kernel/exit.c

   1 /*
   2  *  linux/kernel/exit.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 #include <linux/mm.h>
   8 #include <linux/slab.h>
   9 #include <linux/interrupt.h>
  10 #include <linux/smp_lock.h>
  11 #include <linux/module.h>
  12 #include <linux/capability.h>
  13 #include <linux/completion.h>
  14 #include <linux/personality.h>
  15 #include <linux/tty.h>
  16 #include <linux/mnt_namespace.h>
  17 #include <linux/key.h>
  18 #include <linux/security.h>
  19 #include <linux/cpu.h>
  20 #include <linux/acct.h>
  21 #include <linux/tsacct_kern.h>
  22 #include <linux/file.h>
  23 #include <linux/binfmts.h>
  24 #include <linux/nsproxy.h>
  25 #include <linux/pid_namespace.h>
  26 #include <linux/ptrace.h>
  27 #include <linux/profile.h>
  28 #include <linux/mount.h>
  29 #include <linux/proc_fs.h>
  30 #include <linux/mempolicy.h>
  31 #include <linux/taskstats_kern.h>
  32 #include <linux/delayacct.h>
  33 #include <linux/cpuset.h>
  34 #include <linux/syscalls.h>
  35 #include <linux/signal.h>
  36 #include <linux/posix-timers.h>
  37 #include <linux/cn_proc.h>
  38 #include <linux/mutex.h>
  39 #include <linux/futex.h>
  40 #include <linux/compat.h>
  41 #include <linux/pipe_fs_i.h>
  42 #include <linux/audit.h> /* for audit_free() */
  43 #include <linux/resource.h>
  44 #include <linux/blkdev.h>
  45
  46 #include <asm/uaccess.h>
  47 #include <asm/unistd.h>
  48 #include <asm/pgtable.h>
  49 #include <asm/mmu_context.h>
  50
  51 extern void sem_exit (void);
  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                         sig->group_exit_task = NULL;
  96                 }
  97                 if (tsk == sig->curr_target)
  98                         sig->curr_target = next_thread(tsk);
  99                 /*
 100                  * Accumulate here the counters for all threads but the
 101                  * group leader as they die, so they can be added into
 102                  * the process-wide totals when those are taken.
 103                  * The group leader stays around as a zombie as long
 104                  * as there are other threads.  When it gets reaped,
 105                  * the exit.c code will add its counts into these totals.
 106                  * We won't ever get here for the group leader, since it
 107                  * will have been the last reference on the signal_struct.
 108                  */
 109                 sig->utime = cputime_add(sig->utime, tsk->utime);
 110                 sig->stime = cputime_add(sig->stime, tsk->stime);
 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->sched_time += tsk->sched_time;
 116                 sig = NULL; /* Marker for below. */
 117         }
 118
 119         __unhash_process(tsk);
 120
 121         tsk->signal = NULL;
 122         tsk->sighand = NULL;
 123         spin_unlock(&sighand->siglock);
 124         rcu_read_unlock();
 125
 126         __cleanup_sighand(sighand);
 127         clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
 128         flush_sigqueue(&tsk->pending);
 129         if (sig) {
 130                 flush_sigqueue(&sig->shared_pending);
 131                 taskstats_tgid_free(sig);
 132                 __cleanup_signal(sig);
 133         }
 134 }
 135
 136 static void delayed_put_task_struct(struct rcu_head *rhp)
 137 {
 138         put_task_struct(container_of(rhp, struct task_struct, rcu));
 139 }
 140
 141 void release_task(struct task_struct * p)
 142 {
 143         struct task_struct *leader;
 144         int zap_leader;
 145 repeat:
 146         atomic_dec(&p->user->processes);
 147         write_lock_irq(&tasklist_lock);
 148         ptrace_unlink(p);
 149         BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
 150         __exit_signal(p);
 151
 152         /*
 153          * If we are the last non-leader member of the thread
 154          * group, and the leader is zombie, then notify the
 155          * group leader's parent process. (if it wants notification.)
 156          */
 157         zap_leader = 0;
 158         leader = p->group_leader;
 159         if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
 160                 BUG_ON(leader->exit_signal == -1);
 161                 do_notify_parent(leader, leader->exit_signal);
 162                 /*
 163                  * If we were the last child thread and the leader has
 164                  * exited already, and the leader's parent ignores SIGCHLD,
 165                  * then we are the one who should release the leader.
 166                  *
 167                  * do_notify_parent() will have marked it self-reaping in
 168                  * that case.
 169                  */
 170                 zap_leader = (leader->exit_signal == -1);
 171         }
 172
 173         sched_exit(p);
 174         write_unlock_irq(&tasklist_lock);
 175         proc_flush_task(p);
 176         release_thread(p);
 177         call_rcu(&p->rcu, delayed_put_task_struct);
 178
 179         p = leader;
 180         if (unlikely(zap_leader))
 181                 goto repeat;
 182 }
 183
 184 /*
 185  * This checks not only the pgrp, but falls back on the pid if no
 186  * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
 187  * without this...
 188  */
 189 int session_of_pgrp(int pgrp)
 190 {
 191         struct task_struct *p;
 192         int sid = 0;
 193
 194         read_lock(&tasklist_lock);
 195
 196         p = find_task_by_pid_type(PIDTYPE_PGID, pgrp);
 197         if (p == NULL)
 198                 p = find_task_by_pid(pgrp);
 199         if (p != NULL)
 200                 sid = process_session(p);
 201
 202         read_unlock(&tasklist_lock);
 203
 204         return sid;
 205 }
 206
 207 /*
 208  * Determine if a process group is "orphaned", according to the POSIX
 209  * definition in 2.2.2.52.  Orphaned process groups are not to be affected
 210  * by terminal-generated stop signals.  Newly orphaned process groups are
 211  * to receive a SIGHUP and a SIGCONT.
 212  *
 213  * "I ask you, have you ever known what it is to be an orphan?"
 214  */
 215 static int will_become_orphaned_pgrp(int pgrp, struct task_struct *ignored_task)
 216 {
 217         struct task_struct *p;
 218         int ret = 1;
 219
 220         do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
 221                 if (p == ignored_task
 222                                 || p->exit_state
 223                                 || is_init(p->real_parent))
 224                         continue;
 225                 if (process_group(p->real_parent) != pgrp &&
 226                     process_session(p->real_parent) == process_session(p)) {
 227                         ret = 0;
 228                         break;
 229                 }
 230         } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
 231         return ret;     /* (sighing) "Often!" */
 232 }
 233
 234 int is_orphaned_pgrp(int pgrp)
 235 {
 236         int retval;
 237
 238         read_lock(&tasklist_lock);
 239         retval = will_become_orphaned_pgrp(pgrp, NULL);
 240         read_unlock(&tasklist_lock);
 241
 242         return retval;
 243 }
 244
 245 static int has_stopped_jobs(int pgrp)
 246 {
 247         int retval = 0;
 248         struct task_struct *p;
 249
 250         do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
 251                 if (p->state != TASK_STOPPED)
 252                         continue;
 253                 retval = 1;
 254                 break;
 255         } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
 256         return retval;
 257 }
 258
 259 /**
 260  * reparent_to_init - Reparent the calling kernel thread to the init task
 261  * of the pid space that the thread belongs to.
