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
 912         exit_mm(tsk);
 913
 914         if (group_dead)
 915                 acct_process();
 916         exit_sem(tsk);
 917         __exit_files(tsk);
 918         __exit_fs(tsk);
 919         exit_namespace(tsk);
 920         exit_thread();
 921         cpuset_exit(tsk);
 922         exit_keys(tsk);
 923
 924         if (group_dead && tsk->signal->leader)
 925                 disassociate_ctty(1);
 926
 927         module_put(task_thread_info(tsk)->exec_domain->module);
 928         if (tsk->binfmt)
 929                 module_put(tsk->binfmt->module);
 930
 931         tsk->exit_code = code;
 932         proc_exit_connector(tsk);
 933         exit_notify(tsk);
 934 #ifdef CONFIG_NUMA
 935         mpol_free(tsk->mempolicy);
 936         tsk->mempolicy = NULL;
 937 #endif
 938         /*
 939          * This must happen late, after the PID is not
 940          * hashed anymore:
 941          */
 942         if (unlikely(!list_empty(&tsk->pi_state_list)))
 943                 exit_pi_state_list(tsk);
 944         if (unlikely(current->pi_state_cache))
 945                 kfree(current->pi_state_cache);
 946         /*
 947          * Make sure we are holding no locks:
 948          */
 949         debug_check_no_locks_held(tsk);
 950
 951         if (tsk->io_context)
 952                 exit_io_context();
 953
 954         if (tsk->splice_pipe)
 955                 __free_pipe_info(tsk->splice_pipe);
 956
 957         /* PF_DEAD causes final put_task_struct after we schedule. */
 958         preempt_disable();
 959         BUG_ON(tsk->flags & PF_DEAD);
 960         tsk->flags |= PF_DEAD;
 961
 962         schedule();
 963         BUG();
 964         /* Avoid "noreturn function does return".  */
 965         for (;;) ;
 966 }
 967
 968 EXPORT_SYMBOL_GPL(do_exit);
 969
 970 NORET_TYPE void complete_and_exit(struct completion *comp, long code)
 971 {
 972         if (comp)
 973                 complete(comp);
 974
 975         do_exit(code);
 976 }
 977
 978 EXPORT_SYMBOL(complete_and_exit);
 979
 980 asmlinkage long sys_exit(int error_code)
 981 {
 982         do_exit((error_code&0xff)<<8);
 983 }
 984
 985 /*
 986  * Take down every thread in the group.  This is called by fatal signals
 987  * as well as by sys_exit_group (below).
 988  */
 989 NORET_TYPE void
 990 do_group_exit(int exit_code)
 991 {
 992         BUG_ON(exit_code & 0x80); /* core dumps don't get here */
 993
 994         if (current->signal->flags & SIGNAL_GROUP_EXIT)
 995                 exit_code = current->signal->group_exit_code;
 996         else if (!thread_group_empty(current)) {
 997                 struct signal_struct *const sig = current->signal;
 998                 struct sighand_struct *const sighand = current->sighand;
 999                 spin_lock_irq(&sighand->siglock);
1000                 if (sig->flags & SIGNAL_GROUP_EXIT)
1001                         /* Another thread got here before we took the lock.  */
1002                         exit_code = sig->group_exit_code;
1003                 else {
1004                         sig->group_exit_code = exit_code;
1005                         zap_other_threads(current);
1006                 }
1007                 spin_unlock_irq(&sighand->siglock);
1008         }
1009
1010         do_exit(exit_code);
1011         /* NOTREACHED */
1012 }
1013
1014 /*
1015  * this kills every thread in the thread group. Note that any externally
1016  * wait4()-ing process will get the correct exit code - even if this
1017  * thread is not the thread group leader.
