kernel/exit.c

   1 /*
   2  *  linux/kernel/exit.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 #include <linux/mm.h>
   8 #include <linux/slab.h>
   9 #include <linux/interrupt.h>
  10 #include <linux/smp_lock.h>
  11 #include <linux/module.h>
  12 #include <linux/capability.h>
  13 #include <linux/completion.h>
  14 #include <linux/personality.h>
  15 #include <linux/tty.h>
  16 #include <linux/mnt_namespace.h>
  17 #include <linux/key.h>
  18 #include <linux/security.h>
  19 #include <linux/cpu.h>
  20 #include <linux/acct.h>
  21 #include <linux/tsacct_kern.h>
  22 #include <linux/file.h>
  23 #include <linux/binfmts.h>
  24 #include <linux/nsproxy.h>
  25 #include <linux/pid_namespace.h>
  26 #include <linux/ptrace.h>
  27 #include <linux/profile.h>
  28 #include <linux/mount.h>
  29 #include <linux/proc_fs.h>
  30 #include <linux/mempolicy.h>
  31 #include <linux/taskstats_kern.h>
  32 #include <linux/delayacct.h>
  33 #include <linux/cpuset.h>
  34 #include <linux/syscalls.h>
  35 #include <linux/signal.h>
  36 #include <linux/posix-timers.h>
  37 #include <linux/cn_proc.h>
  38 #include <linux/mutex.h>
  39 #include <linux/futex.h>
  40 #include <linux/compat.h>
  41 #include <linux/pipe_fs_i.h>
  42 #include <linux/audit.h> /* for audit_free() */
  43 #include <linux/resource.h>
  44 #include <linux/blkdev.h>
  45
  46 #include <asm/uaccess.h>
  47 #include <asm/unistd.h>
  48 #include <asm/pgtable.h>
  49 #include <asm/mmu_context.h>
  50
  51 extern void sem_exit (void);
  52
  53 static void exit_mm(struct task_struct * tsk);
  54
  55 static void __unhash_process(struct task_struct *p)
  56 {
  57         nr_threads--;
  58         detach_pid(p, PIDTYPE_PID);
  59         if (thread_group_leader(p)) {
  60                 detach_pid(p, PIDTYPE_PGID);
  61                 detach_pid(p, PIDTYPE_SID);
  62
  63                 list_del_rcu(&p->tasks);
  64                 __get_cpu_var(process_counts)--;
  65         }
  66         list_del_rcu(&p->thread_group);
  67         remove_parent(p);
  68 }
  69
  70 /*
  71  * This function expects the tasklist_lock write-locked.
  72  */
  73 static void __exit_signal(struct task_struct *tsk)
  74 {
  75         struct signal_struct *sig = tsk->signal;
  76         struct sighand_struct *sighand;
  77
  78         BUG_ON(!sig);
  79         BUG_ON(!atomic_read(&sig->count));
  80
  81         rcu_read_lock();
  82         sighand = rcu_dereference(tsk->sighand);
  83         spin_lock(&sighand->siglock);
  84
  85         posix_cpu_timers_exit(tsk);
  86         if (atomic_dec_and_test(&sig->count))
  87                 posix_cpu_timers_exit_group(tsk);
  88         else {
  89                 /*
  90                  * If there is any task waiting for the group exit
  91                  * then notify it:
  92                  */
  93                 if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count) {
  94                         wake_up_process(sig->group_exit_task);
  95                         sig->group_exit_task = NULL;
  96                 }
  97                 if (tsk == sig->curr_target)
  98                         sig->curr_target = next_thread(tsk);
  99                 /*
 100                  * Accumulate here the counters for all threads but the
 101                  * group leader as they die, so they can be added into
 102                  * the process-wide totals when those are taken.
 103                  * The group leader stays around as a zombie as long
 104                  * as there are other threads.  When it gets reaped,
 105                  * the exit.c code will add its counts into these totals.
 106                  * We won't ever get here for the group leader, since it
 107                  * will have been the last reference on the signal_struct.
 108                  */
 109                 sig->utime = cputime_add(sig->utime, tsk->utime);
 110                 sig->stime = cputime_add(sig->stime, tsk->stime);
 111                 sig->min_flt += tsk->min_flt;
 112                 sig->maj_flt += tsk->maj_flt;
 113                 sig->nvcsw += tsk->nvcsw;
 114                 sig->nivcsw += tsk->nivcsw;
 115                 sig->sched_time += tsk->sched_time;
 116                 sig = NULL; /* Marker for below. */
 117         }
 118
 119         __unhash_process(tsk);
 120
 121         tsk->signal = NULL;
 122         tsk->sighand = NULL;
 123         spin_unlock(&sighand->siglock);
 124         rcu_read_unlock();
 125
 126         __cleanup_sighand(sighand);
 127         clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
 128         flush_sigqueue(&tsk->pending);
 129         if (sig) {
 130                 flush_sigqueue(&sig->shared_pending);
 131                 taskstats_tgid_free(sig);
 132                 __cleanup_signal(sig);
 133         }
 134 }
 135
 136 static void delayed_put_task_struct(struct rcu_head *rhp)
 137 {
 138         put_task_struct(container_of(rhp, struct task_struct, rcu));
 139 }
 140
 141 void release_task(struct task_struct * p)
 142 {
 143         struct task_struct *leader;
 144         int zap_leader;
 145 repeat:
 146         atomic_dec(&p->user->processes);
 147         write_lock_irq(&tasklist_lock);
 148         ptrace_unlink(p);
 149         BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
 150         __exit_signal(p);
 151
 152         /*
 153          * If we are the last non-leader member of the thread
 154          * group, and the leader is zombie, then notify the
 155          * group leader's parent process. (if it wants notification.)
 156          */
 157         zap_leader = 0;
 158         leader = p->group_leader;
 159         if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
 160                 BUG_ON(leader->exit_signal == -1);
 161                 do_notify_parent(leader, leader->exit_signal);
 162                 /*
 163                  * If we were the last child thread and the leader has
 164                  * exited already, and the leader's parent ignores SIGCHLD,
 165                  * then we are the one who should release the leader.
 166                  *
 167                  * do_notify_parent() will have marked it self-reaping in
 168                  * that case.
 169                  */
 170                 zap_leader = (leader->exit_signal == -1);
 171         }
 172
 173         sched_exit(p);
 174         write_unlock_irq(&tasklist_lock);
 175         proc_flush_task(p);
 176         release_thread(p);
 177         call_rcu(&p->rcu, delayed_put_task_struct);
 178
 179         p = leader;
 180         if (unlikely(zap_leader))
 181                 goto repeat;
 182 }
 183
 184 /*
 185  * This checks not only the pgrp, but falls back on the pid if no
 186  * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
 187  * without this...
