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         int ret = 1;
 218
 219         do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
 220                 if (p == ignored_task
 221                                 || p->exit_state
 222                                 || is_global_init(p->real_parent))
 223                         continue;
 224                 if (task_pgrp(p->real_parent) != pgrp &&
 225                     task_session(p->real_parent) == task_session(p)) {
 226                         ret = 0;
 227                         break;
 228                 }
 229         } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
 230         return ret;     /* (sighing) "Often!" */
 231 }
 232
 233 int is_current_pgrp_orphaned(void)
 234 {
 235         int retval;
 236
 237         read_lock(&tasklist_lock);
 238         retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
 239         read_unlock(&tasklist_lock);
 240
 241         return retval;
 242 }
 243
 244 static int has_stopped_jobs(struct pid *pgrp)
 245 {
 246         int retval = 0;
 247         struct task_struct *p;
 248
 249         do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
 250                 if (!task_is_stopped(p))
 251                         continue;
 252                 retval = 1;
 253                 break;
 254         } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
 255         return retval;
 256 }
 257
 258 /**
 259  * reparent_to_kthreadd - Reparent the calling kernel thread to kthreadd
 260  *
 261  * If a kernel thread is launched as a result of a system call, or if
 262  * it ever exits, it should generally reparent itself to kthreadd so it
 263  * isn't in the way of other processes and is correctly cleaned up on exit.
 264  *
 265  * The various task state such as scheduling policy and priority may have
 266  * been inherited from a user process, so we reset them to sane values here.
 267  *
 268  * NOTE that reparent_to_kthreadd() gives the caller full capabilities.
 269  */
 270 static void reparent_to_kthreadd(void)
 271 {
 272         write_lock_irq(&tasklist_lock);
 273
 274         ptrace_unlink(current);
 275         /* Reparent to init */
 276         remove_parent(current);
 277         current->real_parent = current->parent = kthreadd_task;
 278         add_parent(current);
 279
 280         /* Set the exit signal to SIGCHLD so we signal init on exit */
 281         current->exit_signal = SIGCHLD;
 282
 283         if (task_nice(current) < 0)
 284                 set_user_nice(current, 0);
 285         /* cpus_allowed? */
 286         /* rt_priority? */
 287         /* signals? */
 288         security_task_reparent_to_init(current);
 289         memcpy(current->signal->rlim, init_task.signal->rlim,
 290                sizeof(current->signal->rlim));
 291         atomic_inc(&(INIT_USER->__count));
 292         write_unlock_irq(&tasklist_lock);
 293         switch_uid(INIT_USER);
 294 }
 295
 296 void __set_special_pids(pid_t session, pid_t pgrp)
 297 {
 298         struct task_struct *curr = current->group_leader;
 299
 300         if (task_session_nr(curr) != session) {
 301                 detach_pid(curr, PIDTYPE_SID);
 302                 set_task_session(curr, session);
 303                 attach_pid(curr, PIDTYPE_SID, find_pid(session));
 304         }
 305         if (task_pgrp_nr(curr) != pgrp) {
 306                 detach_pid(curr, PIDTYPE_PGID);
 307                 set_task_pgrp(curr, pgrp);
 308                 attach_pid(curr, PIDTYPE_PGID, find_pid(pgrp));
 309         }
 310 }
 311
 312 static void set_special_pids(pid_t session, pid_t pgrp)
 313 {
 314         write_lock_irq(&tasklist_lock);
 315         __set_special_pids(session, pgrp);
 316         write_unlock_irq(&tasklist_lock);
 317 }
 318
 319 /*
 320  * Let kernel threads use this to say that they
 321  * allow a certain signal (since daemonize() will
 322  * have disabled all of them by default).
 323  */
 324 int allow_signal(int sig)
 325 {
 326         if (!valid_signal(sig) || sig < 1)
 327                 return -EINVAL;
 328
 329         spin_lock_irq(&current->sighand->siglock);
 330         sigdelset(&current->blocked, sig);
 331         if (!current->mm) {
 332                 /* Kernel threads handle their own signals.
 333                    Let the signal code know it'll be handled, so
 334                    that they don't get converted to SIGKILL or
 335                    just silently dropped */
 336                 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
 337         }
 338         recalc_sigpending();
 339         spin_unlock_irq(&current->sighand->siglock);
 340         return 0;
 341 }
 342
 343 EXPORT_SYMBOL(allow_signal);
 344
 345 int disallow_signal(int sig)
 346 {
 347         if (!valid_signal(sig) || sig < 1)
 348                 return -EINVAL;
 349
 350         spin_lock_irq(&current->sighand->siglock);
 351         current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN;
 352         recalc_sigpending();
 353         spin_unlock_irq(&current->sighand->siglock);
 354         return 0;
 355 }
 356
 357 EXPORT_SYMBOL(disallow_signal);
 358
 359 /*
 360  *      Put all the gunge required to become a kernel thread without
 361  *      attached user resources in one place where it belongs.
 362  */
 363
 364 void daemonize(const char *name, ...)
 365 {
 366         va_list args;
 367         struct fs_struct *fs;
 368         sigset_t blocked;
 369
 370         va_start(args, name);
 371         vsnprintf(current->comm, sizeof(current->comm), name, args);
 372         va_end(args);
 373
 374         /*
 375          * If we were started as result of loading a module, close all of the
 376          * user space pages.  We don't need them, and if we didn't close them
 377          * they would be locked into memory.
 378          */
 379         exit_mm(current);
 380         /*
 381          * We don't want to have TIF_FREEZE set if the system-wide hibernation
 382          * or suspend transition begins right now.
 383          */
 384         current->flags |= PF_NOFREEZE;
 385
 386         set_special_pids(1, 1);
 387         proc_clear_tty(current);
 388
 389         /* Block and flush all signals */
 390         sigfillset(&blocked);
 391         sigprocmask(SIG_BLOCK, &blocked, NULL);
 392         flush_signals(current);
 393
 394         /* Become as one with the init task */
 395
 396         exit_fs(current);       /* current->fs->count--; */
 397         fs = init_task.fs;
 398         current->fs = fs;
 399         atomic_inc(&fs->count);
 400
 401         if (current->nsproxy != init_task.nsproxy) {
 402                 get_nsproxy(init_task.nsproxy);
 403                 switch_task_namespaces(current, init_task.nsproxy);
 404         }
 405
 406         exit_files(current);
 407         current->files = init_task.files;
 408         atomic_inc(&current->files->count);
 409
 410         reparent_to_kthreadd();
 411 }
 412
 413 EXPORT_SYMBOL(daemonize);
 414
 415 static void close_files(struct files_struct * files)
 416 {
 417         int i, j;
 418         struct fdtable *fdt;
 419
 420         j = 0;
 421
 422         /*
 423          * It is safe to dereference the fd table without RCU or
 424          * ->file_lock because this is the last reference to the
 425          * files structure.
