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/module.h>
  11 #include <linux/capability.h>
  12 #include <linux/completion.h>
  13 #include <linux/personality.h>
  14 #include <linux/tty.h>
  15 #include <linux/mnt_namespace.h>
  16 #include <linux/key.h>
  17 #include <linux/security.h>
  18 #include <linux/cpu.h>
  19 #include <linux/acct.h>
  20 #include <linux/tsacct_kern.h>
  21 #include <linux/file.h>
  22 #include <linux/binfmts.h>
  23 #include <linux/nsproxy.h>
  24 #include <linux/pid_namespace.h>
  25 #include <linux/ptrace.h>
  26 #include <linux/profile.h>
  27 #include <linux/mount.h>
  28 #include <linux/proc_fs.h>
  29 #include <linux/kthread.h>
  30 #include <linux/mempolicy.h>
  31 #include <linux/taskstats_kern.h>
  32 #include <linux/delayacct.h>
  33 #include <linux/freezer.h>
  34 #include <linux/cgroup.h>
  35 #include <linux/syscalls.h>
  36 #include <linux/signal.h>
  37 #include <linux/posix-timers.h>
  38 #include <linux/cn_proc.h>
  39 #include <linux/mutex.h>
  40 #include <linux/futex.h>
  41 #include <linux/compat.h>
  42 #include <linux/pipe_fs_i.h>
  43 #include <linux/audit.h> /* for audit_free() */
  44 #include <linux/resource.h>
  45 #include <linux/blkdev.h>
  46 #include <linux/task_io_accounting_ops.h>
  47
  48 #include <asm/uaccess.h>
  49 #include <asm/unistd.h>
  50 #include <asm/pgtable.h>
  51 #include <asm/mmu_context.h>
  52
  53 static void exit_mm(struct task_struct * tsk);
  54
  55 static void __unhash_process(struct task_struct *p)
  56 {
  57         nr_threads--;
  58         detach_pid(p, PIDTYPE_PID);
  59         if (thread_group_leader(p)) {
  60                 detach_pid(p, PIDTYPE_PGID);
  61                 detach_pid(p, PIDTYPE_SID);
  62
  63                 list_del_rcu(&p->tasks);
  64                 __get_cpu_var(process_counts)--;
  65         }
  66         list_del_rcu(&p->thread_group);
  67         remove_parent(p);
  68 }
  69
  70 /*
  71  * This function expects the tasklist_lock write-locked.
  72  */
  73 static void __exit_signal(struct task_struct *tsk)
  74 {
  75         struct signal_struct *sig = tsk->signal;
  76         struct sighand_struct *sighand;
  77
  78         BUG_ON(!sig);
  79         BUG_ON(!atomic_read(&sig->count));
  80
  81         rcu_read_lock();
  82         sighand = rcu_dereference(tsk->sighand);
  83         spin_lock(&sighand->siglock);
  84
  85         posix_cpu_timers_exit(tsk);
  86         if (atomic_dec_and_test(&sig->count))
  87                 posix_cpu_timers_exit_group(tsk);
  88         else {
  89                 /*
  90                  * If there is any task waiting for the group exit
  91                  * then notify it:
  92                  */
  93                 if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count)
  94                         wake_up_process(sig->group_exit_task);
  95
  96                 if (tsk == sig->curr_target)
  97                         sig->curr_target = next_thread(tsk);
  98                 /*
  99                  * Accumulate here the counters for all threads but the
 100                  * group leader as they die, so they can be added into
 101                  * the process-wide totals when those are taken.
 102                  * The group leader stays around as a zombie as long
 103                  * as there are other threads.  When it gets reaped,
 104                  * the exit.c code will add its counts into these totals.
 105                  * We won't ever get here for the group leader, since it
 106                  * will have been the last reference on the signal_struct.
 107                  */
 108                 sig->utime = cputime_add(sig->utime, tsk->utime);
 109                 sig->stime = cputime_add(sig->stime, tsk->stime);
 110                 sig->gtime = cputime_add(sig->gtime, tsk->gtime);
 111                 sig->min_flt += tsk->min_flt;
 112                 sig->maj_flt += tsk->maj_flt;
 113                 sig->nvcsw += tsk->nvcsw;
 114                 sig->nivcsw += tsk->nivcsw;
 115                 sig->inblock += task_io_get_inblock(tsk);
 116                 sig->oublock += task_io_get_oublock(tsk);
 117                 sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
 118                 sig = NULL; /* Marker for below. */
 119         }
 120
 121         __unhash_process(tsk);
 122
 123         tsk->signal = NULL;
 124         tsk->sighand = NULL;
 125         spin_unlock(&sighand->siglock);
 126         rcu_read_unlock();
 127
 128         __cleanup_sighand(sighand);
 129         clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
 130         flush_sigqueue(&tsk->pending);
 131         if (sig) {
 132                 flush_sigqueue(&sig->shared_pending);
 133                 taskstats_tgid_free(sig);
 134                 __cleanup_signal(sig);
 135         }
 136 }
 137
 138 static void delayed_put_task_struct(struct rcu_head *rhp)
 139 {
 140         put_task_struct(container_of(rhp, struct task_struct, rcu));
 141 }
 142
 143 void release_task(struct task_struct * p)
 144 {
 145         struct task_struct *leader;
 146         int zap_leader;
 147 repeat:
 148         atomic_dec(&p->user->processes);
 149         proc_flush_task(p);
 150         write_lock_irq(&tasklist_lock);
 151         ptrace_unlink(p);
 152         BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
 153         __exit_signal(p);
 154
 155         /*
 156          * If we are the last non-leader member of the thread
 157          * group, and the leader is zombie, then notify the
 158          * group leader's parent process. (if it wants notification.)
 159          */
 160         zap_leader = 0;
 161         leader = p->group_leader;
 162         if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
 163                 BUG_ON(leader->exit_signal == -1);
 164                 do_notify_parent(leader, leader->exit_signal);
 165                 /*
 166                  * If we were the last child thread and the leader has
 167                  * exited already, and the leader's parent ignores SIGCHLD,
 168                  * then we are the one who should release the leader.
 169                  *
 170                  * do_notify_parent() will have marked it self-reaping in
 171                  * that case.
 172                  */
 173                 zap_leader = (leader->exit_signal == -1);
 174         }
 175
 176         write_unlock_irq(&tasklist_lock);
 177         release_thread(p);
 178         call_rcu(&p->rcu, delayed_put_task_struct);
 179
 180         p = leader;
 181         if (unlikely(zap_leader))
 182                 goto repeat;
 183 }
 184
 185 /*
 186  * This checks not only the pgrp, but falls back on the pid if no
 187  * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
 188  * without this...
 189  *
 190  * The caller must hold rcu lock or the tasklist lock.