 188  */
 189 int session_of_pgrp(int pgrp)
 190 {
 191         struct task_struct *p;
 192         int sid = 0;
 193
 194         read_lock(&tasklist_lock);
 195
 196         p = find_task_by_pid_type(PIDTYPE_PGID, pgrp);
 197         if (p == NULL)
 198                 p = find_task_by_pid(pgrp);
 199         if (p != NULL)
 200                 sid = process_session(p);
 201
 202         read_unlock(&tasklist_lock);
 203
 204         return sid;
 205 }
 206
 207 /*
 208  * Determine if a process group is "orphaned", according to the POSIX
 209  * definition in 2.2.2.52.  Orphaned process groups are not to be affected
 210  * by terminal-generated stop signals.  Newly orphaned process groups are
 211  * to receive a SIGHUP and a SIGCONT.
 212  *
 213  * "I ask you, have you ever known what it is to be an orphan?"
 214  */
 215 static int will_become_orphaned_pgrp(int pgrp, struct task_struct *ignored_task)
 216 {
 217         struct task_struct *p;
 218         int ret = 1;
 219
 220         do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
 221                 if (p == ignored_task
 222                                 || p->exit_state
 223                                 || is_init(p->real_parent))
 224                         continue;
 225                 if (process_group(p->real_parent) != pgrp &&
 226                     process_session(p->real_parent) == process_session(p)) {
 227                         ret = 0;
 228                         break;
 229                 }
 230         } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
 231         return ret;     /* (sighing) "Often!" */
 232 }
 233
 234 int is_orphaned_pgrp(int pgrp)
 235 {
 236         int retval;
 237
 238         read_lock(&tasklist_lock);
 239         retval = will_become_orphaned_pgrp(pgrp, NULL);
 240         read_unlock(&tasklist_lock);
 241
 242         return retval;
 243 }
 244
 245 static int has_stopped_jobs(int pgrp)
 246 {
 247         int retval = 0;
 248         struct task_struct *p;
 249
 250         do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
 251                 if (p->state != TASK_STOPPED)
 252                         continue;
 253                 retval = 1;
 254                 break;
 255         } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
 256         return retval;
 257 }
 258
 259 /**
 260  * reparent_to_init - Reparent the calling kernel thread to the init task
 261  * of the pid space that the thread belongs to.
 262  *
 263  * If a kernel thread is launched as a result of a system call, or if
 264  * it ever exits, it should generally reparent itself to init so that
 265  * it is correctly cleaned up on exit.
 266  *
 267  * The various task state such as scheduling policy and priority may have
 268  * been inherited from a user process, so we reset them to sane values here.
 269  *
 270  * NOTE that reparent_to_init() gives the caller full capabilities.
 271  */
 272 static void reparent_to_init(void)
 273 {
 274         write_lock_irq(&tasklist_lock);
 275
 276         ptrace_unlink(current);
 277         /* Reparent to init */
 278         remove_parent(current);
 279         current->parent = child_reaper(current);
 280         current->real_parent = child_reaper(current);
 281         add_parent(current);
 282
 283         /* Set the exit signal to SIGCHLD so we signal init on exit */
 284         current->exit_signal = SIGCHLD;
 285
 286         if (!has_rt_policy(current) && (task_nice(current) < 0))
 287                 set_user_nice(current, 0);
 288         /* cpus_allowed? */
 289         /* rt_priority? */
 290         /* signals? */
 291         security_task_reparent_to_init(current);
 292         memcpy(current->signal->rlim, init_task.signal->rlim,
 293                sizeof(current->signal->rlim));
 294         atomic_inc(&(INIT_USER->__count));
 295         write_unlock_irq(&tasklist_lock);
 296         switch_uid(INIT_USER);
 297 }
 298
 299 void __set_special_pids(pid_t session, pid_t pgrp)
 300 {
 301         struct task_struct *curr = current->group_leader;
 302
 303         if (process_session(curr) != session) {
 304                 detach_pid(curr, PIDTYPE_SID);
 305                 set_signal_session(curr->signal, session);
 306                 attach_pid(curr, PIDTYPE_SID, session);
 307         }
 308         if (process_group(curr) != pgrp) {
 309                 detach_pid(curr, PIDTYPE_PGID);
 310                 curr->signal->pgrp = pgrp;
 311                 attach_pid(curr, PIDTYPE_PGID, pgrp);
 312         }
 313 }
 314
 315 static void set_special_pids(pid_t session, pid_t pgrp)
 316 {
 317         write_lock_irq(&tasklist_lock);
 318         __set_special_pids(session, pgrp);
 319         write_unlock_irq(&tasklist_lock);
 320 }
 321
 322 /*
 323  * Let kernel threads use this to say that they
 324  * allow a certain signal (since daemonize() will
 325  * have disabled all of them by default).
 326  */
 327 int allow_signal(int sig)
 328 {
 329         if (!valid_signal(sig) || sig < 1)
 330                 return -EINVAL;
 331
 332         spin_lock_irq(&current->sighand->siglock);
 333         sigdelset(&current->blocked, sig);
 334         if (!current->mm) {
 335                 /* Kernel threads handle their own signals.
 336                    Let the signal code know it'll be handled, so
 337                    that they don't get converted to SIGKILL or
 338                    just silently dropped */
 339                 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
 340         }
 341         recalc_sigpending();
 342         spin_unlock_irq(&current->sighand->siglock);
 343         return 0;
 344 }
 345
 346 EXPORT_SYMBOL(allow_signal);
 347
 348 int disallow_signal(int sig)
 349 {
 350         if (!valid_signal(sig) || sig < 1)
 351                 return -EINVAL;
 352
 353         spin_lock_irq(&current->sighand->siglock);
 354         sigaddset(&current->blocked, sig);
 355         recalc_sigpending();
 356         spin_unlock_irq(&current->sighand->siglock);
 357         return 0;
 358 }
 359
 360 EXPORT_SYMBOL(disallow_signal);
 361
 362 /*
 363  *      Put all the gunge required to become a kernel thread without
 364  *      attached user resources in one place where it belongs.
 365  */
 366
 367 void daemonize(const char *name, ...)
 368 {
 369         va_list args;
 370         struct fs_struct *fs;
 371         sigset_t blocked;
 372
 373         va_start(args, name);
 374         vsnprintf(current->comm, sizeof(current->comm), name, args);
 375         va_end(args);
 376
 377         /*
 378          * If we were started as result of loading a module, close all of the
 379          * user space pages.  We don't need them, and if we didn't close them
 380          * they would be locked into memory.
