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  * The caller must hold rcu lock or the tasklist lock.
 190  */
 191 struct pid *session_of_pgrp(struct pid *pgrp)
 192 {
 193         struct task_struct *p;
 194         struct pid *sid = NULL;
 195
 196         p = pid_task(pgrp, PIDTYPE_PGID);
 197         if (p == NULL)
 198                 p = pid_task(pgrp, PIDTYPE_PID);
 199         if (p != NULL)
 200                 sid = task_session(p);
 201
 202         return sid;
 203 }
 204
 205 /*
 206  * Determine if a process group is "orphaned", according to the POSIX
 207  * definition in 2.2.2.52.  Orphaned process groups are not to be affected
 208  * by terminal-generated stop signals.  Newly orphaned process groups are
 209  * to receive a SIGHUP and a SIGCONT.
 210  *
 211  * "I ask you, have you ever known what it is to be an orphan?"
 212  */
 213 static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task)
 214 {
 215         struct task_struct *p;
 216         int ret = 1;
 217
 218         do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
 219                 if (p == ignored_task
 220                                 || p->exit_state
 221                                 || is_init(p->real_parent))
 222                         continue;
 223                 if (task_pgrp(p->real_parent) != pgrp &&
 224                     task_session(p->real_parent) == task_session(p)) {
 225                         ret = 0;
 226                         break;
 227                 }
 228         } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
 229         return ret;     /* (sighing) "Often!" */
 230 }
 231
 232 int is_current_pgrp_orphaned(void)
 233 {
 234         int retval;
 235
 236         read_lock(&tasklist_lock);
 237         retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
 238         read_unlock(&tasklist_lock);
 239
 240         return retval;
 241 }
 242
 243 static int has_stopped_jobs(struct pid *pgrp)
 244 {
 245         int retval = 0;
 246         struct task_struct *p;
 247
 248         do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
 249                 if (p->state != TASK_STOPPED)
 250                         continue;
 251                 retval = 1;
 252                 break;
 253         } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
 254         return retval;
 255 }
 256
 257 /**
 258  * reparent_to_init - Reparent the calling kernel thread to the init task of the pid space that the thread belongs to.
 259  *
 260  * If a kernel thread is launched as a result of a system call, or if
 261  * it ever exits, it should generally reparent itself to init so that
 262  * it is correctly cleaned up on exit.
 263  *
 264  * The various task state such as scheduling policy and priority may have
 265  * been inherited from a user process, so we reset them to sane values here.
 266  *
 267  * NOTE that reparent_to_init() gives the caller full capabilities.
 268  */
 269 static void reparent_to_init(void)
 270 {
 271         write_lock_irq(&tasklist_lock);
 272
 273         ptrace_unlink(current);
 274         /* Reparent to init */
 275         remove_parent(current);
 276         current->parent = child_reaper(current);
 277         current->real_parent = child_reaper(current);
 278         add_parent(current);
 279
 280         /* Set the exit signal to SIGCHLD so we signal init on exit */
 281         current->exit_signal = SIGCHLD;
 282
 283         if (!has_rt_policy(current) && (task_nice(current) < 0))
 284                 set_user_nice(current, 0);
 285         /* cpus_allowed? */
 286         /* rt_priority? */
 287         /* signals? */
 288         security_task_reparent_to_init(current);
 289         memcpy(current->signal->rlim, init_task.signal->rlim,
 290                sizeof(current->signal->rlim));
 291         atomic_inc(&(INIT_USER->__count));
 292         write_unlock_irq(&tasklist_lock);
 293         switch_uid(INIT_USER);
 294 }
 295
 296 void __set_special_pids(pid_t session, pid_t pgrp)
 297 {
 298         struct task_struct *curr = current->group_leader;
 299
 300         if (process_session(curr) != session) {
 301                 detach_pid(curr, PIDTYPE_SID);
 302                 set_signal_session(curr->signal, session);
 303                 attach_pid(curr, PIDTYPE_SID, session);
 304         }
 305         if (process_group(curr) != pgrp) {
 306                 detach_pid(curr, PIDTYPE_PGID);
 307                 curr->signal->pgrp = pgrp;
 308                 attach_pid(curr, PIDTYPE_PGID, pgrp);
 309         }
 310 }
 311
 312 static void set_special_pids(pid_t session, pid_t pgrp)
 313 {
 314         write_lock_irq(&tasklist_lock);
 315         __set_special_pids(session, pgrp);
 316         write_unlock_irq(&tasklist_lock);
 317 }
 318
 319 /*
 320  * Let kernel threads use this to say that they
 321  * allow a certain signal (since daemonize() will
 322  * have disabled all of them by default).
 323  */
 324 int allow_signal(int sig)
 325 {
 326         if (!valid_signal(sig) || sig < 1)
 327                 return -EINVAL;
 328
 329         spin_lock_irq(&current->sighand->siglock);
 330         sigdelset(&current->blocked, sig);
 331         if (!current->mm) {
 332                 /* Kernel threads handle their own signals.