 262  *
 263  * If a kernel thread is launched as a result of a system call, or if
 264  * it ever exits, it should generally reparent itself to init so that
 265  * it is correctly cleaned up on exit.
 266  *
 267  * The various task state such as scheduling policy and priority may have
 268  * been inherited from a user process, so we reset them to sane values here.
 269  *
 270  * NOTE that reparent_to_init() gives the caller full capabilities.
 271  */
 272 static void reparent_to_init(void)
 273 {
 274         write_lock_irq(&tasklist_lock);
 275
 276         ptrace_unlink(current);
 277         /* Reparent to init */
 278         remove_parent(current);
 279         current->parent = child_reaper(current);
 280         current->real_parent = child_reaper(current);
 281         add_parent(current);
 282
 283         /* Set the exit signal to SIGCHLD so we signal init on exit */
 284         current->exit_signal = SIGCHLD;
 285
 286         if (!has_rt_policy(current) && (task_nice(current) < 0))
 287                 set_user_nice(current, 0);
 288         /* cpus_allowed? */
 289         /* rt_priority? */
 290         /* signals? */
 291         security_task_reparent_to_init(current);
 292         memcpy(current->signal->rlim, init_task.signal->rlim,
 293                sizeof(current->signal->rlim));
 294         atomic_inc(&(INIT_USER->__count));
 295         write_unlock_irq(&tasklist_lock);
 296         switch_uid(INIT_USER);
 297 }
 298
 299 void __set_special_pids(pid_t session, pid_t pgrp)
 300 {
 301         struct task_struct *curr = current->group_leader;
 302
 303         if (process_session(curr) != session) {
 304                 detach_pid(curr, PIDTYPE_SID);
 305                 set_signal_session(curr->signal, session);
 306                 attach_pid(curr, PIDTYPE_SID, session);
 307         }
 308         if (process_group(curr) != pgrp) {
 309                 detach_pid(curr, PIDTYPE_PGID);
 310                 curr->signal->pgrp = pgrp;
 311                 attach_pid(curr, PIDTYPE_PGID, pgrp);
 312         }
 313 }
 314
 315 static void set_special_pids(pid_t session, pid_t pgrp)
 316 {
 317         write_lock_irq(&tasklist_lock);
 318         __set_special_pids(session, pgrp);
 319         write_unlock_irq(&tasklist_lock);
 320 }
 321
 322 /*
 323  * Let kernel threads use this to say that they
 324  * allow a certain signal (since daemonize() will
 325  * have disabled all of them by default).
 326  */
 327 int allow_signal(int sig)
 328 {
 329         if (!valid_signal(sig) || sig < 1)
 330                 return -EINVAL;
 331
 332         spin_lock_irq(&current->sighand->siglock);
 333         sigdelset(&current->blocked, sig);
 334         if (!current->mm) {
 335                 /* Kernel threads handle their own signals.
 336                    Let the signal code know it'll be handled, so
 337                    that they don't get converted to SIGKILL or
 338                    just silently dropped */
 339                 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
 340         }
 341         recalc_sigpending();
 342         spin_unlock_irq(&current->sighand->siglock);
 343         return 0;
 344 }
 345
 346 EXPORT_SYMBOL(allow_signal);
 347
 348 int disallow_signal(int sig)
 349 {
 350         if (!valid_signal(sig) || sig < 1)
 351                 return -EINVAL;
 352
 353         spin_lock_irq(&current->sighand->siglock);
 354         sigaddset(&current->blocked, sig);
 355         recalc_sigpending();
 356         spin_unlock_irq(&current->sighand->siglock);
 357         return 0;
 358 }
 359
 360 EXPORT_SYMBOL(disallow_signal);
 361
 362 /*
 363  *      Put all the gunge required to become a kernel thread without
 364  *      attached user resources in one place where it belongs.
 365  */
 366
 367 void daemonize(const char *name, ...)
 368 {
 369         va_list args;
 370         struct fs_struct *fs;
 371         sigset_t blocked;
 372
 373         va_start(args, name);
 374         vsnprintf(current->comm, sizeof(current->comm), name, args);
 375         va_end(args);
 376
 377         /*
 378          * If we were started as result of loading a module, close all of the
 379          * user space pages.  We don't need them, and if we didn't close them
 380          * they would be locked into memory.
 381          */
 382         exit_mm(current);
 383
 384         set_special_pids(1, 1);
 385         proc_clear_tty(current);
 386
 387         /* Block and flush all signals */
 388         sigfillset(&blocked);
 389         sigprocmask(SIG_BLOCK, &blocked, NULL);
 390         flush_signals(current);
 391
 392         /* Become as one with the init task */
 393
 394         exit_fs(current);       /* current->fs->count--; */
 395         fs = init_task.fs;
 396         current->fs = fs;
 397         atomic_inc(&fs->count);
 398
 399         exit_task_namespaces(current);
 400         current->nsproxy = init_task.nsproxy;
 401         get_task_namespaces(current);
 402
 403         exit_files(current);
 404         current->files = init_task.files;
 405         atomic_inc(&current->files->count);
 406
 407         reparent_to_init();
 408 }
 409
 410 EXPORT_SYMBOL(daemonize);
 411
 412 static void close_files(struct files_struct * files)
 413 {
 414         int i, j;
 415         struct fdtable *fdt;
 416
 417         j = 0;
 418
 419         /*
 420          * It is safe to dereference the fd table without RCU or
 421          * ->file_lock because this is the last reference to the
 422          * files structure.
 423          */
 424         fdt = files_fdtable(files);
 425         for (;;) {
 426                 unsigned long set;
 427                 i = j * __NFDBITS;
 428                 if (i >= fdt->max_fds)
 429                         break;
 430                 set = fdt->open_fds->fds_bits[j++];
 431                 while (set) {
 432                         if (set & 1) {
 433                                 struct file * file = xchg(&fdt->fd[i], NULL);
 434                                 if (file)
 435                                         filp_close(file, files);
 436                         }
 437                         i++;
 438                         set >>= 1;
 439                 }
 440         }
 441 }
 442
 443 struct files_struct *get_files_struct(struct task_struct *task)
 444 {
 445         struct files_struct *files;
 446
 447         task_lock(task);
 448         files = task->files;
 449         if (files)
 450                 atomic_inc(&files->count);
 451         task_unlock(task);
 452
 453         return files;
 454 }
 455
 456 void fastcall put_files_struct(struct files_struct *files)
 457 {
 458         struct fdtable *fdt;
 459
 460         if (atomic_dec_and_test(&files->count)) {
 461                 close_files(files);
 462                 /*
 463                  * Free the fd and fdset arrays if we expanded them.
 464                  * If the fdtable was embedded, pass files for freeing
 465                  * at the end of the RCU grace period. Otherwise,
 466                  * you can free files immediately.