 381          */
 382         exit_mm(current);
 383
 384         set_special_pids(1, 1);
 385         proc_clear_tty(current);
 386
 387         /* Block and flush all signals */
 388         sigfillset(&blocked);
 389         sigprocmask(SIG_BLOCK, &blocked, NULL);
 390         flush_signals(current);
 391
 392         /* Become as one with the init task */
 393
 394         exit_fs(current);       /* current->fs->count--; */
 395         fs = init_task.fs;
 396         current->fs = fs;
 397         atomic_inc(&fs->count);
 398
 399         put_and_finalize_nsproxy(current->nsproxy);
 400         current->nsproxy = init_task.nsproxy;
 401         get_task_namespaces(current);
 402
 403         exit_files(current);
 404         current->files = init_task.files;
 405         atomic_inc(&current->files->count);
 406
 407         reparent_to_init();
 408 }
 409
 410 EXPORT_SYMBOL(daemonize);
 411
 412 static void close_files(struct files_struct * files)
 413 {
 414         int i, j;
 415         struct fdtable *fdt;
 416
 417         j = 0;
 418
 419         /*
 420          * It is safe to dereference the fd table without RCU or
 421          * ->file_lock because this is the last reference to the
 422          * files structure.
 423          */
 424         fdt = files_fdtable(files);
 425         for (;;) {
 426                 unsigned long set;
 427                 i = j * __NFDBITS;
 428                 if (i >= fdt->max_fds)
 429                         break;
 430                 set = fdt->open_fds->fds_bits[j++];
 431                 while (set) {
 432                         if (set & 1) {
 433                                 struct file * file = xchg(&fdt->fd[i], NULL);
 434                                 if (file)
 435                                         filp_close(file, files);
 436                         }
 437                         i++;
 438                         set >>= 1;
 439                 }
 440         }
 441 }
 442
 443 struct files_struct *get_files_struct(struct task_struct *task)
 444 {
 445         struct files_struct *files;
 446
 447         task_lock(task);
 448         files = task->files;
 449         if (files)
 450                 atomic_inc(&files->count);
 451         task_unlock(task);
 452
 453         return files;
 454 }
 455
 456 void fastcall put_files_struct(struct files_struct *files)
 457 {
 458         struct fdtable *fdt;
 459
 460         if (atomic_dec_and_test(&files->count)) {
 461                 close_files(files);
 462                 /*
 463                  * Free the fd and fdset arrays if we expanded them.
 464                  * If the fdtable was embedded, pass files for freeing
 465                  * at the end of the RCU grace period. Otherwise,
 466                  * you can free files immediately.
 467                  */
 468                 fdt = files_fdtable(files);
 469                 if (fdt != &files->fdtab)
 470                         kmem_cache_free(files_cachep, files);
 471                 free_fdtable(fdt);
 472         }
 473 }
 474
 475 EXPORT_SYMBOL(put_files_struct);
 476
 477 void reset_files_struct(struct task_struct *tsk, struct files_struct *files)
 478 {
 479         struct files_struct *old;
 480
 481         old = tsk->files;
 482         task_lock(tsk);
 483         tsk->files = files;
 484         task_unlock(tsk);
 485         put_files_struct(old);
 486 }
 487 EXPORT_SYMBOL(reset_files_struct);
 488
 489 static inline void __exit_files(struct task_struct *tsk)
 490 {
 491         struct files_struct * files = tsk->files;
 492
 493         if (files) {
 494                 task_lock(tsk);
 495                 tsk->files = NULL;
 496                 task_unlock(tsk);
 497                 put_files_struct(files);
 498         }
 499 }
 500
 501 void exit_files(struct task_struct *tsk)
 502 {
 503         __exit_files(tsk);
 504 }
 505
 506 static inline void __put_fs_struct(struct fs_struct *fs)
 507 {
 508         /* No need to hold fs->lock if we are killing it */
 509         if (atomic_dec_and_test(&fs->count)) {
 510                 dput(fs->root);
 511                 mntput(fs->rootmnt);
 512                 dput(fs->pwd);
 513                 mntput(fs->pwdmnt);
 514                 if (fs->altroot) {
 515                         dput(fs->altroot);
 516                         mntput(fs->altrootmnt);
 517                 }
 518                 kmem_cache_free(fs_cachep, fs);
 519         }
 520 }
 521
 522 void put_fs_struct(struct fs_struct *fs)
 523 {
 524         __put_fs_struct(fs);
 525 }
 526
 527 static inline void __exit_fs(struct task_struct *tsk)
 528 {
 529         struct fs_struct * fs = tsk->fs;
 530
 531         if (fs) {
 532                 task_lock(tsk);
 533                 tsk->fs = NULL;
 534                 task_unlock(tsk);
 535                 __put_fs_struct(fs);
 536         }
 537 }
 538
 539 void exit_fs(struct task_struct *tsk)
 540 {
 541         __exit_fs(tsk);
 542 }
 543
 544 EXPORT_SYMBOL_GPL(exit_fs);
 545
 546 /*
 547  * Turn us into a lazy TLB process if we
 548  * aren't already..
 549  */
 550 static void exit_mm(struct task_struct * tsk)
 551 {
 552         struct mm_struct *mm = tsk->mm;
 553
 554         mm_release(tsk, mm);
 555         if (!mm)
 556                 return;
 557         /*
 558          * Serialize with any possible pending coredump.
 559          * We must hold mmap_sem around checking core_waiters
 560          * and clearing tsk->mm.  The core-inducing thread
 561          * will increment core_waiters for each thread in the
 562          * group with ->mm != NULL.
 563          */
 564         down_read(&mm->mmap_sem);
 565         if (mm->core_waiters) {
 566                 up_read(&mm->mmap_sem);
 567                 down_write(&mm->mmap_sem);
 568                 if (!--mm->core_waiters)
 569                         complete(mm->core_startup_done);
 570                 up_write(&mm->mmap_sem);
 571
 572                 wait_for_completion(&mm->core_done);
 573                 down_read(&mm->mmap_sem);
 574         }
 575         atomic_inc(&mm->mm_count);
 576         BUG_ON(mm != tsk->active_mm);
 577         /* more a memory barrier than a real lock */
 578         task_lock(tsk);
 579         tsk->mm = NULL;
 580         up_read(&mm->mmap_sem);
 581         enter_lazy_tlb(mm, current);
 582         task_unlock(tsk);
 583         mmput(mm);
 584 }
 585
 586 static inline void
 587 choose_new_parent(struct task_struct *p, struct task_struct *reaper)
 588 {
 589         /*
 590          * Make sure we're not reparenting to ourselves and that
 591          * the parent is not a zombie.
 592          */
 593         BUG_ON(p == reaper || reaper->exit_state);
 594         p->real_parent = reaper;
 595 }
 596
 597 static void
 598 reparent_thread(struct task_struct *p, struct task_struct *father, int traced)
 599 {
 600         if (p->pdeath_signal)
 601                 /* We already hold the tasklist_lock here.  */
 602                 group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);
 603
 604         /* Move the child from its dying parent to the new one.  */
 605         if (unlikely(traced)) {
 606                 /* Preserve ptrace links if someone else is tracing this child.  */
 607                 list_del_init(&p->ptrace_list);
 608                 if (p->parent != p->real_parent)
 609                         list_add(&p->ptrace_list, &p->real_parent->ptrace_children);
 610         } else {
 611                 /* If this child is being traced, then we're the one tracing it
 612                  * anyway, so let go of it.