 333                    Let the signal code know it'll be handled, so
 334                    that they don't get converted to SIGKILL or
 335                    just silently dropped */
 336                 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
 337         }
 338         recalc_sigpending();
 339         spin_unlock_irq(&current->sighand->siglock);
 340         return 0;
 341 }
 342
 343 EXPORT_SYMBOL(allow_signal);
 344
 345 int disallow_signal(int sig)
 346 {
 347         if (!valid_signal(sig) || sig < 1)
 348                 return -EINVAL;
 349
 350         spin_lock_irq(&current->sighand->siglock);
 351         sigaddset(&current->blocked, sig);
 352         recalc_sigpending();
 353         spin_unlock_irq(&current->sighand->siglock);
 354         return 0;
 355 }
 356
 357 EXPORT_SYMBOL(disallow_signal);
 358
 359 /*
 360  *      Put all the gunge required to become a kernel thread without
 361  *      attached user resources in one place where it belongs.
 362  */
 363
 364 void daemonize(const char *name, ...)
 365 {
 366         va_list args;
 367         struct fs_struct *fs;
 368         sigset_t blocked;
 369
 370         va_start(args, name);
 371         vsnprintf(current->comm, sizeof(current->comm), name, args);
 372         va_end(args);
 373
 374         /*
 375          * If we were started as result of loading a module, close all of the
 376          * user space pages.  We don't need them, and if we didn't close them
 377          * they would be locked into memory.
 378          */
 379         exit_mm(current);
 380
 381         set_special_pids(1, 1);
 382         proc_clear_tty(current);
 383
 384         /* Block and flush all signals */
 385         sigfillset(&blocked);
 386         sigprocmask(SIG_BLOCK, &blocked, NULL);
 387         flush_signals(current);
 388
 389         /* Become as one with the init task */
 390
 391         exit_fs(current);       /* current->fs->count--; */
 392         fs = init_task.fs;
 393         current->fs = fs;
 394         atomic_inc(&fs->count);
 395
 396         exit_task_namespaces(current);
 397         current->nsproxy = init_task.nsproxy;
 398         get_task_namespaces(current);
 399
 400         exit_files(current);
 401         current->files = init_task.files;
 402         atomic_inc(&current->files->count);
 403
 404         reparent_to_init();
 405 }
 406
 407 EXPORT_SYMBOL(daemonize);
 408
 409 static void close_files(struct files_struct * files)
 410 {
 411         int i, j;
 412         struct fdtable *fdt;
 413
 414         j = 0;
 415
 416         /*
 417          * It is safe to dereference the fd table without RCU or
 418          * ->file_lock because this is the last reference to the
 419          * files structure.
 420          */
 421         fdt = files_fdtable(files);
 422         for (;;) {
 423                 unsigned long set;
 424                 i = j * __NFDBITS;
 425                 if (i >= fdt->max_fds)
 426                         break;
 427                 set = fdt->open_fds->fds_bits[j++];
 428                 while (set) {
 429                         if (set & 1) {
 430                                 struct file * file = xchg(&fdt->fd[i], NULL);
 431                                 if (file) {
 432                                         filp_close(file, files);
 433                                         cond_resched();
 434                                 }
 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 ((task_pgrp(p) != task_pgrp(father)) &&
 652             (task_session(p) == task_session(father))) {
 653                 struct pid *pgrp = task_pgrp(p);
 654
 655                 if (will_become_orphaned_pgrp(pgrp, NULL) &&
 656                     has_stopped_jobs(pgrp)) {
 657                         __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
 658                         __kill_pgrp_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         struct pid *pgrp;
 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         pgrp = task_pgrp(tsk);
 792         if ((task_pgrp(t) != pgrp) &&
 793             (task_session(t) == task_session(tsk)) &&
 794             will_become_orphaned_pgrp(pgrp, tsk) &&
 795             has_stopped_jobs(pgrp)) {
 796                 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
 797                 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
 798         }
 799
 800         /* Let father know we died
 801          *
 802          * Thread signals are configurable, but you aren't going to use
 803          * that to send signals to arbitary processes.
 804          * That stops right now.
 805          *
 806          * If the parent exec id doesn't match the exec id we saved
 807          * when we started then we know the parent has changed security
 808          * domain.
 809          *
 810          * If our self_exec id doesn't match our parent_exec_id then
 811          * we have changed execution domain as these two values started
 812          * the same after a fork.
 813          *
 814          */
 815
 816         if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 &&
 817             ( tsk->parent_exec_id != t->self_exec_id  ||
 818               tsk->self_exec_id != tsk->parent_exec_id)
 819             && !capable(CAP_KILL))
 820                 tsk->exit_signal = SIGCHLD;
 821
 822
 823         /* If something other than our normal parent is ptracing us, then
 824          * send it a SIGCHLD instead of honoring exit_signal.  exit_signal
 825          * only has special meaning to our real parent.