 426          */
 427         fdt = files_fdtable(files);
 428         for (;;) {
 429                 unsigned long set;
 430                 i = j * __NFDBITS;
 431                 if (i >= fdt->max_fds)
 432                         break;
 433                 set = fdt->open_fds->fds_bits[j++];
 434                 while (set) {
 435                         if (set & 1) {
 436                                 struct file * file = xchg(&fdt->fd[i], NULL);
 437                                 if (file) {
 438                                         filp_close(file, files);
 439                                         cond_resched();
 440                                 }
 441                         }
 442                         i++;
 443                         set >>= 1;
 444                 }
 445         }
 446 }
 447
 448 struct files_struct *get_files_struct(struct task_struct *task)
 449 {
 450         struct files_struct *files;
 451
 452         task_lock(task);
 453         files = task->files;
 454         if (files)
 455                 atomic_inc(&files->count);
 456         task_unlock(task);
 457
 458         return files;
 459 }
 460
 461 void fastcall put_files_struct(struct files_struct *files)
 462 {
 463         struct fdtable *fdt;
 464
 465         if (atomic_dec_and_test(&files->count)) {
 466                 close_files(files);
 467                 /*
 468                  * Free the fd and fdset arrays if we expanded them.
 469                  * If the fdtable was embedded, pass files for freeing
 470                  * at the end of the RCU grace period. Otherwise,
 471                  * you can free files immediately.
 472                  */
 473                 fdt = files_fdtable(files);
 474                 if (fdt != &files->fdtab)
 475                         kmem_cache_free(files_cachep, files);
 476                 free_fdtable(fdt);
 477         }
 478 }
 479
 480 EXPORT_SYMBOL(put_files_struct);
 481
 482 void reset_files_struct(struct task_struct *tsk, struct files_struct *files)
 483 {
 484         struct files_struct *old;
 485
 486         old = tsk->files;
 487         task_lock(tsk);
 488         tsk->files = files;
 489         task_unlock(tsk);
 490         put_files_struct(old);
 491 }
 492 EXPORT_SYMBOL(reset_files_struct);
 493
 494 static void __exit_files(struct task_struct *tsk)
 495 {
 496         struct files_struct * files = tsk->files;
 497
 498         if (files) {
 499                 task_lock(tsk);
 500                 tsk->files = NULL;
 501                 task_unlock(tsk);
 502                 put_files_struct(files);
 503         }
 504 }
 505
 506 void exit_files(struct task_struct *tsk)
 507 {
 508         __exit_files(tsk);
 509 }
 510
 511 static void __put_fs_struct(struct fs_struct *fs)
 512 {
 513         /* No need to hold fs->lock if we are killing it */
 514         if (atomic_dec_and_test(&fs->count)) {
 515                 dput(fs->root);
 516                 mntput(fs->rootmnt);
 517                 dput(fs->pwd);
 518                 mntput(fs->pwdmnt);
 519                 if (fs->altroot) {
 520                         dput(fs->altroot);
 521                         mntput(fs->altrootmnt);
 522                 }
 523                 kmem_cache_free(fs_cachep, fs);
 524         }
 525 }
 526
 527 void put_fs_struct(struct fs_struct *fs)
 528 {
 529         __put_fs_struct(fs);
 530 }
 531
 532 static void __exit_fs(struct task_struct *tsk)
 533 {
 534         struct fs_struct * fs = tsk->fs;
 535
 536         if (fs) {
 537                 task_lock(tsk);
 538                 tsk->fs = NULL;
 539                 task_unlock(tsk);
 540                 __put_fs_struct(fs);
 541         }
 542 }
 543
 544 void exit_fs(struct task_struct *tsk)
 545 {
 546         __exit_fs(tsk);
 547 }
 548
 549 EXPORT_SYMBOL_GPL(exit_fs);
 550
 551 /*
 552  * Turn us into a lazy TLB process if we
 553  * aren't already..
 554  */
 555 static void exit_mm(struct task_struct * tsk)
 556 {
 557         struct mm_struct *mm = tsk->mm;
 558
 559         mm_release(tsk, mm);
 560         if (!mm)
 561                 return;
 562         /*
 563          * Serialize with any possible pending coredump.
 564          * We must hold mmap_sem around checking core_waiters
 565          * and clearing tsk->mm.  The core-inducing thread
 566          * will increment core_waiters for each thread in the
 567          * group with ->mm != NULL.
 568          */
 569         down_read(&mm->mmap_sem);
 570         if (mm->core_waiters) {
 571                 up_read(&mm->mmap_sem);
 572                 down_write(&mm->mmap_sem);
 573                 if (!--mm->core_waiters)
 574                         complete(mm->core_startup_done);
 575                 up_write(&mm->mmap_sem);
 576
 577                 wait_for_completion(&mm->core_done);
 578                 down_read(&mm->mmap_sem);
 579         }
 580         atomic_inc(&mm->mm_count);
 581         BUG_ON(mm != tsk->active_mm);
 582         /* more a memory barrier than a real lock */
 583         task_lock(tsk);
 584         tsk->mm = NULL;
 585         up_read(&mm->mmap_sem);
 586         enter_lazy_tlb(mm, current);
 587         /* We don't want this task to be frozen prematurely */
 588         clear_freeze_flag(tsk);
 589         task_unlock(tsk);
 590         mmput(mm);
 591 }
 592
 593 static void
 594 reparent_thread(struct task_struct *p, struct task_struct *father, int traced)
 595 {
 596         if (p->pdeath_signal)
 597                 /* We already hold the tasklist_lock here.  */
 598                 group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);
 599
 600         /* Move the child from its dying parent to the new one.  */
 601         if (unlikely(traced)) {
 602                 /* Preserve ptrace links if someone else is tracing this child.  */
 603                 list_del_init(&p->ptrace_list);
 604                 if (p->parent != p->real_parent)
 605                         list_add(&p->ptrace_list, &p->real_parent->ptrace_children);
 606         } else {
 607                 /* If this child is being traced, then we're the one tracing it
 608                  * anyway, so let go of it.
 609                  */
 610                 p->ptrace = 0;
 611                 remove_parent(p);
 612                 p->parent = p->real_parent;
 613                 add_parent(p);
 614
 615                 if (task_is_traced(p)) {
 616                         /*
 617                          * If it was at a trace stop, turn it into
 618                          * a normal stop since it's no longer being
 619                          * traced.
 620                          */
 621                         ptrace_untrace(p);
 622                 }
 623         }
 624
 625         /* If this is a threaded reparent there is no need to
 626          * notify anyone anything has happened.
