 2.2.2.52.  Orphaned process groups are not to be affected
 209  * by terminal-generated stop signals.  Newly orphaned process groups are
 210  * to receive a SIGHUP and a SIGCONT.
 211  *
 212  * "I ask you, have you ever known what it is to be an orphan?"
 213  */
 214 static int will_become_orphaned_pgrp(int pgrp, struct task_struct *ignored_task)
 215 {
 216         struct task_struct *p;
 217         int ret = 1;
 218
 219         do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
 220                 if (p == ignored_task
 221                                 || p->exit_state
 222                                 || p->real_parent->pid == 1)
 223                         continue;
 224                 if (process_group(p->real_parent) != pgrp
 225                             && p->real_parent->signal->session == p->signal->session) {
 226                         ret = 0;
 227                         break;
 228                 }
 229         } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
 230         return ret;     /* (sighing) "Often!" */
 231 }
 232
 233 int is_orphaned_pgrp(int pgrp)
 234 {
 235         int retval;
 236
 237         read_lock(&tasklist_lock);
 238         retval = will_become_orphaned_pgrp(pgrp, NULL);
 239         read_unlock(&tasklist_lock);
 240
 241         return retval;
 242 }
 243
 244 static int has_stopped_jobs(int pgrp)
 245 {
 246         int retval = 0;
 247         struct task_struct *p;
 248
 249         do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
 250                 if (p->state != TASK_STOPPED)
 251                         continue;
 252
 253                 /* If p is stopped by a debugger on a signal that won't
 254                    stop it, then don't count p as stopped.  This isn't
 255                    perfect but it's a good approximation.  */
 256                 if (unlikely (p->ptrace)
 257                     && p->exit_code != SIGSTOP
 258                     && p->exit_code != SIGTSTP
 259                     && p->exit_code != SIGTTOU
 260                     && p->exit_code != SIGTTIN)
 261                         continue;
 262
 263                 retval = 1;
 264                 break;
 265         } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
 266         return retval;
 267 }
 268
 269 /**
 270  * reparent_to_init - Reparent the calling kernel thread to the init task.
 271  *
 272  * If a kernel thread is launched as a result of a system call, or if
 273  * it ever exits, it should generally reparent itself to init so that
 274  * it is correctly cleaned up on exit.
 275  *
 276  * The various task state such as scheduling policy and priority may have
 277  * been inherited from a user process, so we reset them to sane values here.
 278  *
 279  * NOTE that reparent_to_init() gives the caller full capabilities.
 280  */
 281 static void reparent_to_init(void)
 282 {
 283         write_lock_irq(&tasklist_lock);
 284
 285         ptrace_unlink(current);
 286         /* Reparent to init */
 287         remove_parent(current);
 288         current->parent = child_reaper;
 289         current->real_parent = child_reaper;
 290         add_parent(current);
 291
 292         /* Set the exit signal to SIGCHLD so we signal init on exit */
 293         current->exit_signal = SIGCHLD;
 294
 295         if ((current->policy == SCHED_NORMAL ||
 296                         current->policy == SCHED_BATCH)
 297                                 && (task_nice(current) < 0))
 298                 set_user_nice(current, 0);
 299         /* cpus_allowed? */
 300         /* rt_priority? */
 301         /* signals? */
 302         security_task_reparent_to_init(current);
 303         memcpy(current->signal->rlim, init_task.signal->rlim,
 304                sizeof(current->signal->rlim));
 305         atomic_inc(&(INIT_USER->__count));
 306         write_unlock_irq(&tasklist_lock);
 307         switch_uid(INIT_USER);
 308 }
 309
 310 void __set_special_pids(pid_t session, pid_t pgrp)
 311 {
 312         struct task_struct *curr = current->group_leader;
 313
 314         if (curr->signal->session != session) {
 315                 detach_pid(curr, PIDTYPE_SID);
 316                 curr->signal->session = session;
 317                 attach_pid(curr, PIDTYPE_SID, session);
 318         }
 319         if (process_group(curr) != pgrp) {
 320                 detach_pid(curr, PIDTYPE_PGID);
 321                 curr->signal->pgrp = pgrp;
 322                 attach_pid(curr, PIDTYPE_PGID, pgrp);
 323         }
 324 }
 325
 326 void set_special_pids(pid_t session, pid_t pgrp)
 327 {
 328         write_lock_irq(&tasklist_lock);
 329         __set_special_pids(session, pgrp);
 330         write_unlock_irq(&tasklist_lock);
 331 }
 332
 333 /*
 334  * Let kernel threads use this to say that they
 335  * allow a certain signal (since daemonize() will
 336  * have disabled all of them by default).
 337  */
 338 int allow_signal(int sig)
 339 {
 340         if (!valid_signal(sig) || sig < 1)
 341                 return -EINVAL;
 342
 343         spin_lock_irq(&current->sighand->siglock);
 344         sigdelset(&current->blocked, sig);
 345         if (!current->mm) {
 346                 /* Kernel threads handle their own signals.
 347                    Let the signal code know it'll be handled, so
 348                    that they don't get converted to SIGKILL or
 349                    just silently dropped */
 350                 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
 351         }
 352         recalc_sigpending();
 353         spin_unlock_irq(&current->sighand->siglock);
 354         return 0;
 355 }
 356
 357 EXPORT_SYMBOL(allow_signal);
 358
 359 int disallow_signal(int sig)
 360 {
 361         if (!valid_signal(sig) || sig < 1)
 362                 return -EINVAL;
 363
 364         spin_lock_irq(&current->sighand->siglock);
 365         sigaddset(&current->blocked, sig);
 366         recalc_sigpending();
 367         spin_unlock_irq(&current->sighand->siglock);
 368         return 0;
 369 }
 370
 371 EXPORT_SYMBOL(disallow_signal);
 372
 373 /*
 374  *      Put all the gunge required to become a kernel thread without
 375  *      attached user resources in one place where it belongs.
 376  */
 377
 378 void daemonize(const char *name, ...)
 379 {
 380         va_list args;
 381         struct fs_struct *fs;
 382         sigset_t blocked;
 383
 384         va_start(args, name);
 385         vsnprintf(current->comm, sizeof(current->comm), name, args);
 386         va_end(args);
 387
 388         /*
 389          * If we were started as result of loading a module, close all of the
 390          * user space pages.  We don't need them, and if we didn't close them
 391          * they would be locked into memory.