 826          */
 827         if (tsk->exit_signal != -1 && thread_group_empty(tsk)) {
 828                 int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD;
 829                 do_notify_parent(tsk, signal);
 830         } else if (tsk->ptrace) {
 831                 do_notify_parent(tsk, SIGCHLD);
 832         }
 833
 834         state = EXIT_ZOMBIE;
 835         if (tsk->exit_signal == -1 &&
 836             (likely(tsk->ptrace == 0) ||
 837              unlikely(tsk->parent->signal->flags & SIGNAL_GROUP_EXIT)))
 838                 state = EXIT_DEAD;
 839         tsk->exit_state = state;
 840
 841         write_unlock_irq(&tasklist_lock);
 842
 843         list_for_each_safe(_p, _n, &ptrace_dead) {
 844                 list_del_init(_p);
 845                 t = list_entry(_p, struct task_struct, ptrace_list);
 846                 release_task(t);
 847         }
 848
 849         /* If the process is dead, release it - nobody will wait for it */
 850         if (state == EXIT_DEAD)
 851                 release_task(tsk);
 852 }
 853
 854 fastcall NORET_TYPE void do_exit(long code)
 855 {
 856         struct task_struct *tsk = current;
 857         int group_dead;
 858
 859         profile_task_exit(tsk);
 860
 861         WARN_ON(atomic_read(&tsk->fs_excl));
 862
 863         if (unlikely(in_interrupt()))
 864                 panic("Aiee, killing interrupt handler!");
 865         if (unlikely(!tsk->pid))
 866                 panic("Attempted to kill the idle task!");
 867         if (unlikely(tsk == child_reaper(tsk))) {
 868                 if (tsk->nsproxy->pid_ns != &init_pid_ns)
 869                         tsk->nsproxy->pid_ns->child_reaper = init_pid_ns.child_reaper;
 870                 else
 871                         panic("Attempted to kill init!");
 872         }
 873
 874
 875         if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
 876                 current->ptrace_message = code;
 877                 ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP);
 878         }
 879
 880         /*
 881          * We're taking recursive faults here in do_exit. Safest is to just
 882          * leave this task alone and wait for reboot.
 883          */
 884         if (unlikely(tsk->flags & PF_EXITING)) {
 885                 printk(KERN_ALERT
 886                         "Fixing recursive fault but reboot is needed!\n");
 887                 if (tsk->io_context)
 888                         exit_io_context();
 889                 set_current_state(TASK_UNINTERRUPTIBLE);
 890                 schedule();
 891         }
 892
 893         tsk->flags |= PF_EXITING;
 894
 895         if (unlikely(in_atomic()))
 896                 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
 897                                 current->comm, current->pid,
 898                                 preempt_count());
 899
 900         acct_update_integrals(tsk);
 901         if (tsk->mm) {
 902                 update_hiwater_rss(tsk->mm);
 903                 update_hiwater_vm(tsk->mm);
 904         }
 905         group_dead = atomic_dec_and_test(&tsk->signal->live);
 906         if (group_dead) {
 907                 hrtimer_cancel(&tsk->signal->real_timer);
 908                 exit_itimers(tsk->signal);
 909         }
 910         acct_collect(code, group_dead);
 911         if (unlikely(tsk->robust_list))
 912                 exit_robust_list(tsk);
 913 #if defined(CONFIG_FUTEX) && defined(CONFIG_COMPAT)
 914         if (unlikely(tsk->compat_robust_list))
 915                 compat_exit_robust_list(tsk);
 916 #endif
 917         if (unlikely(tsk->audit_context))
 918                 audit_free(tsk);
 919
 920         taskstats_exit(tsk, group_dead);
 921
 922         exit_mm(tsk);
 923
 924         if (group_dead)
 925                 acct_process();
 926         exit_sem(tsk);
 927         __exit_files(tsk);
 928         __exit_fs(tsk);
 929         exit_thread();
 930         cpuset_exit(tsk);
 931         exit_keys(tsk);
 932
 933         if (group_dead && tsk->signal->leader)
 934                 disassociate_ctty(1);
 935
 936         module_put(task_thread_info(tsk)->exec_domain->module);
 937         if (tsk->binfmt)
 938                 module_put(tsk->binfmt->module);
 939
 940         tsk->exit_code = code;
 941         proc_exit_connector(tsk);
 942         exit_task_namespaces(tsk);
 943         exit_notify(tsk);
 944 #ifdef CONFIG_NUMA
 945         mpol_free(tsk->mempolicy);
 946         tsk->mempolicy = NULL;
 947 #endif
 948         /*
 949          * This must happen late, after the PID is not
 950          * hashed anymore:
 951          */
 952         if (unlikely(!list_empty(&tsk->pi_state_list)))
 953                 exit_pi_state_list(tsk);
 954         if (unlikely(current->pi_state_cache))
 955                 kfree(current->pi_state_cache);
 956         /*
 957          * Make sure we are holding no locks:
 958          */
 959         debug_check_no_locks_held(tsk);
 960
 961         if (tsk->io_context)
 962                 exit_io_context();
 963
 964         if (tsk->splice_pipe)
 965                 __free_pipe_info(tsk->splice_pipe);
 966
 967         preempt_disable();
 968         /* causes final put_task_struct in finish_task_switch(). */
 969         tsk->state = TASK_DEAD;
 970
 971         schedule();
 972         BUG();
 973         /* Avoid "noreturn function does return".  */
 974         for (;;)
 975                 cpu_relax();    /* For when BUG is null */
 976 }
 977
 978 EXPORT_SYMBOL_GPL(do_exit);
 979
 980 NORET_TYPE void complete_and_exit(struct completion *comp, long code)
 981 {
 982         if (comp)
 983                 complete(comp);
 984
 985         do_exit(code);
 986 }
 987
 988 EXPORT_SYMBOL(complete_and_exit);
 989
 990 asmlinkage long sys_exit(int error_code)
 991 {
 992         do_exit((error_code&0xff)<<8);
 993 }
 994
 995 /*
 996  * Take down every thread in the group.  This is called by fatal signals
 997  * as well as by sys_exit_group (below).
