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