exit.c 41 KB

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  1. /*
  2. * linux/kernel/exit.c
  3. *
  4. * Copyright (C) 1991, 1992 Linus Torvalds
  5. */
  6. #include <linux/mm.h>
  7. #include <linux/slab.h>
  8. #include <linux/interrupt.h>
  9. #include <linux/smp_lock.h>
  10. #include <linux/module.h>
  11. #include <linux/capability.h>
  12. #include <linux/completion.h>
  13. #include <linux/personality.h>
  14. #include <linux/tty.h>
  15. #include <linux/namespace.h>
  16. #include <linux/key.h>
  17. #include <linux/security.h>
  18. #include <linux/cpu.h>
  19. #include <linux/acct.h>
  20. #include <linux/tsacct_kern.h>
  21. #include <linux/file.h>
  22. #include <linux/binfmts.h>
  23. #include <linux/nsproxy.h>
  24. #include <linux/ptrace.h>
  25. #include <linux/profile.h>
  26. #include <linux/mount.h>
  27. #include <linux/proc_fs.h>
  28. #include <linux/mempolicy.h>
  29. #include <linux/taskstats_kern.h>
  30. #include <linux/delayacct.h>
  31. #include <linux/cpuset.h>
  32. #include <linux/syscalls.h>
  33. #include <linux/signal.h>
  34. #include <linux/posix-timers.h>
  35. #include <linux/cn_proc.h>
  36. #include <linux/mutex.h>
  37. #include <linux/futex.h>
  38. #include <linux/compat.h>
  39. #include <linux/pipe_fs_i.h>
  40. #include <linux/audit.h> /* for audit_free() */
  41. #include <linux/resource.h>
  42. #include <linux/blkdev.h>
  43. #include <asm/uaccess.h>
  44. #include <asm/unistd.h>
  45. #include <asm/pgtable.h>
  46. #include <asm/mmu_context.h>
  47. extern void sem_exit (void);
  48. extern struct task_struct *child_reaper;
  49. static void exit_mm(struct task_struct * tsk);
  50. static void __unhash_process(struct task_struct *p)
  51. {
  52. nr_threads--;
  53. detach_pid(p, PIDTYPE_PID);
  54. if (thread_group_leader(p)) {
  55. detach_pid(p, PIDTYPE_PGID);
  56. detach_pid(p, PIDTYPE_SID);
  57. list_del_rcu(&p->tasks);
  58. __get_cpu_var(process_counts)--;
  59. }
  60. list_del_rcu(&p->thread_group);
  61. remove_parent(p);
  62. }
  63. /*
  64. * This function expects the tasklist_lock write-locked.
  65. */
  66. static void __exit_signal(struct task_struct *tsk)
  67. {
  68. struct signal_struct *sig = tsk->signal;
  69. struct sighand_struct *sighand;
  70. BUG_ON(!sig);
  71. BUG_ON(!atomic_read(&sig->count));
  72. rcu_read_lock();
  73. sighand = rcu_dereference(tsk->sighand);
  74. spin_lock(&sighand->siglock);
  75. posix_cpu_timers_exit(tsk);
  76. if (atomic_dec_and_test(&sig->count))
  77. posix_cpu_timers_exit_group(tsk);
  78. else {
  79. /*
  80. * If there is any task waiting for the group exit
  81. * then notify it:
  82. */
  83. if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count) {
  84. wake_up_process(sig->group_exit_task);
  85. sig->group_exit_task = NULL;
  86. }
  87. if (tsk == sig->curr_target)
  88. sig->curr_target = next_thread(tsk);
  89. /*
  90. * Accumulate here the counters for all threads but the
  91. * group leader as they die, so they can be added into
  92. * the process-wide totals when those are taken.
  93. * The group leader stays around as a zombie as long
  94. * as there are other threads. When it gets reaped,
  95. * the exit.c code will add its counts into these totals.
  96. * We won't ever get here for the group leader, since it
  97. * will have been the last reference on the signal_struct.
  98. */
  99. sig->utime = cputime_add(sig->utime, tsk->utime);
  100. sig->stime = cputime_add(sig->stime, tsk->stime);
  101. sig->min_flt += tsk->min_flt;
  102. sig->maj_flt += tsk->maj_flt;
  103. sig->nvcsw += tsk->nvcsw;
  104. sig->nivcsw += tsk->nivcsw;
  105. sig->sched_time += tsk->sched_time;
  106. sig = NULL; /* Marker for below. */
  107. }
  108. __unhash_process(tsk);
  109. tsk->signal = NULL;
  110. tsk->sighand = NULL;
  111. spin_unlock(&sighand->siglock);
  112. rcu_read_unlock();
  113. __cleanup_sighand(sighand);
  114. clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
  115. flush_sigqueue(&tsk->pending);
  116. if (sig) {
  117. flush_sigqueue(&sig->shared_pending);
  118. taskstats_tgid_free(sig);
  119. __cleanup_signal(sig);
  120. }
  121. }
  122. static void delayed_put_task_struct(struct rcu_head *rhp)
  123. {
  124. put_task_struct(container_of(rhp, struct task_struct, rcu));
  125. }
  126. void release_task(struct task_struct * p)
  127. {
  128. struct task_struct *leader;
  129. int zap_leader;
  130. repeat:
  131. atomic_dec(&p->user->processes);
  132. write_lock_irq(&tasklist_lock);
  133. ptrace_unlink(p);
  134. BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
  135. __exit_signal(p);
  136. /*
  137. * If we are the last non-leader member of the thread
  138. * group, and the leader is zombie, then notify the
  139. * group leader's parent process. (if it wants notification.)
  140. */
  141. zap_leader = 0;
  142. leader = p->group_leader;
  143. if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
  144. BUG_ON(leader->exit_signal == -1);
  145. do_notify_parent(leader, leader->exit_signal);
  146. /*
  147. * If we were the last child thread and the leader has
  148. * exited already, and the leader's parent ignores SIGCHLD,
  149. * then we are the one who should release the leader.
  150. *
  151. * do_notify_parent() will have marked it self-reaping in
  152. * that case.
  153. */
  154. zap_leader = (leader->exit_signal == -1);
  155. }
  156. sched_exit(p);
  157. write_unlock_irq(&tasklist_lock);
  158. proc_flush_task(p);
  159. release_thread(p);
  160. call_rcu(&p->rcu, delayed_put_task_struct);
  161. p = leader;
  162. if (unlikely(zap_leader))
  163. goto repeat;
  164. }
  165. /*
  166. * This checks not only the pgrp, but falls back on the pid if no
  167. * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
  168. * without this...