 191  */
 192 struct pid *session_of_pgrp(struct pid *pgrp)
 193 {
 194         struct task_struct *p;
 195         struct pid *sid = NULL;
 196
 197         p = pid_task(pgrp, PIDTYPE_PGID);
 198         if (p == NULL)
 199                 p = pid_task(pgrp, PIDTYPE_PID);
 200         if (p != NULL)
 201                 sid = task_session(p);
 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(struct pid *pgrp, struct task_struct *ignored_task)
 215 {
 216         struct task_struct *p;
 217
 218         do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
 219                 if ((p == ignored_task) ||
 220                     (p->exit_state && thread_group_empty(p)) ||
 221                     is_global_init(p->real_parent))
 222                         continue;
 223
 224                 if (task_pgrp(p->real_parent) != pgrp &&
 225                     task_session(p->real_parent) == task_session(p))
 226                         return 0;
 227         } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
 228
 229         return 1;
 230 }
 231
 232 int is_current_pgrp_orphaned(void)
 233 {
 234         int retval;
 235
 236         read_lock(&tasklist_lock);
 237         retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
 238         read_unlock(&tasklist_lock);
 239
 240         return retval;
 241 }
 242
 243 static int has_stopped_jobs(struct pid *pgrp)
 244 {
 245         int retval = 0;
 246         struct task_struct *p;
 247
 248         do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
 249                 if (!task_is_stopped(p))
 250                         continue;
 251                 retval = 1;
 252                 break;
 253         } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
 254         return retval;
 255 }
 256
 257 /*
 258  * Check to see if any process groups have become orphaned as
 259  * a result of our exiting, and if they have any stopped jobs,
 260  * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
 261  */
 262 static void
 263 kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
 264 {
 265         struct pid *pgrp = task_pgrp(tsk);
 266         struct task_struct *ignored_task = tsk;
 267
 268         if (!parent)
 269                  /* exit: our father is in a different pgrp than
 270                   * we are and we were the only connection outside.
 271                   */
 272                 parent = tsk->real_parent;
 273         else
 274                 /* reparent: our child is in a different pgrp than
 275                  * we are, and it was the only connection outside.
 276                  */
 277                 ignored_task = NULL;
 278
 279         if (task_pgrp(parent) != pgrp &&
 280             task_session(parent) == task_session(tsk) &&
 281             will_become_orphaned_pgrp(pgrp, ignored_task) &&
 282             has_stopped_jobs(pgrp)) {
 283                 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
 284                 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
 285         }
 286 }
 287
 288 /**
 289  * reparent_to_kthreadd - Reparent the calling kernel thread to kthreadd
 290  *
 291  * If a kernel thread is launched as a result of a system call, or if
 292  * it ever exits, it should generally reparent itself to kthreadd so it
 293  * isn't in the way of other processes and is correctly cleaned up on exit.
 294  *
 295  * The various task state such as scheduling policy and priority may have
 296  * been inherited from a user process, so we reset them to sane values here.
 297  *
 298  * NOTE that reparent_to_kthreadd() gives the caller full capabilities.
 299  */
 300 static void reparent_to_kthreadd(void)
 301 {
 302         write_lock_irq(&tasklist_lock);
 303
 304         ptrace_unlink(current);
 305         /* Reparent to init */
 306         remove_parent(current);
 307         current->real_parent = current->parent = kthreadd_task;
 308         add_parent(current);
 309
 310         /* Set the exit signal to SIGCHLD so we signal init on exit */
 311         current->exit_signal = SIGCHLD;
 312
 313         if (task_nice(current) < 0)
 314                 set_user_nice(current, 0);
 315         /* cpus_allowed? */
 316         /* rt_priority? */
 317         /* signals? */
 318         security_task_reparent_to_init(current);
 319         memcpy(current->signal->rlim, init_task.signal->rlim,
 320                sizeof(current->signal->rlim));
 321         atomic_inc(&(INIT_USER->__count));
 322         write_unlock_irq(&tasklist_lock);
 323         switch_uid(INIT_USER);
 324 }
 325
 326 void __set_special_pids(struct pid *pid)
 327 {
 328         struct task_struct *curr = current->group_leader;
 329         pid_t nr = pid_nr(pid);
 330
 331         if (task_session(curr) != pid) {
 332                 detach_pid(curr, PIDTYPE_SID);
 333                 attach_pid(curr, PIDTYPE_SID, pid);
 334                 set_task_session(curr, nr);
 335         }
 336         if (task_pgrp(curr) != pid) {
 337                 detach_pid(curr, PIDTYPE_PGID);
 338                 attach_pid(curr, PIDTYPE_PGID, pid);
 339                 set_task_pgrp(curr, nr);
 340         }
 341 }
 342
 343 static void set_special_pids(struct pid *pid)
 344 {
 345         write_lock_irq(&tasklist_lock);
 346         __set_special_pids(pid);
 347         write_unlock_irq(&tasklist_lock);
 348 }
 349
 350 /*
 351  * Let kernel threads use this to say that they
 352  * allow a certain signal (since daemonize() will
 353  * have disabled all of them by default).
 354  */
 355 int allow_signal(int sig)
 356 {
 357         if (!valid_signal(sig) || sig < 1)
 358                 return -EINVAL;
 359
 360         spin_lock_irq(&current->sighand->siglock);
 361         sigdelset(&current->blocked, sig);
 362         if (!current->mm) {
 363                 /* Kernel threads handle their own signals.
 364                    Let the signal code know it'll be handled, so
 365                    that they don't get converted to SIGKILL or
 366                    just silently dropped */
 367                 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
 368         }
 369         recalc_sigpending();
 370         spin_unlock_irq(&current->sighand->siglock);
 371         return 0;
 372 }
 373
 374 EXPORT_SYMBOL(allow_signal);
 375
 376 int disallow_signal(int sig)
 377 {
 378         if (!valid_signal(sig) || sig < 1)
 379                 return -EINVAL;
 380
 381         spin_lock_irq(&current->sighand->siglock);
 382         current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN;
 383         recalc_sigpending();
 384         spin_unlock_irq(&current->sighand->siglock);
 385         return 0;
 386 }
 387
 388 EXPORT_SYMBOL(disallow_signal);
 389
 390 /*
 391  *      Put all the gunge required to become a kernel thread without
 392  *      attached user resources in one place where it belongs.
 393  */
 394
 395 void daemonize(const char *name, ...)
 396 {
 397         va_list args;
 398         struct fs_struct *fs;
 399         sigset_t blocked;
 400
 401         va_start(args, name);
 402         vsnprintf(current->comm, sizeof(current->comm), name, args);
 403         va_end(args);
 404
 405         /*
 406          * If we were started as result of loading a module, close all of the
 407          * user space pages.  We don't need them, and if we didn't close them
 408          * they would be locked into memory.
 409          */
 410         exit_mm(current);
 411         /*
 412          * We don't want to have TIF_FREEZE set if the system-wide hibernation
 413          * or suspend transition begins right now.