 467                  */
 468                 fdt = files_fdtable(files);
 469                 if (fdt != &files->fdtab)
 470                         kmem_cache_free(files_cachep, files);
 471                 free_fdtable(fdt);
 472         }
 473 }
 474
 475 EXPORT_SYMBOL(put_files_struct);
 476
 477 void reset_files_struct(struct task_struct *tsk, struct files_struct *files)
 478 {
 479         struct files_struct *old;
 480
 481         old = tsk->files;
 482         task_lock(tsk);
 483         tsk->files = files;
 484         task_unlock(tsk);
 485         put_files_struct(old);
 486 }
 487 EXPORT_SYMBOL(reset_files_struct);
 488
 489 static inline void __exit_files(struct task_struct *tsk)
 490 {
 491         struct files_struct * files = tsk->files;
 492
 493         if (files) {
 494                 task_lock(tsk);
 495                 tsk->files = NULL;
 496                 task_unlock(tsk);
 497                 put_files_struct(files);
 498         }
 499 }
 500
 501 void exit_files(struct task_struct *tsk)
 502 {
 503         __exit_files(tsk);
 504 }
 505
 506 static inline void __put_fs_struct(struct fs_struct *fs)
 507 {
 508         /* No need to hold fs->lock if we are killing it */
 509         if (atomic_dec_and_test(&fs->count)) {
 510                 dput(fs->root);
 511                 mntput(fs->rootmnt);
 512                 dput(fs->pwd);
 513                 mntput(fs->pwdmnt);
 514                 if (fs->altroot) {
 515                         dput(fs->altroot);
 516                         mntput(fs->altrootmnt);
 517                 }
 518                 kmem_cache_free(fs_cachep, fs);
 519         }
 520 }
 521
 522 void put_fs_struct(struct fs_struct *fs)
 523 {
 524         __put_fs_struct(fs);
 525 }
 526
 527 static inline void __exit_fs(struct task_struct *tsk)
 528 {
 529         struct fs_struct * fs = tsk->fs;
 530
 531         if (fs) {
 532                 task_lock(tsk);
 533                 tsk->fs = NULL;
 534                 task_unlock(tsk);
 535                 __put_fs_struct(fs);
 536         }
 537 }
 538
 539 void exit_fs(struct task_struct *tsk)
 540 {
 541         __exit_fs(tsk);
 542 }
 543
 544 EXPORT_SYMBOL_GPL(exit_fs);
 545
 546 /*
 547  * Turn us into a lazy TLB process if we
 548  * aren't already..
 549  */
 550 static void exit_mm(struct task_struct * tsk)
 551 {
 552         struct mm_struct *mm = tsk->mm;
 553
 554         mm_release(tsk, mm);
 555         if (!mm)
 556                 return;
 557         /*
 558          * Serialize with any possible pending coredump.
 559          * We must hold mmap_sem around checking core_waiters
 560          * and clearing tsk->mm.  The core-inducing thread
 561          * will increment core_waiters for each thread in the
 562          * group with ->mm != NULL.
 563          */
 564         down_read(&mm->mmap_sem);
 565         if (mm->core_waiters) {
 566                 up_read(&mm->mmap_sem);
 567                 down_write(&mm->mmap_sem);
 568                 if (!--mm->core_waiters)
 569                         complete(mm->core_startup_done);
 570                 up_write(&mm->mmap_sem);
 571
 572                 wait_for_completion(&mm->core_done);
 573                 down_read(&mm->mmap_sem);
 574         }
 575         atomic_inc(&mm->mm_count);
 576         BUG_ON(mm != tsk->active_mm);
 577         /* more a memory barrier than a real lock */
 578         task_lock(tsk);
 579         tsk->mm = NULL;
 580         up_read(&mm->mmap_sem);
 581         enter_lazy_tlb(mm, current);
 582         task_unlock(tsk);
 583         mmput(mm);
 584 }
 585
 586 static inline void
 587 choose_new_parent(struct task_struct *p, struct task_struct *reaper)
 588 {
 589         /*
 590          * Make sure we're not reparenting to ourselves and that
 591          * the parent is not a zombie.
 592          */
 593         BUG_ON(p == reaper || reaper->exit_state);
 594         p->real_parent = reaper;
 595 }
 596
 597 static void
 598 reparent_thread(struct task_struct *p, struct task_struct *father, int traced)
 599 {
 600         if (p->pdeath_signal)
 601                 /* We already hold the tasklist_lock here.  */
 602                 group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);
 603
 604         /* Move the child from its dying parent to the new one.  */
 605         if (unlikely(traced)) {
 606                 /* Preserve ptrace links if someone else is tracing this child.  */
 607                 list_del_init(&p->ptrace_list);
 608                 if (p->parent != p->real_parent)
 609                         list_add(&p->ptrace_list, &p->real_parent->ptrace_children);
 610         } else {
 611                 /* If this child is being traced, then we're the one tracing it
 612                  * anyway, so let go of it.
 613                  */
 614                 p->ptrace = 0;
 615                 remove_parent(p);
 616                 p->parent = p->real_parent;
 617                 add_parent(p);
 618
 619                 if (p->state == TASK_TRACED) {
 620                         /*
 621                          * If it was at a trace stop, turn it into
 622                          * a normal stop since it's no longer being
 623                          * traced.
 624                          */
 625                         ptrace_untrace(p);
 626                 }
 627         }
 628
 629         /* If this is a threaded reparent there is no need to
 630          * notify anyone anything has happened.
 631          */
 632         if (p->real_parent->group_leader == father->group_leader)
 633                 return;
 634
 635         /* We don't want people slaying init.  */
 636         if (p->exit_signal != -1)
 637                 p->exit_signal = SIGCHLD;
 638
 639         /* If we'd notified the old parent about this child's death,
 640          * also notify the new parent.
 641          */
 642         if (!traced && p->exit_state == EXIT_ZOMBIE &&
 643             p->exit_signal != -1 && thread_group_empty(p))
 644                 do_notify_parent(p, p->exit_signal);
 645
 646         /*
 647          * process group orphan check
 648          * Case ii: Our child is in a different pgrp
 649          * than we are, and it was the only connection
 650          * outside, so the child pgrp is now orphaned.
 651          */
 652         if ((process_group(p) != process_group(father)) &&
 653             (process_session(p) == process_session(father))) {
 654                 int pgrp = process_group(p);
 655
 656                 if (will_become_orphaned_pgrp(pgrp, NULL) &&
 657                     has_stopped_jobs(pgrp)) {
 658                         __kill_pg_info(SIGHUP, SEND_SIG_PRIV, pgrp);
 659                         __kill_pg_info(SIGCONT, SEND_SIG_PRIV, pgrp);
 660                 }
 661         }
 662 }
 663
 664 /*
 665  * When we die, we re-parent all our children.
 666  * Try to give them to another thread in our thread
 667  * group, and if no such member exists, give it to
 668  * the child reaper process (ie "init") in our pid
 669  * space.