1018  */
1019 asmlinkage void sys_exit_group(int error_code)
1020 {
1021         do_group_exit((error_code & 0xff) << 8);
1022 }
1023
1024 static int eligible_child(pid_t pid, int options, struct task_struct *p)
1025 {
1026         if (pid > 0) {
1027                 if (p->pid != pid)
1028                         return 0;
1029         } else if (!pid) {
1030                 if (process_group(p) != process_group(current))
1031                         return 0;
1032         } else if (pid != -1) {
1033                 if (process_group(p) != -pid)
1034                         return 0;
1035         }
1036
1037         /*
1038          * Do not consider detached threads that are
1039          * not ptraced:
1040          */
1041         if (p->exit_signal == -1 && !p->ptrace)
1042                 return 0;
1043
1044         /* Wait for all children (clone and not) if __WALL is set;
1045          * otherwise, wait for clone children *only* if __WCLONE is
1046          * set; otherwise, wait for non-clone children *only*.  (Note:
1047          * A "clone" child here is one that reports to its parent
1048          * using a signal other than SIGCHLD.) */
1049         if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
1050             && !(options & __WALL))
1051                 return 0;
1052         /*
1053          * Do not consider thread group leaders that are
1054          * in a non-empty thread group:
1055          */
1056         if (delay_group_leader(p))
1057                 return 2;
1058
1059         if (security_task_wait(p))
1060                 return 0;
1061
1062         return 1;
1063 }
1064
1065 static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,
1066                                int why, int status,
1067                                struct siginfo __user *infop,
1068                                struct rusage __user *rusagep)
1069 {
1070         int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
1071
1072         put_task_struct(p);
1073         if (!retval)
1074                 retval = put_user(SIGCHLD, &infop->si_signo);
1075         if (!retval)
1076                 retval = put_user(0, &infop->si_errno);
1077         if (!retval)
1078                 retval = put_user((short)why, &infop->si_code);
1079         if (!retval)
1080                 retval = put_user(pid, &infop->si_pid);
1081         if (!retval)
1082                 retval = put_user(uid, &infop->si_uid);
1083         if (!retval)
1084                 retval = put_user(status, &infop->si_status);
1085         if (!retval)
1086                 retval = pid;
1087         return retval;
1088 }
1089
1090 /*
1091  * Handle sys_wait4 work for one task in state EXIT_ZOMBIE.  We hold
1092  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1093  * the lock and this task is uninteresting.  If we return nonzero, we have
1094  * released the lock and the system call should return.
1095  */
1096 static int wait_task_zombie(struct task_struct *p, int noreap,
1097                             struct siginfo __user *infop,
1098                             int __user *stat_addr, struct rusage __user *ru)
1099 {
1100         unsigned long state;
1101         int retval;
1102         int status;
1103
1104         if (unlikely(noreap)) {
1105                 pid_t pid = p->pid;
1106                 uid_t uid = p->uid;
1107                 int exit_code = p->exit_code;
1108                 int why, status;
1109
1110                 if (unlikely(p->exit_state != EXIT_ZOMBIE))
1111                         return 0;
1112                 if (unlikely(p->exit_signal == -1 && p->ptrace == 0))
1113                         return 0;
1114                 get_task_struct(p);
1115                 read_unlock(&tasklist_lock);
1116                 if ((exit_code & 0x7f) == 0) {
1117                         why = CLD_EXITED;
1118                         status = exit_code >> 8;
1119                 } else {
1120                         why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1121                         status = exit_code & 0x7f;
1122                 }
1123                 return wait_noreap_copyout(p, pid, uid, why,
1124                                            status, infop, ru);
1125         }
1126
1127         /*
1128          * Try to move the task's state to DEAD
1129          * only one thread is allowed to do this:
1130          */
1131         state = xchg(&p->exit_state, EXIT_DEAD);
1132         if (state != EXIT_ZOMBIE) {
1133                 BUG_ON(state != EXIT_DEAD);
1134                 return 0;
1135         }
1136         if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) {
1137                 /*
1138                  * This can only happen in a race with a ptraced thread
1139                  * dying on another processor.
1140                  */
1141                 return 0;
1142         }
1143
1144         if (likely(p->real_parent == p->parent) && likely(p->signal)) {
1145                 struct signal_struct *psig;
1146                 struct signal_struct *sig;
1147
1148                 /*
1149                  * The resource counters for the group leader are in its
1150                  * own task_struct.  Those for dead threads in the group
1151                  * are in its signal_struct, as are those for the child
1152                  * processes it has previously reaped.  All these
1153                  * accumulate in the parent's signal_struct c* fields.
1154                  *
1155                  * We don't bother to take a lock here to protect these
1156                  * p->signal fields, because they are only touched by
1157                  * __exit_signal, which runs with tasklist_lock
1158                  * write-locked anyway, and so is excluded here.  We do
1159                  * need to protect the access to p->parent->signal fields,
1160                  * as other threads in the parent group can be right
1161                  * here reaping other children at the same time.