  169. */
  170. int session_of_pgrp(int pgrp)
  171. {
  172. struct task_struct *p;
  173. int sid = -1;
  174. read_lock(&tasklist_lock);
  175. do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
  176. if (process_session(p) > 0) {
  177. sid = process_session(p);
  178. goto out;
  179. }
  180. } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
  181. p = find_task_by_pid(pgrp);
  182. if (p)
  183. sid = process_session(p);
  184. out:
  185. read_unlock(&tasklist_lock);
  186. return sid;
  187. }
  188. /*
  189. * Determine if a process group is "orphaned", according to the POSIX
  190. * definition in 2.2.2.52. Orphaned process groups are not to be affected
  191. * by terminal-generated stop signals. Newly orphaned process groups are
  192. * to receive a SIGHUP and a SIGCONT.
  193. *
  194. * "I ask you, have you ever known what it is to be an orphan?"
  195. */
  196. static int will_become_orphaned_pgrp(int pgrp, struct task_struct *ignored_task)
  197. {
  198. struct task_struct *p;
  199. int ret = 1;
  200. do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
  201. if (p == ignored_task
  202. || p->exit_state
  203. || is_init(p->real_parent))
  204. continue;
  205. if (process_group(p->real_parent) != pgrp &&
  206. process_session(p->real_parent) == process_session(p)) {
  207. ret = 0;
  208. break;
  209. }
  210. } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
  211. return ret; /* (sighing) "Often!" */
  212. }
  213. int is_orphaned_pgrp(int pgrp)
  214. {
  215. int retval;
  216. read_lock(&tasklist_lock);
  217. retval = will_become_orphaned_pgrp(pgrp, NULL);
  218. read_unlock(&tasklist_lock);
  219. return retval;
  220. }
  221. static int has_stopped_jobs(int pgrp)
  222. {
  223. int retval = 0;
  224. struct task_struct *p;
  225. do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
  226. if (p->state != TASK_STOPPED)
  227. continue;
  228. retval = 1;
  229. break;
  230. } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
  231. return retval;
  232. }
  233. /**
  234. * reparent_to_init - Reparent the calling kernel thread to the init task.
  235. *
  236. * If a kernel thread is launched as a result of a system call, or if
  237. * it ever exits, it should generally reparent itself to init so that
  238. * it is correctly cleaned up on exit.
  239. *
  240. * The various task state such as scheduling policy and priority may have
  241. * been inherited from a user process, so we reset them to sane values here.
  242. *
  243. * NOTE that reparent_to_init() gives the caller full capabilities.
  244. */
  245. static void reparent_to_init(void)
  246. {
  247. write_lock_irq(&tasklist_lock);
  248. ptrace_unlink(current);
  249. /* Reparent to init */
  250. remove_parent(current);
  251. current->parent = child_reaper;
  252. current->real_parent = child_reaper;
  253. add_parent(current);
  254. /* Set the exit signal to SIGCHLD so we signal init on exit */
  255. current->exit_signal = SIGCHLD;
  256. if (!has_rt_policy(current) && (task_nice(current) < 0))
  257. set_user_nice(current, 0);
  258. /* cpus_allowed? */
  259. /* rt_priority? */
  260. /* signals? */
  261. security_task_reparent_to_init(current);
  262. memcpy(current->signal->rlim, init_task.signal->rlim,
  263. sizeof(current->signal->rlim));
  264. atomic_inc(&(INIT_USER->__count));
  265. write_unlock_irq(&tasklist_lock);
  266. switch_uid(INIT_USER);
  267. }
  268. void __set_special_pids(pid_t session, pid_t pgrp)
  269. {
  270. struct task_struct *curr = current->group_leader;
  271. if (process_session(curr) != session) {
  272. detach_pid(curr, PIDTYPE_SID);
  273. set_signal_session(curr->signal, session);
  274. attach_pid(curr, PIDTYPE_SID, session);
  275. }
  276. if (process_group(curr) != pgrp) {
  277. detach_pid(curr, PIDTYPE_PGID);
  278. curr->signal->pgrp = pgrp;
  279. attach_pid(curr, PIDTYPE_PGID, pgrp);
  280. }
  281. }
  282. static void set_special_pids(pid_t session, pid_t pgrp)
  283. {
  284. write_lock_irq(&tasklist_lock);
  285. __set_special_pids(session, pgrp);
  286. write_unlock_irq(&tasklist_lock);
  287. }
  288. /*
  289. * Let kernel threads use this to say that they
  290. * allow a certain signal (since daemonize() will
  291. * have disabled all of them by default).
  292. */
  293. int allow_signal(int sig)
  294. {
  295. if (!valid_signal(sig) || sig < 1)
  296. return -EINVAL;
  297. spin_lock_irq(&current->sighand->siglock);
  298. sigdelset(&current->blocked, sig);
  299. if (!current->mm) {
  300. /* Kernel threads handle their own signals.
  301. Let the signal code know it'll be handled, so
  302. that they don't get converted to SIGKILL or
  303. just silently dropped */
  304. current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
  305. }
  306. recalc_sigpending();
  307. spin_unlock_irq(&current->sighand->siglock);
  308. return 0;
  309. }
  310. EXPORT_SYMBOL(allow_signal);
  311. int disallow_signal(int sig)
  312. {
  313. if (!valid_signal(sig) || sig < 1)
  314. return -EINVAL;
  315. spin_lock_irq(&current->sighand->siglock);
  316. sigaddset(&current->blocked, sig);
  317. recalc_sigpending();
  318. spin_unlock_irq(&current->sighand->siglock);
  319. return 0;
  320. }
  321. EXPORT_SYMBOL(disallow_signal);
  322. /*
  323. * Put all the gunge required to become a kernel thread without
  324. * attached user resources in one place where it belongs.
  325. */
  326. void daemonize(const char *name, ...)
  327. {
  328. va_list args;
  329. struct fs_struct *fs;
  330. sigset_t blocked;
  331. va_start(args, name);
  332. vsnprintf(current->comm, sizeof(current->comm), name, args);
  333. va_end(args);
  334. /*
  335. * If we were started as result of loading a module, close all of the
  336. * user space pages. We don't need them, and if we didn't close them
  337. * they would be locked into memory.
  338. */
  339. exit_mm(current);
  340. set_special_pids(1, 1);
  341. proc_clear_tty(current);
  342. /* Block and flush all signals */
  343. sigfillset(&blocked);
  344. sigprocmask(SIG_BLOCK, &blocked, NULL);
  345. flush_signals(current);
  346. /* Become as one with the init task */
  347. exit_fs(current); /* current->fs->count--; */
  348. fs = init_task.fs;
  349. current->fs = fs;
  350. atomic_inc(&fs->count);
  351. exit_task_namespaces(current);
  352. current->nsproxy = init_task.nsproxy;
  353. get_task_namespaces(current);
  354. exit_files(current);
  355. current->files = init_task.files;
  356. atomic_inc(&current->files->count);
  357. reparent_to_init();
  358. }
  359. EXPORT_SYMBOL(daemonize);
  360. static void close_files(struct files_struct * files)
  361. {
  362. int i, j;
  363. struct fdtable *fdt;
  364. j = 0;
  365. /*
  366. * It is safe to dereference the fd table without RCU or
  367. * ->file_lock because this is the last reference to the
  368. * files structure.