 627          */
 628         if (p->real_parent->group_leader == father->group_leader)
 629                 return;
 630
 631         /* We don't want people slaying init.  */
 632         if (p->exit_signal != -1)
 633                 p->exit_signal = SIGCHLD;
 634
 635         /* If we'd notified the old parent about this child's death,
 636          * also notify the new parent.
 637          */
 638         if (!traced && p->exit_state == EXIT_ZOMBIE &&
 639             p->exit_signal != -1 && thread_group_empty(p))
 640                 do_notify_parent(p, p->exit_signal);
 641
 642         /*
 643          * process group orphan check
 644          * Case ii: Our child is in a different pgrp
 645          * than we are, and it was the only connection
 646          * outside, so the child pgrp is now orphaned.
 647          */
 648         if ((task_pgrp(p) != task_pgrp(father)) &&
 649             (task_session(p) == task_session(father))) {
 650                 struct pid *pgrp = task_pgrp(p);
 651
 652                 if (will_become_orphaned_pgrp(pgrp, NULL) &&
 653                     has_stopped_jobs(pgrp)) {
 654                         __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
 655                         __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
 656                 }
 657         }
 658 }
 659
 660 /*
 661  * When we die, we re-parent all our children.
 662  * Try to give them to another thread in our thread
 663  * group, and if no such member exists, give it to
 664  * the child reaper process (ie "init") in our pid
 665  * space.
 666  */
 667 static void forget_original_parent(struct task_struct *father)
 668 {
 669         struct task_struct *p, *n, *reaper = father;
 670         struct list_head ptrace_dead;
 671
 672         INIT_LIST_HEAD(&ptrace_dead);
 673
 674         write_lock_irq(&tasklist_lock);
 675
 676         do {
 677                 reaper = next_thread(reaper);
 678                 if (reaper == father) {
 679                         reaper = task_child_reaper(father);
 680                         break;
 681                 }
 682         } while (reaper->flags & PF_EXITING);
 683
 684         /*
 685          * There are only two places where our children can be:
 686          *
 687          * - in our child list
 688          * - in our ptraced child list
 689          *
 690          * Search them and reparent children.
 691          */
 692         list_for_each_entry_safe(p, n, &father->children, sibling) {
 693                 int ptrace;
 694
 695                 ptrace = p->ptrace;
 696
 697                 /* if father isn't the real parent, then ptrace must be enabled */
 698                 BUG_ON(father != p->real_parent && !ptrace);
 699
 700                 if (father == p->real_parent) {
 701                         /* reparent with a reaper, real father it's us */
 702                         p->real_parent = reaper;
 703                         reparent_thread(p, father, 0);
 704                 } else {
 705                         /* reparent ptraced task to its real parent */
 706                         __ptrace_unlink (p);
 707                         if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
 708                             thread_group_empty(p))
 709                                 do_notify_parent(p, p->exit_signal);
 710                 }
 711
 712                 /*
 713                  * if the ptraced child is a zombie with exit_signal == -1
 714                  * we must collect it before we exit, or it will remain
 715                  * zombie forever since we prevented it from self-reap itself
 716                  * while it was being traced by us, to be able to see it in wait4.
 717                  */
 718                 if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && p->exit_signal == -1))
 719                         list_add(&p->ptrace_list, &ptrace_dead);
 720         }
 721
 722         list_for_each_entry_safe(p, n, &father->ptrace_children, ptrace_list) {
 723                 p->real_parent = reaper;
 724                 reparent_thread(p, father, 1);
 725         }
 726
 727         write_unlock_irq(&tasklist_lock);
 728         BUG_ON(!list_empty(&father->children));
 729         BUG_ON(!list_empty(&father->ptrace_children));
 730
 731         list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_list) {
 732                 list_del_init(&p->ptrace_list);
 733                 release_task(p);
 734         }
 735
 736 }
 737
 738 /*
 739  * Send signals to all our closest relatives so that they know
 740  * to properly mourn us..
 741  */
 742 static void exit_notify(struct task_struct *tsk)
 743 {
 744         int state;
 745         struct task_struct *t;
 746         struct pid *pgrp;
 747
 748         if (signal_pending(tsk) && !(tsk->signal->flags & SIGNAL_GROUP_EXIT)
 749             && !thread_group_empty(tsk)) {
 750                 /*
 751                  * This occurs when there was a race between our exit
 752                  * syscall and a group signal choosing us as the one to
 753                  * wake up.  It could be that we are the only thread
 754                  * alerted to check for pending signals, but another thread
 755                  * should be woken now to take the signal since we will not.
 756                  * Now we'll wake all the threads in the group just to make
 757                  * sure someone gets all the pending signals.
 758                  */
 759                 spin_lock_irq(&tsk->sighand->siglock);
 760                 for (t = next_thread(tsk); t != tsk; t = next_thread(t))
 761                         if (!signal_pending(t) && !(t->flags & PF_EXITING))
 762                                 recalc_sigpending_and_wake(t);
 763                 spin_unlock_irq(&tsk->sighand->siglock);
 764         }
 765
 766         /*
 767          * This does two things:
 768          *
 769          * A.  Make init inherit all the child processes
 770          * B.  Check to see if any process groups have become orphaned
 771          *      as a result of our exiting, and if they have any stopped
 772          *      jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
 773          */
 774         forget_original_parent(tsk);
 775         exit_task_namespaces(tsk);
 776
 777         write_lock_irq(&tasklist_lock);
 778         /*
 779          * Check to see if any process groups have become orphaned
 780          * as a result of our exiting, and if they have any stopped
 781          * jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
 782          *
 783          * Case i: Our father is in a different pgrp than we are
 784          * and we were the only connection outside, so our pgrp
 785          * is about to become orphaned.
 786          */
 787         t = tsk->real_parent;
 788
 789         pgrp = task_pgrp(tsk);
 790         if ((task_pgrp(t) != pgrp) &&
 791             (task_session(t) == task_session(tsk)) &&
 792             will_become_orphaned_pgrp(pgrp, tsk) &&
 793             has_stopped_jobs(pgrp)) {
 794                 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
 795                 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
 796         }
 797
 798         /* Let father know we died
 799          *
 800          * Thread signals are configurable, but you aren't going to use
 801          * that to send signals to arbitary processes.
 802          * That stops right now.
 803          *
 804          * If the parent exec id doesn't match the exec id we saved
 805          * when we started then we know the parent has changed security
 806          * domain.
 807          *
 808          * If our self_exec id doesn't match our parent_exec_id then
 809          * we have changed execution domain as these two values started
 810          * the same after a fork.