1162                  */
1163                 spin_lock_irq(&p->parent->sighand->siglock);
1164                 psig = p->parent->signal;
1165                 sig = p->signal;
1166                 psig->cutime =
1167                         cputime_add(psig->cutime,
1168                         cputime_add(p->utime,
1169                         cputime_add(sig->utime,
1170                                     sig->cutime)));
1171                 psig->cstime =
1172                         cputime_add(psig->cstime,
1173                         cputime_add(p->stime,
1174                         cputime_add(sig->stime,
1175                                     sig->cstime)));
1176                 psig->cmin_flt +=
1177                         p->min_flt + sig->min_flt + sig->cmin_flt;
1178                 psig->cmaj_flt +=
1179                         p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1180                 psig->cnvcsw +=
1181                         p->nvcsw + sig->nvcsw + sig->cnvcsw;
1182                 psig->cnivcsw +=
1183                         p->nivcsw + sig->nivcsw + sig->cnivcsw;
1184                 spin_unlock_irq(&p->parent->sighand->siglock);
1185         }
1186
1187         /*
1188          * Now we are sure this task is interesting, and no other
1189          * thread can reap it because we set its state to EXIT_DEAD.
1190          */
1191         read_unlock(&tasklist_lock);
1192
1193         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1194         status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1195                 ? p->signal->group_exit_code : p->exit_code;
1196         if (!retval && stat_addr)
1197                 retval = put_user(status, stat_addr);
1198         if (!retval && infop)
1199                 retval = put_user(SIGCHLD, &infop->si_signo);
1200         if (!retval && infop)
1201                 retval = put_user(0, &infop->si_errno);
1202         if (!retval && infop) {
1203                 int why;
1204
1205                 if ((status & 0x7f) == 0) {
1206                         why = CLD_EXITED;
1207                         status >>= 8;
1208                 } else {
1209                         why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1210                         status &= 0x7f;
1211                 }
1212                 retval = put_user((short)why, &infop->si_code);
1213                 if (!retval)
1214                         retval = put_user(status, &infop->si_status);
1215         }
1216         if (!retval && infop)
1217                 retval = put_user(p->pid, &infop->si_pid);
1218         if (!retval && infop)
1219                 retval = put_user(p->uid, &infop->si_uid);
1220         if (retval) {
1221                 // TODO: is this safe?
1222                 p->exit_state = EXIT_ZOMBIE;
1223                 return retval;
1224         }
1225         retval = p->pid;
1226         if (p->real_parent != p->parent) {
1227                 write_lock_irq(&tasklist_lock);
1228                 /* Double-check with lock held.  */
1229                 if (p->real_parent != p->parent) {
1230                         __ptrace_unlink(p);
1231                         // TODO: is this safe?
1232                         p->exit_state = EXIT_ZOMBIE;
1233                         /*
1234                          * If this is not a detached task, notify the parent.
1235                          * If it's still not detached after that, don't release
1236                          * it now.
1237                          */
1238                         if (p->exit_signal != -1) {
1239                                 do_notify_parent(p, p->exit_signal);
1240                                 if (p->exit_signal != -1)
1241                                         p = NULL;
1242                         }
1243                 }
1244                 write_unlock_irq(&tasklist_lock);
1245         }
1246         if (p != NULL)
1247                 release_task(p);
1248         BUG_ON(!retval);
1249         return retval;
1250 }
1251
1252 /*
1253  * Handle sys_wait4 work for one task in state TASK_STOPPED.  We hold
1254  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1255  * the lock and this task is uninteresting.  If we return nonzero, we have
1256  * released the lock and the system call should return.
1257  */
1258 static int wait_task_stopped(struct task_struct *p, int delayed_group_leader,
1259                              int noreap, struct siginfo __user *infop,
1260                              int __user *stat_addr, struct rusage __user *ru)
1261 {
1262         int retval, exit_code;
1263
1264         if (!p->exit_code)
1265                 return 0;
1266         if (delayed_group_leader && !(p->ptrace & PT_PTRACED) &&
1267             p->signal && p->signal->group_stop_count > 0)
1268                 /*
1269                  * A group stop is in progress and this is the group leader.
1270                  * We won't report until all threads have stopped.
1271                  */
1272                 return 0;
1273
1274         /*
1275          * Now we are pretty sure this task is interesting.