 392          */
 393         exit_mm(current);
 394
 395         set_special_pids(1, 1);
 396         mutex_lock(&tty_mutex);
 397         current->signal->tty = NULL;
 398         mutex_unlock(&tty_mutex);
 399
 400         /* Block and flush all signals */
 401         sigfillset(&blocked);
 402         sigprocmask(SIG_BLOCK, &blocked, NULL);
 403         flush_signals(current);
 404
 405         /* Become as one with the init task */
 406
 407         exit_fs(current);       /* current->fs->count--; */
 408         fs = init_task.fs;
 409         current->fs = fs;
 410         atomic_inc(&fs->count);
 411         exit_namespace(current);
 412         current->namespace = init_task.namespace;
 413         get_namespace(current->namespace);
 414         exit_files(current);
 415         current->files = init_task.files;
 416         atomic_inc(&current->files->count);
 417
 418         reparent_to_init();
 419 }
 420
 421 EXPORT_SYMBOL(daemonize);
 422
 423 static void close_files(struct files_struct * files)
 424 {
 425         int i, j;
 426         struct fdtable *fdt;
 427
 428         j = 0;
 429
 430         /*
 431          * It is safe to dereference the fd table without RCU or
 432          * ->file_lock because this is the last reference to the
 433          * files structure.
 434          */
 435         fdt = files_fdtable(files);
 436         for (;;) {
 437                 unsigned long set;
 438                 i = j * __NFDBITS;
 439                 if (i >= fdt->max_fdset || i >= fdt->max_fds)
 440                         break;
 441                 set = fdt->open_fds->fds_bits[j++];
 442                 while (set) {
 443                         if (set & 1) {
 444                                 struct file * file = xchg(&fdt->fd[i], NULL);
 445                                 if (file)
 446                                         filp_close(file, files);
 447                         }
 448                         i++;
 449                         set >>= 1;
 450                 }
 451         }
 452 }
 453
 454 struct files_struct *get_files_struct(struct task_struct *task)
 455 {
 456         struct files_struct *files;
 457
 458         task_lock(task);
 459         files = task->files;
 460         if (files)
 461                 atomic_inc(&files->count);
 462         task_unlock(task);
 463
 464         return files;
 465 }
 466
 467 void fastcall put_files_struct(struct files_struct *files)
 468 {
 469         struct fdtable *fdt;
 470
 471         if (atomic_dec_and_test(&files->count)) {
 472                 close_files(files);
 473                 /*
 474                  * Free the fd and fdset arrays if we expanded them.
 475                  * If the fdtable was embedded, pass files for freeing
 476                  * at the end of the RCU grace period. Otherwise,
 477                  * you can free files immediately.
 478                  */
 479                 fdt = files_fdtable(files);
 480                 if (fdt == &files->fdtab)
 481                         fdt->free_files = files;
 482                 else
 483                         kmem_cache_free(files_cachep, files);
 484                 free_fdtable(fdt);
 485         }
 486 }
 487
 488 EXPORT_SYMBOL(put_files_struct);
 489
 490 static inline void __exit_files(struct task_struct *tsk)
 491 {
 492         struct files_struct * files = tsk->files;
 493
 494         if (files) {
 495                 task_lock(tsk);
 496                 tsk->files = NULL;
 497                 task_unlock(tsk);
 498                 put_files_struct(files);
 499         }
 500 }
 501
 502 void exit_files(struct task_struct *tsk)
 503 {
 504         __exit_files(tsk);
 505 }
 506
 507 static inline void __put_fs_struct(struct fs_struct *fs)
 508 {
 509         /* No need to hold fs->lock if we are killing it */
 510         if (atomic_dec_and_test(&fs->count)) {
 511                 dput(fs->root);
 512                 mntput(fs->rootmnt);
 513                 dput(fs->pwd);
 514                 mntput(fs->pwdmnt);
 515                 if (fs->altroot) {
 516                         dput(fs->altroot);
 517                         mntput(fs->altrootmnt);
 518                 }
 519                 kmem_cache_free(fs_cachep, fs);
 520         }
 521 }
 522
 523 void put_fs_struct(struct fs_struct *fs)
 524 {
 525         __put_fs_struct(fs);
 526 }
 527
 528 static inline void __exit_fs(struct task_struct *tsk)
 529 {
 530         struct fs_struct * fs = tsk->fs;
 531
 532         if (fs) {
 533                 task_lock(tsk);
 534                 tsk->fs = NULL;
 535                 task_unlock(tsk);
 536                 __put_fs_struct(fs);
 537         }
 538 }
 539
 540 void exit_fs(struct task_struct *tsk)
 541 {
 542         __exit_fs(tsk);
 543 }
 544
 545 EXPORT_SYMBOL_GPL(exit_fs);
 546
 547 /*
 548  * Turn us into a lazy TLB process if we
 549  * aren't already..
 550  */
 551 static void exit_mm(struct task_struct * tsk)
 552 {
 553         struct mm_struct *mm = tsk->mm;
 554
 555         mm_release(tsk, mm);
 556         if (!mm)
 557                 return;
 558         /*
 559          * Serialize with any possible pending coredump.
 560          * We must hold mmap_sem around checking core_waiters
 561          * and clearing tsk->mm.  The core-inducing thread
 562          * will increment core_waiters for each thread in the
 563          * group with ->mm != NULL.
 564          */
 565         down_read(&mm->mmap_sem);
 566         if (mm->core_waiters) {
 567                 up_read(&mm->mmap_sem);
 568                 down_write(&mm->mmap_sem);
 569                 if (!--mm->core_waiters)
 570                         complete(mm->core_startup_done);
 571                 up_write(&mm->mmap_sem);
 572
 573                 wait_for_completion(&mm->core_done);
 574                 down_read(&mm->mmap_sem);
 575         }
 576         atomic_inc(&mm->mm_count);
 577         BUG_ON(mm != tsk->active_mm);
 578         /* more a memory barrier than a real lock */
 579         task_lock(tsk);
 580         tsk->mm = NULL;
 581         up_read(&mm->mmap_sem);
 582         enter_lazy_tlb(mm, current);
 583         task_unlock(tsk);
 584         mmput(mm);
 585 }
 586
 587 static inline void
 588 choose_new_parent(struct task_struct *p, struct task_struct *reaper)
 589 {
 590         /*
 591          * Make sure we're not reparenting to ourselves and that
 592          * the parent is not a zombie.