 613                  */
 614                 p->ptrace = 0;
 615                 remove_parent(p);
 616                 p->parent = p->real_parent;
 617                 add_parent(p);
 618
 619                 if (p->state == TASK_TRACED) {
 620                         /*
 621                          * If it was at a trace stop, turn it into
 622                          * a normal stop since it's no longer being
 623                          * traced.
 624                          */
 625                         ptrace_untrace(p);
 626                 }
 627         }
 628
 629         /* If this is a threaded reparent there is no need to
 630          * notify anyone anything has happened.
 631          */
 632         if (p->real_parent->group_leader == father->group_leader)
 633                 return;
 634
 635         /* We don't want people slaying init.  */
 636         if (p->exit_signal != -1)
 637                 p->exit_signal = SIGCHLD;
 638
 639         /* If we'd notified the old parent about this child's death,
 640          * also notify the new parent.
 641          */
 642         if (!traced && p->exit_state == EXIT_ZOMBIE &&
 643             p->exit_signal != -1 && thread_group_empty(p))
 644                 do_notify_parent(p, p->exit_signal);
 645
 646         /*
 647          * process group orphan check
 648          * Case ii: Our child is in a different pgrp
 649          * than we are, and it was the only connection
 650          * outside, so the child pgrp is now orphaned.
 651          */
 652         if ((process_group(p) != process_group(father)) &&
 653             (process_session(p) == process_session(father))) {
 654                 int pgrp = process_group(p);
 655
 656                 if (will_become_orphaned_pgrp(pgrp, NULL) &&
 657                     has_stopped_jobs(pgrp)) {
 658                         __kill_pg_info(SIGHUP, SEND_SIG_PRIV, pgrp);
 659                         __kill_pg_info(SIGCONT, SEND_SIG_PRIV, pgrp);
 660                 }
 661         }
 662 }
 663
 664 /*
 665  * When we die, we re-parent all our children.
 666  * Try to give them to another thread in our thread
 667  * group, and if no such member exists, give it to
 668  * the child reaper process (ie "init") in our pid
 669  * space.
 670  */
 671 static void
 672 forget_original_parent(struct task_struct *father, struct list_head *to_release)
 673 {
 674         struct task_struct *p, *reaper = father;
 675         struct list_head *_p, *_n;
 676
 677         do {
 678                 reaper = next_thread(reaper);
 679                 if (reaper == father) {
 680                         reaper = child_reaper(father);
 681                         break;
 682                 }
 683         } while (reaper->exit_state);
 684
 685         /*
 686          * There are only two places where our children can be:
 687          *
 688          * - in our child list
 689          * - in our ptraced child list
 690          *
 691          * Search them and reparent children.
 692          */
 693         list_for_each_safe(_p, _n, &father->children) {
 694                 int ptrace;
 695                 p = list_entry(_p, struct task_struct, sibling);
 696
 697                 ptrace = p->ptrace;
 698
 699                 /* if father isn't the real parent, then ptrace must be enabled */
 700                 BUG_ON(father != p->real_parent && !ptrace);
 701
 702                 if (father == p->real_parent) {
 703                         /* reparent with a reaper, real father it's us */
 704                         choose_new_parent(p, reaper);
 705                         reparent_thread(p, father, 0);
 706                 } else {
 707                         /* reparent ptraced task to its real parent */
 708                         __ptrace_unlink (p);
 709                         if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
 710                             thread_group_empty(p))
 711                                 do_notify_parent(p, p->exit_signal);
 712                 }
 713
 714                 /*
 715                  * if the ptraced child is a zombie with exit_signal == -1
 716                  * we must collect it before we exit, or it will remain
 717                  * zombie forever since we prevented it from self-reap itself
 718                  * while it was being traced by us, to be able to see it in wait4.
 719                  */
 720                 if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && p->exit_signal == -1))
 721                         list_add(&p->ptrace_list, to_release);
 722         }
 723         list_for_each_safe(_p, _n, &father->ptrace_children) {
 724                 p = list_entry(_p, struct task_struct, ptrace_list);
 725                 choose_new_parent(p, reaper);
 726                 reparent_thread(p, father, 1);
 727         }
 728 }
 729
 730 /*
 731  * Send signals to all our closest relatives so that they know
 732  * to properly mourn us..
 733  */
 734 static void exit_notify(struct task_struct *tsk)
 735 {
 736         int state;
 737         struct task_struct *t;
 738         struct list_head ptrace_dead, *_p, *_n;
 739
 740         if (signal_pending(tsk) && !(tsk->signal->flags & SIGNAL_GROUP_EXIT)
 741             && !thread_group_empty(tsk)) {
 742                 /*
 743                  * This occurs when there was a race between our exit
 744                  * syscall and a group signal choosing us as the one to
 745                  * wake up.  It could be that we are the only thread
 746                  * alerted to check for pending signals, but another thread
 747                  * should be woken now to take the signal since we will not.
 748                  * Now we'll wake all the threads in the group just to make
 749                  * sure someone gets all the pending signals.
 750                  */
 751                 read_lock(&tasklist_lock);
 752                 spin_lock_irq(&tsk->sighand->siglock);
 753                 for (t = next_thread(tsk); t != tsk; t = next_thread(t))
 754                         if (!signal_pending(t) && !(t->flags & PF_EXITING)) {
 755                                 recalc_sigpending_tsk(t);
 756                                 if (signal_pending(t))
 757                                         signal_wake_up(t, 0);
 758                         }
 759                 spin_unlock_irq(&tsk->sighand->siglock);
 760                 read_unlock(&tasklist_lock);
 761         }
 762
 763         write_lock_irq(&tasklist_lock);
 764
 765         /*
 766          * This does two things:
 767          *
 768          * A.  Make init inherit all the child processes
 769          * B.  Check to see if any process groups have become orphaned
 770          *      as a result of our exiting, and if they have any stopped
 771          *      jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
 772          */
 773
 774         INIT_LIST_HEAD(&ptrace_dead);
 775         forget_original_parent(tsk, &ptrace_dead);
 776         BUG_ON(!list_empty(&tsk->children));
 777         BUG_ON(!list_empty(&tsk->ptrace_children));
 778
 779         /*
 780          * Check to see if any process groups have become orphaned
 781          * as a result of our exiting, and if they have any stopped
 782          * jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
 783          *
 784          * Case i: Our father is in a different pgrp than we are
 785          * and we were the only connection outside, so our pgrp
 786          * is about to become orphaned.
 787          */
 788
 789         t = tsk->real_parent;
 790
 791         if ((process_group(t) != process_group(tsk)) &&
 792             (process_session(t) == process_session(tsk)) &&
 793             will_become_orphaned_pgrp(process_group(tsk), tsk) &&
 794             has_stopped_jobs(process_group(tsk))) {
 795                 __kill_pg_info(SIGHUP, SEND_SIG_PRIV, process_group(tsk));
 796                 __kill_pg_info(SIGCONT, SEND_SIG_PRIV, process_group(tsk));
 797         }
 798
 799         /* Let father know we died
 800          *
 801          * Thread signals are configurable, but you aren't going to use
 802          * that to send signals to arbitary processes.