 414          */
 415         current->flags |= PF_NOFREEZE;
 416
 417         if (current->nsproxy != &init_nsproxy) {
 418                 get_nsproxy(&init_nsproxy);
 419                 switch_task_namespaces(current, &init_nsproxy);
 420         }
 421         set_special_pids(&init_struct_pid);
 422         proc_clear_tty(current);
 423
 424         /* Block and flush all signals */
 425         sigfillset(&blocked);
 426         sigprocmask(SIG_BLOCK, &blocked, NULL);
 427         flush_signals(current);
 428
 429         /* Become as one with the init task */
 430
 431         exit_fs(current);       /* current->fs->count--; */
 432         fs = init_task.fs;
 433         current->fs = fs;
 434         atomic_inc(&fs->count);
 435
 436         exit_files(current);
 437         current->files = init_task.files;
 438         atomic_inc(&current->files->count);
 439
 440         reparent_to_kthreadd();
 441 }
 442
 443 EXPORT_SYMBOL(daemonize);
 444
 445 static void close_files(struct files_struct * files)
 446 {
 447         int i, j;
 448         struct fdtable *fdt;
 449
 450         j = 0;
 451
 452         /*
 453          * It is safe to dereference the fd table without RCU or
 454          * ->file_lock because this is the last reference to the
 455          * files structure.
 456          */
 457         fdt = files_fdtable(files);
 458         for (;;) {
 459                 unsigned long set;
 460                 i = j * __NFDBITS;
 461                 if (i >= fdt->max_fds)
 462                         break;
 463                 set = fdt->open_fds->fds_bits[j++];
 464                 while (set) {
 465                         if (set & 1) {
 466                                 struct file * file = xchg(&fdt->fd[i], NULL);
 467                                 if (file) {
 468                                         filp_close(file, files);
 469                                         cond_resched();
 470                                 }
 471                         }
 472                         i++;
 473                         set >>= 1;
 474                 }
 475         }
 476 }
 477
 478 struct files_struct *get_files_struct(struct task_struct *task)
 479 {
 480         struct files_struct *files;
 481
 482         task_lock(task);
 483         files = task->files;
 484         if (files)
 485                 atomic_inc(&files->count);
 486         task_unlock(task);
 487
 488         return files;
 489 }
 490
 491 void put_files_struct(struct files_struct *files)
 492 {
 493         struct fdtable *fdt;
 494
 495         if (atomic_dec_and_test(&files->count)) {
 496                 close_files(files);
 497                 /*
 498                  * Free the fd and fdset arrays if we expanded them.
 499                  * If the fdtable was embedded, pass files for freeing
 500                  * at the end of the RCU grace period. Otherwise,
 501                  * you can free files immediately.
 502                  */
 503                 fdt = files_fdtable(files);
 504                 if (fdt != &files->fdtab)
 505                         kmem_cache_free(files_cachep, files);
 506                 free_fdtable(fdt);
 507         }
 508 }
 509
 510 EXPORT_SYMBOL(put_files_struct);
 511
 512 void reset_files_struct(struct task_struct *tsk, struct files_struct *files)
 513 {
 514         struct files_struct *old;
 515
 516         old = tsk->files;
 517         task_lock(tsk);
 518         tsk->files = files;
 519         task_unlock(tsk);
 520         put_files_struct(old);
 521 }
 522 EXPORT_SYMBOL(reset_files_struct);
 523
 524 static void __exit_files(struct task_struct *tsk)
 525 {
 526         struct files_struct * files = tsk->files;
 527
 528         if (files) {
 529                 task_lock(tsk);
 530                 tsk->files = NULL;
 531                 task_unlock(tsk);
 532                 put_files_struct(files);
 533         }
 534 }
 535
 536 void exit_files(struct task_struct *tsk)
 537 {
 538         __exit_files(tsk);
 539 }
 540
 541 static void __put_fs_struct(struct fs_struct *fs)
 542 {
 543         /* No need to hold fs->lock if we are killing it */
 544         if (atomic_dec_and_test(&fs->count)) {
 545                 path_put(&fs->root);
 546                 path_put(&fs->pwd);
 547                 if (fs->altroot.dentry)
 548                         path_put(&fs->altroot);
 549                 kmem_cache_free(fs_cachep, fs);
 550         }
 551 }
 552
 553 void put_fs_struct(struct fs_struct *fs)
 554 {
 555         __put_fs_struct(fs);
 556 }
 557
 558 static void __exit_fs(struct task_struct *tsk)
 559 {
 560         struct fs_struct * fs = tsk->fs;
 561
 562         if (fs) {
 563                 task_lock(tsk);
 564                 tsk->fs = NULL;
 565                 task_unlock(tsk);
 566                 __put_fs_struct(fs);
 567         }
 568 }
 569
 570 void exit_fs(struct task_struct *tsk)
 571 {
 572         __exit_fs(tsk);
 573 }
 574
 575 EXPORT_SYMBOL_GPL(exit_fs);
 576
 577 /*
 578  * Turn us into a lazy TLB process if we
 579  * aren't already..
 580  */
 581 static void exit_mm(struct task_struct * tsk)
 582 {
 583         struct mm_struct *mm = tsk->mm;
 584
 585         mm_release(tsk, mm);
 586         if (!mm)
 587                 return;
 588         /*
 589          * Serialize with any possible pending coredump.
 590          * We must hold mmap_sem around checking core_waiters
 591          * and clearing tsk->mm.  The core-inducing thread
 592          * will increment core_waiters for each thread in the
 593          * group with ->mm != NULL.
 594          */
 595         down_read(&mm->mmap_sem);
 596         if (mm->core_waiters) {
 597                 up_read(&mm->mmap_sem);
 598                 down_write(&mm->mmap_sem);
 599                 if (!--mm->core_waiters)
 600                         complete(mm->core_startup_done);
 601                 up_write(&mm->mmap_sem);
 602
 603                 wait_for_completion(&mm->core_done);
 604                 down_read(&mm->mmap_sem);
 605         }
 606         atomic_inc(&mm->mm_count);
 607         BUG_ON(mm != tsk->active_mm);
 608         /* more a memory barrier than a real lock */
 609         task_lock(tsk);
 610         tsk->mm = NULL;
 611         up_read(&mm->mmap_sem);
 612         enter_lazy_tlb(mm, current);
 613         /* We don't want this task to be frozen prematurely */
 614         clear_freeze_flag(tsk);
 615         task_unlock(tsk);
 616         mmput(mm);
 617 }
 618
 619 static void
 620 reparent_thread(struct task_struct *p, struct task_struct *father, int traced)
 621 {
 622         if (p->pdeath_signal)
 623                 /* We already hold the tasklist_lock here.  */
 624                 group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);
 625
 626         /* Move the child from its dying parent to the new one.  */
 627         if (unlikely(traced)) {
 628                 /* Preserve ptrace links if someone else is tracing this child.  */
 629                 list_del_init(&p->ptrace_list);
 630                 if (p->parent != p->real_parent)
 631                         list_add(&p->ptrace_list, &p->real_parent->ptrace_children);
 632         } else {
 633                 /* If this child is being traced, then we're the one tracing it
 634                  * anyway, so let go of it.
 635                  */
 636                 p->ptrace = 0;
 637                 remove_parent(p);
 638                 p->parent = p->real_parent;
 639                 add_parent(p);
 640
 641                 if (task_is_traced(p)) {
 642                         /*
 643                          * If it was at a trace stop, turn it into
 644                          * a normal stop since it's no longer being
 645                          * traced.
 646                          */
 647                         ptrace_untrace(p);
 648                 }
 649         }
 650
 651         /* If this is a threaded reparent there is no need to
 652          * notify anyone anything has happened.