 593          */
 594         BUG_ON(p == reaper || reaper->exit_state);
 595         p->real_parent = reaper;
 596 }
 597
 598 static void
 599 reparent_thread(struct task_struct *p, struct task_struct *father, int traced)
 600 {
 601         /* We don't want people slaying init.  */
 602         if (p->exit_signal != -1)
 603                 p->exit_signal = SIGCHLD;
 604
 605         if (p->pdeath_signal)
 606                 /* We already hold the tasklist_lock here.  */
 607                 group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);
 608
 609         /* Move the child from its dying parent to the new one.  */
 610         if (unlikely(traced)) {
 611                 /* Preserve ptrace links if someone else is tracing this child.  */
 612                 list_del_init(&p->ptrace_list);
 613                 if (p->parent != p->real_parent)
 614                         list_add(&p->ptrace_list, &p->real_parent->ptrace_children);
 615         } else {
 616                 /* If this child is being traced, then we're the one tracing it
 617                  * anyway, so let go of it.
 618                  */
 619                 p->ptrace = 0;
 620                 remove_parent(p);
 621                 p->parent = p->real_parent;
 622                 add_parent(p);
 623
 624                 /* If we'd notified the old parent about this child's death,
 625                  * also notify the new parent.
 626                  */
 627                 if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
 628                     thread_group_empty(p))
 629                         do_notify_parent(p, p->exit_signal);
 630                 else if (p->state == TASK_TRACED) {
 631                         /*
 632                          * If it was at a trace stop, turn it into
 633                          * a normal stop since it's no longer being
 634                          * traced.
 635                          */
 636                         ptrace_untrace(p);
 637                 }
 638         }
 639
 640         /*
 641          * process group orphan check
 642          * Case ii: Our child is in a different pgrp
 643          * than we are, and it was the only connection
 644          * outside, so the child pgrp is now orphaned.
 645          */
 646         if ((process_group(p) != process_group(father)) &&
 647             (p->signal->session == father->signal->session)) {
 648                 int pgrp = process_group(p);
 649
 650                 if (will_become_orphaned_pgrp(pgrp, NULL) && has_stopped_jobs(pgrp)) {
 651                         __kill_pg_info(SIGHUP, SEND_SIG_PRIV, pgrp);
 652                         __kill_pg_info(SIGCONT, SEND_SIG_PRIV, pgrp);
 653                 }
 654         }
 655 }
 656
 657 /*
 658  * When we die, we re-parent all our children.
 659  * Try to give them to another thread in our thread
 660  * group, and if no such member exists, give it to
 661  * the global child reaper process (ie "init")
 662  */
 663 static void
 664 forget_original_parent(struct task_struct *father, struct list_head *to_release)
 665 {
 666         struct task_struct *p, *reaper = father;
 667         struct list_head *_p, *_n;
 668
 669         do {
 670                 reaper = next_thread(reaper);
 671                 if (reaper == father) {
 672                         reaper = child_reaper;
 673                         break;
 674                 }
 675         } while (reaper->exit_state);
 676
 677         /*
 678          * There are only two places where our children can be:
 679          *
 680          * - in our child list
 681          * - in our ptraced child list
 682          *
 683          * Search them and reparent children.
 684          */
 685         list_for_each_safe(_p, _n, &father->children) {
 686                 int ptrace;
 687                 p = list_entry(_p, struct task_struct, sibling);
 688
 689                 ptrace = p->ptrace;
 690
 691                 /* if father isn't the real parent, then ptrace must be enabled */
 692                 BUG_ON(father != p->real_parent && !ptrace);
 693
 694                 if (father == p->real_parent) {
 695                         /* reparent with a reaper, real father it's us */
 696                         choose_new_parent(p, reaper);
 697                         reparent_thread(p, father, 0);
 698                 } else {
 699                         /* reparent ptraced task to its real parent */
 700                         __ptrace_unlink (p);
 701                         if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
 702                             thread_group_empty(p))
 703                                 do_notify_parent(p, p->exit_signal);
 704                 }
 705
 706                 /*
 707                  * if the ptraced child is a zombie with exit_signal == -1
 708                  * we must collect it before we exit, or it will remain
 709                  * zombie forever since we prevented it from self-reap itself
 710                  * while it was being traced by us, to be able to see it in wait4.
 711                  */
 712                 if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && p->exit_signal == -1))
 713                         list_add(&p->ptrace_list, to_release);
 714         }
 715         list_for_each_safe(_p, _n, &father->ptrace_children) {
 716                 p = list_entry(_p, struct task_struct, ptrace_list);
 717                 choose_new_parent(p, reaper);
 718                 reparent_thread(p, father, 1);
 719         }
 720 }
 721
 722 /*
 723  * Send signals to all our closest relatives so that they know
 724  * to properly mourn us..
 725  */
 726 static void exit_notify(struct task_struct *tsk)
 727 {
 728         int state;
 729         struct task_struct *t;
 730         struct list_head ptrace_dead, *_p, *_n;
 731
 732         if (signal_pending(tsk) && !(tsk->signal->flags & SIGNAL_GROUP_EXIT)
 733             && !thread_group_empty(tsk)) {
 734                 /*
 735                  * This occurs when there was a race between our exit
 736                  * syscall and a group signal choosing us as the one to
 737                  * wake up.  It could be that we are the only thread
 738                  * alerted to check for pending signals, but another thread
 739                  * should be woken now to take the signal since we will not.
 740                  * Now we'll wake all the threads in the group just to make
 741                  * sure someone gets all the pending signals.
 742                  */
 743                 read_lock(&tasklist_lock);
 744                 spin_lock_irq(&tsk->sighand->siglock);
 745                 for (t = next_thread(tsk); t != tsk; t = next_thread(t))
 746                         if (!signal_pending(t) && !(t->flags & PF_EXITING)) {
 747                                 recalc_sigpending_tsk(t);
 748                                 if (signal_pending(t))
 749                                         signal_wake_up(t, 0);
 750                         }
 751                 spin_unlock_irq(&tsk->sighand->siglock);
 752                 read_unlock(&tasklist_lock);
 753         }
 754
 755         write_lock_irq(&tasklist_lock);
 756
 757         /*
 758          * This does two things:
 759          *
 760          * A.  Make init inherit all the child processes
 761          * B.  Check to see if any process groups have become orphaned
 762          *      as a result of our exiting, and if they have any stopped
 763          *      jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
 764          */
 765
 766         INIT_LIST_HEAD(&ptrace_dead);
 767         forget_original_parent(tsk, &ptrace_dead);
 768         BUG_ON(!list_empty(&tsk->children));
 769         BUG_ON(!list_empty(&tsk->ptrace_children));
 770
 771         /*
 772          * Check to see if any process groups have become orphaned
 773          * as a result of our exiting, and if they have any stopped
 774          * jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
 775          *
 776          * Case i: Our father is in a different pgrp than we are
 777          * and we were the only connection outside, so our pgrp
 778          * is about to become orphaned.