 803          * That stops right now.
 804          *
 805          * If the parent exec id doesn't match the exec id we saved
 806          * when we started then we know the parent has changed security
 807          * domain.
 808          *
 809          * If our self_exec id doesn't match our parent_exec_id then
 810          * we have changed execution domain as these two values started
 811          * the same after a fork.
 812          *
 813          */
 814
 815         if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 &&
 816             ( tsk->parent_exec_id != t->self_exec_id  ||
 817               tsk->self_exec_id != tsk->parent_exec_id)
 818             && !capable(CAP_KILL))
 819                 tsk->exit_signal = SIGCHLD;
 820
 821
 822         /* If something other than our normal parent is ptracing us, then
 823          * send it a SIGCHLD instead of honoring exit_signal.  exit_signal
 824          * only has special meaning to our real parent.
 825          */
 826         if (tsk->exit_signal != -1 && thread_group_empty(tsk)) {
 827                 int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD;
 828                 do_notify_parent(tsk, signal);
 829         } else if (tsk->ptrace) {
 830                 do_notify_parent(tsk, SIGCHLD);
 831         }
 832
 833         state = EXIT_ZOMBIE;
 834         if (tsk->exit_signal == -1 &&
 835             (likely(tsk->ptrace == 0) ||
 836              unlikely(tsk->parent->signal->flags & SIGNAL_GROUP_EXIT)))
 837                 state = EXIT_DEAD;
 838         tsk->exit_state = state;
 839
 840         write_unlock_irq(&tasklist_lock);
 841
 842         list_for_each_safe(_p, _n, &ptrace_dead) {
 843                 list_del_init(_p);
 844                 t = list_entry(_p, struct task_struct, ptrace_list);
 845                 release_task(t);
 846         }
 847
 848         /* If the process is dead, release it - nobody will wait for it */
 849         if (state == EXIT_DEAD)
 850                 release_task(tsk);
 851 }
 852
 853 fastcall NORET_TYPE void do_exit(long code)
 854 {
 855         struct task_struct *tsk = current;
 856         struct nsproxy *ns;
 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         ns = preexit_task_namespaces(tsk);
 943         exit_notify(tsk);
 944         exit_task_namespaces(tsk, ns);
 945 #ifdef CONFIG_NUMA
 946         mpol_free(tsk->mempolicy);
 947         tsk->mempolicy = NULL;
 948 #endif
 949         /*
 950          * This must happen late, after the PID is not
 951          * hashed anymore:
 952          */
 953         if (unlikely(!list_empty(&tsk->pi_state_list)))
 954                 exit_pi_state_list(tsk);
 955         if (unlikely(current->pi_state_cache))
 956                 kfree(current->pi_state_cache);
 957         /*
 958          * Make sure we are holding no locks:
 959          */
 960         debug_check_no_locks_held(tsk);
 961
 962         if (tsk->io_context)
 963                 exit_io_context();
 964
 965         if (tsk->splice_pipe)
 966                 __free_pipe_info(tsk->splice_pipe);
 967
 968         preempt_disable();
 969         /* causes final put_task_struct in finish_task_switch(). */
 970         tsk->state = TASK_DEAD;
 971
 972         schedule();
 973         BUG();
 974         /* Avoid "noreturn function does return".  */
 975         for (;;)
 976                 cpu_relax();    /* For when BUG is null */
 977 }
 978
 979 EXPORT_SYMBOL_GPL(do_exit);
 980
 981 NORET_TYPE void complete_and_exit(struct completion *comp, long code)
 982 {
 983         if (comp)
 984                 complete(comp);
 985
 986         do_exit(code);
 987 }
 988
 989 EXPORT_SYMBOL(complete_and_exit);
 990
 991 asmlinkage long sys_exit(int error_code)
 992 {
 993         do_exit((error_code&0xff)<<8);
 994 }
 995
 996 /*
 997  * Take down every thread in the group.  This is called by fatal signals
 998  * as well as by sys_exit_group (below).
 999  */
1000 NORET_TYPE void
1001 do_group_exit(int exit_code)
1002 {
1003         BUG_ON(exit_code & 0x80); /* core dumps don't get here */
1004
1005         if (current->signal->flags & SIGNAL_GROUP_EXIT)
1006                 exit_code = current->signal->group_exit_code;
1007         else if (!thread_group_empty(current)) {
1008                 struct signal_struct *const sig = current->signal;
1009                 struct sighand_struct *const sighand = current->sighand;
1010                 spin_lock_irq(&sighand->siglock);
1011                 if (sig->flags & SIGNAL_GROUP_EXIT)
1012                         /* Another thread got here before we took the lock.  */
1013                         exit_code = sig->group_exit_code;
1014                 else {
1015                         sig->group_exit_code = exit_code;
1016                         zap_other_threads(current);
1017                 }
1018                 spin_unlock_irq(&sighand->siglock);
1019         }
1020
1021         do_exit(exit_code);
1022         /* NOTREACHED */
1023 }
1024
1025 /*
1026  * this kills every thread in the thread group. Note that any externally
1027  * wait4()-ing process will get the correct exit code - even if this
1028  * thread is not the thread group leader.
1029  */
1030 asmlinkage void sys_exit_group(int error_code)
1031 {
1032         do_group_exit((error_code & 0xff) << 8);
1033 }
1034
1035 static int eligible_child(pid_t pid, int options, struct task_struct *p)
1036 {
1037         if (pid > 0) {
1038                 if (p->pid != pid)
1039                         return 0;
1040         } else if (!pid) {
1041                 if (process_group(p) != process_group(current))
1042                         return 0;
1043         } else if (pid != -1) {
1044                 if (process_group(p) != -pid)
1045                         return 0;
1046         }
1047
1048         /*
1049          * Do not consider detached threads that are
1050          * not ptraced:
1051          */
1052         if (p->exit_signal == -1 && !p->ptrace)
1053                 return 0;
1054
1055         /* Wait for all children (clone and not) if __WALL is set;
1056          * otherwise, wait for clone children *only* if __WCLONE is
1057          * set; otherwise, wait for non-clone children *only*.  (Note:
1058          * A "clone" child here is one that reports to its parent
1059          * using a signal other than SIGCHLD.) */
1060         if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
1061             && !(options & __WALL))
1062                 return 0;
1063         /*
1064          * Do not consider thread group leaders that are
1065          * in a non-empty thread group:
1066          */
1067         if (delay_group_leader(p))
1068                 return 2;
1069
1070         if (security_task_wait(p))
1071                 return 0;
1072
1073         return 1;
1074 }
1075
1076 static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,
1077                                int why, int status,
1078                                struct siginfo __user *infop,
1079                                struct rusage __user *rusagep)
1080 {
1081         int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
1082
1083         put_task_struct(p);
1084         if (!retval)
1085                 retval = put_user(SIGCHLD, &infop->si_signo);
1086         if (!retval)
1087                 retval = put_user(0, &infop->si_errno);
1088         if (!retval)
1089                 retval = put_user((short)why, &infop->si_code);
1090         if (!retval)
1091                 retval = put_user(pid, &infop->si_pid);
1092         if (!retval)
1093                 retval = put_user(uid, &infop->si_uid);
1094         if (!retval)
1095                 retval = put_user(status, &infop->si_status);
1096         if (!retval)
1097                 retval = pid;
1098         return retval;
1099 }
1100
1101 /*
1102  * Handle sys_wait4 work for one task in state EXIT_ZOMBIE.  We hold
1103  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1104  * the lock and this task is uninteresting.  If we return nonzero, we have
1105  * released the lock and the system call should return.