 811          */
 812         if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 &&
 813             ( tsk->parent_exec_id != t->self_exec_id  ||
 814               tsk->self_exec_id != tsk->parent_exec_id)
 815             && !capable(CAP_KILL))
 816                 tsk->exit_signal = SIGCHLD;
 817
 818
 819         /* If something other than our normal parent is ptracing us, then
 820          * send it a SIGCHLD instead of honoring exit_signal.  exit_signal
 821          * only has special meaning to our real parent.
 822          */
 823         if (tsk->exit_signal != -1 && thread_group_empty(tsk)) {
 824                 int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD;
 825                 do_notify_parent(tsk, signal);
 826         } else if (tsk->ptrace) {
 827                 do_notify_parent(tsk, SIGCHLD);
 828         }
 829
 830         state = EXIT_ZOMBIE;
 831         if (tsk->exit_signal == -1 && likely(!tsk->ptrace))
 832                 state = EXIT_DEAD;
 833         tsk->exit_state = state;
 834
 835         if (thread_group_leader(tsk) &&
 836             tsk->signal->notify_count < 0 &&
 837             tsk->signal->group_exit_task)
 838                 wake_up_process(tsk->signal->group_exit_task);
 839
 840         write_unlock_irq(&tasklist_lock);
 841
 842         /* If the process is dead, release it - nobody will wait for it */
 843         if (state == EXIT_DEAD)
 844                 release_task(tsk);
 845 }
 846
 847 #ifdef CONFIG_DEBUG_STACK_USAGE
 848 static void check_stack_usage(void)
 849 {
 850         static DEFINE_SPINLOCK(low_water_lock);
 851         static int lowest_to_date = THREAD_SIZE;
 852         unsigned long *n = end_of_stack(current);
 853         unsigned long free;
 854
 855         while (*n == 0)
 856                 n++;
 857         free = (unsigned long)n - (unsigned long)end_of_stack(current);
 858
 859         if (free >= lowest_to_date)
 860                 return;
 861
 862         spin_lock(&low_water_lock);
 863         if (free < lowest_to_date) {
 864                 printk(KERN_WARNING "%s used greatest stack depth: %lu bytes "
 865                                 "left\n",
 866                                 current->comm, free);
 867                 lowest_to_date = free;
 868         }
 869         spin_unlock(&low_water_lock);
 870 }
 871 #else
 872 static inline void check_stack_usage(void) {}
 873 #endif
 874
 875 static inline void exit_child_reaper(struct task_struct *tsk)
 876 {
 877         if (likely(tsk->group_leader != task_child_reaper(tsk)))
 878                 return;
 879
 880         if (tsk->nsproxy->pid_ns == &init_pid_ns)
 881                 panic("Attempted to kill init!");
 882
 883         /*
 884          * @tsk is the last thread in the 'cgroup-init' and is exiting.
 885          * Terminate all remaining processes in the namespace and reap them
 886          * before exiting @tsk.
 887          *
 888          * Note that @tsk (last thread of cgroup-init) may not necessarily
 889          * be the child-reaper (i.e main thread of cgroup-init) of the
 890          * namespace i.e the child_reaper may have already exited.
 891          *
 892          * Even after a child_reaper exits, we let it inherit orphaned children,
 893          * because, pid_ns->child_reaper remains valid as long as there is
 894          * at least one living sub-thread in the cgroup init.
 895
 896          * This living sub-thread of the cgroup-init will be notified when
 897          * a child inherited by the 'child-reaper' exits (do_notify_parent()
 898          * uses __group_send_sig_info()). Further, when reaping child processes,
 899          * do_wait() iterates over children of all living sub threads.
 900
 901          * i.e even though 'child_reaper' thread is listed as the parent of the
 902          * orphaned children, any living sub-thread in the cgroup-init can
 903          * perform the role of the child_reaper.
 904          */
 905         zap_pid_ns_processes(tsk->nsproxy->pid_ns);
 906 }
 907
 908 fastcall NORET_TYPE void do_exit(long code)
 909 {
 910         struct task_struct *tsk = current;
 911         int group_dead;
 912
 913         profile_task_exit(tsk);
 914
 915         WARN_ON(atomic_read(&tsk->fs_excl));
 916
 917         if (unlikely(in_interrupt()))
 918                 panic("Aiee, killing interrupt handler!");
 919         if (unlikely(!tsk->pid))
 920                 panic("Attempted to kill the idle task!");
 921
 922         if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
 923                 current->ptrace_message = code;
 924                 ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP);
 925         }
 926
 927         /*
 928          * We're taking recursive faults here in do_exit. Safest is to just
 929          * leave this task alone and wait for reboot.
 930          */
 931         if (unlikely(tsk->flags & PF_EXITING)) {
 932                 printk(KERN_ALERT
 933                         "Fixing recursive fault but reboot is needed!\n");
 934                 /*
 935                  * We can do this unlocked here. The futex code uses
 936                  * this flag just to verify whether the pi state
 937                  * cleanup has been done or not. In the worst case it
 938                  * loops once more. We pretend that the cleanup was
 939                  * done as there is no way to return. Either the
 940                  * OWNER_DIED bit is set by now or we push the blocked
 941                  * task into the wait for ever nirwana as well.
 942                  */
 943                 tsk->flags |= PF_EXITPIDONE;
 944                 if (tsk->io_context)
 945                         exit_io_context();
 946                 set_current_state(TASK_UNINTERRUPTIBLE);
 947                 schedule();
 948         }
 949
 950         tsk->flags |= PF_EXITING;
 951         /*
 952          * tsk->flags are checked in the futex code to protect against
 953          * an exiting task cleaning up the robust pi futexes.