 779          */
 780
 781         t = tsk->real_parent;
 782
 783         if ((process_group(t) != process_group(tsk)) &&
 784             (t->signal->session == tsk->signal->session) &&
 785             will_become_orphaned_pgrp(process_group(tsk), tsk) &&
 786             has_stopped_jobs(process_group(tsk))) {
 787                 __kill_pg_info(SIGHUP, SEND_SIG_PRIV, process_group(tsk));
 788                 __kill_pg_info(SIGCONT, SEND_SIG_PRIV, process_group(tsk));
 789         }
 790
 791         /* Let father know we died
 792          *
 793          * Thread signals are configurable, but you aren't going to use
 794          * that to send signals to arbitary processes.
 795          * That stops right now.
 796          *
 797          * If the parent exec id doesn't match the exec id we saved
 798          * when we started then we know the parent has changed security
 799          * domain.
 800          *
 801          * If our self_exec id doesn't match our parent_exec_id then
 802          * we have changed execution domain as these two values started
 803          * the same after a fork.
 804          *
 805          */
 806
 807         if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 &&
 808             ( tsk->parent_exec_id != t->self_exec_id  ||
 809               tsk->self_exec_id != tsk->parent_exec_id)
 810             && !capable(CAP_KILL))
 811                 tsk->exit_signal = SIGCHLD;
 812
 813
 814         /* If something other than our normal parent is ptracing us, then
 815          * send it a SIGCHLD instead of honoring exit_signal.  exit_signal
 816          * only has special meaning to our real parent.
 817          */
 818         if (tsk->exit_signal != -1 && thread_group_empty(tsk)) {
 819                 int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD;
 820                 do_notify_parent(tsk, signal);
 821         } else if (tsk->ptrace) {
 822                 do_notify_parent(tsk, SIGCHLD);
 823         }
 824
 825         state = EXIT_ZOMBIE;
 826         if (tsk->exit_signal == -1 &&
 827             (likely(tsk->ptrace == 0) ||
 828              unlikely(tsk->parent->signal->flags & SIGNAL_GROUP_EXIT)))
 829                 state = EXIT_DEAD;
 830         tsk->exit_state = state;
 831
 832         write_unlock_irq(&tasklist_lock);
 833
 834         list_for_each_safe(_p, _n, &ptrace_dead) {
 835                 list_del_init(_p);
 836                 t = list_entry(_p, struct task_struct, ptrace_list);
 837                 release_task(t);
 838         }
 839
 840         /* If the process is dead, release it - nobody will wait for it */
 841         if (state == EXIT_DEAD)
 842                 release_task(tsk);
 843 }
 844
 845 fastcall NORET_TYPE void do_exit(long code)
 846 {
 847         struct task_struct *tsk = current;
 848         struct taskstats *tidstats;
 849         int group_dead;
 850         unsigned int mycpu;
 851
 852         profile_task_exit(tsk);
 853
 854         WARN_ON(atomic_read(&tsk->fs_excl));
 855
 856         if (unlikely(in_interrupt()))
 857                 panic("Aiee, killing interrupt handler!");
 858         if (unlikely(!tsk->pid))
 859                 panic("Attempted to kill the idle task!");
 860         if (unlikely(tsk == child_reaper))
 861                 panic("Attempted to kill init!");
 862
 863         if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
 864                 current->ptrace_message = code;
 865                 ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP);
 866         }
 867
 868         /*
 869          * We're taking recursive faults here in do_exit. Safest is to just
 870          * leave this task alone and wait for reboot.
 871          */
 872         if (unlikely(tsk->flags & PF_EXITING)) {
 873                 printk(KERN_ALERT
 874                         "Fixing recursive fault but reboot is needed!\n");
 875                 if (tsk->io_context)
 876                         exit_io_context();
 877                 set_current_state(TASK_UNINTERRUPTIBLE);
 878                 schedule();
 879         }
 880
 881         tsk->flags |= PF_EXITING;
 882
 883         if (unlikely(in_atomic()))
 884                 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
 885                                 current->comm, current->pid,
 886                                 preempt_count());
 887
 888         taskstats_exit_alloc(&tidstats, &mycpu);
 889
 890         acct_update_integrals(tsk);
 891         if (tsk->mm) {
 892                 update_hiwater_rss(tsk->mm);
 893                 update_hiwater_vm(tsk->mm);
 894         }
 895         group_dead = atomic_dec_and_test(&tsk->signal->live);
 896         if (group_dead) {
 897                 hrtimer_cancel(&tsk->signal->real_timer);
 898                 exit_itimers(tsk->signal);
 899         }
 900         acct_collect(code, group_dead);
 901         if (unlikely(tsk->robust_list))
 902                 exit_robust_list(tsk);
 903 #if defined(CONFIG_FUTEX) && defined(CONFIG_COMPAT)
 904         if (unlikely(tsk->compat_robust_list))
 905                 compat_exit_robust_list(tsk);
 906 #endif
 907         if (unlikely(tsk->audit_context))
 908                 audit_free(tsk);
 909         taskstats_exit_send(tsk, tidstats, group_dead, mycpu);
 910         taskstats_exit_free(tidstats);
 911         delayacct_tsk_exit(tsk);
 912
 913         exit_mm(tsk);
 914
 915         if (group_dead)
 916                 acct_process();
 917         exit_sem(tsk);
 918         __exit_files(tsk);
 919         __exit_fs(tsk);
 920         exit_namespace(tsk);
 921         exit_thread();
 922         cpuset_exit(tsk);
 923         exit_keys(tsk);
 924
 925         if (group_dead && tsk->signal->leader)
 926                 disassociate_ctty(1);
 927
 928         module_put(task_thread_info(tsk)->exec_domain->module);
 929         if (tsk->binfmt)