 653          */
 654         if (p->real_parent->group_leader == father->group_leader)
 655                 return;
 656
 657         /* We don't want people slaying init.  */
 658         if (p->exit_signal != -1)
 659                 p->exit_signal = SIGCHLD;
 660
 661         /* If we'd notified the old parent about this child's death,
 662          * also notify the new parent.
 663          */
 664         if (!traced && p->exit_state == EXIT_ZOMBIE &&
 665             p->exit_signal != -1 && thread_group_empty(p))
 666                 do_notify_parent(p, p->exit_signal);
 667
 668         kill_orphaned_pgrp(p, father);
 669 }
 670
 671 /*
 672  * When we die, we re-parent all our children.
 673  * Try to give them to another thread in our thread
 674  * group, and if no such member exists, give it to
 675  * the child reaper process (ie "init") in our pid
 676  * space.
 677  */
 678 static void forget_original_parent(struct task_struct *father)
 679 {
 680         struct task_struct *p, *n, *reaper = father;
 681         struct list_head ptrace_dead;
 682
 683         INIT_LIST_HEAD(&ptrace_dead);
 684
 685         write_lock_irq(&tasklist_lock);
 686
 687         do {
 688                 reaper = next_thread(reaper);
 689                 if (reaper == father) {
 690                         reaper = task_child_reaper(father);
 691                         break;
 692                 }
 693         } while (reaper->flags & PF_EXITING);
 694
 695         /*
 696          * There are only two places where our children can be:
 697          *
 698          * - in our child list
 699          * - in our ptraced child list
 700          *
 701          * Search them and reparent children.
 702          */
 703         list_for_each_entry_safe(p, n, &father->children, sibling) {
 704                 int ptrace;
 705
 706                 ptrace = p->ptrace;
 707
 708                 /* if father isn't the real parent, then ptrace must be enabled */
 709                 BUG_ON(father != p->real_parent && !ptrace);
 710
 711                 if (father == p->real_parent) {
 712                         /* reparent with a reaper, real father it's us */
 713                         p->real_parent = reaper;
 714                         reparent_thread(p, father, 0);
 715                 } else {
 716                         /* reparent ptraced task to its real parent */
 717                         __ptrace_unlink (p);
 718                         if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
 719                             thread_group_empty(p))
 720                                 do_notify_parent(p, p->exit_signal);
 721                 }
 722
 723                 /*
 724                  * if the ptraced child is a zombie with exit_signal == -1
 725                  * we must collect it before we exit, or it will remain
 726                  * zombie forever since we prevented it from self-reap itself
 727                  * while it was being traced by us, to be able to see it in wait4.
 728                  */
 729                 if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && p->exit_signal == -1))
 730                         list_add(&p->ptrace_list, &ptrace_dead);
 731         }
 732
 733         list_for_each_entry_safe(p, n, &father->ptrace_children, ptrace_list) {
 734                 p->real_parent = reaper;
 735                 reparent_thread(p, father, 1);
 736         }
 737
 738         write_unlock_irq(&tasklist_lock);
 739         BUG_ON(!list_empty(&father->children));
 740         BUG_ON(!list_empty(&father->ptrace_children));
 741
 742         list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_list) {
 743                 list_del_init(&p->ptrace_list);
 744                 release_task(p);
 745         }
 746
 747 }
 748
 749 /*
 750  * Send signals to all our closest relatives so that they know
 751  * to properly mourn us..
 752  */
 753 static void exit_notify(struct task_struct *tsk, int group_dead)
 754 {
 755         int state;
 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         forget_original_parent(tsk);
 766         exit_task_namespaces(tsk);
 767
 768         write_lock_irq(&tasklist_lock);
 769         if (group_dead)
 770                 kill_orphaned_pgrp(tsk->group_leader, NULL);
 771
 772         /* Let father know we died
 773          *
 774          * Thread signals are configurable, but you aren't going to use
 775          * that to send signals to arbitary processes.
 776          * That stops right now.
 777          *
 778          * If the parent exec id doesn't match the exec id we saved
 779          * when we started then we know the parent has changed security
 780          * domain.
 781          *
 782          * If our self_exec id doesn't match our parent_exec_id then
 783          * we have changed execution domain as these two values started
 784          * the same after a fork.
 785          */
 786         if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 &&
 787             (tsk->parent_exec_id != tsk->real_parent->self_exec_id ||
 788              tsk->self_exec_id != tsk->parent_exec_id)
 789             && !capable(CAP_KILL))
 790                 tsk->exit_signal = SIGCHLD;
 791
 792
 793         /* If something other than our normal parent is ptracing us, then
 794          * send it a SIGCHLD instead of honoring exit_signal.  exit_signal
 795          * only has special meaning to our real parent.
 796          */
 797         if (tsk->exit_signal != -1 && thread_group_empty(tsk)) {
 798                 int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD;
 799                 do_notify_parent(tsk, signal);
 800         } else if (tsk->ptrace) {
 801                 do_notify_parent(tsk, SIGCHLD);
 802         }
 803
 804         state = EXIT_ZOMBIE;
 805         if (tsk->exit_signal == -1 && likely(!tsk->ptrace))
 806                 state = EXIT_DEAD;
 807         tsk->exit_state = state;
 808
 809         if (thread_group_leader(tsk) &&
 810             tsk->signal->notify_count < 0 &&
 811             tsk->signal->group_exit_task)
 812                 wake_up_process(tsk->signal->group_exit_task);
 813
 814         write_unlock_irq(&tasklist_lock);
 815
 816         /* If the process is dead, release it - nobody will wait for it */
 817         if (state == EXIT_DEAD)
 818                 release_task(tsk);
 819 }
 820
 821 #ifdef CONFIG_DEBUG_STACK_USAGE
 822 static void check_stack_usage(void)
 823 {
 824         static DEFINE_SPINLOCK(low_water_lock);
 825         static int lowest_to_date = THREAD_SIZE;
 826         unsigned long *n = end_of_stack(current);
 827         unsigned long free;
 828
 829         while (*n == 0)
 830                 n++;
 831         free = (unsigned long)n - (unsigned long)end_of_stack(current);
 832
 833         if (free >= lowest_to_date)
 834                 return;
 835
 836         spin_lock(&low_water_lock);
 837         if (free < lowest_to_date) {
 838                 printk(KERN_WARNING "%s used greatest stack depth: %lu bytes "
 839                                 "left\n",
 840                                 current->comm, free);
 841                 lowest_to_date = free;
 842         }
 843         spin_unlock(&low_water_lock);
 844 }
 845 #else
 846 static inline void check_stack_usage(void) {}
 847 #endif
 848
 849 static inline void exit_child_reaper(struct task_struct *tsk)
 850 {
 851         if (likely(tsk->group_leader != task_child_reaper(tsk)))
 852                 return;
 853
 854         if (tsk->nsproxy->pid_ns == &init_pid_ns)
 855                 panic("Attempted to kill init!");
 856
 857         /*
 858          * @tsk is the last thread in the 'cgroup-init' and is exiting.