  369. */
  370. fdt = files_fdtable(files);
  371. for (;;) {
  372. unsigned long set;
  373. i = j * __NFDBITS;
  374. if (i >= fdt->max_fdset || i >= fdt->max_fds)
  375. break;
  376. set = fdt->open_fds->fds_bits[j++];
  377. while (set) {
  378. if (set & 1) {
  379. struct file * file = xchg(&fdt->fd[i], NULL);
  380. if (file)
  381. filp_close(file, files);
  382. }
  383. i++;
  384. set >>= 1;
  385. }
  386. }
  387. }
  388. struct files_struct *get_files_struct(struct task_struct *task)
  389. {
  390. struct files_struct *files;
  391. task_lock(task);
  392. files = task->files;
  393. if (files)
  394. atomic_inc(&files->count);
  395. task_unlock(task);
  396. return files;
  397. }
  398. void fastcall put_files_struct(struct files_struct *files)
  399. {
  400. struct fdtable *fdt;
  401. if (atomic_dec_and_test(&files->count)) {
  402. close_files(files);
  403. /*
  404. * Free the fd and fdset arrays if we expanded them.
  405. * If the fdtable was embedded, pass files for freeing
  406. * at the end of the RCU grace period. Otherwise,
  407. * you can free files immediately.
  408. */
  409. fdt = files_fdtable(files);
  410. if (fdt == &files->fdtab)
  411. fdt->free_files = files;
  412. else
  413. kmem_cache_free(files_cachep, files);
  414. free_fdtable(fdt);
  415. }
  416. }
  417. EXPORT_SYMBOL(put_files_struct);
  418. void reset_files_struct(struct task_struct *tsk, struct files_struct *files)
  419. {
  420. struct files_struct *old;
  421. old = tsk->files;
  422. task_lock(tsk);
  423. tsk->files = files;
  424. task_unlock(tsk);
  425. put_files_struct(old);
  426. }
  427. EXPORT_SYMBOL(reset_files_struct);
  428. static inline void __exit_files(struct task_struct *tsk)
  429. {
  430. struct files_struct * files = tsk->files;
  431. if (files) {
  432. task_lock(tsk);
  433. tsk->files = NULL;
  434. task_unlock(tsk);
  435. put_files_struct(files);
  436. }
  437. }
  438. void exit_files(struct task_struct *tsk)
  439. {
  440. __exit_files(tsk);
  441. }
  442. static inline void __put_fs_struct(struct fs_struct *fs)
  443. {
  444. /* No need to hold fs->lock if we are killing it */
  445. if (atomic_dec_and_test(&fs->count)) {
  446. dput(fs->root);
  447. mntput(fs->rootmnt);
  448. dput(fs->pwd);
  449. mntput(fs->pwdmnt);
  450. if (fs->altroot) {
  451. dput(fs->altroot);
  452. mntput(fs->altrootmnt);
  453. }
  454. kmem_cache_free(fs_cachep, fs);
  455. }
  456. }
  457. void put_fs_struct(struct fs_struct *fs)
  458. {
  459. __put_fs_struct(fs);
  460. }
  461. static inline void __exit_fs(struct task_struct *tsk)
  462. {
  463. struct fs_struct * fs = tsk->fs;
  464. if (fs) {
  465. task_lock(tsk);
  466. tsk->fs = NULL;
  467. task_unlock(tsk);
  468. __put_fs_struct(fs);
  469. }
  470. }
  471. void exit_fs(struct task_struct *tsk)
  472. {
  473. __exit_fs(tsk);
  474. }
  475. EXPORT_SYMBOL_GPL(exit_fs);
  476. /*
  477. * Turn us into a lazy TLB process if we
  478. * aren't already..
  479. */
  480. static void exit_mm(struct task_struct * tsk)
  481. {
  482. struct mm_struct *mm = tsk->mm;
  483. mm_release(tsk, mm);
  484. if (!mm)
  485. return;
  486. /*
  487. * Serialize with any possible pending coredump.
  488. * We must hold mmap_sem around checking core_waiters
  489. * and clearing tsk->mm. The core-inducing thread
  490. * will increment core_waiters for each thread in the
  491. * group with ->mm != NULL.
  492. */
  493. down_read(&mm->mmap_sem);
  494. if (mm->core_waiters) {
  495. up_read(&mm->mmap_sem);
  496. down_write(&mm->mmap_sem);
  497. if (!--mm->core_waiters)
  498. complete(mm->core_startup_done);
  499. up_write(&mm->mmap_sem);
  500. wait_for_completion(&mm->core_done);
  501. down_read(&mm->mmap_sem);
  502. }
  503. atomic_inc(&mm->mm_count);
  504. BUG_ON(mm != tsk->active_mm);
  505. /* more a memory barrier than a real lock */
  506. task_lock(tsk);
  507. tsk->mm = NULL;
  508. up_read(&mm->mmap_sem);
  509. enter_lazy_tlb(mm, current);
  510. task_unlock(tsk);
  511. mmput(mm);
  512. }
  513. static inline void
  514. choose_new_parent(struct task_struct *p, struct task_struct *reaper)
  515. {
  516. /*
  517. * Make sure we're not reparenting to ourselves and that
  518. * the parent is not a zombie.
  519. */
  520. BUG_ON(p == reaper || reaper->exit_state);
  521. p->real_parent = reaper;
  522. }
  523. static void
  524. reparent_thread(struct task_struct *p, struct task_struct *father, int traced)
  525. {
  526. /* We don't want people slaying init. */
  527. if (p->exit_signal != -1)
  528. p->exit_signal = SIGCHLD;
  529. if (p->pdeath_signal)
  530. /* We already hold the tasklist_lock here. */
  531. group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);
  532. /* Move the child from its dying parent to the new one. */
  533. if (unlikely(traced)) {
  534. /* Preserve ptrace links if someone else is tracing this child. */
  535. list_del_init(&p->ptrace_list);
  536. if (p->parent != p->real_parent)
  537. list_add(&p->ptrace_list, &p->real_parent->ptrace_children);
  538. } else {
  539. /* If this child is being traced, then we're the one tracing it
  540. * anyway, so let go of it.
  541. */
  542. p->ptrace = 0;
  543. remove_parent(p);
  544. p->parent = p->real_parent;
  545. add_parent(p);
  546. /* If we'd notified the old parent about this child's death,
  547. * also notify the new parent.
  548. */
  549. if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
  550. thread_group_empty(p))
  551. do_notify_parent(p, p->exit_signal);
  552. else if (p->state == TASK_TRACED) {
  553. /*
  554. * If it was at a trace stop, turn it into
  555. * a normal stop since it's no longer being
  556. * traced.
  557. */
  558. ptrace_untrace(p);
  559. }
  560. }
  561. /*
  562. * process group orphan check
  563. * Case ii: Our child is in a different pgrp
  564. * than we are, and it was the only connection
  565. * outside, so the child pgrp is now orphaned.