 930                 module_put(tsk->binfmt->module);
 931
 932         tsk->exit_code = code;
 933         proc_exit_connector(tsk);
 934         exit_notify(tsk);
 935 #ifdef CONFIG_NUMA
 936         mpol_free(tsk->mempolicy);
 937         tsk->mempolicy = NULL;
 938 #endif
 939         /*
 940          * This must happen late, after the PID is not
 941          * hashed anymore:
 942          */
 943         if (unlikely(!list_empty(&tsk->pi_state_list)))
 944                 exit_pi_state_list(tsk);
 945         if (unlikely(current->pi_state_cache))
 946                 kfree(current->pi_state_cache);
 947         /*
 948          * Make sure we are holding no locks:
 949          */
 950         debug_check_no_locks_held(tsk);
 951
 952         if (tsk->io_context)
 953                 exit_io_context();
 954
 955         if (tsk->splice_pipe)
 956                 __free_pipe_info(tsk->splice_pipe);
 957
 958         /* PF_DEAD causes final put_task_struct after we schedule. */
 959         preempt_disable();
 960         BUG_ON(tsk->flags & PF_DEAD);
 961         tsk->flags |= PF_DEAD;
 962
 963         schedule();
 964         BUG();
 965         /* Avoid "noreturn function does return".  */
 966         for (;;) ;
 967 }
 968
 969 EXPORT_SYMBOL_GPL(do_exit);
 970
 971 NORET_TYPE void complete_and_exit(struct completion *comp, long code)
 972 {
 973         if (comp)
 974                 complete(comp);
 975
 976         do_exit(code);
 977 }
 978
 979 EXPORT_SYMBOL(complete_and_exit);
 980
 981 asmlinkage long sys_exit(int error_code)
 982 {
 983         do_exit((error_code&0xff)<<8);
 984 }
 985
 986 /*
 987  * Take down every thread in the group.  This is called by fatal signals
 988  * as well as by sys_exit_group (below).
 989  */
 990 NORET_TYPE void
 991 do_group_exit(int exit_code)
 992 {
 993         BUG_ON(exit_code & 0x80); /* core dumps don't get here */
 994
 995         if (current->signal->flags & SIGNAL_GROUP_EXIT)
 996                 exit_code = current->signal->group_exit_code;
 997         else if (!thread_group_empty(current)) {
 998                 struct signal_struct *const sig = current->signal;
 999                 struct sighand_struct *const sighand = current->sighand;
1000                 spin_lock_irq(&sighand->siglock);
1001                 if (sig->flags & SIGNAL_GROUP_EXIT)
1002                         /* Another thread got here before we took the lock.  */
1003                         exit_code = sig->group_exit_code;
1004                 else {
1005                         sig->group_exit_code = exit_code;
1006                         zap_other_threads(current);
1007                 }
1008                 spin_unlock_irq(&sighand->siglock);
1009         }
1010
1011         do_exit(exit_code);
1012         /* NOTREACHED */
1013 }
1014
1015 /*
1016  * this kills every thread in the thread group. Note that any externally
1017  * wait4()-ing process will get the correct exit code - even if this
1018  * thread is not the thread group leader.
1019  */
1020 asmlinkage void sys_exit_group(int error_code)
1021 {
1022         do_group_exit((error_code & 0xff) << 8);
1023 }
1024
1025 static int eligible_child(pid_t pid, int options, struct task_struct *p)
1026 {
1027         if (pid > 0) {
1028                 if (p->pid != pid)
1029                         return 0;
1030         } else if (!pid) {
1031                 if (process_group(p) != process_group(current))
1032                         return 0;
1033         } else if (pid != -1) {
1034                 if (process_group(p) != -pid)
1035                         return 0;
1036         }
1037
1038         /*
1039          * Do not consider detached threads that are
1040          * not ptraced:
1041          */
1042         if (p->exit_signal == -1 && !p->ptrace)
1043                 return 0;
1044
1045         /* Wait for all children (clone and not) if __WALL is set;
1046          * otherwise, wait for clone children *only* if __WCLONE is
1047          * set; otherwise, wait for non-clone children *only*.  (Note:
1048          * A "clone" child here is one that reports to its parent
1049          * using a signal other than SIGCHLD.) */
1050         if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
1051             && !(options & __WALL))
1052                 return 0;
1053         /*
1054          * Do not consider thread group leaders that are
1055          * in a non-empty thread group:
1056          */
1057         if (current->tgid != p->tgid && delay_group_leader(p))
1058                 return 2;
1059
1060         if (security_task_wait(p))
1061                 return 0;
1062
1063         return 1;
1064 }
1065
1066 static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,
1067                                int why, int status,
1068                                struct siginfo __user *infop,
1069                                struct rusage __user *rusagep)
1070 {
1071         int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
1072
1073         put_task_struct(p);
1074         if (!retval)
1075                 retval = put_user(SIGCHLD, &infop->si_signo);
1076         if (!retval)
1077                 retval = put_user(0, &infop->si_errno);
1078         if (!retval)
1079                 retval = put_user((short)why, &infop->si_code);
1080         if (!retval)
1081                 retval = put_user(pid, &infop->si_pid);
1082         if (!retval)
1083                 retval = put_user(uid, &infop->si_uid);
1084         if (!retval)
1085                 retval = put_user(status, &infop->si_status);
1086         if (!retval)
1087                 retval = pid;
1088         return retval;
1089 }
1090
1091 /*
1092  * Handle sys_wait4 work for one task in state EXIT_ZOMBIE.  We hold
1093  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1094  * the lock and this task is uninteresting.  If we return nonzero, we have
1095  * released the lock and the system call should return.