 670  */
 671 static void
 672 forget_original_parent(struct task_struct *father, struct list_head *to_release)
 673 {
 674         struct task_struct *p, *reaper = father;
 675         struct list_head *_p, *_n;
 676
 677         do {
 678                 reaper = next_thread(reaper);
 679                 if (reaper == father) {
 680                         reaper = child_reaper(father);
 681                         break;
 682                 }
 683         } while (reaper->exit_state);
 684
 685         /*
 686          * There are only two places where our children can be:
 687          *
 688          * - in our child list
 689          * - in our ptraced child list
 690          *
 691          * Search them and reparent children.
 692          */
 693         list_for_each_safe(_p, _n, &father->children) {
 694                 int ptrace;
 695                 p = list_entry(_p, struct task_struct, sibling);
 696
 697                 ptrace = p->ptrace;
 698
 699                 /* if father isn't the real parent, then ptrace must be enabled */
 700                 BUG_ON(father != p->real_parent && !ptrace);
 701
 702                 if (father == p->real_parent) {
 703                         /* reparent with a reaper, real father it's us */
 704                         choose_new_parent(p, reaper);
 705                         reparent_thread(p, father, 0);
 706                 } else {
 707                         /* reparent ptraced task to its real parent */
 708                         __ptrace_unlink (p);
 709                         if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
 710                             thread_group_empty(p))
 711                                 do_notify_parent(p, p->exit_signal);
 712                 }
 713
 714                 /*
 715                  * if the ptraced child is a zombie with exit_signal == -1
 716                  * we must collect it before we exit, or it will remain
 717                  * zombie forever since we prevented it from self-reap itself
 718                  * while it was being traced by us, to be able to see it in wait4.
 719                  */
 720                 if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && p->exit_signal == -1))
 721                         list_add(&p->ptrace_list, to_release);
 722         }
 723         list_for_each_safe(_p, _n, &father->ptrace_children) {
 724                 p = list_entry(_p, struct task_struct, ptrace_list);
 725                 choose_new_parent(p, reaper);
 726                 reparent_thread(p, father, 1);
 727         }
 728 }
 729
 730 /*
 731  * Send signals to all our closest relatives so that they know
 732  * to properly mourn us..
 733  */
 734 static void exit_notify(struct task_struct *tsk)
 735 {
 736         int state;
 737         struct task_struct *t;
 738         struct list_head ptrace_dead, *_p, *_n;
 739
 740         if (signal_pending(tsk) && !(tsk->signal->flags & SIGNAL_GROUP_EXIT)
 741             && !thread_group_empty(tsk)) {
 742                 /*
 743                  * This occurs when there was a race between our exit
 744                  * syscall and a group signal choosing us as the one to
 745                  * wake up.  It could be that we are the only thread
 746                  * alerted to check for pending signals, but another thread
 747                  * should be woken now to take the signal since we will not.
 748                  * Now we'll wake all the threads in the group just to make
 749                  * sure someone gets all the pending signals.
 750                  */
 751                 read_lock(&tasklist_lock);
 752                 spin_lock_irq(&tsk->sighand->siglock);
 753                 for (t = next_thread(tsk); t != tsk; t = next_thread(t))
 754                         if (!signal_pending(t) && !(t->flags & PF_EXITING)) {
 755                                 recalc_sigpending_tsk(t);
 756                                 if (signal_pending(t))
 757                                         signal_wake_up(t, 0);
 758                         }
 759                 spin_unlock_irq(&tsk->sighand->siglock);
 760                 read_unlock(&tasklist_lock);
 761         }
 762
 763         write_lock_irq(&tasklist_lock);
 764
 765         /*
 766          * This does two things:
 767          *
 768          * A.  Make init inherit all the child processes
 769          * B.  Check to see if any process groups have become orphaned
 770          *      as a result of our exiting, and if they have any stopped
 771          *      jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
 772          */
 773
 774         INIT_LIST_HEAD(&ptrace_dead);
 775         forget_original_parent(tsk, &ptrace_dead);
 776         BUG_ON(!list_empty(&tsk->children));
 777         BUG_ON(!list_empty(&tsk->ptrace_children));
 778
 779         /*
 780          * Check to see if any process groups have become orphaned
 781          * as a result of our exiting, and if they have any stopped
 782          * jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
 783          *
 784          * Case i: Our father is in a different pgrp than we are
 785          * and we were the only connection outside, so our pgrp
 786          * is about to become orphaned.
 787          */
 788
 789         t = tsk->real_parent;
 790
 791         if ((process_group(t) != process_group(tsk)) &&
 792             (process_session(t) == process_session(tsk)) &&
 793             will_become_orphaned_pgrp(process_group(tsk), tsk) &&
 794             has_stopped_jobs(process_group(tsk))) {
 795                 __kill_pg_info(SIGHUP, SEND_SIG_PRIV, process_group(tsk));
 796                 __kill_pg_info(SIGCONT, SEND_SIG_PRIV, process_group(tsk));
 797         }
 798
 799         /* Let father know we died
 800          *
 801          * Thread signals are configurable, but you aren't going to use
 802          * that to send signals to arbitary processes.
 803          * That stops right now.
 804          *
 805          * If the parent exec id doesn't match the exec id we saved
 806          * when we started then we know the parent has changed security
 807          * domain.
 808          *
 809          * If our self_exec id doesn't match our parent_exec_id then
 810          * we have changed execution domain as these two values started
 811          * the same after a fork.
 812          *
 813          */
 814
 815         if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 &&
 816             ( tsk->parent_exec_id != t->self_exec_id  ||
 817               tsk->self_exec_id != tsk->parent_exec_id)
 818             && !capable(CAP_KILL))
 819                 tsk->exit_signal = SIGCHLD;
 820
 821
 822         /* If something other than our normal parent is ptracing us, then
 823          * send it a SIGCHLD instead of honoring exit_signal.  exit_signal
 824          * only has special meaning to our real parent.
 825          */
 826         if (tsk->exit_signal != -1 && thread_group_empty(tsk)) {
 827                 int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD;
 828                 do_notify_parent(tsk, signal);
 829         } else if (tsk->ptrace) {
 830                 do_notify_parent(tsk, SIGCHLD);
 831         }
 832
 833         state = EXIT_ZOMBIE;
 834         if (tsk->exit_signal == -1 &&
 835             (likely(tsk->ptrace == 0) ||
 836              unlikely(tsk->parent->signal->flags & SIGNAL_GROUP_EXIT)))
 837                 state = EXIT_DEAD;
 838         tsk->exit_state = state;
 839
 840         write_unlock_irq(&tasklist_lock);
 841
 842         list_for_each_safe(_p, _n, &ptrace_dead) {
 843                 list_del_init(_p);
 844                 t = list_entry(_p, struct task_struct, ptrace_list);
 845                 release_task(t);
 846         }
 847
 848         /* If the process is dead, release it - nobody will wait for it */
 849         if (state == EXIT_DEAD)
 850                 release_task(tsk);
 851 }
 852
 853 fastcall NORET_TYPE void do_exit(long code)
 854 {
 855         struct task_struct *tsk = current;
 856         int group_dead;
 857
 858         profile_task_exit(tsk);
 859
 860         WARN_ON(atomic_read(&tsk->fs_excl));
 861
 862         if (unlikely(in_interrupt()))
 863                 panic("Aiee, killing interrupt handler!");
 864         if (unlikely(!tsk->pid))
 865                 panic("Attempted to kill the idle task!");
 866         if (unlikely(tsk == child_reaper(tsk))) {
 867                 if (tsk->nsproxy->pid_ns != &init_pid_ns)
 868                         tsk->nsproxy->pid_ns->child_reaper = init_pid_ns.child_reaper;
 869                 else
 870                         panic("Attempted to kill init!");
 871         }
 872
 873
 874         if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
 875                 current->ptrace_message = code;
 876                 ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP);
 877         }
 878
 879         /*
 880          * We're taking recursive faults here in do_exit. Safest is to just
 881          * leave this task alone and wait for reboot.