1276          * Make sure it doesn't get reaped out from under us while we
1277          * give up the lock and then examine it below.  We don't want to
1278          * keep holding onto the tasklist_lock while we call getrusage and
1279          * possibly take page faults for user memory.
1280          */
1281         get_task_struct(p);
1282         read_unlock(&tasklist_lock);
1283
1284         if (unlikely(noreap)) {
1285                 pid_t pid = p->pid;
1286                 uid_t uid = p->uid;
1287                 int why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
1288
1289                 exit_code = p->exit_code;
1290                 if (unlikely(!exit_code) ||
1291                     unlikely(p->state & TASK_TRACED))
1292                         goto bail_ref;
1293                 return wait_noreap_copyout(p, pid, uid,
1294                                            why, (exit_code << 8) | 0x7f,
1295                                            infop, ru);
1296         }
1297
1298         write_lock_irq(&tasklist_lock);
1299
1300         /*
1301          * This uses xchg to be atomic with the thread resuming and setting
1302          * it.  It must also be done with the write lock held to prevent a
1303          * race with the EXIT_ZOMBIE case.
1304          */
1305         exit_code = xchg(&p->exit_code, 0);
1306         if (unlikely(p->exit_state)) {
1307                 /*
1308                  * The task resumed and then died.  Let the next iteration
1309                  * catch it in EXIT_ZOMBIE.  Note that exit_code might
1310                  * already be zero here if it resumed and did _exit(0).
1311                  * The task itself is dead and won't touch exit_code again;
1312                  * other processors in this function are locked out.
1313                  */
1314                 p->exit_code = exit_code;
1315                 exit_code = 0;
1316         }
1317         if (unlikely(exit_code == 0)) {
1318                 /*
1319                  * Another thread in this function got to it first, or it
1320                  * resumed, or it resumed and then died.
1321                  */
1322                 write_unlock_irq(&tasklist_lock);
1323 bail_ref:
1324                 put_task_struct(p);
1325                 /*
1326                  * We are returning to the wait loop without having successfully
1327                  * removed the process and having released the lock. We cannot
1328                  * continue, since the "p" task pointer is potentially stale.
1329                  *
1330                  * Return -EAGAIN, and do_wait() will restart the loop from the
1331                  * beginning. Do _not_ re-acquire the lock.
1332                  */
1333                 return -EAGAIN;
1334         }
1335
1336         /* move to end of parent's list to avoid starvation */
1337         remove_parent(p);
1338         add_parent(p);
1339
1340         write_unlock_irq(&tasklist_lock);
1341
1342         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1343         if (!retval && stat_addr)
1344                 retval = put_user((exit_code << 8) | 0x7f, stat_addr);
1345         if (!retval && infop)
1346                 retval = put_user(SIGCHLD, &infop->si_signo);
1347         if (!retval && infop)
1348                 retval = put_user(0, &infop->si_errno);
1349         if (!retval && infop)
1350                 retval = put_user((short)((p->ptrace & PT_PTRACED)
1351                                           ? CLD_TRAPPED : CLD_STOPPED),
1352                                   &infop->si_code);
1353         if (!retval && infop)
1354                 retval = put_user(exit_code, &infop->si_status);
1355         if (!retval && infop)
1356                 retval = put_user(p->pid, &infop->si_pid);
1357         if (!retval && infop)
1358                 retval = put_user(p->uid, &infop->si_uid);
1359         if (!retval)
1360                 retval = p->pid;
1361         put_task_struct(p);
1362
1363         BUG_ON(!retval);
1364         return retval;
1365 }
1366
1367 /*
1368  * Handle do_wait work for one task in a live, non-stopped state.
1369  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1370  * the lock and this task is uninteresting.  If we return nonzero, we have
1371  * released the lock and the system call should return.