1106  */
1107 static int wait_task_zombie(struct task_struct *p, int noreap,
1108                             struct siginfo __user *infop,
1109                             int __user *stat_addr, struct rusage __user *ru)
1110 {
1111         unsigned long state;
1112         int retval;
1113         int status;
1114
1115         if (unlikely(noreap)) {
1116                 pid_t pid = p->pid;
1117                 uid_t uid = p->uid;
1118                 int exit_code = p->exit_code;
1119                 int why, status;
1120
1121                 if (unlikely(p->exit_state != EXIT_ZOMBIE))
1122                         return 0;
1123                 if (unlikely(p->exit_signal == -1 && p->ptrace == 0))
1124                         return 0;
1125                 get_task_struct(p);
1126                 read_unlock(&tasklist_lock);
1127                 if ((exit_code & 0x7f) == 0) {
1128                         why = CLD_EXITED;
1129                         status = exit_code >> 8;
1130                 } else {
1131                         why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1132                         status = exit_code & 0x7f;
1133                 }
1134                 return wait_noreap_copyout(p, pid, uid, why,
1135                                            status, infop, ru);
1136         }
1137
1138         /*
1139          * Try to move the task's state to DEAD
1140          * only one thread is allowed to do this:
1141          */
1142         state = xchg(&p->exit_state, EXIT_DEAD);
1143         if (state != EXIT_ZOMBIE) {
1144                 BUG_ON(state != EXIT_DEAD);
1145                 return 0;
1146         }
1147         if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) {
1148                 /*
1149                  * This can only happen in a race with a ptraced thread
1150                  * dying on another processor.
1151                  */
1152                 return 0;
1153         }
1154
1155         if (likely(p->real_parent == p->parent) && likely(p->signal)) {
1156                 struct signal_struct *psig;
1157                 struct signal_struct *sig;
1158
1159                 /*
1160                  * The resource counters for the group leader are in its
1161                  * own task_struct.  Those for dead threads in the group
1162                  * are in its signal_struct, as are those for the child
1163                  * processes it has previously reaped.  All these
1164                  * accumulate in the parent's signal_struct c* fields.
1165                  *
1166                  * We don't bother to take a lock here to protect these
1167                  * p->signal fields, because they are only touched by
1168                  * __exit_signal, which runs with tasklist_lock
1169                  * write-locked anyway, and so is excluded here.  We do
1170                  * need to protect the access to p->parent->signal fields,
1171                  * as other threads in the parent group can be right
1172                  * here reaping other children at the same time.
1173                  */
1174                 spin_lock_irq(&p->parent->sighand->siglock);
1175                 psig = p->parent->signal;
1176                 sig = p->signal;
1177                 psig->cutime =
1178                         cputime_add(psig->cutime,
1179                         cputime_add(p->utime,
1180                         cputime_add(sig->utime,
1181                                     sig->cutime)));
1182                 psig->cstime =
1183                         cputime_add(psig->cstime,
1184                         cputime_add(p->stime,
1185                         cputime_add(sig->stime,
1186                                     sig->cstime)));
1187                 psig->cmin_flt +=
1188                         p->min_flt + sig->min_flt + sig->cmin_flt;
1189                 psig->cmaj_flt +=
1190                         p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1191                 psig->cnvcsw +=
1192                         p->nvcsw + sig->nvcsw + sig->cnvcsw;
1193                 psig->cnivcsw +=
1194                         p->nivcsw + sig->nivcsw + sig->cnivcsw;
1195                 spin_unlock_irq(&p->parent->sighand->siglock);
1196         }
1197
1198         /*
1199          * Now we are sure this task is interesting, and no other
1200          * thread can reap it because we set its state to EXIT_DEAD.
1201          */
1202         read_unlock(&tasklist_lock);
1203
1204         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1205         status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1206                 ? p->signal->group_exit_code : p->exit_code;
1207         if (!retval && stat_addr)
1208                 retval = put_user(status, stat_addr);
1209         if (!retval && infop)
1210                 retval = put_user(SIGCHLD, &infop->si_signo);
1211         if (!retval && infop)
1212                 retval = put_user(0, &infop->si_errno);
1213         if (!retval && infop) {
1214                 int why;
1215
1216                 if ((status & 0x7f) == 0) {
1217                         why = CLD_EXITED;
1218                         status >>= 8;
1219                 } else {
1220                         why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1221                         status &= 0x7f;
1222                 }
1223                 retval = put_user((short)why, &infop->si_code);
1224                 if (!retval)
1225                         retval = put_user(status, &infop->si_status);
1226         }
1227         if (!retval && infop)
1228                 retval = put_user(p->pid, &infop->si_pid);
1229         if (!retval && infop)
1230                 retval = put_user(p->uid, &infop->si_uid);
1231         if (retval) {
1232                 // TODO: is this safe?
1233                 p->exit_state = EXIT_ZOMBIE;
1234                 return retval;
1235         }
1236         retval = p->pid;
1237         if (p->real_parent != p->parent) {
1238                 write_lock_irq(&tasklist_lock);
1239                 /* Double-check with lock held.  */
1240                 if (p->real_parent != p->parent) {
1241                         __ptrace_unlink(p);
1242                         // TODO: is this safe?
1243                         p->exit_state = EXIT_ZOMBIE;
1244                         /*
1245                          * If this is not a detached task, notify the parent.
1246                          * If it's still not detached after that, don't release
1247                          * it now.
1248                          */
1249                         if (p->exit_signal != -1) {
1250                                 do_notify_parent(p, p->exit_signal);
1251                                 if (p->exit_signal != -1)
1252                                         p = NULL;
1253                         }
1254                 }
1255                 write_unlock_irq(&tasklist_lock);
1256         }
1257         if (p != NULL)
1258                 release_task(p);
1259         BUG_ON(!retval);
1260         return retval;
1261 }
1262
1263 /*
1264  * Handle sys_wait4 work for one task in state TASK_STOPPED.  We hold
1265  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1266  * the lock and this task is uninteresting.  If we return nonzero, we have
1267  * released the lock and the system call should return.