 882          */
 883         if (unlikely(tsk->flags & PF_EXITING)) {
 884                 printk(KERN_ALERT
 885                         "Fixing recursive fault but reboot is needed!\n");
 886                 if (tsk->io_context)
 887                         exit_io_context();
 888                 set_current_state(TASK_UNINTERRUPTIBLE);
 889                 schedule();
 890         }
 891
 892         tsk->flags |= PF_EXITING;
 893
 894         if (unlikely(in_atomic()))
 895                 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
 896                                 current->comm, current->pid,
 897                                 preempt_count());
 898
 899         acct_update_integrals(tsk);
 900         if (tsk->mm) {
 901                 update_hiwater_rss(tsk->mm);
 902                 update_hiwater_vm(tsk->mm);
 903         }
 904         group_dead = atomic_dec_and_test(&tsk->signal->live);
 905         if (group_dead) {
 906                 hrtimer_cancel(&tsk->signal->real_timer);
 907                 exit_itimers(tsk->signal);
 908         }
 909         acct_collect(code, group_dead);
 910         if (unlikely(tsk->robust_list))
 911                 exit_robust_list(tsk);
 912 #if defined(CONFIG_FUTEX) && defined(CONFIG_COMPAT)
 913         if (unlikely(tsk->compat_robust_list))
 914                 compat_exit_robust_list(tsk);
 915 #endif
 916         if (unlikely(tsk->audit_context))
 917                 audit_free(tsk);
 918
 919         taskstats_exit(tsk, group_dead);
 920
 921         exit_mm(tsk);
 922
 923         if (group_dead)
 924                 acct_process();
 925         exit_sem(tsk);
 926         __exit_files(tsk);
 927         __exit_fs(tsk);
 928         exit_thread();
 929         cpuset_exit(tsk);
 930         exit_keys(tsk);
 931
 932         if (group_dead && tsk->signal->leader)
 933                 disassociate_ctty(1);
 934
 935         module_put(task_thread_info(tsk)->exec_domain->module);
 936         if (tsk->binfmt)
 937                 module_put(tsk->binfmt->module);
 938
 939         tsk->exit_code = code;
 940         proc_exit_connector(tsk);
 941         exit_task_namespaces(tsk);
 942         exit_notify(tsk);
 943 #ifdef CONFIG_NUMA
 944         mpol_free(tsk->mempolicy);
 945         tsk->mempolicy = NULL;
 946 #endif
 947         /*
 948          * This must happen late, after the PID is not
 949          * hashed anymore:
 950          */
 951         if (unlikely(!list_empty(&tsk->pi_state_list)))
 952                 exit_pi_state_list(tsk);
 953         if (unlikely(current->pi_state_cache))
 954                 kfree(current->pi_state_cache);
 955         /*
 956          * Make sure we are holding no locks:
 957          */
 958         debug_check_no_locks_held(tsk);
 959
 960         if (tsk->io_context)
 961                 exit_io_context();
 962
 963         if (tsk->splice_pipe)
 964                 __free_pipe_info(tsk->splice_pipe);
 965
 966         preempt_disable();
 967         /* causes final put_task_struct in finish_task_switch(). */
 968         tsk->state = TASK_DEAD;
 969
 970         schedule();
 971         BUG();
 972         /* Avoid "noreturn function does return".  */
 973         for (;;)
 974                 cpu_relax();    /* For when BUG is null */
 975 }
 976
 977 EXPORT_SYMBOL_GPL(do_exit);
 978
 979 NORET_TYPE void complete_and_exit(struct completion *comp, long code)
 980 {
 981         if (comp)
 982                 complete(comp);
 983
 984         do_exit(code);
 985 }
 986
 987 EXPORT_SYMBOL(complete_and_exit);
 988
 989 asmlinkage long sys_exit(int error_code)
 990 {
 991         do_exit((error_code&0xff)<<8);
 992 }
 993
 994 /*
 995  * Take down every thread in the group.  This is called by fatal signals
 996  * as well as by sys_exit_group (below).
 997  */
 998 NORET_TYPE void
 999 do_group_exit(int exit_code)
1000 {
1001         BUG_ON(exit_code & 0x80); /* core dumps don't get here */
1002
1003         if (current->signal->flags & SIGNAL_GROUP_EXIT)
1004                 exit_code = current->signal->group_exit_code;
1005         else if (!thread_group_empty(current)) {
1006                 struct signal_struct *const sig = current->signal;
1007                 struct sighand_struct *const sighand = current->sighand;
1008                 spin_lock_irq(&sighand->siglock);
1009                 if (sig->flags & SIGNAL_GROUP_EXIT)
1010                         /* Another thread got here before we took the lock.  */
1011                         exit_code = sig->group_exit_code;
1012                 else {
1013                         sig->group_exit_code = exit_code;
1014                         zap_other_threads(current);
1015                 }
1016                 spin_unlock_irq(&sighand->siglock);
1017         }
1018
1019         do_exit(exit_code);
1020         /* NOTREACHED */
1021 }
1022
1023 /*
1024  * this kills every thread in the thread group. Note that any externally
1025  * wait4()-ing process will get the correct exit code - even if this
1026  * thread is not the thread group leader.