  566. */
  567. if ((process_group(p) != process_group(father)) &&
  568. (process_session(p) == process_session(father))) {
  569. int pgrp = process_group(p);
  570. if (will_become_orphaned_pgrp(pgrp, NULL) &&
  571. has_stopped_jobs(pgrp)) {
  572. __kill_pg_info(SIGHUP, SEND_SIG_PRIV, pgrp);
  573. __kill_pg_info(SIGCONT, SEND_SIG_PRIV, pgrp);
  574. }
  575. }
  576. }
  577. /*
  578. * When we die, we re-parent all our children.
  579. * Try to give them to another thread in our thread
  580. * group, and if no such member exists, give it to
  581. * the global child reaper process (ie "init")
  582. */
  583. static void
  584. forget_original_parent(struct task_struct *father, struct list_head *to_release)
  585. {
  586. struct task_struct *p, *reaper = father;
  587. struct list_head *_p, *_n;
  588. do {
  589. reaper = next_thread(reaper);
  590. if (reaper == father) {
  591. reaper = child_reaper;
  592. break;
  593. }
  594. } while (reaper->exit_state);
  595. /*
  596. * There are only two places where our children can be:
  597. *
  598. * - in our child list
  599. * - in our ptraced child list
  600. *
  601. * Search them and reparent children.
  602. */
  603. list_for_each_safe(_p, _n, &father->children) {
  604. int ptrace;
  605. p = list_entry(_p, struct task_struct, sibling);
  606. ptrace = p->ptrace;
  607. /* if father isn't the real parent, then ptrace must be enabled */
  608. BUG_ON(father != p->real_parent && !ptrace);
  609. if (father == p->real_parent) {
  610. /* reparent with a reaper, real father it's us */
  611. choose_new_parent(p, reaper);
  612. reparent_thread(p, father, 0);
  613. } else {
  614. /* reparent ptraced task to its real parent */
  615. __ptrace_unlink (p);
  616. if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
  617. thread_group_empty(p))
  618. do_notify_parent(p, p->exit_signal);
  619. }
  620. /*
  621. * if the ptraced child is a zombie with exit_signal == -1
  622. * we must collect it before we exit, or it will remain
  623. * zombie forever since we prevented it from self-reap itself
  624. * while it was being traced by us, to be able to see it in wait4.
  625. */
  626. if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && p->exit_signal == -1))
  627. list_add(&p->ptrace_list, to_release);
  628. }
  629. list_for_each_safe(_p, _n, &father->ptrace_children) {
  630. p = list_entry(_p, struct task_struct, ptrace_list);
  631. choose_new_parent(p, reaper);
  632. reparent_thread(p, father, 1);
  633. }
  634. }
  635. /*
  636. * Send signals to all our closest relatives so that they know
  637. * to properly mourn us..
  638. */
  639. static void exit_notify(struct task_struct *tsk)
  640. {
  641. int state;
  642. struct task_struct *t;
  643. struct list_head ptrace_dead, *_p, *_n;
  644. if (signal_pending(tsk) && !(tsk->signal->flags & SIGNAL_GROUP_EXIT)
  645. && !thread_group_empty(tsk)) {
  646. /*
  647. * This occurs when there was a race between our exit
  648. * syscall and a group signal choosing us as the one to
  649. * wake up. It could be that we are the only thread
  650. * alerted to check for pending signals, but another thread
  651. * should be woken now to take the signal since we will not.
  652. * Now we'll wake all the threads in the group just to make
  653. * sure someone gets all the pending signals.
  654. */
  655. read_lock(&tasklist_lock);
  656. spin_lock_irq(&tsk->sighand->siglock);
  657. for (t = next_thread(tsk); t != tsk; t = next_thread(t))
  658. if (!signal_pending(t) && !(t->flags & PF_EXITING)) {
  659. recalc_sigpending_tsk(t);
  660. if (signal_pending(t))
  661. signal_wake_up(t, 0);
  662. }
  663. spin_unlock_irq(&tsk->sighand->siglock);
  664. read_unlock(&tasklist_lock);
  665. }
  666. write_lock_irq(&tasklist_lock);
  667. /*
  668. * This does two things:
  669. *
  670. * A. Make init inherit all the child processes
  671. * B. Check to see if any process groups have become orphaned
  672. * as a result of our exiting, and if they have any stopped
  673. * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
  674. */
  675. INIT_LIST_HEAD(&ptrace_dead);
  676. forget_original_parent(tsk, &ptrace_dead);
  677. BUG_ON(!list_empty(&tsk->children));
  678. BUG_ON(!list_empty(&tsk->ptrace_children));
  679. /*
  680. * Check to see if any process groups have become orphaned
  681. * as a result of our exiting, and if they have any stopped
  682. * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
  683. *
  684. * Case i: Our father is in a different pgrp than we are
  685. * and we were the only connection outside, so our pgrp
  686. * is about to become orphaned.
  687. */
  688. t = tsk->real_parent;
  689. if ((process_group(t) != process_group(tsk)) &&
  690. (process_session(t) == process_session(tsk)) &&
  691. will_become_orphaned_pgrp(process_group(tsk), tsk) &&
  692. has_stopped_jobs(process_group(tsk))) {
  693. __kill_pg_info(SIGHUP, SEND_SIG_PRIV, process_group(tsk));
  694. __kill_pg_info(SIGCONT, SEND_SIG_PRIV, process_group(tsk));
  695. }
  696. /* Let father know we died
  697. *
  698. * Thread signals are configurable, but you aren't going to use
  699. * that to send signals to arbitary processes.
  700. * That stops right now.
  701. *
  702. * If the parent exec id doesn't match the exec id we saved
  703. * when we started then we know the parent has changed security
  704. * domain.
  705. *
  706. * If our self_exec id doesn't match our parent_exec_id then
  707. * we have changed execution domain as these two values started
  708. * the same after a fork.
  709. *
  710. */
  711. if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 &&
  712. ( tsk->parent_exec_id != t->self_exec_id ||
  713. tsk->self_exec_id != tsk->parent_exec_id)
  714. && !capable(CAP_KILL))
  715. tsk->exit_signal = SIGCHLD;
  716. /* If something other than our normal parent is ptracing us, then
  717. * send it a SIGCHLD instead of honoring exit_signal. exit_signal
  718. * only has special meaning to our real parent.