1372  */
1373 static int wait_task_continued(struct task_struct *p, int noreap,
1374                                struct siginfo __user *infop,
1375                                int __user *stat_addr, struct rusage __user *ru)
1376 {
1377         int retval;
1378         pid_t pid;
1379         uid_t uid;
1380
1381         if (unlikely(!p->signal))
1382                 return 0;
1383
1384         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1385                 return 0;
1386
1387         spin_lock_irq(&p->sighand->siglock);
1388         /* Re-check with the lock held.  */
1389         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1390                 spin_unlock_irq(&p->sighand->siglock);
1391                 return 0;
1392         }
1393         if (!noreap)
1394                 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1395         spin_unlock_irq(&p->sighand->siglock);
1396
1397         pid = p->pid;
1398         uid = p->uid;
1399         get_task_struct(p);
1400         read_unlock(&tasklist_lock);
1401
1402         if (!infop) {
1403                 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1404                 put_task_struct(p);
1405                 if (!retval && stat_addr)
1406                         retval = put_user(0xffff, stat_addr);
1407                 if (!retval)
1408                         retval = p->pid;
1409         } else {
1410                 retval = wait_noreap_copyout(p, pid, uid,
1411                                              CLD_CONTINUED, SIGCONT,
1412                                              infop, ru);
1413                 BUG_ON(retval == 0);
1414         }
1415
1416         return retval;
1417 }
1418
1419
1420 static inline int my_ptrace_child(struct task_struct *p)
1421 {
1422         if (!(p->ptrace & PT_PTRACED))
1423                 return 0;
1424         if (!(p->ptrace & PT_ATTACHED))
1425                 return 1;
1426         /*
1427          * This child was PTRACE_ATTACH'd.  We should be seeing it only if
1428          * we are the attacher.  If we are the real parent, this is a race
1429          * inside ptrace_attach.  It is waiting for the tasklist_lock,
1430          * which we have to switch the parent links, but has already set
1431          * the flags in p->ptrace.
1432          */
1433         return (p->parent != p->real_parent);
1434 }
1435
1436 static long do_wait(pid_t pid, int options, struct siginfo __user *infop,
1437                     int __user *stat_addr, struct rusage __user *ru)
1438 {
1439         DECLARE_WAITQUEUE(wait, current);
1440         struct task_struct *tsk;
1441         int flag, retval;
1442
1443         add_wait_queue(&current->signal->wait_chldexit,&wait);
1444 repeat:
1445         /*
1446          * We will set this flag if we see any child that might later
1447          * match our criteria, even if we are not able to reap it yet.
1448          */
1449         flag = 0;
1450         current->state = TASK_INTERRUPTIBLE;
1451         read_lock(&tasklist_lock);
1452         tsk = current;
1453         do {
1454                 struct task_struct *p;
1455                 struct list_head *_p;
1456                 int ret;
1457
1458                 list_for_each(_p,&tsk->children) {
1459                         p = list_entry(_p, struct task_struct, sibling);
1460
1461                         ret = eligible_child(pid, options, p);
1462                         if (!ret)
1463                                 continue;
1464
1465                         switch (p->state) {
1466                         case TASK_TRACED:
1467                                 /*
1468                                  * When we hit the race with PTRACE_ATTACH,
1469                                  * we will not report this child.  But the
1470                                  * race means it has not yet been moved to
1471                                  * our ptrace_children list, so we need to
1472                                  * set the flag here to avoid a spurious ECHILD
1473                                  * when the race happens with the only child.
1474                                  */
1475                                 flag = 1;
1476                                 if (!my_ptrace_child(p))
1477                                         continue;
1478                                 /*FALLTHROUGH*/
1479                         case TASK_STOPPED:
1480                                 /*
1481                                  * It's stopped now, so it might later
1482                                  * continue, exit, or stop again.
1483                                  */
1484                                 flag = 1;
1485                                 if (!(options & WUNTRACED) &&
1486                                     !my_ptrace_child(p))
1487                                         continue;
1488                                 retval = wait_task_stopped(p, ret == 2,
1489                                                            (options & WNOWAIT),
1490                                                            infop,
1491                                                            stat_addr, ru);
1492                                 if (retval == -EAGAIN)
1493                                         goto repeat;
1494                                 if (retval != 0) /* He released the lock.  */
1495                                         goto end;
1496                                 break;
1497                         default:
1498                         // case EXIT_DEAD:
1499                                 if (p->exit_state == EXIT_DEAD)
1500                                         continue;
1501                         // case EXIT_ZOMBIE:
1502                                 if (p->exit_state == EXIT_ZOMBIE) {
1503                                         /*
1504                                          * Eligible but we cannot release
1505                                          * it yet:
1506                                          */
1507                                         if (ret == 2)
1508                                                 goto check_continued;
1509                                         if (!likely(options & WEXITED))
1510                                                 continue;
1511                                         retval = wait_task_zombie(
1512                                                 p, (options & WNOWAIT),
1513                                                 infop, stat_addr, ru);
1514                                         /* He released the lock.  */
1515                                         if (retval != 0)
1516                                                 goto end;
1517                                         break;
1518                                 }
1519 check_continued:
1520                                 /*
1521                                  * It's running now, so it might later
1522                                  * exit, stop, or stop and then continue.