 998  */
 999 NORET_TYPE void
1000 do_group_exit(int exit_code)
1001 {
1002         BUG_ON(exit_code & 0x80); /* core dumps don't get here */
1003
1004         if (current->signal->flags & SIGNAL_GROUP_EXIT)
1005                 exit_code = current->signal->group_exit_code;
1006         else if (!thread_group_empty(current)) {
1007                 struct signal_struct *const sig = current->signal;
1008                 struct sighand_struct *const sighand = current->sighand;
1009                 spin_lock_irq(&sighand->siglock);
1010                 if (sig->flags & SIGNAL_GROUP_EXIT)
1011                         /* Another thread got here before we took the lock.  */
1012                         exit_code = sig->group_exit_code;
1013                 else {
1014                         sig->group_exit_code = exit_code;
1015                         zap_other_threads(current);
1016                 }
1017                 spin_unlock_irq(&sighand->siglock);
1018         }
1019
1020         do_exit(exit_code);
1021         /* NOTREACHED */
1022 }
1023
1024 /*
1025  * this kills every thread in the thread group. Note that any externally
1026  * wait4()-ing process will get the correct exit code - even if this
1027  * thread is not the thread group leader.
1028  */
1029 asmlinkage void sys_exit_group(int error_code)
1030 {
1031         do_group_exit((error_code & 0xff) << 8);
1032 }
1033
1034 static int eligible_child(pid_t pid, int options, struct task_struct *p)
1035 {
1036         if (pid > 0) {
1037                 if (p->pid != pid)
1038                         return 0;
1039         } else if (!pid) {
1040                 if (process_group(p) != process_group(current))
1041                         return 0;
1042         } else if (pid != -1) {
1043                 if (process_group(p) != -pid)
1044                         return 0;
1045         }
1046
1047         /*
1048          * Do not consider detached threads that are
1049          * not ptraced:
1050          */
1051         if (p->exit_signal == -1 && !p->ptrace)
1052                 return 0;
1053
1054         /* Wait for all children (clone and not) if __WALL is set;
1055          * otherwise, wait for clone children *only* if __WCLONE is
1056          * set; otherwise, wait for non-clone children *only*.  (Note:
1057          * A "clone" child here is one that reports to its parent
1058          * using a signal other than SIGCHLD.) */
1059         if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
1060             && !(options & __WALL))
1061                 return 0;
1062         /*
1063          * Do not consider thread group leaders that are
1064          * in a non-empty thread group:
1065          */
1066         if (delay_group_leader(p))
1067                 return 2;
1068
1069         if (security_task_wait(p))
1070                 return 0;
1071
1072         return 1;
1073 }
1074
1075 static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,
1076                                int why, int status,
1077                                struct siginfo __user *infop,
1078                                struct rusage __user *rusagep)
1079 {
1080         int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
1081
1082         put_task_struct(p);
1083         if (!retval)
1084                 retval = put_user(SIGCHLD, &infop->si_signo);
1085         if (!retval)
1086                 retval = put_user(0, &infop->si_errno);
1087         if (!retval)
1088                 retval = put_user((short)why, &infop->si_code);
1089         if (!retval)
1090                 retval = put_user(pid, &infop->si_pid);
1091         if (!retval)
1092                 retval = put_user(uid, &infop->si_uid);
1093         if (!retval)
1094                 retval = put_user(status, &infop->si_status);
1095         if (!retval)
1096                 retval = pid;
1097         return retval;
1098 }
1099
1100 /*
1101  * Handle sys_wait4 work for one task in state EXIT_ZOMBIE.  We hold
1102  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1103  * the lock and this task is uninteresting.  If we return nonzero, we have
1104  * released the lock and the system call should return.