1096  */
1097 static int wait_task_zombie(struct task_struct *p, int noreap,
1098                             struct siginfo __user *infop,
1099                             int __user *stat_addr, struct rusage __user *ru)
1100 {
1101         unsigned long state;
1102         int retval;
1103         int status;
1104
1105         if (unlikely(noreap)) {
1106                 pid_t pid = p->pid;
1107                 uid_t uid = p->uid;
1108                 int exit_code = p->exit_code;
1109                 int why, status;
1110
1111                 if (unlikely(p->exit_state != EXIT_ZOMBIE))
1112                         return 0;
1113                 if (unlikely(p->exit_signal == -1 && p->ptrace == 0))
1114                         return 0;
1115                 get_task_struct(p);
1116                 read_unlock(&tasklist_lock);
1117                 if ((exit_code & 0x7f) == 0) {
1118                         why = CLD_EXITED;
1119                         status = exit_code >> 8;
1120                 } else {
1121                         why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1122                         status = exit_code & 0x7f;
1123                 }
1124                 return wait_noreap_copyout(p, pid, uid, why,
1125                                            status, infop, ru);
1126         }
1127
1128         /*
1129          * Try to move the task's state to DEAD
1130          * only one thread is allowed to do this:
1131          */
1132         state = xchg(&p->exit_state, EXIT_DEAD);
1133         if (state != EXIT_ZOMBIE) {
1134                 BUG_ON(state != EXIT_DEAD);
1135                 return 0;
1136         }
1137         if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) {
1138                 /*
1139                  * This can only happen in a race with a ptraced thread
1140                  * dying on another processor.
1141                  */
1142                 return 0;
1143         }
1144
1145         if (likely(p->real_parent == p->parent) && likely(p->signal)) {
1146                 struct signal_struct *psig;
1147                 struct signal_struct *sig;
1148
1149                 /*
1150                  * The resource counters for the group leader are in its
1151                  * own task_struct.  Those for dead threads in the group
1152                  * are in its signal_struct, as are those for the child
1153                  * processes it has previously reaped.  All these
1154                  * accumulate in the parent's signal_struct c* fields.
1155                  *
1156                  * We don't bother to take a lock here to protect these
1157                  * p->signal fields, because they are only touched by
1158                  * __exit_signal, which runs with tasklist_lock
1159                  * write-locked anyway, and so is excluded here.  We do
1160                  * need to protect the access to p->parent->signal fields,
1161                  * as other threads in the parent group can be right
1162                  * here reaping other children at the same time.
1163                  */
1164                 spin_lock_irq(&p->parent->sighand->siglock);
1165                 psig = p->parent->signal;
1166                 sig = p->signal;
1167                 psig->cutime =
1168                         cputime_add(psig->cutime,
1169                         cputime_add(p->utime,
1170                         cputime_add(sig->utime,
1171                                     sig->cutime)));
1172                 psig->cstime =
1173                         cputime_add(psig->cstime,
1174                         cputime_add(p->stime,
1175                         cputime_add(sig->stime,
1176                                     sig->cstime)));
1177                 psig->cmin_flt +=
1178                         p->min_flt + sig->min_flt + sig->cmin_flt;
1179                 psig->cmaj_flt +=
1180                         p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1181                 psig->cnvcsw +=
1182                         p->nvcsw + sig->nvcsw + sig->cnvcsw;
1183                 psig->cnivcsw +=
1184                         p->nivcsw + sig->nivcsw + sig->cnivcsw;
1185                 spin_unlock_irq(&p->parent->sighand->siglock);
1186         }
1187
1188         /*
1189          * Now we are sure this task is interesting, and no other
1190          * thread can reap it because we set its state to EXIT_DEAD.
1191          */
1192         read_unlock(&tasklist_lock);
1193
1194         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1195         status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1196                 ? p->signal->group_exit_code : p->exit_code;
1197         if (!retval && stat_addr)
1198                 retval = put_user(status, stat_addr);
1199         if (!retval && infop)
1200                 retval = put_user(SIGCHLD, &infop->si_signo);
1201         if (!retval && infop)
1202                 retval = put_user(0, &infop->si_errno);
1203         if (!retval && infop) {
1204                 int why;
1205
1206                 if ((status & 0x7f) == 0) {
1207                         why = CLD_EXITED;
1208                         status >>= 8;
1209                 } else {
1210                         why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1211                         status &= 0x7f;
1212                 }
1213                 retval = put_user((short)why, &infop->si_code);
1214                 if (!retval)
1215                         retval = put_user(status, &infop->si_status);
1216         }
1217         if (!retval && infop)
1218                 retval = put_user(p->pid, &infop->si_pid);
1219         if (!retval && infop)
1220                 retval = put_user(p->uid, &infop->si_uid);
1221         if (retval) {
1222                 // TODO: is this safe?
1223                 p->exit_state = EXIT_ZOMBIE;
1224                 return retval;
1225         }
1226         retval = p->pid;
1227         if (p->real_parent != p->parent) {
1228                 write_lock_irq(&tasklist_lock);
1229                 /* Double-check with lock held.  */
1230                 if (p->real_parent != p->parent) {
1231                         __ptrace_unlink(p);
1232                         // TODO: is this safe?
1233                         p->exit_state = EXIT_ZOMBIE;
1234                         /*
1235                          * If this is not a detached task, notify the parent.
1236                          * If it's still not detached after that, don't release
1237                          * it now.
1238                          */
1239                         if (p->exit_signal != -1) {
1240                                 do_notify_parent(p, p->exit_signal);
1241                                 if (p->exit_signal != -1)
1242                                         p = NULL;
1243                         }
1244                 }
1245                 write_unlock_irq(&tasklist_lock);
1246         }
1247         if (p != NULL)
1248                 release_task(p);
1249         BUG_ON(!retval);
1250         return retval;
1251 }
1252
1253 /*
1254  * Handle sys_wait4 work for one task in state TASK_STOPPED.  We hold
1255  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1256  * the lock and this task is uninteresting.  If we return nonzero, we have
1257  * released the lock and the system call should return.
1258  */
1259 static int wait_task_stopped(struct task_struct *p, int delayed_group_leader,
1260                              int noreap, struct siginfo __user *infop,
1261                              int __user *stat_addr, struct rusage __user *ru)
1262 {
1263         int retval, exit_code;
1264
1265         if (!p->exit_code)
1266                 return 0;
1267         if (delayed_group_leader && !(p->ptrace & PT_PTRACED) &&
1268             p->signal && p->signal->group_stop_count > 0)
1269                 /*
1270                  * A group stop is in progress and this is the group leader.
1271                  * We won't report until all threads have stopped.
1272                  */
1273                 return 0;
1274
1275         /*
1276          * Now we are pretty sure this task is interesting.
1277          * Make sure it doesn't get reaped out from under us while we
1278          * give up the lock and then examine it below.  We don't want to
1279          * keep holding onto the tasklist_lock while we call getrusage and
1280          * possibly take page faults for user memory.