 859          * Terminate all remaining processes in the namespace and reap them
 860          * before exiting @tsk.
 861          *
 862          * Note that @tsk (last thread of cgroup-init) may not necessarily
 863          * be the child-reaper (i.e main thread of cgroup-init) of the
 864          * namespace i.e the child_reaper may have already exited.
 865          *
 866          * Even after a child_reaper exits, we let it inherit orphaned children,
 867          * because, pid_ns->child_reaper remains valid as long as there is
 868          * at least one living sub-thread in the cgroup init.
 869
 870          * This living sub-thread of the cgroup-init will be notified when
 871          * a child inherited by the 'child-reaper' exits (do_notify_parent()
 872          * uses __group_send_sig_info()). Further, when reaping child processes,
 873          * do_wait() iterates over children of all living sub threads.
 874
 875          * i.e even though 'child_reaper' thread is listed as the parent of the
 876          * orphaned children, any living sub-thread in the cgroup-init can
 877          * perform the role of the child_reaper.
 878          */
 879         zap_pid_ns_processes(tsk->nsproxy->pid_ns);
 880 }
 881
 882 NORET_TYPE void do_exit(long code)
 883 {
 884         struct task_struct *tsk = current;
 885         int group_dead;
 886
 887         profile_task_exit(tsk);
 888
 889         WARN_ON(atomic_read(&tsk->fs_excl));
 890
 891         if (unlikely(in_interrupt()))
 892                 panic("Aiee, killing interrupt handler!");
 893         if (unlikely(!tsk->pid))
 894                 panic("Attempted to kill the idle task!");
 895
 896         if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
 897                 current->ptrace_message = code;
 898                 ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP);
 899         }
 900
 901         /*
 902          * We're taking recursive faults here in do_exit. Safest is to just
 903          * leave this task alone and wait for reboot.
 904          */
 905         if (unlikely(tsk->flags & PF_EXITING)) {
 906                 printk(KERN_ALERT
 907                         "Fixing recursive fault but reboot is needed!\n");
 908                 /*
 909                  * We can do this unlocked here. The futex code uses
 910                  * this flag just to verify whether the pi state
 911                  * cleanup has been done or not. In the worst case it
 912                  * loops once more. We pretend that the cleanup was
 913                  * done as there is no way to return. Either the
 914                  * OWNER_DIED bit is set by now or we push the blocked
 915                  * task into the wait for ever nirwana as well.
 916                  */
 917                 tsk->flags |= PF_EXITPIDONE;
 918                 if (tsk->io_context)
 919                         exit_io_context();
 920                 set_current_state(TASK_UNINTERRUPTIBLE);
 921                 schedule();
 922         }
 923
 924         exit_signals(tsk);  /* sets PF_EXITING */
 925         /*
 926          * tsk->flags are checked in the futex code to protect against
 927          * an exiting task cleaning up the robust pi futexes.
 928          */
 929         smp_mb();
 930         spin_unlock_wait(&tsk->pi_lock);
 931
 932         if (unlikely(in_atomic()))
 933                 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
 934                                 current->comm, task_pid_nr(current),
 935                                 preempt_count());
 936
 937         acct_update_integrals(tsk);
 938         if (tsk->mm) {
 939                 update_hiwater_rss(tsk->mm);
 940                 update_hiwater_vm(tsk->mm);
 941         }
 942         group_dead = atomic_dec_and_test(&tsk->signal->live);
 943         if (group_dead) {
 944                 exit_child_reaper(tsk);
 945                 hrtimer_cancel(&tsk->signal->real_timer);
 946                 exit_itimers(tsk->signal);
 947         }
 948         acct_collect(code, group_dead);
 949 #ifdef CONFIG_FUTEX
 950         if (unlikely(tsk->robust_list))
 951                 exit_robust_list(tsk);
 952 #ifdef CONFIG_COMPAT
 953         if (unlikely(tsk->compat_robust_list))
 954                 compat_exit_robust_list(tsk);
 955 #endif
 956 #endif
 957         if (group_dead)
 958                 tty_audit_exit();
 959         if (unlikely(tsk->audit_context))
 960                 audit_free(tsk);
 961
 962         tsk->exit_code = code;
 963         taskstats_exit(tsk, group_dead);
 964
 965         exit_mm(tsk);
 966
 967         if (group_dead)
 968                 acct_process();
 969         exit_sem(tsk);
 970         __exit_files(tsk);
 971         __exit_fs(tsk);
 972         check_stack_usage();
 973         exit_thread();
 974         cgroup_exit(tsk, 1);
 975         exit_keys(tsk);
 976
 977         if (group_dead && tsk->signal->leader)
 978                 disassociate_ctty(1);
 979
 980         module_put(task_thread_info(tsk)->exec_domain->module);
 981         if (tsk->binfmt)
 982                 module_put(tsk->binfmt->module);
 983
 984         proc_exit_connector(tsk);
 985         exit_notify(tsk, group_dead);
 986 #ifdef CONFIG_NUMA
 987         mpol_free(tsk->mempolicy);
 988         tsk->mempolicy = NULL;
 989 #endif
 990 #ifdef CONFIG_FUTEX
 991         /*
 992          * This must happen late, after the PID is not
 993          * hashed anymore:
 994          */
 995         if (unlikely(!list_empty(&tsk->pi_state_list)))
 996                 exit_pi_state_list(tsk);
 997         if (unlikely(current->pi_state_cache))
 998                 kfree(current->pi_state_cache);
 999 #endif
1000         /*
1001          * Make sure we are holding no locks:
1002          */
1003         debug_check_no_locks_held(tsk);
1004         /*
1005          * We can do this unlocked here. The futex code uses this flag
1006          * just to verify whether the pi state cleanup has been done
1007          * or not. In the worst case it loops once more.
1008          */
1009         tsk->flags |= PF_EXITPIDONE;
1010
1011         if (tsk->io_context)
1012                 exit_io_context();
1013
1014         if (tsk->splice_pipe)
1015                 __free_pipe_info(tsk->splice_pipe);
1016
1017         preempt_disable();
1018         /* causes final put_task_struct in finish_task_switch(). */
1019         tsk->state = TASK_DEAD;
1020
1021         schedule();
1022         BUG();
1023         /* Avoid "noreturn function does return".  */
1024         for (;;)
1025                 cpu_relax();    /* For when BUG is null */
1026 }
1027
1028 EXPORT_SYMBOL_GPL(do_exit);
1029
1030 NORET_TYPE void complete_and_exit(struct completion *comp, long code)
1031 {
1032         if (comp)
1033                 complete(comp);
1034
1035         do_exit(code);
1036 }
1037
1038 EXPORT_SYMBOL(complete_and_exit);
1039
1040 asmlinkage long sys_exit(int error_code)
1041 {
1042         do_exit((error_code&0xff)<<8);
1043 }
1044
1045 /*
1046  * Take down every thread in the group.  This is called by fatal signals
1047  * as well as by sys_exit_group (below).