1105  */
1106 static int wait_task_zombie(struct task_struct *p, int noreap,
1107                             struct siginfo __user *infop,
1108                             int __user *stat_addr, struct rusage __user *ru)
1109 {
1110         unsigned long state;
1111         int retval;
1112         int status;
1113
1114         if (unlikely(noreap)) {
1115                 pid_t pid = p->pid;
1116                 uid_t uid = p->uid;
1117                 int exit_code = p->exit_code;
1118                 int why, status;
1119
1120                 if (unlikely(p->exit_state != EXIT_ZOMBIE))
1121                         return 0;
1122                 if (unlikely(p->exit_signal == -1 && p->ptrace == 0))
1123                         return 0;
1124                 get_task_struct(p);
1125                 read_unlock(&tasklist_lock);
1126                 if ((exit_code & 0x7f) == 0) {
1127                         why = CLD_EXITED;
1128                         status = exit_code >> 8;
1129                 } else {
1130                         why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1131                         status = exit_code & 0x7f;
1132                 }
1133                 return wait_noreap_copyout(p, pid, uid, why,
1134                                            status, infop, ru);
1135         }
1136
1137         /*
1138          * Try to move the task's state to DEAD
1139          * only one thread is allowed to do this:
1140          */
1141         state = xchg(&p->exit_state, EXIT_DEAD);
1142         if (state != EXIT_ZOMBIE) {
1143                 BUG_ON(state != EXIT_DEAD);
1144                 return 0;
1145         }
1146         if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) {
1147                 /*
1148                  * This can only happen in a race with a ptraced thread
1149                  * dying on another processor.
1150                  */
1151                 return 0;
1152         }
1153
1154         if (likely(p->real_parent == p->parent) && likely(p->signal)) {
1155                 struct signal_struct *psig;
1156                 struct signal_struct *sig;
1157
1158                 /*
1159                  * The resource counters for the group leader are in its
1160                  * own task_struct.  Those for dead threads in the group
1161                  * are in its signal_struct, as are those for the child
1162                  * processes it has previously reaped.  All these
1163                  * accumulate in the parent's signal_struct c* fields.
1164                  *
1165                  * We don't bother to take a lock here to protect these
1166                  * p->signal fields, because they are only touched by
1167                  * __exit_signal, which runs with tasklist_lock
1168                  * write-locked anyway, and so is excluded here.  We do
1169                  * need to protect the access to p->parent->signal fields,
1170                  * as other threads in the parent group can be right
1171                  * here reaping other children at the same time.
1172                  */
1173                 spin_lock_irq(&p->parent->sighand->siglock);
1174                 psig = p->parent->signal;
1175                 sig = p->signal;
1176                 psig->cutime =
1177                         cputime_add(psig->cutime,
1178                         cputime_add(p->utime,
1179                         cputime_add(sig->utime,
1180                                     sig->cutime)));
1181                 psig->cstime =
1182                         cputime_add(psig->cstime,
1183                         cputime_add(p->stime,
1184                         cputime_add(sig->stime,
1185                                     sig->cstime)));
1186                 psig->cmin_flt +=
1187                         p->min_flt + sig->min_flt + sig->cmin_flt;
1188                 psig->cmaj_flt +=
1189                         p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1190                 psig->cnvcsw +=
1191                         p->nvcsw + sig->nvcsw + sig->cnvcsw;
1192                 psig->cnivcsw +=
1193                         p->nivcsw + sig->nivcsw + sig->cnivcsw;
1194                 spin_unlock_irq(&p->parent->sighand->siglock);
1195         }
1196
1197         /*
1198          * Now we are sure this task is interesting, and no other
1199          * thread can reap it because we set its state to EXIT_DEAD.
1200          */
1201         read_unlock(&tasklist_lock);
1202
1203         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1204         status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1205                 ? p->signal->group_exit_code : p->exit_code;
1206         if (!retval && stat_addr)
1207                 retval = put_user(status, stat_addr);
1208         if (!retval && infop)
1209                 retval = put_user(SIGCHLD, &infop->si_signo);
1210         if (!retval && infop)
1211                 retval = put_user(0, &infop->si_errno);
1212         if (!retval && infop) {
1213                 int why;
1214
1215                 if ((status & 0x7f) == 0) {
1216                         why = CLD_EXITED;
1217                         status >>= 8;
1218                 } else {
1219                         why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1220                         status &= 0x7f;
1221                 }
1222                 retval = put_user((short)why, &infop->si_code);
1223                 if (!retval)
1224                         retval = put_user(status, &infop->si_status);
1225         }
1226         if (!retval && infop)
1227                 retval = put_user(p->pid, &infop->si_pid);
1228         if (!retval && infop)
1229                 retval = put_user(p->uid, &infop->si_uid);
1230         if (retval) {
1231                 // TODO: is this safe?
1232                 p->exit_state = EXIT_ZOMBIE;
1233                 return retval;
1234         }
1235         retval = p->pid;
1236         if (p->real_parent != p->parent) {
1237                 write_lock_irq(&tasklist_lock);
1238                 /* Double-check with lock held.  */
1239                 if (p->real_parent != p->parent) {
1240                         __ptrace_unlink(p);
1241                         // TODO: is this safe?