  719. */
  720. if (tsk->exit_signal != -1 && thread_group_empty(tsk)) {
  721. int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD;
  722. do_notify_parent(tsk, signal);
  723. } else if (tsk->ptrace) {
  724. do_notify_parent(tsk, SIGCHLD);
  725. }
  726. state = EXIT_ZOMBIE;
  727. if (tsk->exit_signal == -1 &&
  728. (likely(tsk->ptrace == 0) ||
  729. unlikely(tsk->parent->signal->flags & SIGNAL_GROUP_EXIT)))
  730. state = EXIT_DEAD;
  731. tsk->exit_state = state;
  732. write_unlock_irq(&tasklist_lock);
  733. list_for_each_safe(_p, _n, &ptrace_dead) {
  734. list_del_init(_p);
  735. t = list_entry(_p, struct task_struct, ptrace_list);
  736. release_task(t);
  737. }
  738. /* If the process is dead, release it - nobody will wait for it */
  739. if (state == EXIT_DEAD)
  740. release_task(tsk);
  741. }
  742. fastcall NORET_TYPE void do_exit(long code)
  743. {
  744. struct task_struct *tsk = current;
  745. int group_dead;
  746. profile_task_exit(tsk);
  747. WARN_ON(atomic_read(&tsk->fs_excl));
  748. if (unlikely(in_interrupt()))
  749. panic("Aiee, killing interrupt handler!");
  750. if (unlikely(!tsk->pid))
  751. panic("Attempted to kill the idle task!");
  752. if (unlikely(tsk == child_reaper))
  753. panic("Attempted to kill init!");
  754. if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
  755. current->ptrace_message = code;
  756. ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP);
  757. }
  758. /*
  759. * We're taking recursive faults here in do_exit. Safest is to just
  760. * leave this task alone and wait for reboot.
  761. */
  762. if (unlikely(tsk->flags & PF_EXITING)) {
  763. printk(KERN_ALERT
  764. "Fixing recursive fault but reboot is needed!\n");
  765. if (tsk->io_context)
  766. exit_io_context();
  767. set_current_state(TASK_UNINTERRUPTIBLE);
  768. schedule();
  769. }
  770. tsk->flags |= PF_EXITING;
  771. if (unlikely(in_atomic()))
  772. printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
  773. current->comm, current->pid,
  774. preempt_count());
  775. acct_update_integrals(tsk);
  776. if (tsk->mm) {
  777. update_hiwater_rss(tsk->mm);
  778. update_hiwater_vm(tsk->mm);
  779. }
  780. group_dead = atomic_dec_and_test(&tsk->signal->live);
  781. if (group_dead) {
  782. hrtimer_cancel(&tsk->signal->real_timer);
  783. exit_itimers(tsk->signal);
  784. }
  785. acct_collect(code, group_dead);
  786. if (unlikely(tsk->robust_list))
  787. exit_robust_list(tsk);
  788. #if defined(CONFIG_FUTEX) && defined(CONFIG_COMPAT)
  789. if (unlikely(tsk->compat_robust_list))
  790. compat_exit_robust_list(tsk);
  791. #endif
  792. if (unlikely(tsk->audit_context))
  793. audit_free(tsk);
  794. taskstats_exit(tsk, group_dead);
  795. exit_mm(tsk);
  796. if (group_dead)
  797. acct_process();
  798. exit_sem(tsk);
  799. __exit_files(tsk);
  800. __exit_fs(tsk);
  801. exit_thread();
  802. cpuset_exit(tsk);
  803. exit_keys(tsk);
  804. if (group_dead && tsk->signal->leader)
  805. disassociate_ctty(1);
  806. module_put(task_thread_info(tsk)->exec_domain->module);
  807. if (tsk->binfmt)
  808. module_put(tsk->binfmt->module);
  809. tsk->exit_code = code;
  810. proc_exit_connector(tsk);
  811. exit_notify(tsk);
  812. exit_task_namespaces(tsk);
  813. #ifdef CONFIG_NUMA
  814. mpol_free(tsk->mempolicy);
  815. tsk->mempolicy = NULL;
  816. #endif
  817. /*
  818. * This must happen late, after the PID is not
  819. * hashed anymore:
  820. */
  821. if (unlikely(!list_empty(&tsk->pi_state_list)))
  822. exit_pi_state_list(tsk);
  823. if (unlikely(current->pi_state_cache))
  824. kfree(current->pi_state_cache);
  825. /*
  826. * Make sure we are holding no locks:
  827. */
  828. debug_check_no_locks_held(tsk);
  829. if (tsk->io_context)
  830. exit_io_context();
  831. if (tsk->splice_pipe)
  832. __free_pipe_info(tsk->splice_pipe);
  833. preempt_disable();
  834. /* causes final put_task_struct in finish_task_switch(). */
  835. tsk->state = TASK_DEAD;
  836. schedule();
  837. BUG();
  838. /* Avoid "noreturn function does return". */
  839. for (;;)
  840. cpu_relax(); /* For when BUG is null */
  841. }
  842. EXPORT_SYMBOL_GPL(do_exit);
  843. NORET_TYPE void complete_and_exit(struct completion *comp, long code)
  844. {
  845. if (comp)
  846. complete(comp);
  847. do_exit(code);
  848. }
  849. EXPORT_SYMBOL(complete_and_exit);
  850. asmlinkage long sys_exit(int error_code)
  851. {
  852. do_exit((error_code&0xff)<<8);
  853. }
  854. /*
  855. * Take down every thread in the group. This is called by fatal signals
  856. * as well as by sys_exit_group (below).
  857. */
  858. NORET_TYPE void
  859. do_group_exit(int exit_code)
  860. {
  861. BUG_ON(exit_code & 0x80); /* core dumps don't get here */
  862. if (current->signal->flags & SIGNAL_GROUP_EXIT)
  863. exit_code = current->signal->group_exit_code;
  864. else if (!thread_group_empty(current)) {
  865. struct signal_struct *const sig = current->signal;
  866. struct sighand_struct *const sighand = current->sighand;
  867. spin_lock_irq(&sighand->siglock);
  868. if (sig->flags & SIGNAL_GROUP_EXIT)
  869. /* Another thread got here before we took the lock. */
  870. exit_code = sig->group_exit_code;
  871. else {
  872. sig->group_exit_code = exit_code;
  873. zap_other_threads(current);
  874. }
  875. spin_unlock_irq(&sighand->siglock);
  876. }
  877. do_exit(exit_code);
  878. /* NOTREACHED */
  879. }
  880. /*
  881. * this kills every thread in the thread group. Note that any externally
  882. * wait4()-ing process will get the correct exit code - even if this
  883. * thread is not the thread group leader.