1281          */
1282         get_task_struct(p);
1283         read_unlock(&tasklist_lock);
1284
1285         if (unlikely(noreap)) {
1286                 pid_t pid = p->pid;
1287                 uid_t uid = p->uid;
1288                 int why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
1289
1290                 exit_code = p->exit_code;
1291                 if (unlikely(!exit_code) ||
1292                     unlikely(p->state & TASK_TRACED))
1293                         goto bail_ref;
1294                 return wait_noreap_copyout(p, pid, uid,
1295                                            why, (exit_code << 8) | 0x7f,
1296                                            infop, ru);
1297         }
1298
1299         write_lock_irq(&tasklist_lock);
1300
1301         /*
1302          * This uses xchg to be atomic with the thread resuming and setting
1303          * it.  It must also be done with the write lock held to prevent a
1304          * race with the EXIT_ZOMBIE case.
1305          */
1306         exit_code = xchg(&p->exit_code, 0);
1307         if (unlikely(p->exit_state)) {
1308                 /*
1309                  * The task resumed and then died.  Let the next iteration
1310                  * catch it in EXIT_ZOMBIE.  Note that exit_code might
1311                  * already be zero here if it resumed and did _exit(0).
1312                  * The task itself is dead and won't touch exit_code again;
1313                  * other processors in this function are locked out.
1314                  */
1315                 p->exit_code = exit_code;
1316                 exit_code = 0;
1317         }
1318         if (unlikely(exit_code == 0)) {
1319                 /*
1320                  * Another thread in this function got to it first, or it
1321                  * resumed, or it resumed and then died.
1322                  */
1323                 write_unlock_irq(&tasklist_lock);
1324 bail_ref:
1325                 put_task_struct(p);
1326                 /*
1327                  * We are returning to the wait loop without having successfully
1328                  * removed the process and having released the lock. We cannot
1329                  * continue, since the "p" task pointer is potentially stale.
1330                  *
1331                  * Return -EAGAIN, and do_wait() will restart the loop from the
1332                  * beginning. Do _not_ re-acquire the lock.
1333                  */
1334                 return -EAGAIN;
1335         }
1336
1337         /* move to end of parent's list to avoid starvation */
1338         remove_parent(p);
1339         add_parent(p);
1340
1341         write_unlock_irq(&tasklist_lock);
1342
1343         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1344         if (!retval && stat_addr)
1345                 retval = put_user((exit_code << 8) | 0x7f, stat_addr);
1346         if (!retval && infop)
1347                 retval = put_user(SIGCHLD, &infop->si_signo);
1348         if (!retval && infop)
1349                 retval = put_user(0, &infop->si_errno);
1350         if (!retval && infop)
1351                 retval = put_user((short)((p->ptrace & PT_PTRACED)
1352                                           ? CLD_TRAPPED : CLD_STOPPED),
1353                                   &infop->si_code);
1354         if (!retval && infop)
1355                 retval = put_user(exit_code, &infop->si_status);
1356         if (!retval && infop)
1357                 retval = put_user(p->pid, &infop->si_pid);
1358         if (!retval && infop)
1359                 retval = put_user(p->uid, &infop->si_uid);
1360         if (!retval)
1361                 retval = p->pid;
1362         put_task_struct(p);
1363
1364         BUG_ON(!retval);
1365         return retval;
1366 }
1367
1368 /*
1369  * Handle do_wait work for one task in a live, non-stopped state.
1370  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1371  * the lock and this task is uninteresting.  If we return nonzero, we have
1372  * released the lock and the system call should return.
1373  */
1374 static int wait_task_continued(struct task_struct *p, int noreap,
1375                                struct siginfo __user *infop,
1376                                int __user *stat_addr, struct rusage __user *ru)
1377 {
1378         int retval;
1379         pid_t pid;
1380         uid_t uid;
1381
1382         if (unlikely(!p->signal))
1383                 return 0;
1384
1385         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1386                 return 0;
1387
1388         spin_lock_irq(&p->sighand->siglock);
1389         /* Re-check with the lock held.  */
1390         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1391                 spin_unlock_irq(&p->sighand->siglock);
1392                 return 0;
1393         }
1394         if (!noreap)
1395                 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1396         spin_unlock_irq(&p->sighand->siglock);
1397
1398         pid = p->pid;
1399         uid = p->uid;
1400         get_task_struct(p);
1401         read_unlock(&tasklist_lock);
1402
1403         if (!infop) {
1404                 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1405                 put_task_struct(p);
1406                 if (!retval && stat_addr)
1407                         retval = put_user(0xffff, stat_addr);
1408                 if (!retval)
1409                         retval = p->pid;
1410         } else {
1411                 retval = wait_noreap_copyout(p, pid, uid,
1412                                              CLD_CONTINUED, SIGCONT,
1413                                              infop, ru);
1414                 BUG_ON(retval == 0);
1415         }
1416
1417         return retval;
1418 }
1419
1420
1421 static inline int my_ptrace_child(struct task_struct *p)
1422 {
1423         if (!(p->ptrace & PT_PTRACED))
1424                 return 0;
1425         if (!(p->ptrace & PT_ATTACHED))
1426                 return 1;
1427         /*
1428          * This child was PTRACE_ATTACH'd.  We should be seeing it only if
1429          * we are the attacher.  If we are the real parent, this is a race
1430          * inside ptrace_attach.  It is waiting for the tasklist_lock,
1431          * which we have to switch the parent links, but has already set
1432          * the flags in p->ptrace.
1433          */
1434         return (p->parent != p->real_parent);
1435 }
1436
1437 static long do_wait(pid_t pid, int options, struct siginfo __user *infop,
1438                     int __user *stat_addr, struct rusage __user *ru)
1439 {
1440         DECLARE_WAITQUEUE(wait, current);
1441         struct task_struct *tsk;
1442         int flag, retval;
1443
1444         add_wait_queue(&current->signal->wait_chldexit,&wait);
1445 repeat:
1446         /*
1447          * We will set this flag if we see any child that might later
1448          * match our criteria, even if we are not able to reap it yet.