1242                         p->exit_state = EXIT_ZOMBIE;
1243                         /*
1244                          * If this is not a detached task, notify the parent.
1245                          * If it's still not detached after that, don't release
1246                          * it now.
1247                          */
1248                         if (p->exit_signal != -1) {
1249                                 do_notify_parent(p, p->exit_signal);
1250                                 if (p->exit_signal != -1)
1251                                         p = NULL;
1252                         }
1253                 }
1254                 write_unlock_irq(&tasklist_lock);
1255         }
1256         if (p != NULL)
1257                 release_task(p);
1258         BUG_ON(!retval);
1259         return retval;
1260 }
1261
1262 /*
1263  * Handle sys_wait4 work for one task in state TASK_STOPPED.  We hold
1264  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1265  * the lock and this task is uninteresting.  If we return nonzero, we have
1266  * released the lock and the system call should return.
1267  */
1268 static int wait_task_stopped(struct task_struct *p, int delayed_group_leader,
1269                              int noreap, struct siginfo __user *infop,
1270                              int __user *stat_addr, struct rusage __user *ru)
1271 {
1272         int retval, exit_code;
1273
1274         if (!p->exit_code)
1275                 return 0;
1276         if (delayed_group_leader && !(p->ptrace & PT_PTRACED) &&
1277             p->signal && p->signal->group_stop_count > 0)
1278                 /*
1279                  * A group stop is in progress and this is the group leader.
1280                  * We won't report until all threads have stopped.
1281                  */
1282                 return 0;
1283
1284         /*
1285          * Now we are pretty sure this task is interesting.
1286          * Make sure it doesn't get reaped out from under us while we
1287          * give up the lock and then examine it below.  We don't want to
1288          * keep holding onto the tasklist_lock while we call getrusage and
1289          * possibly take page faults for user memory.
1290          */
1291         get_task_struct(p);
1292         read_unlock(&tasklist_lock);
1293
1294         if (unlikely(noreap)) {
1295                 pid_t pid = p->pid;
1296                 uid_t uid = p->uid;
1297                 int why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
1298
1299                 exit_code = p->exit_code;
1300                 if (unlikely(!exit_code) ||
1301                     unlikely(p->state & TASK_TRACED))
1302                         goto bail_ref;
1303                 return wait_noreap_copyout(p, pid, uid,
1304                                            why, (exit_code << 8) | 0x7f,
1305                                            infop, ru);
1306         }
1307
1308         write_lock_irq(&tasklist_lock);
1309
1310         /*
1311          * This uses xchg to be atomic with the thread resuming and setting
1312          * it.  It must also be done with the write lock held to prevent a
1313          * race with the EXIT_ZOMBIE case.
1314          */
1315         exit_code = xchg(&p->exit_code, 0);
1316         if (unlikely(p->exit_state)) {
1317                 /*
1318                  * The task resumed and then died.  Let the next iteration
1319                  * catch it in EXIT_ZOMBIE.  Note that exit_code might
1320                  * already be zero here if it resumed and did _exit(0).
1321                  * The task itself is dead and won't touch exit_code again;
1322                  * other processors in this function are locked out.
1323                  */
1324                 p->exit_code = exit_code;
1325                 exit_code = 0;
1326         }
1327         if (unlikely(exit_code == 0)) {
1328                 /*
1329                  * Another thread in this function got to it first, or it
1330                  * resumed, or it resumed and then died.
1331                  */
1332                 write_unlock_irq(&tasklist_lock);
1333 bail_ref:
1334                 put_task_struct(p);
1335                 /*
1336                  * We are returning to the wait loop without having successfully
1337                  * removed the process and having released the lock. We cannot
1338                  * continue, since the "p" task pointer is potentially stale.
1339                  *
1340                  * Return -EAGAIN, and do_wait() will restart the loop from the
1341                  * beginning. Do _not_ re-acquire the lock.
1342                  */
1343                 return -EAGAIN;
1344         }
1345
1346         /* move to end of parent's list to avoid starvation */
1347         remove_parent(p);
1348         add_parent(p);
1349
1350         write_unlock_irq(&tasklist_lock);
1351
1352         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1353         if (!retval && stat_addr)
1354                 retval = put_user((exit_code << 8) | 0x7f, stat_addr);
1355         if (!retval && infop)
1356                 retval = put_user(SIGCHLD, &infop->si_signo);
1357         if (!retval && infop)
1358                 retval = put_user(0, &infop->si_errno);
1359         if (!retval && infop)
1360                 retval = put_user((short)((p->ptrace & PT_PTRACED)
1361                                           ? CLD_TRAPPED : CLD_STOPPED),
1362                                   &infop->si_code);
1363         if (!retval && infop)
1364                 retval = put_user(exit_code, &infop->si_status);
1365         if (!retval && infop)
1366                 retval = put_user(p->pid, &infop->si_pid);
1367         if (!retval && infop)
1368                 retval = put_user(p->uid, &infop->si_uid);
1369         if (!retval)
1370                 retval = p->pid;
1371         put_task_struct(p);
1372
1373         BUG_ON(!retval);
1374         return retval;
1375 }
1376
1377 /*
1378  * Handle do_wait work for one task in a live, non-stopped state.