  884. */
  885. asmlinkage void sys_exit_group(int error_code)
  886. {
  887. do_group_exit((error_code & 0xff) << 8);
  888. }
  889. static int eligible_child(pid_t pid, int options, struct task_struct *p)
  890. {
  891. if (pid > 0) {
  892. if (p->pid != pid)
  893. return 0;
  894. } else if (!pid) {
  895. if (process_group(p) != process_group(current))
  896. return 0;
  897. } else if (pid != -1) {
  898. if (process_group(p) != -pid)
  899. return 0;
  900. }
  901. /*
  902. * Do not consider detached threads that are
  903. * not ptraced:
  904. */
  905. if (p->exit_signal == -1 && !p->ptrace)
  906. return 0;
  907. /* Wait for all children (clone and not) if __WALL is set;
  908. * otherwise, wait for clone children *only* if __WCLONE is
  909. * set; otherwise, wait for non-clone children *only*. (Note:
  910. * A "clone" child here is one that reports to its parent
  911. * using a signal other than SIGCHLD.) */
  912. if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
  913. && !(options & __WALL))
  914. return 0;
  915. /*
  916. * Do not consider thread group leaders that are
  917. * in a non-empty thread group:
  918. */
  919. if (delay_group_leader(p))
  920. return 2;
  921. if (security_task_wait(p))
  922. return 0;
  923. return 1;
  924. }
  925. static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,
  926. int why, int status,
  927. struct siginfo __user *infop,
  928. struct rusage __user *rusagep)
  929. {
  930. int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
  931. put_task_struct(p);
  932. if (!retval)
  933. retval = put_user(SIGCHLD, &infop->si_signo);
  934. if (!retval)
  935. retval = put_user(0, &infop->si_errno);
  936. if (!retval)
  937. retval = put_user((short)why, &infop->si_code);
  938. if (!retval)
  939. retval = put_user(pid, &infop->si_pid);
  940. if (!retval)
  941. retval = put_user(uid, &infop->si_uid);
  942. if (!retval)
  943. retval = put_user(status, &infop->si_status);
  944. if (!retval)
  945. retval = pid;
  946. return retval;
  947. }
  948. /*
  949. * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
  950. * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
  951. * the lock and this task is uninteresting. If we return nonzero, we have
  952. * released the lock and the system call should return.
  953. */
  954. static int wait_task_zombie(struct task_struct *p, int noreap,
  955. struct siginfo __user *infop,
  956. int __user *stat_addr, struct rusage __user *ru)
  957. {
  958. unsigned long state;
  959. int retval;
  960. int status;
  961. if (unlikely(noreap)) {
  962. pid_t pid = p->pid;
  963. uid_t uid = p->uid;
  964. int exit_code = p->exit_code;
  965. int why, status;
  966. if (unlikely(p->exit_state != EXIT_ZOMBIE))
  967. return 0;
  968. if (unlikely(p->exit_signal == -1 && p->ptrace == 0))
  969. return 0;
  970. get_task_struct(p);
  971. read_unlock(&tasklist_lock);
  972. if ((exit_code & 0x7f) == 0) {
  973. why = CLD_EXITED;
  974. status = exit_code >> 8;
  975. } else {
  976. why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
  977. status = exit_code & 0x7f;
  978. }
  979. return wait_noreap_copyout(p, pid, uid, why,
  980. status, infop, ru);
  981. }
  982. /*
  983. * Try to move the task's state to DEAD
  984. * only one thread is allowed to do this:
  985. */
  986. state = xchg(&p->exit_state, EXIT_DEAD);
  987. if (state != EXIT_ZOMBIE) {
  988. BUG_ON(state != EXIT_DEAD);
  989. return 0;
  990. }
  991. if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) {
  992. /*
  993. * This can only happen in a race with a ptraced thread
  994. * dying on another processor.
  995. */
  996. return 0;
  997. }
  998. if (likely(p->real_parent == p->parent) && likely(p->signal)) {
  999. struct signal_struct *psig;
  1000. struct signal_struct *sig;
  1001. /*
  1002. * The resource counters for the group leader are in its
  1003. * own task_struct. Those for dead threads in the group
  1004. * are in its signal_struct, as are those for the child
  1005. * processes it has previously reaped. All these
  1006. * accumulate in the parent's signal_struct c* fields.
  1007. *
  1008. * We don't bother to take a lock here to protect these
  1009. * p->signal fields, because they are only touched by
  1010. * __exit_signal, which runs with tasklist_lock
  1011. * write-locked anyway, and so is excluded here. We do
  1012. * need to protect the access to p->parent->signal fields,
  1013. * as other threads in the parent group can be right
  1014. * here reaping other children at the same time.
  1015. */
  1016. spin_lock_irq(&p->parent->sighand->siglock);
  1017. psig = p->parent->signal;
  1018. sig = p->signal;
  1019. psig->cutime =
  1020. cputime_add(psig->cutime,
  1021. cputime_add(p->utime,
  1022. cputime_add(sig->utime,
  1023. sig->cutime)));
  1024. psig->cstime =
  1025. cputime_add(psig->cstime,
  1026. cputime_add(p->stime,
  1027. cputime_add(sig->stime,
  1028. sig->cstime)));
  1029. psig->cmin_flt +=
  1030. p->min_flt + sig->min_flt + sig->cmin_flt;
  1031. psig->cmaj_flt +=
  1032. p->maj_flt + sig->maj_flt + sig->cmaj_flt;
  1033. psig->cnvcsw +=
  1034. p->nvcsw + sig->nvcsw + sig->cnvcsw;
  1035. psig->cnivcsw +=
  1036. p->nivcsw + sig->nivcsw + sig->cnivcsw;
  1037. spin_unlock_irq(&p->parent->sighand->siglock);
  1038. }
  1039. /*
  1040. * Now we are sure this task is interesting, and no other
  1041. * thread can reap it because we set its state to EXIT_DEAD.
  1042. */
  1043. read_unlock(&tasklist_lock);
  1044. retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
  1045. status = (p->signal->flags & SIGNAL_GROUP_EXIT)
  1046. ? p->signal->group_exit_code : p->exit_code;
  1047. if (!retval && stat_addr)
  1048. retval = put_user(status, stat_addr);
  1049. if (!retval && infop)
  1050. retval = put_user(SIGCHLD, &infop->si_signo);
  1051. if (!retval && infop)
  1052. retval = put_user(0, &infop->si_errno);
  1053. if (!retval && infop) {
  1054. int why;
  1055. if ((status & 0x7f) == 0) {
  1056. why = CLD_EXITED;
  1057. status >>= 8;
  1058. } else {
  1059. why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
  1060. status &= 0x7f;
  1061. }
  1062. retval = put_user((short)why, &infop->si_code);
  1063. if (!retval)
  1064. retval = put_user(status, &infop->si_status);
  1065. }
  1066. if (!retval && infop)
  1067. retval = put_user(p->pid, &infop->si_pid);
  1068. if (!retval && infop)
  1069. retval = put_user(p->uid, &infop->si_uid);
  1070. if (retval) {
  1071. // TODO: is this safe?
  1072. p->exit_state = EXIT_ZOMBIE;
  1073. return retval;
  1074. }
  1075. retval = p->pid;
  1076. if (p->real_parent != p->parent) {
  1077. write_lock_irq(&tasklist_lock);
  1078. /* Double-check with lock held. */
  1079. if (p->real_parent != p->parent) {
  1080. __ptrace_unlink(p);
  1081. // TODO: is this safe?
  1082. p->exit_state = EXIT_ZOMBIE;
  1083. /*
  1084. * If this is not a detached task, notify the parent.
  1085. * If it's still not detached after that, don't release
  1086. * it now.