1027  */
1028 asmlinkage void sys_exit_group(int error_code)
1029 {
1030         do_group_exit((error_code & 0xff) << 8);
1031 }
1032
1033 static int eligible_child(pid_t pid, int options, struct task_struct *p)
1034 {
1035         if (pid > 0) {
1036                 if (p->pid != pid)
1037                         return 0;
1038         } else if (!pid) {
1039                 if (process_group(p) != process_group(current))
1040                         return 0;
1041         } else if (pid != -1) {
1042                 if (process_group(p) != -pid)
1043                         return 0;
1044         }
1045
1046         /*
1047          * Do not consider detached threads that are
1048          * not ptraced:
1049          */
1050         if (p->exit_signal == -1 && !p->ptrace)
1051                 return 0;
1052
1053         /* Wait for all children (clone and not) if __WALL is set;
1054          * otherwise, wait for clone children *only* if __WCLONE is
1055          * set; otherwise, wait for non-clone children *only*.  (Note:
1056          * A "clone" child here is one that reports to its parent
1057          * using a signal other than SIGCHLD.) */
1058         if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
1059             && !(options & __WALL))
1060                 return 0;
1061         /*
1062          * Do not consider thread group leaders that are
1063          * in a non-empty thread group:
1064          */
1065         if (delay_group_leader(p))
1066                 return 2;
1067
1068         if (security_task_wait(p))
1069                 return 0;
1070
1071         return 1;
1072 }
1073
1074 static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,
1075                                int why, int status,
1076                                struct siginfo __user *infop,
1077                                struct rusage __user *rusagep)
1078 {
1079         int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
1080
1081         put_task_struct(p);
1082         if (!retval)
1083                 retval = put_user(SIGCHLD, &infop->si_signo);
1084         if (!retval)
1085                 retval = put_user(0, &infop->si_errno);
1086         if (!retval)
1087                 retval = put_user((short)why, &infop->si_code);
1088         if (!retval)
1089                 retval = put_user(pid, &infop->si_pid);
1090         if (!retval)
1091                 retval = put_user(uid, &infop->si_uid);
1092         if (!retval)
1093                 retval = put_user(status, &infop->si_status);
1094         if (!retval)
1095                 retval = pid;
1096         return retval;
1097 }
1098
1099 /*
1100  * Handle sys_wait4 work for one task in state EXIT_ZOMBIE.  We hold
1101  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1102  * the lock and this task is uninteresting.  If we return nonzero, we have
1103  * released the lock and the system call should return.
1104  */
1105 static int wait_task_zombie(struct task_struct *p, int noreap,
1106                             struct siginfo __user *infop,
1107                             int __user *stat_addr, struct rusage __user *ru)
1108 {
1109         unsigned long state;
1110         int retval;
1111         int status;
1112
1113         if (unlikely(noreap)) {
1114                 pid_t pid = p->pid;
1115                 uid_t uid = p->uid;
1116                 int exit_code = p->exit_code;
1117                 int why, status;
1118
1119                 if (unlikely(p->exit_state != EXIT_ZOMBIE))
1120                         return 0;
1121                 if (unlikely(p->exit_signal == -1 && p->ptrace == 0))
1122                         return 0;
1123                 get_task_struct(p);
1124                 read_unlock(&tasklist_lock);
1125                 if ((exit_code & 0x7f) == 0) {
1126                         why = CLD_EXITED;
1127                         status = exit_code >> 8;
1128                 } else {
1129                         why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1130                         status = exit_code & 0x7f;
1131                 }
1132                 return wait_noreap_copyout(p, pid, uid, why,
1133                                            status, infop, ru);
1134         }
1135
1136         /*
1137          * Try to move the task's state to DEAD
1138          * only one thread is allowed to do this:
1139          */
1140         state = xchg(&p->exit_state, EXIT_DEAD);
1141         if (state != EXIT_ZOMBIE) {
1142                 BUG_ON(state != EXIT_DEAD);
1143                 return 0;
1144         }
1145         if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) {
1146                 /*
1147                  * This can only happen in a race with a ptraced thread
1148                  * dying on another processor.
1149                  */
1150                 return 0;
1151         }
1152
1153         if (likely(p->real_parent == p->parent) && likely(p->signal)) {
1154                 struct signal_struct *psig;
1155                 struct signal_struct *sig;
1156
1157                 /*
1158                  * The resource counters for the group leader are in its
1159                  * own task_struct.  Those for dead threads in the group
1160                  * are in its signal_struct, as are those for the child
1161                  * processes it has previously reaped.  All these
1162                  * accumulate in the parent's signal_struct c* fields.
1163                  *
1164                  * We don't bother to take a lock here to protect these
1165                  * p->signal fields, because they are only touched by
1166                  * __exit_signal, which runs with tasklist_lock
1167                  * write-locked anyway, and so is excluded here.  We do
1168                  * need to protect the access to p->parent->signal fields,
1169                  * as other threads in the parent group can be right
1170                  * here reaping other children at the same time.
1171                  */
1172                 spin_lock_irq(&p->parent->sighand->siglock);
1173                 psig = p->parent->signal;
1174                 sig = p->signal;
1175                 psig->cutime =
1176                         cputime_add(psig->cutime,
1177                         cputime_add(p->utime,
1178                         cputime_add(sig->utime,
1179                                     sig->cutime)));
1180                 psig->cstime =
1181                         cputime_add(psig->cstime,
1182                         cputime_add(p->stime,
1183                         cputime_add(sig->stime,
1184                                     sig->cstime)));
1185                 psig->cmin_flt +=
1186                         p->min_flt + sig->min_flt + sig->cmin_flt;
1187                 psig->cmaj_flt +=
1188                         p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1189                 psig->cnvcsw +=
1190                         p->nvcsw + sig->nvcsw + sig->cnvcsw;
1191                 psig->cnivcsw +=
1192                         p->nivcsw + sig->nivcsw + sig->cnivcsw;
1193                 spin_unlock_irq(&p->parent->sighand->siglock);
1194         }
1195
1196         /*
1197          * Now we are sure this task is interesting, and no other
1198          * thread can reap it because we set its state to EXIT_DEAD.
1199          */
1200         read_unlock(&tasklist_lock);
1201
1202         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1203         status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1204                 ? p->signal->group_exit_code : p->exit_code;
1205         if (!retval && stat_addr)
1206                 retval = put_user(status, stat_addr);
1207         if (!retval && infop)
1208                 retval = put_user(SIGCHLD, &infop->si_signo);
1209         if (!retval && infop)
1210                 retval = put_user(0, &infop->si_errno);
1211         if (!retval && infop) {
1212                 int why;
1213
1214                 if ((status & 0x7f) == 0) {
1215                         why = CLD_EXITED;
1216                         status >>= 8;
1217                 } else {
1218                         why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1219                         status &= 0x7f;
1220                 }
1221                 retval = put_user((short)why, &infop->si_code);
1222                 if (!retval)
1223                         retval = put_user(status, &infop->si_status);
1224         }
1225         if (!retval && infop)
1226                 retval = put_user(p->pid, &infop->si_pid);
1227         if (!retval && infop)
1228                 retval = put_user(p->uid, &infop->si_uid);
1229         if (retval) {
1230                 // TODO: is this safe?
1231                 p->exit_state = EXIT_ZOMBIE;
1232                 return retval;
1233         }
1234         retval = p->pid;
1235         if (p->real_parent != p->parent) {
1236                 write_lock_irq(&tasklist_lock);
1237                 /* Double-check with lock held.  */
1238                 if (p->real_parent != p->parent) {
1239                         __ptrace_unlink(p);
1240                         // TODO: is this safe?
1241                         p->exit_state = EXIT_ZOMBIE;
1242                         /*
1243                          * If this is not a detached task, notify the parent.
1244                          * If it's still not detached after that, don't release
1245                          * it now.