1379  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1380  * the lock and this task is uninteresting.  If we return nonzero, we have
1381  * released the lock and the system call should return.
1382  */
1383 static int wait_task_continued(struct task_struct *p, int noreap,
1384                                struct siginfo __user *infop,
1385                                int __user *stat_addr, struct rusage __user *ru)
1386 {
1387         int retval;
1388         pid_t pid;
1389         uid_t uid;
1390
1391         if (unlikely(!p->signal))
1392                 return 0;
1393
1394         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1395                 return 0;
1396
1397         spin_lock_irq(&p->sighand->siglock);
1398         /* Re-check with the lock held.  */
1399         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1400                 spin_unlock_irq(&p->sighand->siglock);
1401                 return 0;
1402         }
1403         if (!noreap)
1404                 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1405         spin_unlock_irq(&p->sighand->siglock);
1406
1407         pid = p->pid;
1408         uid = p->uid;
1409         get_task_struct(p);
1410         read_unlock(&tasklist_lock);
1411
1412         if (!infop) {
1413                 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1414                 put_task_struct(p);
1415                 if (!retval && stat_addr)
1416                         retval = put_user(0xffff, stat_addr);
1417                 if (!retval)
1418                         retval = p->pid;
1419         } else {
1420                 retval = wait_noreap_copyout(p, pid, uid,
1421                                              CLD_CONTINUED, SIGCONT,
1422                                              infop, ru);
1423                 BUG_ON(retval == 0);
1424         }
1425
1426         return retval;
1427 }
1428
1429
1430 static inline int my_ptrace_child(struct task_struct *p)
1431 {
1432         if (!(p->ptrace & PT_PTRACED))
1433                 return 0;
1434         if (!(p->ptrace & PT_ATTACHED))
1435                 return 1;
1436         /*
1437          * This child was PTRACE_ATTACH'd.  We should be seeing it only if
1438          * we are the attacher.  If we are the real parent, this is a race
1439          * inside ptrace_attach.  It is waiting for the tasklist_lock,
1440          * which we have to switch the parent links, but has already set
1441          * the flags in p->ptrace.
1442          */
1443         return (p->parent != p->real_parent);
1444 }
1445
1446 static long do_wait(pid_t pid, int options, struct siginfo __user *infop,
1447                     int __user *stat_addr, struct rusage __user *ru)
1448 {
1449         DECLARE_WAITQUEUE(wait, current);
1450         struct task_struct *tsk;
1451         int flag, retval;
1452
1453         add_wait_queue(&current->signal->wait_chldexit,&wait);
1454 repeat:
1455         /*
1456          * We will set this flag if we see any child that might later
1457          * match our criteria, even if we are not able to reap it yet.
1458          */
1459         flag = 0;
1460         current->state = TASK_INTERRUPTIBLE;
1461         read_lock(&tasklist_lock);
1462         tsk = current;
1463         do {
1464                 struct task_struct *p;
1465                 struct list_head *_p;
1466                 int ret;
1467
1468                 list_for_each(_p,&tsk->children) {
1469                         p = list_entry(_p, struct task_struct, sibling);
1470
1471                         ret = eligible_child(pid, options, p);
1472                         if (!ret)
1473                                 continue;
1474
1475                         switch (p->state) {
1476                         case TASK_TRACED:
1477                                 /*
1478                                  * When we hit the race with PTRACE_ATTACH,
1479                                  * we will not report this child.  But the
1480                                  * race means it has not yet been moved to
1481                                  * our ptrace_children list, so we need to
1482                                  * set the flag here to avoid a spurious ECHILD
1483                                  * when the race happens with the only child.
1484                                  */
1485                                 flag = 1;
1486                                 if (!my_ptrace_child(p))
1487                                         continue;
1488                                 /*FALLTHROUGH*/
1489                         case TASK_STOPPED:
1490                                 /*
1491                                  * It's stopped now, so it might later
1492                                  * continue, exit, or stop again.