 954          */
 955         smp_mb();
 956         spin_unlock_wait(&tsk->pi_lock);
 957
 958         if (unlikely(in_atomic()))
 959                 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
 960                                 current->comm, task_pid_nr(current),
 961                                 preempt_count());
 962
 963         acct_update_integrals(tsk);
 964         if (tsk->mm) {
 965                 update_hiwater_rss(tsk->mm);
 966                 update_hiwater_vm(tsk->mm);
 967         }
 968         group_dead = atomic_dec_and_test(&tsk->signal->live);
 969         if (group_dead) {
 970                 exit_child_reaper(tsk);
 971                 hrtimer_cancel(&tsk->signal->real_timer);
 972                 exit_itimers(tsk->signal);
 973         }
 974         acct_collect(code, group_dead);
 975 #ifdef CONFIG_FUTEX
 976         if (unlikely(tsk->robust_list))
 977                 exit_robust_list(tsk);
 978 #ifdef CONFIG_COMPAT
 979         if (unlikely(tsk->compat_robust_list))
 980                 compat_exit_robust_list(tsk);
 981 #endif
 982 #endif
 983         if (group_dead)
 984                 tty_audit_exit();
 985         if (unlikely(tsk->audit_context))
 986                 audit_free(tsk);
 987
 988         tsk->exit_code = code;
 989         taskstats_exit(tsk, group_dead);
 990
 991         exit_mm(tsk);
 992
 993         if (group_dead)
 994                 acct_process();
 995         exit_sem(tsk);
 996         __exit_files(tsk);
 997         __exit_fs(tsk);
 998         check_stack_usage();
 999         exit_thread();
1000         cgroup_exit(tsk, 1);
1001         exit_keys(tsk);
1002
1003         if (group_dead && tsk->signal->leader)
1004                 disassociate_ctty(1);
1005
1006         module_put(task_thread_info(tsk)->exec_domain->module);
1007         if (tsk->binfmt)
1008                 module_put(tsk->binfmt->module);
1009
1010         proc_exit_connector(tsk);
1011         exit_notify(tsk);
1012 #ifdef CONFIG_NUMA
1013         mpol_free(tsk->mempolicy);
1014         tsk->mempolicy = NULL;
1015 #endif
1016 #ifdef CONFIG_FUTEX
1017         /*
1018          * This must happen late, after the PID is not
1019          * hashed anymore:
1020          */
1021         if (unlikely(!list_empty(&tsk->pi_state_list)))
1022                 exit_pi_state_list(tsk);
1023         if (unlikely(current->pi_state_cache))
1024                 kfree(current->pi_state_cache);
1025 #endif
1026         /*
1027          * Make sure we are holding no locks:
1028          */
1029         debug_check_no_locks_held(tsk);
1030         /*
1031          * We can do this unlocked here. The futex code uses this flag
1032          * just to verify whether the pi state cleanup has been done
1033          * or not. In the worst case it loops once more.
1034          */
1035         tsk->flags |= PF_EXITPIDONE;
1036
1037         if (tsk->io_context)
1038                 exit_io_context();
1039
1040         if (tsk->splice_pipe)
1041                 __free_pipe_info(tsk->splice_pipe);
1042
1043         preempt_disable();
1044         /* causes final put_task_struct in finish_task_switch(). */
1045         tsk->state = TASK_DEAD;
1046
1047         schedule();
1048         BUG();
1049         /* Avoid "noreturn function does return".  */
1050         for (;;)
1051                 cpu_relax();    /* For when BUG is null */
1052 }
1053
1054 EXPORT_SYMBOL_GPL(do_exit);
1055
1056 NORET_TYPE void complete_and_exit(struct completion *comp, long code)
1057 {
1058         if (comp)
1059                 complete(comp);
1060
1061         do_exit(code);
1062 }
1063
1064 EXPORT_SYMBOL(complete_and_exit);
1065
1066 asmlinkage long sys_exit(int error_code)
1067 {
1068         do_exit((error_code&0xff)<<8);
1069 }
1070
1071 /*
1072  * Take down every thread in the group.  This is called by fatal signals
1073  * as well as by sys_exit_group (below).
1074  */
1075 NORET_TYPE void
1076 do_group_exit(int exit_code)
1077 {
1078         BUG_ON(exit_code & 0x80); /* core dumps don't get here */
1079
1080         if (current->signal->flags & SIGNAL_GROUP_EXIT)
1081                 exit_code = current->signal->group_exit_code;
1082         else if (!thread_group_empty(current)) {
1083                 struct signal_struct *const sig = current->signal;
1084                 struct sighand_struct *const sighand = current->sighand;
1085                 spin_lock_irq(&sighand->siglock);
1086                 if (signal_group_exit(sig))
1087                         /* Another thread got here before we took the lock.  */
1088                         exit_code = sig->group_exit_code;
1089                 else {
1090                         sig->group_exit_code = exit_code;
1091                         sig->flags = SIGNAL_GROUP_EXIT;
1092                         zap_other_threads(current);
1093                 }
1094                 spin_unlock_irq(&sighand->siglock);
1095         }
1096
1097         do_exit(exit_code);
1098         /* NOTREACHED */
1099 }
1100
1101 /*
1102  * this kills every thread in the thread group. Note that any externally
1103  * wait4()-ing process will get the correct exit code - even if this
1104  * thread is not the thread group leader.
1105  */
1106 asmlinkage void sys_exit_group(int error_code)
1107 {
1108         do_group_exit((error_code & 0xff) << 8);
1109 }
1110
1111 static int eligible_child(pid_t pid, int options, struct task_struct *p)
1112 {
1113         int err;
1114         struct pid_namespace *ns;
1115
1116         ns = current->nsproxy->pid_ns;
1117         if (pid > 0) {
1118                 if (task_pid_nr_ns(p, ns) != pid)
1119                         return 0;
1120         } else if (!pid) {
1121                 if (task_pgrp_nr_ns(p, ns) != task_pgrp_vnr(current))
1122                         return 0;
1123         } else if (pid != -1) {
1124                 if (task_pgrp_nr_ns(p, ns) != -pid)
1125                         return 0;
1126         }
1127
1128         /*
1129          * Do not consider detached threads that are
1130          * not ptraced:
1131          */
1132         if (p->exit_signal == -1 && !p->ptrace)
1133                 return 0;
1134
1135         /* Wait for all children (clone and not) if __WALL is set;
1136          * otherwise, wait for clone children *only* if __WCLONE is
1137          * set; otherwise, wait for non-clone children *only*.  (Note:
1138          * A "clone" child here is one that reports to its parent
1139          * using a signal other than SIGCHLD.) */
1140         if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
1141             && !(options & __WALL))
1142                 return 0;
1143         /*
1144          * Do not consider thread group leaders that are
1145          * in a non-empty thread group:
1146          */
1147         if (delay_group_leader(p))
1148                 return 2;
1149
1150         err = security_task_wait(p);
1151         if (err)
1152                 return err;
1153
1154         return 1;
1155 }
1156
1157 static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,
1158                                int why, int status,
1159                                struct siginfo __user *infop,
1160                                struct rusage __user *rusagep)
1161 {
1162         int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
1163
1164         put_task_struct(p);
1165         if (!retval)
1166                 retval = put_user(SIGCHLD, &infop->si_signo);
1167         if (!retval)
1168                 retval = put_user(0, &infop->si_errno);
1169         if (!retval)
1170                 retval = put_user((short)why, &infop->si_code);
1171         if (!retval)
1172                 retval = put_user(pid, &infop->si_pid);
1173         if (!retval)
1174                 retval = put_user(uid, &infop->si_uid);
1175         if (!retval)
1176                 retval = put_user(status, &infop->si_status);
1177         if (!retval)
1178                 retval = pid;
1179         return retval;
1180 }
1181
1182 /*
1183  * Handle sys_wait4 work for one task in state EXIT_ZOMBIE.  We hold
1184  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1185  * the lock and this task is uninteresting.  If we return nonzero, we have
1186  * released the lock and the system call should return.