1048  */
1049 NORET_TYPE void
1050 do_group_exit(int exit_code)
1051 {
1052         BUG_ON(exit_code & 0x80); /* core dumps don't get here */
1053
1054         if (current->signal->flags & SIGNAL_GROUP_EXIT)
1055                 exit_code = current->signal->group_exit_code;
1056         else if (!thread_group_empty(current)) {
1057                 struct signal_struct *const sig = current->signal;
1058                 struct sighand_struct *const sighand = current->sighand;
1059                 spin_lock_irq(&sighand->siglock);
1060                 if (signal_group_exit(sig))
1061                         /* Another thread got here before we took the lock.  */
1062                         exit_code = sig->group_exit_code;
1063                 else {
1064                         sig->group_exit_code = exit_code;
1065                         sig->flags = SIGNAL_GROUP_EXIT;
1066                         zap_other_threads(current);
1067                 }
1068                 spin_unlock_irq(&sighand->siglock);
1069         }
1070
1071         do_exit(exit_code);
1072         /* NOTREACHED */
1073 }
1074
1075 /*
1076  * this kills every thread in the thread group. Note that any externally
1077  * wait4()-ing process will get the correct exit code - even if this
1078  * thread is not the thread group leader.
1079  */
1080 asmlinkage void sys_exit_group(int error_code)
1081 {
1082         do_group_exit((error_code & 0xff) << 8);
1083 }
1084
1085 static struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
1086 {
1087         struct pid *pid = NULL;
1088         if (type == PIDTYPE_PID)
1089                 pid = task->pids[type].pid;
1090         else if (type < PIDTYPE_MAX)
1091                 pid = task->group_leader->pids[type].pid;
1092         return pid;
1093 }
1094
1095 static int eligible_child(enum pid_type type, struct pid *pid, int options,
1096                           struct task_struct *p)
1097 {
1098         int err;
1099
1100         if (type < PIDTYPE_MAX) {
1101                 if (task_pid_type(p, type) != pid)
1102                         return 0;
1103         }
1104
1105         /*
1106          * Do not consider detached threads that are
1107          * not ptraced:
1108          */
1109         if (p->exit_signal == -1 && !p->ptrace)
1110                 return 0;
1111
1112         /* Wait for all children (clone and not) if __WALL is set;
1113          * otherwise, wait for clone children *only* if __WCLONE is
1114          * set; otherwise, wait for non-clone children *only*.  (Note:
1115          * A "clone" child here is one that reports to its parent
1116          * using a signal other than SIGCHLD.) */
1117         if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
1118             && !(options & __WALL))
1119                 return 0;
1120
1121         err = security_task_wait(p);
1122         if (likely(!err))
1123                 return 1;
1124
1125         if (type != PIDTYPE_PID)
1126                 return 0;
1127         /* This child was explicitly requested, abort */
1128         read_unlock(&tasklist_lock);
1129         return err;
1130 }
1131
1132 static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,
1133                                int why, int status,
1134                                struct siginfo __user *infop,
1135                                struct rusage __user *rusagep)
1136 {
1137         int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
1138
1139         put_task_struct(p);
1140         if (!retval)
1141                 retval = put_user(SIGCHLD, &infop->si_signo);
1142         if (!retval)
1143                 retval = put_user(0, &infop->si_errno);
1144         if (!retval)
1145                 retval = put_user((short)why, &infop->si_code);
1146         if (!retval)
1147                 retval = put_user(pid, &infop->si_pid);
1148         if (!retval)
1149                 retval = put_user(uid, &infop->si_uid);
1150         if (!retval)
1151                 retval = put_user(status, &infop->si_status);
1152         if (!retval)
1153                 retval = pid;
1154         return retval;
1155 }
1156
1157 /*
1158  * Handle sys_wait4 work for one task in state EXIT_ZOMBIE.  We hold
1159  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1160  * the lock and this task is uninteresting.  If we return nonzero, we have
1161  * released the lock and the system call should return.
1162  */
1163 static int wait_task_zombie(struct task_struct *p, int noreap,
1164                             struct siginfo __user *infop,
1165                             int __user *stat_addr, struct rusage __user *ru)
1166 {
1167         unsigned long state;
1168         int retval, status, traced;
1169         pid_t pid = task_pid_vnr(p);
1170
1171         if (unlikely(noreap)) {
1172                 uid_t uid = p->uid;
1173                 int exit_code = p->exit_code;
1174                 int why, status;
1175
1176                 get_task_struct(p);
1177                 read_unlock(&tasklist_lock);
1178                 if ((exit_code & 0x7f) == 0) {
1179                         why = CLD_EXITED;
1180                         status = exit_code >> 8;
1181                 } else {
1182                         why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1183                         status = exit_code & 0x7f;
1184                 }
1185                 return wait_noreap_copyout(p, pid, uid, why,
1186                                            status, infop, ru);
1187         }
1188
1189         /*
1190          * Try to move the task's state to DEAD
1191          * only one thread is allowed to do this:
1192          */
1193         state = xchg(&p->exit_state, EXIT_DEAD);
1194         if (state != EXIT_ZOMBIE) {
1195                 BUG_ON(state != EXIT_DEAD);
1196                 return 0;
1197         }
1198
1199         /* traced means p->ptrace, but not vice versa */
1200         traced = (p->real_parent != p->parent);
1201
1202         if (likely(!traced)) {
1203                 struct signal_struct *psig;
1204                 struct signal_struct *sig;
1205
1206                 /*
1207                  * The resource counters for the group leader are in its
1208                  * own task_struct.  Those for dead threads in the group
1209                  * are in its signal_struct, as are those for the child
1210                  * processes it has previously reaped.  All these
1211                  * accumulate in the parent's signal_struct c* fields.
1212                  *
1213                  * We don't bother to take a lock here to protect these
1214                  * p->signal fields, because they are only touched by
1215                  * __exit_signal, which runs with tasklist_lock
1216                  * write-locked anyway, and so is excluded here.  We do
1217                  * need to protect the access to p->parent->signal fields,
1218                  * as other threads in the parent group can be right
1219                  * here reaping other children at the same time.
1220                  */
1221                 spin_lock_irq(&p->parent->sighand->siglock);
1222                 psig = p->parent->signal;
1223                 sig = p->signal;
1224                 psig->cutime =
1225                         cputime_add(psig->cutime,
1226                         cputime_add(p->utime,
1227                         cputime_add(sig->utime,
1228                                     sig->cutime)));
1229                 psig->cstime =
1230                         cputime_add(psig->cstime,
1231                         cputime_add(p->stime,
1232                         cputime_add(sig->stime,
1233                                     sig->cstime)));
1234                 psig->cgtime =
1235                         cputime_add(psig->cgtime,
1236                         cputime_add(p->gtime,
1237                         cputime_add(sig->gtime,
1238                                     sig->cgtime)));
1239                 psig->cmin_flt +=
1240                         p->min_flt + sig->min_flt + sig->cmin_flt;
1241                 psig->cmaj_flt +=
1242                         p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1243                 psig->cnvcsw +=
1244                         p->nvcsw + sig->nvcsw + sig->cnvcsw;
1245                 psig->cnivcsw +=
1246                         p->nivcsw + sig->nivcsw + sig->cnivcsw;
1247                 psig->cinblock +=
1248                         task_io_get_inblock(p) +
1249                         sig->inblock + sig->cinblock;
1250                 psig->coublock +=
1251                         task_io_get_oublock(p) +
1252                         sig->oublock + sig->coublock;
1253                 spin_unlock_irq(&p->parent->sighand->siglock);
1254         }
1255
1256         /*
1257          * Now we are sure this task is interesting, and no other
1258          * thread can reap it because we set its state to EXIT_DEAD.