1493                                  */
1494                                 flag = 1;
1495                                 if (!(options & WUNTRACED) &&
1496                                     !my_ptrace_child(p))
1497                                         continue;
1498                                 retval = wait_task_stopped(p, ret == 2,
1499                                                            (options & WNOWAIT),
1500                                                            infop,
1501                                                            stat_addr, ru);
1502                                 if (retval == -EAGAIN)
1503                                         goto repeat;
1504                                 if (retval != 0) /* He released the lock.  */
1505                                         goto end;
1506                                 break;
1507                         default:
1508                         // case EXIT_DEAD:
1509                                 if (p->exit_state == EXIT_DEAD)
1510                                         continue;
1511                         // case EXIT_ZOMBIE:
1512                                 if (p->exit_state == EXIT_ZOMBIE) {
1513                                         /*
1514                                          * Eligible but we cannot release
1515                                          * it yet:
1516                                          */
1517                                         if (ret == 2)
1518                                                 goto check_continued;
1519                                         if (!likely(options & WEXITED))
1520                                                 continue;
1521                                         retval = wait_task_zombie(
1522                                                 p, (options & WNOWAIT),
1523                                                 infop, stat_addr, ru);
1524                                         /* He released the lock.  */
1525                                         if (retval != 0)
1526                                                 goto end;
1527                                         break;
1528                                 }
1529 check_continued:
1530                                 /*
1531                                  * It's running now, so it might later
1532                                  * exit, stop, or stop and then continue.
1533                                  */
1534                                 flag = 1;
1535                                 if (!unlikely(options & WCONTINUED))
1536                                         continue;
1537                                 retval = wait_task_continued(
1538                                         p, (options & WNOWAIT),
1539                                         infop, stat_addr, ru);
1540                                 if (retval != 0) /* He released the lock.  */
1541                                         goto end;
1542                                 break;
1543                         }
1544                 }
1545                 if (!flag) {
1546                         list_for_each(_p, &tsk->ptrace_children) {
1547                                 p = list_entry(_p, struct task_struct,
1548                                                 ptrace_list);
1549                                 if (!eligible_child(pid, options, p))
1550                                         continue;
1551                                 flag = 1;
1552                                 break;
1553                         }
1554                 }
1555                 if (options & __WNOTHREAD)
1556                         break;
1557                 tsk = next_thread(tsk);
1558                 BUG_ON(tsk->signal != current->signal);
1559         } while (tsk != current);
1560
1561         read_unlock(&tasklist_lock);
1562         if (flag) {
1563                 retval = 0;
1564                 if (options & WNOHANG)
1565                         goto end;
1566                 retval = -ERESTARTSYS;
1567                 if (signal_pending(current))
1568                         goto end;
1569                 schedule();
1570                 goto repeat;
1571         }
1572         retval = -ECHILD;
1573 end:
1574         current->state = TASK_RUNNING;
1575         remove_wait_queue(&current->signal->wait_chldexit,&wait);
1576         if (infop) {
1577                 if (retval > 0)
1578                 retval = 0;
1579                 else {
1580                         /*
1581                          * For a WNOHANG return, clear out all the fields
1582                          * we would set so the user can easily tell the
1583                          * difference.
1584                          */
1585                         if (!retval)
1586                                 retval = put_user(0, &infop->si_signo);
1587                         if (!retval)
1588                                 retval = put_user(0, &infop->si_errno);
1589                         if (!retval)
1590                                 retval = put_user(0, &infop->si_code);
1591                         if (!retval)
1592                                 retval = put_user(0, &infop->si_pid);
1593                         if (!retval)
1594                                 retval = put_user(0, &infop->si_uid);
1595                         if (!retval)
1596                                 retval = put_user(0, &infop->si_status);
1597                 }
1598         }
1599         return retval;
1600 }
1601
1602 asmlinkage long sys_waitid(int which, pid_t pid,
1603                            struct siginfo __user *infop, int options,
1604                            struct rusage __user *ru)
1605 {
1606         long ret;
1607
1608         if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1609                 return -EINVAL;
1610         if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1611                 return -EINVAL;
1612
1613         switch (which) {
1614         case P_ALL:
1615                 pid = -1;
1616                 break;
1617         case P_PID:
1618                 if (pid <= 0)
1619                         return -EINVAL;
1620                 break;
1621         case P_PGID:
1622                 if (pid <= 0)
1623                         return -EINVAL;
1624                 pid = -pid;
1625                 break;
1626         default:
1627                 return -EINVAL;
1628         }
1629
1630         ret = do_wait(pid, options, infop, NULL, ru);
1631
1632         /* avoid REGPARM breakage on x86: */
1633         prevent_tail_call(ret);
1634         return ret;
1635 }
1636
1637 asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr,
1638                           int options, struct rusage __user *ru)
1639 {
1640         long ret;
1641
1642         if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1643                         __WNOTHREAD|__WCLONE|__WALL))
1644                 return -EINVAL;
1645         ret = do_wait(pid, options | WEXITED, NULL, stat_addr, ru);
1646
1647         /* avoid REGPARM breakage on x86: */
1648         prevent_tail_call(ret);
1649         return ret;
1650 }
1651
1652 #ifdef __ARCH_WANT_SYS_WAITPID
1653
1654 /*
1655  * sys_waitpid() remains for compatibility. waitpid() should be
1656  * implemented by calling sys_wait4() from libc.a.
1657  */
1658 asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options)
1659 {
1660         return sys_wait4(pid, stat_addr, options, NULL);
1661 }
1662
1663 #endif