1187  */
1188 static int wait_task_zombie(struct task_struct *p, int noreap,
1189                             struct siginfo __user *infop,
1190                             int __user *stat_addr, struct rusage __user *ru)
1191 {
1192         unsigned long state;
1193         int retval, status, traced;
1194         struct pid_namespace *ns;
1195
1196         ns = current->nsproxy->pid_ns;
1197
1198         if (unlikely(noreap)) {
1199                 pid_t pid = task_pid_nr_ns(p, ns);
1200                 uid_t uid = p->uid;
1201                 int exit_code = p->exit_code;
1202                 int why, status;
1203
1204                 if (unlikely(p->exit_state != EXIT_ZOMBIE))
1205                         return 0;
1206                 if (unlikely(p->exit_signal == -1 && p->ptrace == 0))
1207                         return 0;
1208                 get_task_struct(p);
1209                 read_unlock(&tasklist_lock);
1210                 if ((exit_code & 0x7f) == 0) {
1211                         why = CLD_EXITED;
1212                         status = exit_code >> 8;
1213                 } else {
1214                         why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1215                         status = exit_code & 0x7f;
1216                 }
1217                 return wait_noreap_copyout(p, pid, uid, why,
1218                                            status, infop, ru);
1219         }
1220
1221         /*
1222          * Try to move the task's state to DEAD
1223          * only one thread is allowed to do this:
1224          */
1225         state = xchg(&p->exit_state, EXIT_DEAD);
1226         if (state != EXIT_ZOMBIE) {
1227                 BUG_ON(state != EXIT_DEAD);
1228                 return 0;
1229         }
1230
1231         /* traced means p->ptrace, but not vice versa */
1232         traced = (p->real_parent != p->parent);
1233
1234         if (likely(!traced)) {
1235                 struct signal_struct *psig;
1236                 struct signal_struct *sig;
1237
1238                 /*
1239                  * The resource counters for the group leader are in its
1240                  * own task_struct.  Those for dead threads in the group
1241                  * are in its signal_struct, as are those for the child
1242                  * processes it has previously reaped.  All these
1243                  * accumulate in the parent's signal_struct c* fields.
1244                  *
1245                  * We don't bother to take a lock here to protect these
1246                  * p->signal fields, because they are only touched by
1247                  * __exit_signal, which runs with tasklist_lock
1248                  * write-locked anyway, and so is excluded here.  We do
1249                  * need to protect the access to p->parent->signal fields,
1250                  * as other threads in the parent group can be right
1251                  * here reaping other children at the same time.
1252                  */
1253                 spin_lock_irq(&p->parent->sighand->siglock);
1254                 psig = p->parent->signal;
1255                 sig = p->signal;
1256                 psig->cutime =
1257                         cputime_add(psig->cutime,
1258                         cputime_add(p->utime,
1259                         cputime_add(sig->utime,
1260                                     sig->cutime)));
1261                 psig->cstime =
1262                         cputime_add(psig->cstime,
1263                         cputime_add(p->stime,
1264                         cputime_add(sig->stime,
1265                                     sig->cstime)));
1266                 psig->cgtime =
1267                         cputime_add(psig->cgtime,
1268                         cputime_add(p->gtime,
1269                         cputime_add(sig->gtime,
1270                                     sig->cgtime)));
1271                 psig->cmin_flt +=
1272                         p->min_flt + sig->min_flt + sig->cmin_flt;
1273                 psig->cmaj_flt +=
1274                         p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1275                 psig->cnvcsw +=
1276                         p->nvcsw + sig->nvcsw + sig->cnvcsw;
1277                 psig->cnivcsw +=
1278                         p->nivcsw + sig->nivcsw + sig->cnivcsw;
1279                 psig->cinblock +=
1280                         task_io_get_inblock(p) +
1281                         sig->inblock + sig->cinblock;
1282                 psig->coublock +=
1283                         task_io_get_oublock(p) +
1284                         sig->oublock + sig->coublock;
1285                 spin_unlock_irq(&p->parent->sighand->siglock);
1286         }
1287
1288         /*
1289          * Now we are sure this task is interesting, and no other
1290          * thread can reap it because we set its state to EXIT_DEAD.
1291          */
1292         read_unlock(&tasklist_lock);
1293
1294         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1295         status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1296                 ? p->signal->group_exit_code : p->exit_code;
1297         if (!retval && stat_addr)
1298                 retval = put_user(status, stat_addr);
1299         if (!retval && infop)
1300                 retval = put_user(SIGCHLD, &infop->si_signo);
1301         if (!retval && infop)
1302                 retval = put_user(0, &infop->si_errno);
1303         if (!retval && infop) {
1304                 int why;
1305
1306                 if ((status & 0x7f) == 0) {
1307                         why = CLD_EXITED;
1308                         status >>= 8;
1309                 } else {
1310                         why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1311                         status &= 0x7f;
1312                 }
1313                 retval = put_user((short)why, &infop->si_code);
1314                 if (!retval)
1315                         retval = put_user(status, &infop->si_status);
1316         }
1317         if (!retval && infop)
1318                 retval = put_user(task_pid_nr_ns(p, ns), &infop->si_pid);
1319         if (!retval && infop)
1320                 retval = put_user(p->uid, &infop->si_uid);
1321         if (!retval)
1322                 retval = task_pid_nr_ns(p, ns);
1323
1324         if (traced) {
1325                 write_lock_irq(&tasklist_lock);
1326                 /* We dropped tasklist, ptracer could die and untrace */
1327                 ptrace_unlink(p);
1328                 /*
1329                  * If this is not a detached task, notify the parent.
1330                  * If it's still not detached after that, don't release
1331                  * it now.
1332                  */
1333                 if (p->exit_signal != -1) {
1334                         do_notify_parent(p, p->exit_signal);
1335                         if (p->exit_signal != -1) {
1336                                 p->exit_state = EXIT_ZOMBIE;
1337                                 p = NULL;
1338                         }
1339                 }
1340                 write_unlock_irq(&tasklist_lock);
1341         }
1342         if (p != NULL)
1343                 release_task(p);
1344
1345         return retval;
1346 }
1347
1348 /*
1349  * Handle sys_wait4 work for one task in state TASK_STOPPED.  We hold
1350  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1351  * the lock and this task is uninteresting.  If we return nonzero, we have
1352  * released the lock and the system call should return.