  1087. */
  1088. if (p->exit_signal != -1) {
  1089. do_notify_parent(p, p->exit_signal);
  1090. if (p->exit_signal != -1)
  1091. p = NULL;
  1092. }
  1093. }
  1094. write_unlock_irq(&tasklist_lock);
  1095. }
  1096. if (p != NULL)
  1097. release_task(p);
  1098. BUG_ON(!retval);
  1099. return retval;
  1100. }
  1101. /*
  1102. * Handle sys_wait4 work for one task in state TASK_STOPPED. 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_stopped(struct task_struct *p, int delayed_group_leader,
  1108. int noreap, struct siginfo __user *infop,
  1109. int __user *stat_addr, struct rusage __user *ru)
  1110. {
  1111. int retval, exit_code;
  1112. if (!p->exit_code)
  1113. return 0;
  1114. if (delayed_group_leader && !(p->ptrace & PT_PTRACED) &&
  1115. p->signal && p->signal->group_stop_count > 0)
  1116. /*
  1117. * A group stop is in progress and this is the group leader.
  1118. * We won't report until all threads have stopped.
  1119. */
  1120. return 0;
  1121. /*
  1122. * Now we are pretty sure this task is interesting.
  1123. * Make sure it doesn't get reaped out from under us while we
  1124. * give up the lock and then examine it below. We don't want to
  1125. * keep holding onto the tasklist_lock while we call getrusage and
  1126. * possibly take page faults for user memory.
  1127. */
  1128. get_task_struct(p);
  1129. read_unlock(&tasklist_lock);
  1130. if (unlikely(noreap)) {
  1131. pid_t pid = p->pid;
  1132. uid_t uid = p->uid;
  1133. int why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
  1134. exit_code = p->exit_code;
  1135. if (unlikely(!exit_code) ||
  1136. unlikely(p->state & TASK_TRACED))
  1137. goto bail_ref;
  1138. return wait_noreap_copyout(p, pid, uid,
  1139. why, (exit_code << 8) | 0x7f,
  1140. infop, ru);
  1141. }
  1142. write_lock_irq(&tasklist_lock);
  1143. /*
  1144. * This uses xchg to be atomic with the thread resuming and setting
  1145. * it. It must also be done with the write lock held to prevent a
  1146. * race with the EXIT_ZOMBIE case.
  1147. */
  1148. exit_code = xchg(&p->exit_code, 0);
  1149. if (unlikely(p->exit_state)) {
  1150. /*
  1151. * The task resumed and then died. Let the next iteration
  1152. * catch it in EXIT_ZOMBIE. Note that exit_code might
  1153. * already be zero here if it resumed and did _exit(0).
  1154. * The task itself is dead and won't touch exit_code again;
  1155. * other processors in this function are locked out.
  1156. */
  1157. p->exit_code = exit_code;
  1158. exit_code = 0;
  1159. }
  1160. if (unlikely(exit_code == 0)) {
  1161. /*
  1162. * Another thread in this function got to it first, or it
  1163. * resumed, or it resumed and then died.
  1164. */
  1165. write_unlock_irq(&tasklist_lock);
  1166. bail_ref:
  1167. put_task_struct(p);
  1168. /*
  1169. * We are returning to the wait loop without having successfully
  1170. * removed the process and having released the lock. We cannot
  1171. * continue, since the "p" task pointer is potentially stale.
  1172. *
  1173. * Return -EAGAIN, and do_wait() will restart the loop from the
  1174. * beginning. Do _not_ re-acquire the lock.
  1175. */
  1176. return -EAGAIN;
  1177. }
  1178. /* move to end of parent's list to avoid starvation */
  1179. remove_parent(p);
  1180. add_parent(p);
  1181. write_unlock_irq(&tasklist_lock);
  1182. retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
  1183. if (!retval && stat_addr)
  1184. retval = put_user((exit_code << 8) | 0x7f, stat_addr);
  1185. if (!retval && infop)
  1186. retval = put_user(SIGCHLD, &infop->si_signo);
  1187. if (!retval && infop)
  1188. retval = put_user(0, &infop->si_errno);
  1189. if (!retval && infop)
  1190. retval = put_user((short)((p->ptrace & PT_PTRACED)
  1191. ? CLD_TRAPPED : CLD_STOPPED),
  1192. &infop->si_code);
  1193. if (!retval && infop)
  1194. retval = put_user(exit_code, &infop->si_status);
  1195. if (!retval && infop)
  1196. retval = put_user(p->pid, &infop->si_pid);
  1197. if (!retval && infop)
  1198. retval = put_user(p->uid, &infop->si_uid);
  1199. if (!retval)
  1200. retval = p->pid;
  1201. put_task_struct(p);
  1202. BUG_ON(!retval);
  1203. return retval;
  1204. }
  1205. /*
  1206. * Handle do_wait work for one task in a live, non-stopped state.
  1207. * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
  1208. * the lock and this task is uninteresting. If we return nonzero, we have
  1209. * released the lock and the system call should return.
  1210. */
  1211. static int wait_task_continued(struct task_struct *p, int noreap,
  1212. struct siginfo __user *infop,
  1213. int __user *stat_addr, struct rusage __user *ru)
  1214. {
  1215. int retval;
  1216. pid_t pid;
  1217. uid_t uid;
  1218. if (unlikely(!p->signal))
  1219. return 0;
  1220. if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
  1221. return 0;
  1222. spin_lock_irq(&p->sighand->siglock);
  1223. /* Re-check with the lock held. */
  1224. if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
  1225. spin_unlock_irq(&p->sighand->siglock);
  1226. return 0;
  1227. }
  1228. if (!noreap)
  1229. p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
  1230. spin_unlock_irq(&p->sighand->siglock);
  1231. pid = p->pid;
  1232. uid = p->uid;
  1233. get_task_struct(p);
  1234. read_unlock(&tasklist_lock);
  1235. if (!infop) {
  1236. retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
  1237. put_task_struct(p);
  1238. if (!retval && stat_addr)
  1239. retval = put_user(0xffff, stat_addr);
  1240. if (!retval)
  1241. retval = p->pid;
  1242. } else {
  1243. retval = wait_noreap_copyout(p, pid, uid,
  1244. CLD_CONTINUED, SIGCONT,
  1245. infop, ru);
  1246. BUG_ON(retval == 0);
  1247. }
  1248. return retval;
  1249. }
  1250. static inline int my_ptrace_child(struct task_struct *p)
  1251. {
  1252. if (!(p->ptrace & PT_PTRACED))
  1253. return 0;
  1254. if (!(p->ptrace & PT_ATTACHED))
  1255. return 1;
  1256. /*
  1257. * This child was PTRACE_ATTACH'd. We should be seeing it only if
  1258. * we are the attacher. If we are the real parent, this is a race
  1259. * inside ptrace_attach. It is waiting for the tasklist_lock,
  1260. * which we have to switch the parent links, but has already set
  1261. * the flags in p->ptrace.