1259          */
1260         read_unlock(&tasklist_lock);
1261
1262         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1263         status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1264                 ? p->signal->group_exit_code : p->exit_code;
1265         if (!retval && stat_addr)
1266                 retval = put_user(status, stat_addr);
1267         if (!retval && infop)
1268                 retval = put_user(SIGCHLD, &infop->si_signo);
1269         if (!retval && infop)
1270                 retval = put_user(0, &infop->si_errno);
1271         if (!retval && infop) {
1272                 int why;
1273
1274                 if ((status & 0x7f) == 0) {
1275                         why = CLD_EXITED;
1276                         status >>= 8;
1277                 } else {
1278                         why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1279                         status &= 0x7f;
1280                 }
1281                 retval = put_user((short)why, &infop->si_code);
1282                 if (!retval)
1283                         retval = put_user(status, &infop->si_status);
1284         }
1285         if (!retval && infop)
1286                 retval = put_user(pid, &infop->si_pid);
1287         if (!retval && infop)
1288                 retval = put_user(p->uid, &infop->si_uid);
1289         if (!retval)
1290                 retval = pid;
1291
1292         if (traced) {
1293                 write_lock_irq(&tasklist_lock);
1294                 /* We dropped tasklist, ptracer could die and untrace */
1295                 ptrace_unlink(p);
1296                 /*
1297                  * If this is not a detached task, notify the parent.
1298                  * If it's still not detached after that, don't release
1299                  * it now.
1300                  */
1301                 if (p->exit_signal != -1) {
1302                         do_notify_parent(p, p->exit_signal);
1303                         if (p->exit_signal != -1) {
1304                                 p->exit_state = EXIT_ZOMBIE;
1305                                 p = NULL;
1306                         }
1307                 }
1308                 write_unlock_irq(&tasklist_lock);
1309         }
1310         if (p != NULL)
1311                 release_task(p);
1312
1313         return retval;
1314 }
1315
1316 /*
1317  * Handle sys_wait4 work for one task in state TASK_STOPPED.  We hold
1318  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1319  * the lock and this task is uninteresting.  If we return nonzero, we have
1320  * released the lock and the system call should return.
1321  */
1322 static int wait_task_stopped(struct task_struct *p,
1323                              int noreap, struct siginfo __user *infop,
1324                              int __user *stat_addr, struct rusage __user *ru)
1325 {
1326         int retval, exit_code, why;
1327         uid_t uid = 0; /* unneeded, required by compiler */
1328         pid_t pid;
1329
1330         exit_code = 0;
1331         spin_lock_irq(&p->sighand->siglock);
1332
1333         if (unlikely(!task_is_stopped_or_traced(p)))
1334                 goto unlock_sig;
1335
1336         if (!(p->ptrace & PT_PTRACED) && p->signal->group_stop_count > 0)
1337                 /*
1338                  * A group stop is in progress and this is the group leader.
1339                  * We won't report until all threads have stopped.
1340                  */
1341                 goto unlock_sig;
1342
1343         exit_code = p->exit_code;
1344         if (!exit_code)
1345                 goto unlock_sig;
1346
1347         if (!noreap)
1348                 p->exit_code = 0;
1349
1350         uid = p->uid;
1351 unlock_sig:
1352         spin_unlock_irq(&p->sighand->siglock);
1353         if (!exit_code)
1354                 return 0;
1355
1356         /*
1357          * Now we are pretty sure this task is interesting.
1358          * Make sure it doesn't get reaped out from under us while we
1359          * give up the lock and then examine it below.  We don't want to
1360          * keep holding onto the tasklist_lock while we call getrusage and
1361          * possibly take page faults for user memory.
1362          */
1363         get_task_struct(p);
1364         pid = task_pid_vnr(p);
1365         why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
1366         read_unlock(&tasklist_lock);
1367
1368         if (unlikely(noreap))
1369                 return wait_noreap_copyout(p, pid, uid,
1370                                            why, exit_code,
1371                                            infop, ru);
1372
1373         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1374         if (!retval && stat_addr)
1375                 retval = put_user((exit_code << 8) | 0x7f, stat_addr);
1376         if (!retval && infop)
1377                 retval = put_user(SIGCHLD, &infop->si_signo);
1378         if (!retval && infop)
1379                 retval = put_user(0, &infop->si_errno);
1380         if (!retval && infop)
1381                 retval = put_user((short)why, &infop->si_code);
1382         if (!retval && infop)
1383                 retval = put_user(exit_code, &infop->si_status);
1384         if (!retval && infop)
1385                 retval = put_user(pid, &infop->si_pid);
1386         if (!retval && infop)
1387                 retval = put_user(uid, &infop->si_uid);
1388         if (!retval)
1389                 retval = pid;
1390         put_task_struct(p);
1391
1392         BUG_ON(!retval);
1393         return retval;
1394 }
1395
1396 /*
1397  * Handle do_wait work for one task in a live, non-stopped state.
1398  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1399  * the lock and this task is uninteresting.  If we return nonzero, we have
1400  * released the lock and the system call should return.
1401  */
1402 static int wait_task_continued(struct task_struct *p, int noreap,
1403                                struct siginfo __user *infop,
1404                                int __user *stat_addr, struct rusage __user *ru)
1405 {
1406         int retval;
1407         pid_t pid;
1408         uid_t uid;
1409
1410         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1411                 return 0;
1412
1413         spin_lock_irq(&p->sighand->siglock);
1414         /* Re-check with the lock held.  */
1415         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1416                 spin_unlock_irq(&p->sighand->siglock);
1417                 return 0;
1418         }
1419         if (!noreap)
1420                 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1421         spin_unlock_irq(&p->sighand->siglock);
1422
1423         pid = task_pid_vnr(p);
1424         uid = p->uid;
1425         get_task_struct(p);
1426         read_unlock(&tasklist_lock);
1427
1428         if (!infop) {
1429                 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1430                 put_task_struct(p);
1431                 if (!retval && stat_addr)
1432                         retval = put_user(0xffff, stat_addr);
1433                 if (!retval)
1434                         retval = pid;
1435         } else {
1436                 retval = wait_noreap_copyout(p, pid, uid,
1437                                              CLD_CONTINUED, SIGCONT,
1438                                              infop, ru);
1439                 BUG_ON(retval == 0);
1440         }
1441
1442         return retval;
1443 }
1444
1445 static long do_wait(enum pid_type type, struct pid *pid, int options,
1446                     struct siginfo __user *infop, int __user *stat_addr,
1447                     struct rusage __user *ru)
1448 {
1449         DECLARE_WAITQUEUE(wait, current);
1450         struct task_struct *tsk;
1451         int flag, retval;
1452
1453         add_wait_queue(&current->signal->wait_chldexit,&wait);
1454 repeat:
1455         /* If there is nothing that can match our critier just get out */
1456         retval = -ECHILD;
1457         if ((type < PIDTYPE_MAX) && (!pid || hlist_empty(&pid->tasks[type])))
1458                 goto end;
1459
1460         /*
1461          * We will set this flag if we see any child that might later
1462          * match our criteria, even if we are not able to reap it yet.