1353  */
1354 static int wait_task_stopped(struct task_struct *p, int delayed_group_leader,
1355                              int noreap, struct siginfo __user *infop,
1356                              int __user *stat_addr, struct rusage __user *ru)
1357 {
1358         int retval, exit_code;
1359         pid_t pid;
1360
1361         if (!p->exit_code)
1362                 return 0;
1363         if (delayed_group_leader && !(p->ptrace & PT_PTRACED) &&
1364             p->signal->group_stop_count > 0)
1365                 /*
1366                  * A group stop is in progress and this is the group leader.
1367                  * We won't report until all threads have stopped.
1368                  */
1369                 return 0;
1370
1371         /*
1372          * Now we are pretty sure this task is interesting.
1373          * Make sure it doesn't get reaped out from under us while we
1374          * give up the lock and then examine it below.  We don't want to
1375          * keep holding onto the tasklist_lock while we call getrusage and
1376          * possibly take page faults for user memory.
1377          */
1378         pid = task_pid_nr_ns(p, current->nsproxy->pid_ns);
1379         get_task_struct(p);
1380         read_unlock(&tasklist_lock);
1381
1382         if (unlikely(noreap)) {
1383                 uid_t uid = p->uid;
1384                 int why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
1385
1386                 exit_code = p->exit_code;
1387                 if (unlikely(!exit_code) || unlikely(p->exit_state))
1388                         goto bail_ref;
1389                 return wait_noreap_copyout(p, pid, uid,
1390                                            why, exit_code,
1391                                            infop, ru);
1392         }
1393
1394         write_lock_irq(&tasklist_lock);
1395
1396         /*
1397          * This uses xchg to be atomic with the thread resuming and setting
1398          * it.  It must also be done with the write lock held to prevent a
1399          * race with the EXIT_ZOMBIE case.
1400          */
1401         exit_code = xchg(&p->exit_code, 0);
1402         if (unlikely(p->exit_state)) {
1403                 /*
1404                  * The task resumed and then died.  Let the next iteration
1405                  * catch it in EXIT_ZOMBIE.  Note that exit_code might
1406                  * already be zero here if it resumed and did _exit(0).
1407                  * The task itself is dead and won't touch exit_code again;
1408                  * other processors in this function are locked out.
1409                  */
1410                 p->exit_code = exit_code;
1411                 exit_code = 0;
1412         }
1413         if (unlikely(exit_code == 0)) {
1414                 /*
1415                  * Another thread in this function got to it first, or it
1416                  * resumed, or it resumed and then died.
1417                  */
1418                 write_unlock_irq(&tasklist_lock);
1419 bail_ref:
1420                 put_task_struct(p);
1421                 /*
1422                  * We are returning to the wait loop without having successfully
1423                  * removed the process and having released the lock. We cannot
1424                  * continue, since the "p" task pointer is potentially stale.
1425                  *
1426                  * Return -EAGAIN, and do_wait() will restart the loop from the
1427                  * beginning. Do _not_ re-acquire the lock.
1428                  */
1429                 return -EAGAIN;
1430         }
1431
1432         /* move to end of parent's list to avoid starvation */
1433         remove_parent(p);
1434         add_parent(p);
1435
1436         write_unlock_irq(&tasklist_lock);
1437
1438         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1439         if (!retval && stat_addr)
1440                 retval = put_user((exit_code << 8) | 0x7f, stat_addr);
1441         if (!retval && infop)
1442                 retval = put_user(SIGCHLD, &infop->si_signo);
1443         if (!retval && infop)
1444                 retval = put_user(0, &infop->si_errno);
1445         if (!retval && infop)
1446                 retval = put_user((short)((p->ptrace & PT_PTRACED)
1447                                           ? CLD_TRAPPED : CLD_STOPPED),
1448                                   &infop->si_code);
1449         if (!retval && infop)
1450                 retval = put_user(exit_code, &infop->si_status);
1451         if (!retval && infop)
1452                 retval = put_user(pid, &infop->si_pid);
1453         if (!retval && infop)
1454                 retval = put_user(p->uid, &infop->si_uid);
1455         if (!retval)
1456                 retval = pid;
1457         put_task_struct(p);
1458
1459         BUG_ON(!retval);
1460         return retval;
1461 }
1462
1463 /*
1464  * Handle do_wait work for one task in a live, non-stopped state.
1465  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1466  * the lock and this task is uninteresting.  If we return nonzero, we have
1467  * released the lock and the system call should return.
1468  */
1469 static int wait_task_continued(struct task_struct *p, int noreap,
1470                                struct siginfo __user *infop,
1471                                int __user *stat_addr, struct rusage __user *ru)
1472 {
1473         int retval;
1474         pid_t pid;
1475         uid_t uid;
1476         struct pid_namespace *ns;
1477
1478         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1479                 return 0;
1480
1481         spin_lock_irq(&p->sighand->siglock);
1482         /* Re-check with the lock held.  */
1483         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1484                 spin_unlock_irq(&p->sighand->siglock);
1485                 return 0;
1486         }
1487         if (!noreap)
1488                 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1489         spin_unlock_irq(&p->sighand->siglock);
1490
1491         ns = current->nsproxy->pid_ns;
1492         pid = task_pid_nr_ns(p, ns);
1493         uid = p->uid;
1494         get_task_struct(p);
1495         read_unlock(&tasklist_lock);
1496
1497         if (!infop) {
1498                 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1499                 put_task_struct(p);
1500                 if (!retval && stat_addr)
1501                         retval = put_user(0xffff, stat_addr);
1502                 if (!retval)
1503                         retval = task_pid_nr_ns(p, ns);
1504         } else {
1505                 retval = wait_noreap_copyout(p, pid, uid,
1506                                              CLD_CONTINUED, SIGCONT,
1507                                              infop, ru);
1508                 BUG_ON(retval == 0);
1509         }
1510
1511         return retval;
1512 }
1513
1514
1515 static inline int my_ptrace_child(struct task_struct *p)
1516 {
1517         if (!(p->ptrace & PT_PTRACED))
1518                 return 0;
1519         if (!(p->ptrace & PT_ATTACHED))
1520                 return 1;
1521         /*
1522          * This child was PTRACE_ATTACH'd.  We should be seeing it only if
1523          * we are the attacher.  If we are the real parent, this is a race
1524          * inside ptrace_attach.  It is waiting for the tasklist_lock,
1525          * which we have to switch the parent links, but has already set
1526          * the flags in p->ptrace.
1527          */
1528         return (p->parent != p->real_parent);
1529 }
1530
1531 static long do_wait(pid_t pid, int options, struct siginfo __user *infop,
1532                     int __user *stat_addr, struct rusage __user *ru)
1533 {
1534         DECLARE_WAITQUEUE(wait, current);
1535         struct task_struct *tsk;
1536         int flag, retval;
1537         int allowed, denied;
1538
1539         add_wait_queue(&current->signal->wait_chldexit,&wait);
1540 repeat:
1541         /*
1542          * We will set this flag if we see any child that might later
1543          * match our criteria, even if we are not able to reap it yet.