1523                                  */
1524                                 flag = 1;
1525                                 if (!unlikely(options & WCONTINUED))
1526                                         continue;
1527                                 retval = wait_task_continued(
1528                                         p, (options & WNOWAIT),
1529                                         infop, stat_addr, ru);
1530                                 if (retval != 0) /* He released the lock.  */
1531                                         goto end;
1532                                 break;
1533                         }
1534                 }
1535                 if (!flag) {
1536                         list_for_each(_p, &tsk->ptrace_children) {
1537                                 p = list_entry(_p, struct task_struct,
1538                                                 ptrace_list);
1539                                 if (!eligible_child(pid, options, p))
1540                                         continue;
1541                                 flag = 1;
1542                                 break;
1543                         }
1544                 }
1545                 if (options & __WNOTHREAD)
1546                         break;
1547                 tsk = next_thread(tsk);
1548                 BUG_ON(tsk->signal != current->signal);
1549         } while (tsk != current);
1550
1551         read_unlock(&tasklist_lock);
1552         if (flag) {
1553                 retval = 0;
1554                 if (options & WNOHANG)
1555                         goto end;
1556                 retval = -ERESTARTSYS;
1557                 if (signal_pending(current))
1558                         goto end;
1559                 schedule();
1560                 goto repeat;
1561         }
1562         retval = -ECHILD;
1563 end:
1564         current->state = TASK_RUNNING;
1565         remove_wait_queue(&current->signal->wait_chldexit,&wait);
1566         if (infop) {
1567                 if (retval > 0)
1568                 retval = 0;
1569                 else {
1570                         /*
1571                          * For a WNOHANG return, clear out all the fields
1572                          * we would set so the user can easily tell the
1573                          * difference.
1574                          */
1575                         if (!retval)
1576                                 retval = put_user(0, &infop->si_signo);
1577                         if (!retval)
1578                                 retval = put_user(0, &infop->si_errno);
1579                         if (!retval)
1580                                 retval = put_user(0, &infop->si_code);
1581                         if (!retval)
1582                                 retval = put_user(0, &infop->si_pid);
1583                         if (!retval)
1584                                 retval = put_user(0, &infop->si_uid);
1585                         if (!retval)
1586                                 retval = put_user(0, &infop->si_status);
1587                 }
1588         }
1589         return retval;
1590 }
1591
1592 asmlinkage long sys_waitid(int which, pid_t pid,
1593                            struct siginfo __user *infop, int options,
1594                            struct rusage __user *ru)
1595 {
1596         long ret;
1597
1598         if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1599                 return -EINVAL;
1600         if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1601                 return -EINVAL;
1602
1603         switch (which) {
1604         case P_ALL:
1605                 pid = -1;
1606                 break;
1607         case P_PID:
1608                 if (pid <= 0)
1609                         return -EINVAL;
1610                 break;
1611         case P_PGID:
1612                 if (pid <= 0)
1613                         return -EINVAL;
1614                 pid = -pid;
1615                 break;
1616         default:
1617                 return -EINVAL;
1618         }
1619
1620         ret = do_wait(pid, options, infop, NULL, ru);
1621
1622         /* avoid REGPARM breakage on x86: */
1623         prevent_tail_call(ret);
1624         return ret;
1625 }
1626
1627 asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr,
1628                           int options, struct rusage __user *ru)
1629 {
1630         long ret;
1631
1632         if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1633                         __WNOTHREAD|__WCLONE|__WALL))
1634                 return -EINVAL;
1635         ret = do_wait(pid, options | WEXITED, NULL, stat_addr, ru);
1636
1637         /* avoid REGPARM breakage on x86: */
1638         prevent_tail_call(ret);
1639         return ret;
1640 }
1641
1642 #ifdef __ARCH_WANT_SYS_WAITPID
1643
1644 /*
1645  * sys_waitpid() remains for compatibility. waitpid() should be
1646  * implemented by calling sys_wait4() from libc.a.
1647  */
1648 asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options)
1649 {
1650         return sys_wait4(pid, stat_addr, options, NULL);
1651 }
1652
1653 #endif