1246                          */
1247                         if (p->exit_signal != -1) {
1248                                 do_notify_parent(p, p->exit_signal);
1249                                 if (p->exit_signal != -1)
1250                                         p = NULL;
1251                         }
1252                 }
1253                 write_unlock_irq(&tasklist_lock);
1254         }
1255         if (p != NULL)
1256                 release_task(p);
1257         BUG_ON(!retval);
1258         return retval;
1259 }
1260
1261 /*
1262  * Handle sys_wait4 work for one task in state TASK_STOPPED.  We hold
1263  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1264  * the lock and this task is uninteresting.  If we return nonzero, we have
1265  * released the lock and the system call should return.
1266  */
1267 static int wait_task_stopped(struct task_struct *p, int delayed_group_leader,
1268                              int noreap, struct siginfo __user *infop,
1269                              int __user *stat_addr, struct rusage __user *ru)
1270 {
1271         int retval, exit_code;
1272
1273         if (!p->exit_code)
1274                 return 0;
1275         if (delayed_group_leader && !(p->ptrace & PT_PTRACED) &&
1276             p->signal && p->signal->group_stop_count > 0)
1277                 /*
1278                  * A group stop is in progress and this is the group leader.
1279                  * We won't report until all threads have stopped.
1280                  */
1281                 return 0;
1282
1283         /*
1284          * Now we are pretty sure this task is interesting.
1285          * Make sure it doesn't get reaped out from under us while we
1286          * give up the lock and then examine it below.  We don't want to
1287          * keep holding onto the tasklist_lock while we call getrusage and
1288          * possibly take page faults for user memory.
1289          */
1290         get_task_struct(p);
1291         read_unlock(&tasklist_lock);
1292
1293         if (unlikely(noreap)) {
1294                 pid_t pid = p->pid;
1295                 uid_t uid = p->uid;
1296                 int why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
1297
1298                 exit_code = p->exit_code;
1299                 if (unlikely(!exit_code) ||
1300                     unlikely(p->state & TASK_TRACED))
1301                         goto bail_ref;
1302                 return wait_noreap_copyout(p, pid, uid,
1303                                            why, (exit_code << 8) | 0x7f,
1304                                            infop, ru);
1305         }
1306
1307         write_lock_irq(&tasklist_lock);
1308
1309         /*
1310          * This uses xchg to be atomic with the thread resuming and setting
1311          * it.  It must also be done with the write lock held to prevent a
1312          * race with the EXIT_ZOMBIE case.
1313          */
1314         exit_code = xchg(&p->exit_code, 0);
1315         if (unlikely(p->exit_state)) {
1316                 /*
1317                  * The task resumed and then died.  Let the next iteration
1318                  * catch it in EXIT_ZOMBIE.  Note that exit_code might
1319                  * already be zero here if it resumed and did _exit(0).
1320                  * The task itself is dead and won't touch exit_code again;
1321                  * other processors in this function are locked out.
1322                  */
1323                 p->exit_code = exit_code;
1324                 exit_code = 0;
1325         }
1326         if (unlikely(exit_code == 0)) {
1327                 /*
1328                  * Another thread in this function got to it first, or it
1329                  * resumed, or it resumed and then died.
1330                  */
1331                 write_unlock_irq(&tasklist_lock);
1332 bail_ref:
1333                 put_task_struct(p);
1334                 /*
1335                  * We are returning to the wait loop without having successfully
1336                  * removed the process and having released the lock. We cannot
1337                  * continue, since the "p" task pointer is potentially stale.
1338                  *
1339                  * Return -EAGAIN, and do_wait() will restart the loop from the
1340                  * beginning. Do _not_ re-acquire the lock.
1341                  */
1342                 return -EAGAIN;
1343         }
1344
1345         /* move to end of parent's list to avoid starvation */
1346         remove_parent(p);
1347         add_parent(p);
1348
1349         write_unlock_irq(&tasklist_lock);
1350
1351         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1352         if (!retval && stat_addr)
1353                 retval = put_user((exit_code << 8) | 0x7f, stat_addr);
1354         if (!retval && infop)
1355                 retval = put_user(SIGCHLD, &infop->si_signo);
1356         if (!retval && infop)
1357                 retval = put_user(0, &infop->si_errno);
1358         if (!retval && infop)
1359                 retval = put_user((short)((p->ptrace & PT_PTRACED)
1360                                           ? CLD_TRAPPED : CLD_STOPPED),
1361                                   &infop->si_code);
1362         if (!retval && infop)
1363                 retval = put_user(exit_code, &infop->si_status);
1364         if (!retval && infop)
1365                 retval = put_user(p->pid, &infop->si_pid);
1366         if (!retval && infop)
1367                 retval = put_user(p->uid, &infop->si_uid);
1368         if (!retval)
1369                 retval = p->pid;
1370         put_task_struct(p);
1371
1372         BUG_ON(!retval);
1373         return retval;
1374 }
1375
1376 /*
1377  * Handle do_wait work for one task in a live, non-stopped state.
1378  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1379  * the lock and this task is uninteresting.  If we return nonzero, we have
1380  * released the lock and the system call should return.
1381  */
1382 static int wait_task_continued(struct task_struct *p, int noreap,
1383                                struct siginfo __user *infop,
1384                                int __user *stat_addr, struct rusage __user *ru)
1385 {
1386         int retval;
1387         pid_t pid;
1388         uid_t uid;
1389
1390         if (unlikely(!p->signal))
1391                 return 0;
1392
1393         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1394                 return 0;
1395
1396         spin_lock_irq(&p->sighand->siglock);
1397         /* Re-check with the lock held.  */
1398         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1399                 spin_unlock_irq(&p->sighand->siglock);
1400                 return 0;
1401         }
1402         if (!noreap)
1403                 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1404         spin_unlock_irq(&p->sighand->siglock);
1405
1406         pid = p->pid;
1407         uid = p->uid;
1408         get_task_struct(p);
1409         read_unlock(&tasklist_lock);
1410
1411         if (!infop) {
1412                 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1413                 put_task_struct(p);
1414                 if (!retval && stat_addr)
1415                         retval = put_user(0xffff, stat_addr);
1416                 if (!retval)
1417                         retval = p->pid;
1418         } else {
1419                 retval = wait_noreap_copyout(p, pid, uid,
1420                                              CLD_CONTINUED, SIGCONT,
1421                                              infop, ru);
1422                 BUG_ON(retval == 0);
1423         }
1424
1425         return retval;
1426 }
1427
1428
1429 static inline int my_ptrace_child(struct task_struct *p)
1430 {
1431         if (!(p->ptrace & PT_PTRACED))
1432                 return 0;
1433         if (!(p->ptrace & PT_ATTACHED))
1434                 return 1;
1435         /*
1436          * This child was PTRACE_ATTACH'd.  We should be seeing it only if
1437          * we are the attacher.  If we are the real parent, this is a race
1438          * inside ptrace_attach.  It is waiting for the tasklist_lock,
1439          * which we have to switch the parent links, but has already set
1440          * the flags in p->ptrace.