1544          */
1545         flag = 0;
1546         allowed = denied = 0;
1547         current->state = TASK_INTERRUPTIBLE;
1548         read_lock(&tasklist_lock);
1549         tsk = current;
1550         do {
1551                 struct task_struct *p;
1552                 int ret;
1553
1554                 list_for_each_entry(p, &tsk->children, sibling) {
1555                         ret = eligible_child(pid, options, p);
1556                         if (!ret)
1557                                 continue;
1558
1559                         if (unlikely(ret < 0)) {
1560                                 denied = ret;
1561                                 continue;
1562                         }
1563                         allowed = 1;
1564
1565                         if (task_is_stopped_or_traced(p)) {
1566                                 /*
1567                                  * It's stopped now, so it might later
1568                                  * continue, exit, or stop again.
1569                                  *
1570                                  * When we hit the race with PTRACE_ATTACH, we
1571                                  * will not report this child.  But the race
1572                                  * means it has not yet been moved to our
1573                                  * ptrace_children list, so we need to set the
1574                                  * flag here to avoid a spurious ECHILD when
1575                                  * the race happens with the only child.
1576                                  */
1577                                 flag = 1;
1578
1579                                 if (!my_ptrace_child(p)) {
1580                                         if (task_is_traced(p))
1581                                                 continue;
1582                                         if (!(options & WUNTRACED))
1583                                                 continue;
1584                                 }
1585
1586                                 retval = wait_task_stopped(p, ret == 2,
1587                                                 (options & WNOWAIT), infop,
1588                                                 stat_addr, ru);
1589                                 if (retval == -EAGAIN)
1590                                         goto repeat;
1591                                 if (retval != 0) /* He released the lock.  */
1592                                         goto end;
1593                         } else if (p->exit_state == EXIT_ZOMBIE) {
1594                                 /*
1595                                  * Eligible but we cannot release it yet:
1596                                  */
1597                                 if (ret == 2)
1598                                         goto check_continued;
1599                                 if (!likely(options & WEXITED))
1600                                         continue;
1601                                 retval = wait_task_zombie(p,
1602                                                 (options & WNOWAIT), infop,
1603                                                 stat_addr, ru);
1604                                 /* He released the lock.  */
1605                                 if (retval != 0)
1606                                         goto end;
1607                         } else if (p->exit_state != EXIT_DEAD) {
1608 check_continued:
1609                                 /*
1610                                  * It's running now, so it might later
1611                                  * exit, stop, or stop and then continue.
1612                                  */
1613                                 flag = 1;
1614                                 if (!unlikely(options & WCONTINUED))
1615                                         continue;
1616                                 retval = wait_task_continued(p,
1617                                                 (options & WNOWAIT), infop,
1618                                                 stat_addr, ru);
1619                                 if (retval != 0) /* He released the lock.  */
1620                                         goto end;
1621                         }
1622                 }
1623                 if (!flag) {
1624                         list_for_each_entry(p, &tsk->ptrace_children,
1625                                             ptrace_list) {
1626                                 if (!eligible_child(pid, options, p))
1627                                         continue;
1628                                 flag = 1;
1629                                 break;
1630                         }
1631                 }
1632                 if (options & __WNOTHREAD)
1633                         break;
1634                 tsk = next_thread(tsk);
1635                 BUG_ON(tsk->signal != current->signal);
1636         } while (tsk != current);
1637
1638         read_unlock(&tasklist_lock);
1639         if (flag) {
1640                 retval = 0;
1641                 if (options & WNOHANG)
1642                         goto end;
1643                 retval = -ERESTARTSYS;
1644                 if (signal_pending(current))
1645                         goto end;
1646                 schedule();
1647                 goto repeat;
1648         }
1649         retval = -ECHILD;
1650         if (unlikely(denied) && !allowed)
1651                 retval = denied;
1652 end:
1653         current->state = TASK_RUNNING;
1654         remove_wait_queue(&current->signal->wait_chldexit,&wait);
1655         if (infop) {
1656                 if (retval > 0)
1657                 retval = 0;
1658                 else {
1659                         /*
1660                          * For a WNOHANG return, clear out all the fields
1661                          * we would set so the user can easily tell the
1662                          * difference.
1663                          */
1664                         if (!retval)
1665                                 retval = put_user(0, &infop->si_signo);
1666                         if (!retval)
1667                                 retval = put_user(0, &infop->si_errno);
1668                         if (!retval)
1669                                 retval = put_user(0, &infop->si_code);
1670                         if (!retval)
1671                                 retval = put_user(0, &infop->si_pid);
1672                         if (!retval)
1673                                 retval = put_user(0, &infop->si_uid);
1674                         if (!retval)
1675                                 retval = put_user(0, &infop->si_status);
1676                 }
1677         }
1678         return retval;
1679 }
1680
1681 asmlinkage long sys_waitid(int which, pid_t pid,
1682                            struct siginfo __user *infop, int options,
1683                            struct rusage __user *ru)
1684 {
1685         long ret;
1686
1687         if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1688                 return -EINVAL;
1689         if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1690                 return -EINVAL;
1691
1692         switch (which) {
1693         case P_ALL:
1694                 pid = -1;
1695                 break;
1696         case P_PID:
1697                 if (pid <= 0)
1698                         return -EINVAL;
1699                 break;
1700         case P_PGID:
1701                 if (pid <= 0)
1702                         return -EINVAL;
1703                 pid = -pid;
1704                 break;
1705         default:
1706                 return -EINVAL;
1707         }
1708
1709         ret = do_wait(pid, options, infop, NULL, ru);
1710
1711         /* avoid REGPARM breakage on x86: */
1712         prevent_tail_call(ret);
1713         return ret;
1714 }
1715
1716 asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr,
1717                           int options, struct rusage __user *ru)
1718 {
1719         long ret;
1720
1721         if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1722                         __WNOTHREAD|__WCLONE|__WALL))
1723                 return -EINVAL;
1724         ret = do_wait(pid, options | WEXITED, NULL, stat_addr, ru);
1725
1726         /* avoid REGPARM breakage on x86: */
1727         prevent_tail_call(ret);
1728         return ret;
1729 }
1730
1731 #ifdef __ARCH_WANT_SYS_WAITPID
1732
1733 /*
1734  * sys_waitpid() remains for compatibility. waitpid() should be
1735  * implemented by calling sys_wait4() from libc.a.
1736  */
1737 asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options)
1738 {
1739         return sys_wait4(pid, stat_addr, options, NULL);
1740 }
1741
1742 #endif