1463          */
1464         flag = retval = 0;
1465         current->state = TASK_INTERRUPTIBLE;
1466         read_lock(&tasklist_lock);
1467         tsk = current;
1468         do {
1469                 struct task_struct *p;
1470
1471                 list_for_each_entry(p, &tsk->children, sibling) {
1472                         int ret = eligible_child(type, pid, options, p);
1473                         if (!ret)
1474                                 continue;
1475
1476                         if (unlikely(ret < 0)) {
1477                                 retval = ret;
1478                         } else if (task_is_stopped_or_traced(p)) {
1479                                 /*
1480                                  * It's stopped now, so it might later
1481                                  * continue, exit, or stop again.
1482                                  */
1483                                 flag = 1;
1484                                 if (!(p->ptrace & PT_PTRACED) &&
1485                                     !(options & WUNTRACED))
1486                                         continue;
1487
1488                                 retval = wait_task_stopped(p,
1489                                                 (options & WNOWAIT), infop,
1490                                                 stat_addr, ru);
1491                         } else if (p->exit_state == EXIT_ZOMBIE &&
1492                                         !delay_group_leader(p)) {
1493                                 /*
1494                                  * We don't reap group leaders with subthreads.
1495                                  */
1496                                 if (!likely(options & WEXITED))
1497                                         continue;
1498                                 retval = wait_task_zombie(p,
1499                                                 (options & WNOWAIT), infop,
1500                                                 stat_addr, ru);
1501                         } else if (p->exit_state != EXIT_DEAD) {
1502                                 /*
1503                                  * It's running now, so it might later
1504                                  * exit, stop, or stop and then continue.
1505                                  */
1506                                 flag = 1;
1507                                 if (!unlikely(options & WCONTINUED))
1508                                         continue;
1509                                 retval = wait_task_continued(p,
1510                                                 (options & WNOWAIT), infop,
1511                                                 stat_addr, ru);
1512                         }
1513                         if (retval != 0) /* tasklist_lock released */
1514                                 goto end;
1515                 }
1516                 if (!flag) {
1517                         list_for_each_entry(p, &tsk->ptrace_children,
1518                                                                 ptrace_list) {
1519                                 flag = eligible_child(type, pid, options, p);
1520                                 if (!flag)
1521                                         continue;
1522                                 if (likely(flag > 0))
1523                                         break;
1524                                 retval = flag;
1525                                 goto end;
1526                         }
1527                 }
1528                 if (options & __WNOTHREAD)
1529                         break;
1530                 tsk = next_thread(tsk);
1531                 BUG_ON(tsk->signal != current->signal);
1532         } while (tsk != current);
1533         read_unlock(&tasklist_lock);
1534
1535         if (flag) {
1536                 if (options & WNOHANG)
1537                         goto end;
1538                 retval = -ERESTARTSYS;
1539                 if (signal_pending(current))
1540                         goto end;
1541                 schedule();
1542                 goto repeat;
1543         }
1544         retval = -ECHILD;
1545 end:
1546         current->state = TASK_RUNNING;
1547         remove_wait_queue(&current->signal->wait_chldexit,&wait);
1548         if (infop) {
1549                 if (retval > 0)
1550                         retval = 0;
1551                 else {
1552                         /*
1553                          * For a WNOHANG return, clear out all the fields
1554                          * we would set so the user can easily tell the
1555                          * difference.
1556                          */
1557                         if (!retval)
1558                                 retval = put_user(0, &infop->si_signo);
1559                         if (!retval)
1560                                 retval = put_user(0, &infop->si_errno);
1561                         if (!retval)
1562                                 retval = put_user(0, &infop->si_code);
1563                         if (!retval)
1564                                 retval = put_user(0, &infop->si_pid);
1565                         if (!retval)
1566                                 retval = put_user(0, &infop->si_uid);
1567                         if (!retval)
1568                                 retval = put_user(0, &infop->si_status);
1569                 }
1570         }
1571         return retval;
1572 }
1573
1574 asmlinkage long sys_waitid(int which, pid_t upid,
1575                            struct siginfo __user *infop, int options,
1576                            struct rusage __user *ru)
1577 {
1578         struct pid *pid = NULL;
1579         enum pid_type type;
1580         long ret;
1581
1582         if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1583                 return -EINVAL;
1584         if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1585                 return -EINVAL;
1586
1587         switch (which) {
1588         case P_ALL:
1589                 type = PIDTYPE_MAX;
1590                 break;
1591         case P_PID:
1592                 type = PIDTYPE_PID;
1593                 if (upid <= 0)
1594                         return -EINVAL;
1595                 break;
1596         case P_PGID:
1597                 type = PIDTYPE_PGID;
1598                 if (upid <= 0)
1599                         return -EINVAL;
1600                 break;
1601         default:
1602                 return -EINVAL;
1603         }
1604
1605         if (type < PIDTYPE_MAX)
1606                 pid = find_get_pid(upid);
1607         ret = do_wait(type, pid, options, infop, NULL, ru);
1608         put_pid(pid);
1609
1610         /* avoid REGPARM breakage on x86: */
1611         asmlinkage_protect(5, ret, which, upid, infop, options, ru);
1612         return ret;
1613 }
1614
1615 asmlinkage long sys_wait4(pid_t upid, int __user *stat_addr,
1616                           int options, struct rusage __user *ru)
1617 {
1618         struct pid *pid = NULL;
1619         enum pid_type type;
1620         long ret;
1621
1622         if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1623                         __WNOTHREAD|__WCLONE|__WALL))
1624                 return -EINVAL;
1625
1626         if (upid == -1)
1627                 type = PIDTYPE_MAX;
1628         else if (upid < 0) {
1629                 type = PIDTYPE_PGID;
1630                 pid = find_get_pid(-upid);
1631         } else if (upid == 0) {
1632                 type = PIDTYPE_PGID;
1633                 pid = get_pid(task_pgrp(current));
1634         } else /* upid > 0 */ {
1635                 type = PIDTYPE_PID;
1636                 pid = find_get_pid(upid);
1637         }
1638
1639         ret = do_wait(type, pid, options | WEXITED, NULL, stat_addr, ru);
1640         put_pid(pid);
1641
1642         /* avoid REGPARM breakage on x86: */
1643         asmlinkage_protect(4, ret, upid, stat_addr, options, ru);
1644         return ret;
1645 }
1646
1647 #ifdef __ARCH_WANT_SYS_WAITPID
1648
1649 /*
1650  * sys_waitpid() remains for compatibility. waitpid() should be
1651  * implemented by calling sys_wait4() from libc.a.
1652  */
1653 asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options)
1654 {
1655         return sys_wait4(pid, stat_addr, options, NULL);
1656 }
1657
1658 #endif