1268  */
1269 static int wait_task_stopped(struct task_struct *p, int delayed_group_leader,
1270                              int noreap, struct siginfo __user *infop,
1271                              int __user *stat_addr, struct rusage __user *ru)
1272 {
1273         int retval, exit_code;
1274
1275         if (!p->exit_code)
1276                 return 0;
1277         if (delayed_group_leader && !(p->ptrace & PT_PTRACED) &&
1278             p->signal && p->signal->group_stop_count > 0)
1279                 /*
1280                  * A group stop is in progress and this is the group leader.
1281                  * We won't report until all threads have stopped.
1282                  */
1283                 return 0;
1284
1285         /*
1286          * Now we are pretty sure this task is interesting.
1287          * Make sure it doesn't get reaped out from under us while we
1288          * give up the lock and then examine it below.  We don't want to
1289          * keep holding onto the tasklist_lock while we call getrusage and
1290          * possibly take page faults for user memory.
1291          */
1292         get_task_struct(p);
1293         read_unlock(&tasklist_lock);
1294
1295         if (unlikely(noreap)) {
1296                 pid_t pid = p->pid;
1297                 uid_t uid = p->uid;
1298                 int why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
1299
1300                 exit_code = p->exit_code;
1301                 if (unlikely(!exit_code) ||
1302                     unlikely(p->state & TASK_TRACED))
1303                         goto bail_ref;
1304                 return wait_noreap_copyout(p, pid, uid,
1305                                            why, (exit_code << 8) | 0x7f,
1306                                            infop, ru);
1307         }
1308
1309         write_lock_irq(&tasklist_lock);
1310
1311         /*
1312          * This uses xchg to be atomic with the thread resuming and setting
1313          * it.  It must also be done with the write lock held to prevent a
1314          * race with the EXIT_ZOMBIE case.
1315          */
1316         exit_code = xchg(&p->exit_code, 0);
1317         if (unlikely(p->exit_state)) {
1318                 /*
1319                  * The task resumed and then died.  Let the next iteration
1320                  * catch it in EXIT_ZOMBIE.  Note that exit_code might
1321                  * already be zero here if it resumed and did _exit(0).
1322                  * The task itself is dead and won't touch exit_code again;
1323                  * other processors in this function are locked out.
1324                  */
1325                 p->exit_code = exit_code;
1326                 exit_code = 0;
1327         }
1328         if (unlikely(exit_code == 0)) {
1329                 /*
1330                  * Another thread in this function got to it first, or it
1331                  * resumed, or it resumed and then died.
1332                  */
1333                 write_unlock_irq(&tasklist_lock);
1334 bail_ref:
1335                 put_task_struct(p);
1336                 /*
1337                  * We are returning to the wait loop without having successfully
1338                  * removed the process and having released the lock. We cannot
1339                  * continue, since the "p" task pointer is potentially stale.
1340                  *
1341                  * Return -EAGAIN, and do_wait() will restart the loop from the
1342                  * beginning. Do _not_ re-acquire the lock.
1343                  */
1344                 return -EAGAIN;
1345         }
1346
1347         /* move to end of parent's list to avoid starvation */
1348         remove_parent(p);
1349         add_parent(p);
1350
1351         write_unlock_irq(&tasklist_lock);
1352
1353         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1354         if (!retval && stat_addr)
1355                 retval = put_user((exit_code << 8) | 0x7f, stat_addr);
1356         if (!retval && infop)
1357                 retval = put_user(SIGCHLD, &infop->si_signo);
1358         if (!retval && infop)
1359                 retval = put_user(0, &infop->si_errno);
1360         if (!retval && infop)
1361                 retval = put_user((short)((p->ptrace & PT_PTRACED)
1362                                           ? CLD_TRAPPED : CLD_STOPPED),
1363                                   &infop->si_code);
1364         if (!retval && infop)
1365                 retval = put_user(exit_code, &infop->si_status);
1366         if (!retval && infop)
1367                 retval = put_user(p->pid, &infop->si_pid);
1368         if (!retval && infop)
1369                 retval = put_user(p->uid, &infop->si_uid);
1370         if (!retval)
1371                 retval = p->pid;
1372         put_task_struct(p);
1373
1374         BUG_ON(!retval);
1375         return retval;
1376 }
1377
1378 /*
1379  * Handle do_wait work for one task in a live, non-stopped state.
1380  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1381  * the lock and this task is uninteresting.  If we return nonzero, we have
1382  * released the lock and the system call should return.
1383  */
1384 static int wait_task_continued(struct task_struct *p, int noreap,
1385                                struct siginfo __user *infop,
1386                                int __user *stat_addr, struct rusage __user *ru)
1387 {
1388         int retval;
1389         pid_t pid;
1390         uid_t uid;
1391
1392         if (unlikely(!p->signal))
1393                 return 0;
1394
1395         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1396                 return 0;
1397
1398         spin_lock_irq(&p->sighand->siglock);
1399         /* Re-check with the lock held.  */
1400         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1401                 spin_unlock_irq(&p->sighand->siglock);
1402                 return 0;
1403         }
1404         if (!noreap)
1405                 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1406         spin_unlock_irq(&p->sighand->siglock);
1407
1408         pid = p->pid;
1409         uid = p->uid;
1410         get_task_struct(p);
1411         read_unlock(&tasklist_lock);
1412
1413         if (!infop) {
1414                 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1415                 put_task_struct(p);
1416                 if (!retval && stat_addr)
1417                         retval = put_user(0xffff, stat_addr);
1418                 if (!retval)
1419                         retval = p->pid;
1420         } else {
1421                 retval = wait_noreap_copyout(p, pid, uid,
1422                                              CLD_CONTINUED, SIGCONT,
1423                                              infop, ru);
1424                 BUG_ON(retval == 0);
1425         }
1426
1427         return retval;
1428 }
1429
1430
1431 static inline int my_ptrace_child(struct task_struct *p)
1432 {
1433         if (!(p->ptrace & PT_PTRACED))
1434                 return 0;
1435         if (!(p->ptrace & PT_ATTACHED))
1436                 return 1;
1437         /*
1438          * This child was PTRACE_ATTACH'd.  We should be seeing it only if
1439          * we are the attacher.  If we are the real parent, this is a race
1440          * inside ptrace_attach.  It is waiting for the tasklist_lock,
1441          * which we have to switch the parent links, but has already set
1442          * the flags in p->ptrace.
1443          */
1444         return (p->parent != p->real_parent);
1445 }
1446
1447 static long do_wait(pid_t pid, int options, struct siginfo __user *infop,
1448                     int __user *stat_addr, struct rusage __user *ru)
1449 {
1450         DECLARE_WAITQUEUE(wait, current);
1451         struct task_struct *tsk;
1452         int flag, retval;
1453
1454         add_wait_queue(&current->signal->wait_chldexit,&wait);
1455 repeat:
1456         /*
1457          * We will set this flag if we see any child that might later
1458          * match our criteria, even if we are not able to reap it yet.