1441          */
1442         return (p->parent != p->real_parent);
1443 }
1444
1445 static long do_wait(pid_t pid, int options, struct siginfo __user *infop,
1446                     int __user *stat_addr, struct rusage __user *ru)
1447 {
1448         DECLARE_WAITQUEUE(wait, current);
1449         struct task_struct *tsk;
1450         int flag, retval;
1451
1452         add_wait_queue(&current->signal->wait_chldexit,&wait);
1453 repeat:
1454         /*
1455          * We will set this flag if we see any child that might later
1456          * match our criteria, even if we are not able to reap it yet.
1457          */
1458         flag = 0;
1459         current->state = TASK_INTERRUPTIBLE;
1460         read_lock(&tasklist_lock);
1461         tsk = current;
1462         do {
1463                 struct task_struct *p;
1464                 struct list_head *_p;
1465                 int ret;
1466
1467                 list_for_each(_p,&tsk->children) {
1468                         p = list_entry(_p, struct task_struct, sibling);
1469
1470                         ret = eligible_child(pid, options, p);
1471                         if (!ret)
1472                                 continue;
1473
1474                         switch (p->state) {
1475                         case TASK_TRACED:
1476                                 /*
1477                                  * When we hit the race with PTRACE_ATTACH,
1478                                  * we will not report this child.  But the
1479                                  * race means it has not yet been moved to
1480                                  * our ptrace_children list, so we need to
1481                                  * set the flag here to avoid a spurious ECHILD
1482                                  * when the race happens with the only child.
1483                                  */
1484                                 flag = 1;
1485                                 if (!my_ptrace_child(p))
1486                                         continue;
1487                                 /*FALLTHROUGH*/
1488                         case TASK_STOPPED:
1489                                 /*
1490                                  * It's stopped now, so it might later
1491                                  * continue, exit, or stop again.
1492                                  */
1493                                 flag = 1;
1494                                 if (!(options & WUNTRACED) &&
1495                                     !my_ptrace_child(p))
1496                                         continue;
1497                                 retval = wait_task_stopped(p, ret == 2,
1498                                                            (options & WNOWAIT),
1499                                                            infop,
1500                                                            stat_addr, ru);
1501                                 if (retval == -EAGAIN)
1502                                         goto repeat;
1503                                 if (retval != 0) /* He released the lock.  */
1504                                         goto end;
1505                                 break;
1506                         default:
1507                         // case EXIT_DEAD:
1508                                 if (p->exit_state == EXIT_DEAD)
1509                                         continue;
1510                         // case EXIT_ZOMBIE:
1511                                 if (p->exit_state == EXIT_ZOMBIE) {
1512                                         /*
1513                                          * Eligible but we cannot release
1514                                          * it yet:
1515                                          */
1516                                         if (ret == 2)
1517                                                 goto check_continued;
1518                                         if (!likely(options & WEXITED))
1519                                                 continue;
1520                                         retval = wait_task_zombie(
1521                                                 p, (options & WNOWAIT),
1522                                                 infop, stat_addr, ru);
1523                                         /* He released the lock.  */
1524                                         if (retval != 0)
1525                                                 goto end;
1526                                         break;
1527                                 }
1528 check_continued:
1529                                 /*
1530                                  * It's running now, so it might later
1531                                  * exit, stop, or stop and then continue.
1532                                  */
1533                                 flag = 1;
1534                                 if (!unlikely(options & WCONTINUED))
1535                                         continue;
1536                                 retval = wait_task_continued(
1537                                         p, (options & WNOWAIT),
1538                                         infop, stat_addr, ru);
1539                                 if (retval != 0) /* He released the lock.  */
1540                                         goto end;
1541                                 break;
1542                         }
1543                 }
1544                 if (!flag) {
1545                         list_for_each(_p, &tsk->ptrace_children) {
1546                                 p = list_entry(_p, struct task_struct,
1547                                                 ptrace_list);
1548                                 if (!eligible_child(pid, options, p))
1549                                         continue;
1550                                 flag = 1;
1551                                 break;
1552                         }
1553                 }
1554                 if (options & __WNOTHREAD)
1555                         break;
1556                 tsk = next_thread(tsk);
1557                 BUG_ON(tsk->signal != current->signal);
1558         } while (tsk != current);
1559
1560         read_unlock(&tasklist_lock);
1561         if (flag) {
1562                 retval = 0;
1563                 if (options & WNOHANG)
1564                         goto end;
1565                 retval = -ERESTARTSYS;
1566                 if (signal_pending(current))
1567                         goto end;
1568                 schedule();
1569                 goto repeat;
1570         }
1571         retval = -ECHILD;
1572 end:
1573         current->state = TASK_RUNNING;
1574         remove_wait_queue(&current->signal->wait_chldexit,&wait);
1575         if (infop) {
1576                 if (retval > 0)
1577                 retval = 0;
1578                 else {
1579                         /*
1580                          * For a WNOHANG return, clear out all the fields
1581                          * we would set so the user can easily tell the
1582                          * difference.
1583                          */
1584                         if (!retval)
1585                                 retval = put_user(0, &infop->si_signo);
1586                         if (!retval)
1587                                 retval = put_user(0, &infop->si_errno);
1588                         if (!retval)
1589                                 retval = put_user(0, &infop->si_code);
1590                         if (!retval)
1591                                 retval = put_user(0, &infop->si_pid);
1592                         if (!retval)
1593                                 retval = put_user(0, &infop->si_uid);
1594                         if (!retval)
1595                                 retval = put_user(0, &infop->si_status);
1596                 }
1597         }
1598         return retval;
1599 }
1600
1601 asmlinkage long sys_waitid(int which, pid_t pid,
1602                            struct siginfo __user *infop, int options,
1603                            struct rusage __user *ru)
1604 {
1605         long ret;
1606
1607         if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1608                 return -EINVAL;
1609         if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1610                 return -EINVAL;
1611
1612         switch (which) {
1613         case P_ALL:
1614                 pid = -1;
1615                 break;
1616         case P_PID:
1617                 if (pid <= 0)
1618                         return -EINVAL;
1619                 break;
1620         case P_PGID:
1621                 if (pid <= 0)
1622                         return -EINVAL;
1623                 pid = -pid;
1624                 break;
1625         default:
1626                 return -EINVAL;
1627         }
1628
1629         ret = do_wait(pid, options, infop, NULL, ru);
1630
1631         /* avoid REGPARM breakage on x86: */
1632         prevent_tail_call(ret);
1633         return ret;
1634 }
1635
1636 asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr,
1637                           int options, struct rusage __user *ru)
1638 {
1639         long ret;
1640
1641         if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1642                         __WNOTHREAD|__WCLONE|__WALL))
1643                 return -EINVAL;
1644         ret = do_wait(pid, options | WEXITED, NULL, stat_addr, ru);
1645
1646         /* avoid REGPARM breakage on x86: */
1647         prevent_tail_call(ret);
1648         return ret;
1649 }
1650
1651 #ifdef __ARCH_WANT_SYS_WAITPID
1652
1653 /*
1654  * sys_waitpid() remains for compatibility. waitpid() should be
1655  * implemented by calling sys_wait4() from libc.a.
1656  */
1657 asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options)
1658 {
1659         return sys_wait4(pid, stat_addr, options, NULL);
1660 }
1661
1662 #endif