1449          */
1450         flag = 0;
1451         current->state = TASK_INTERRUPTIBLE;
1452         read_lock(&tasklist_lock);
1453         tsk = current;
1454         do {
1455                 struct task_struct *p;
1456                 struct list_head *_p;
1457                 int ret;
1458
1459                 list_for_each(_p,&tsk->children) {
1460                         p = list_entry(_p, struct task_struct, sibling);
1461
1462                         ret = eligible_child(pid, options, p);
1463                         if (!ret)
1464                                 continue;
1465
1466                         switch (p->state) {
1467                         case TASK_TRACED:
1468                                 /*
1469                                  * When we hit the race with PTRACE_ATTACH,
1470                                  * we will not report this child.  But the
1471                                  * race means it has not yet been moved to
1472                                  * our ptrace_children list, so we need to
1473                                  * set the flag here to avoid a spurious ECHILD
1474                                  * when the race happens with the only child.
1475                                  */
1476                                 flag = 1;
1477                                 if (!my_ptrace_child(p))
1478                                         continue;
1479                                 /*FALLTHROUGH*/
1480                         case TASK_STOPPED:
1481                                 /*
1482                                  * It's stopped now, so it might later
1483                                  * continue, exit, or stop again.
1484                                  */
1485                                 flag = 1;
1486                                 if (!(options & WUNTRACED) &&
1487                                     !my_ptrace_child(p))
1488                                         continue;
1489                                 retval = wait_task_stopped(p, ret == 2,
1490                                                            (options & WNOWAIT),
1491                                                            infop,
1492                                                            stat_addr, ru);
1493                                 if (retval == -EAGAIN)
1494                                         goto repeat;
1495                                 if (retval != 0) /* He released the lock.  */
1496                                         goto end;
1497                                 break;
1498                         default:
1499                         // case EXIT_DEAD:
1500                                 if (p->exit_state == EXIT_DEAD)
1501                                         continue;
1502                         // case EXIT_ZOMBIE:
1503                                 if (p->exit_state == EXIT_ZOMBIE) {
1504                                         /*
1505                                          * Eligible but we cannot release
1506                                          * it yet:
1507                                          */
1508                                         if (ret == 2)
1509                                                 goto check_continued;
1510                                         if (!likely(options & WEXITED))
1511                                                 continue;
1512                                         retval = wait_task_zombie(
1513                                                 p, (options & WNOWAIT),
1514                                                 infop, stat_addr, ru);
1515                                         /* He released the lock.  */
1516                                         if (retval != 0)
1517                                                 goto end;
1518                                         break;
1519                                 }
1520 check_continued:
1521                                 /*
1522                                  * It's running now, so it might later
1523                                  * exit, stop, or stop and then continue.
1524                                  */
1525                                 flag = 1;
1526                                 if (!unlikely(options & WCONTINUED))
1527                                         continue;
1528                                 retval = wait_task_continued(
1529                                         p, (options & WNOWAIT),
1530                                         infop, stat_addr, ru);
1531                                 if (retval != 0) /* He released the lock.  */
1532                                         goto end;
1533                                 break;
1534                         }
1535                 }
1536                 if (!flag) {
1537                         list_for_each(_p, &tsk->ptrace_children) {
1538                                 p = list_entry(_p, struct task_struct,
1539                                                 ptrace_list);
1540                                 if (!eligible_child(pid, options, p))
1541                                         continue;
1542                                 flag = 1;
1543                                 break;
1544                         }
1545                 }
1546                 if (options & __WNOTHREAD)
1547                         break;
1548                 tsk = next_thread(tsk);
1549                 BUG_ON(tsk->signal != current->signal);
1550         } while (tsk != current);
1551
1552         read_unlock(&tasklist_lock);
1553         if (flag) {
1554                 retval = 0;
1555                 if (options & WNOHANG)
1556                         goto end;
1557                 retval = -ERESTARTSYS;
1558                 if (signal_pending(current))
1559                         goto end;
1560                 schedule();
1561                 goto repeat;
1562         }
1563         retval = -ECHILD;
1564 end:
1565         current->state = TASK_RUNNING;
1566         remove_wait_queue(&current->signal->wait_chldexit,&wait);
1567         if (infop) {
1568                 if (retval > 0)
1569                 retval = 0;
1570                 else {
1571                         /*
1572                          * For a WNOHANG return, clear out all the fields
1573                          * we would set so the user can easily tell the
1574                          * difference.
1575                          */
1576                         if (!retval)
1577                                 retval = put_user(0, &infop->si_signo);
1578                         if (!retval)
1579                                 retval = put_user(0, &infop->si_errno);
1580                         if (!retval)
1581                                 retval = put_user(0, &infop->si_code);
1582                         if (!retval)
1583                                 retval = put_user(0, &infop->si_pid);
1584                         if (!retval)
1585                                 retval = put_user(0, &infop->si_uid);
1586                         if (!retval)
1587                                 retval = put_user(0, &infop->si_status);
1588                 }
1589         }
1590         return retval;
1591 }
1592
1593 asmlinkage long sys_waitid(int which, pid_t pid,
1594                            struct siginfo __user *infop, int options,
1595                            struct rusage __user *ru)
1596 {
1597         long ret;
1598
1599         if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1600                 return -EINVAL;
1601         if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1602                 return -EINVAL;
1603
1604         switch (which) {
1605         case P_ALL:
1606                 pid = -1;
1607                 break;
1608         case P_PID:
1609                 if (pid <= 0)
1610                         return -EINVAL;
1611                 break;
1612         case P_PGID:
1613                 if (pid <= 0)
1614                         return -EINVAL;
1615                 pid = -pid;
1616                 break;
1617         default:
1618                 return -EINVAL;
1619         }
1620
1621         ret = do_wait(pid, options, infop, NULL, ru);
1622
1623         /* avoid REGPARM breakage on x86: */
1624         prevent_tail_call(ret);
1625         return ret;
1626 }
1627
1628 asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr,
1629                           int options, struct rusage __user *ru)
1630 {
1631         long ret;
1632
1633         if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1634                         __WNOTHREAD|__WCLONE|__WALL))
1635                 return -EINVAL;
1636         ret = do_wait(pid, options | WEXITED, NULL, stat_addr, ru);
1637
1638         /* avoid REGPARM breakage on x86: */
1639         prevent_tail_call(ret);
1640         return ret;
1641 }
1642
1643 #ifdef __ARCH_WANT_SYS_WAITPID
1644
1645 /*
1646  * sys_waitpid() remains for compatibility. waitpid() should be
1647  * implemented by calling sys_wait4() from libc.a.
1648  */
1649 asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options)
1650 {
1651         return sys_wait4(pid, stat_addr, options, NULL);
1652 }
1653
1654 #endif