1459          */
1460         flag = 0;
1461         current->state = TASK_INTERRUPTIBLE;
1462         read_lock(&tasklist_lock);
1463         tsk = current;
1464         do {
1465                 struct task_struct *p;
1466                 struct list_head *_p;
1467                 int ret;
1468
1469                 list_for_each(_p,&tsk->children) {
1470                         p = list_entry(_p, struct task_struct, sibling);
1471
1472                         ret = eligible_child(pid, options, p);
1473                         if (!ret)
1474                                 continue;
1475
1476                         switch (p->state) {
1477                         case TASK_TRACED:
1478                                 /*
1479                                  * When we hit the race with PTRACE_ATTACH,
1480                                  * we will not report this child.  But the
1481                                  * race means it has not yet been moved to
1482                                  * our ptrace_children list, so we need to
1483                                  * set the flag here to avoid a spurious ECHILD
1484                                  * when the race happens with the only child.
1485                                  */
1486                                 flag = 1;
1487                                 if (!my_ptrace_child(p))
1488                                         continue;
1489                                 /*FALLTHROUGH*/
1490                         case TASK_STOPPED:
1491                                 /*
1492                                  * It's stopped now, so it might later
1493                                  * continue, exit, or stop again.
1494                                  */
1495                                 flag = 1;
1496                                 if (!(options & WUNTRACED) &&
1497                                     !my_ptrace_child(p))
1498                                         continue;
1499                                 retval = wait_task_stopped(p, ret == 2,
1500                                                            (options & WNOWAIT),
1501                                                            infop,
1502                                                            stat_addr, ru);
1503                                 if (retval == -EAGAIN)
1504                                         goto repeat;
1505                                 if (retval != 0) /* He released the lock.  */
1506                                         goto end;
1507                                 break;
1508                         default:
1509                         // case EXIT_DEAD:
1510                                 if (p->exit_state == EXIT_DEAD)
1511                                         continue;
1512                         // case EXIT_ZOMBIE:
1513                                 if (p->exit_state == EXIT_ZOMBIE) {
1514                                         /*
1515                                          * Eligible but we cannot release
1516                                          * it yet:
1517                                          */
1518                                         if (ret == 2)
1519                                                 goto check_continued;
1520                                         if (!likely(options & WEXITED))
1521                                                 continue;
1522                                         retval = wait_task_zombie(
1523                                                 p, (options & WNOWAIT),
1524                                                 infop, stat_addr, ru);
1525                                         /* He released the lock.  */
1526                                         if (retval != 0)
1527                                                 goto end;
1528                                         break;
1529                                 }
1530 check_continued:
1531                                 /*
1532                                  * It's running now, so it might later
1533                                  * exit, stop, or stop and then continue.
1534                                  */
1535                                 flag = 1;
1536                                 if (!unlikely(options & WCONTINUED))
1537                                         continue;
1538                                 retval = wait_task_continued(
1539                                         p, (options & WNOWAIT),
1540                                         infop, stat_addr, ru);
1541                                 if (retval != 0) /* He released the lock.  */
1542                                         goto end;
1543                                 break;
1544                         }
1545                 }
1546                 if (!flag) {
1547                         list_for_each(_p, &tsk->ptrace_children) {
1548                                 p = list_entry(_p, struct task_struct,
1549                                                 ptrace_list);
1550                                 if (!eligible_child(pid, options, p))
1551                                         continue;
1552                                 flag = 1;
1553                                 break;
1554                         }
1555                 }
1556                 if (options & __WNOTHREAD)
1557                         break;
1558                 tsk = next_thread(tsk);
1559                 BUG_ON(tsk->signal != current->signal);
1560         } while (tsk != current);
1561
1562         read_unlock(&tasklist_lock);
1563         if (flag) {
1564                 retval = 0;
1565                 if (options & WNOHANG)
1566                         goto end;
1567                 retval = -ERESTARTSYS;
1568                 if (signal_pending(current))
1569                         goto end;
1570                 schedule();
1571                 goto repeat;
1572         }
1573         retval = -ECHILD;
1574 end:
1575         current->state = TASK_RUNNING;
1576         remove_wait_queue(&current->signal->wait_chldexit,&wait);
1577         if (infop) {
1578                 if (retval > 0)
1579                 retval = 0;
1580                 else {
1581                         /*
1582                          * For a WNOHANG return, clear out all the fields
1583                          * we would set so the user can easily tell the
1584                          * difference.
1585                          */
1586                         if (!retval)
1587                                 retval = put_user(0, &infop->si_signo);
1588                         if (!retval)
1589                                 retval = put_user(0, &infop->si_errno);
1590                         if (!retval)
1591                                 retval = put_user(0, &infop->si_code);
1592                         if (!retval)
1593                                 retval = put_user(0, &infop->si_pid);
1594                         if (!retval)
1595                                 retval = put_user(0, &infop->si_uid);
1596                         if (!retval)
1597                                 retval = put_user(0, &infop->si_status);
1598                 }
1599         }
1600         return retval;
1601 }
1602
1603 asmlinkage long sys_waitid(int which, pid_t pid,
1604                            struct siginfo __user *infop, int options,
1605                            struct rusage __user *ru)
1606 {
1607         long ret;
1608
1609         if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1610                 return -EINVAL;
1611         if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1612                 return -EINVAL;
1613
1614         switch (which) {
1615         case P_ALL:
1616                 pid = -1;
1617                 break;
1618         case P_PID:
1619                 if (pid <= 0)
1620                         return -EINVAL;
1621                 break;
1622         case P_PGID:
1623                 if (pid <= 0)
1624                         return -EINVAL;
1625                 pid = -pid;
1626                 break;
1627         default:
1628                 return -EINVAL;
1629         }
1630
1631         ret = do_wait(pid, options, infop, NULL, ru);
1632
1633         /* avoid REGPARM breakage on x86: */
1634         prevent_tail_call(ret);
1635         return ret;
1636 }
1637
1638 asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr,
1639                           int options, struct rusage __user *ru)
1640 {
1641         long ret;
1642
1643         if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1644                         __WNOTHREAD|__WCLONE|__WALL))
1645                 return -EINVAL;
1646         ret = do_wait(pid, options | WEXITED, NULL, stat_addr, ru);
1647
1648         /* avoid REGPARM breakage on x86: */
1649         prevent_tail_call(ret);
1650         return ret;
1651 }
1652
1653 #ifdef __ARCH_WANT_SYS_WAITPID
1654
1655 /*
1656  * sys_waitpid() remains for compatibility. waitpid() should be
1657  * implemented by calling sys_wait4() from libc.a.
1658  */
1659 asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options)
1660 {
1661         return sys_wait4(pid, stat_addr, options, NULL);
1662 }
1663
1664 #endif