  1262. */
  1263. return (p->parent != p->real_parent);
  1264. }
  1265. static long do_wait(pid_t pid, int options, struct siginfo __user *infop,
  1266. int __user *stat_addr, struct rusage __user *ru)
  1267. {
  1268. DECLARE_WAITQUEUE(wait, current);
  1269. struct task_struct *tsk;
  1270. int flag, retval;
  1271. add_wait_queue(&current->signal->wait_chldexit,&wait);
  1272. repeat:
  1273. /*
  1274. * We will set this flag if we see any child that might later
  1275. * match our criteria, even if we are not able to reap it yet.
  1276. */
  1277. flag = 0;
  1278. current->state = TASK_INTERRUPTIBLE;
  1279. read_lock(&tasklist_lock);
  1280. tsk = current;
  1281. do {
  1282. struct task_struct *p;
  1283. struct list_head *_p;
  1284. int ret;
  1285. list_for_each(_p,&tsk->children) {
  1286. p = list_entry(_p, struct task_struct, sibling);
  1287. ret = eligible_child(pid, options, p);
  1288. if (!ret)
  1289. continue;
  1290. switch (p->state) {
  1291. case TASK_TRACED:
  1292. /*
  1293. * When we hit the race with PTRACE_ATTACH,
  1294. * we will not report this child. But the
  1295. * race means it has not yet been moved to
  1296. * our ptrace_children list, so we need to
  1297. * set the flag here to avoid a spurious ECHILD
  1298. * when the race happens with the only child.
  1299. */
  1300. flag = 1;
  1301. if (!my_ptrace_child(p))
  1302. continue;
  1303. /*FALLTHROUGH*/
  1304. case TASK_STOPPED:
  1305. /*
  1306. * It's stopped now, so it might later
  1307. * continue, exit, or stop again.
  1308. */
  1309. flag = 1;
  1310. if (!(options & WUNTRACED) &&
  1311. !my_ptrace_child(p))
  1312. continue;
  1313. retval = wait_task_stopped(p, ret == 2,
  1314. (options & WNOWAIT),
  1315. infop,
  1316. stat_addr, ru);
  1317. if (retval == -EAGAIN)
  1318. goto repeat;
  1319. if (retval != 0) /* He released the lock. */
  1320. goto end;
  1321. break;
  1322. default:
  1323. // case EXIT_DEAD:
  1324. if (p->exit_state == EXIT_DEAD)
  1325. continue;
  1326. // case EXIT_ZOMBIE:
  1327. if (p->exit_state == EXIT_ZOMBIE) {
  1328. /*
  1329. * Eligible but we cannot release
  1330. * it yet:
  1331. */
  1332. if (ret == 2)
  1333. goto check_continued;
  1334. if (!likely(options & WEXITED))
  1335. continue;
  1336. retval = wait_task_zombie(
  1337. p, (options & WNOWAIT),
  1338. infop, stat_addr, ru);
  1339. /* He released the lock. */
  1340. if (retval != 0)
  1341. goto end;
  1342. break;
  1343. }
  1344. check_continued:
  1345. /*
  1346. * It's running now, so it might later
  1347. * exit, stop, or stop and then continue.
  1348. */
  1349. flag = 1;
  1350. if (!unlikely(options & WCONTINUED))
  1351. continue;
  1352. retval = wait_task_continued(
  1353. p, (options & WNOWAIT),
  1354. infop, stat_addr, ru);
  1355. if (retval != 0) /* He released the lock. */
  1356. goto end;
  1357. break;
  1358. }
  1359. }
  1360. if (!flag) {
  1361. list_for_each(_p, &tsk->ptrace_children) {
  1362. p = list_entry(_p, struct task_struct,
  1363. ptrace_list);
  1364. if (!eligible_child(pid, options, p))
  1365. continue;
  1366. flag = 1;
  1367. break;
  1368. }
  1369. }
  1370. if (options & __WNOTHREAD)
  1371. break;
  1372. tsk = next_thread(tsk);
  1373. BUG_ON(tsk->signal != current->signal);
  1374. } while (tsk != current);
  1375. read_unlock(&tasklist_lock);
  1376. if (flag) {
  1377. retval = 0;
  1378. if (options & WNOHANG)
  1379. goto end;
  1380. retval = -ERESTARTSYS;
  1381. if (signal_pending(current))
  1382. goto end;
  1383. schedule();
  1384. goto repeat;
  1385. }
  1386. retval = -ECHILD;
  1387. end:
  1388. current->state = TASK_RUNNING;
  1389. remove_wait_queue(&current->signal->wait_chldexit,&wait);
  1390. if (infop) {
  1391. if (retval > 0)
  1392. retval = 0;
  1393. else {
  1394. /*
  1395. * For a WNOHANG return, clear out all the fields
  1396. * we would set so the user can easily tell the
  1397. * difference.
  1398. */
  1399. if (!retval)
  1400. retval = put_user(0, &infop->si_signo);
  1401. if (!retval)
  1402. retval = put_user(0, &infop->si_errno);
  1403. if (!retval)
  1404. retval = put_user(0, &infop->si_code);
  1405. if (!retval)
  1406. retval = put_user(0, &infop->si_pid);
  1407. if (!retval)
  1408. retval = put_user(0, &infop->si_uid);
  1409. if (!retval)
  1410. retval = put_user(0, &infop->si_status);
  1411. }
  1412. }
  1413. return retval;
  1414. }
  1415. asmlinkage long sys_waitid(int which, pid_t pid,
  1416. struct siginfo __user *infop, int options,
  1417. struct rusage __user *ru)
  1418. {
  1419. long ret;
  1420. if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
  1421. return -EINVAL;
  1422. if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
  1423. return -EINVAL;
  1424. switch (which) {
  1425. case P_ALL:
  1426. pid = -1;
  1427. break;
  1428. case P_PID:
  1429. if (pid <= 0)
  1430. return -EINVAL;
  1431. break;
  1432. case P_PGID:
  1433. if (pid <= 0)
  1434. return -EINVAL;
  1435. pid = -pid;
  1436. break;
  1437. default:
  1438. return -EINVAL;
  1439. }
  1440. ret = do_wait(pid, options, infop, NULL, ru);
  1441. /* avoid REGPARM breakage on x86: */
  1442. prevent_tail_call(ret);
  1443. return ret;
  1444. }
  1445. asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr,
  1446. int options, struct rusage __user *ru)
  1447. {
  1448. long ret;
  1449. if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
  1450. __WNOTHREAD|__WCLONE|__WALL))
  1451. return -EINVAL;
  1452. ret = do_wait(pid, options | WEXITED, NULL, stat_addr, ru);
  1453. /* avoid REGPARM breakage on x86: */
  1454. prevent_tail_call(ret);
  1455. return ret;
  1456. }
  1457. #ifdef __ARCH_WANT_SYS_WAITPID
  1458. /*
  1459. * sys_waitpid() remains for compatibility. waitpid() should be
  1460. * implemented by calling sys_wait4() from libc.a.
  1461. */
  1462. asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options)
  1463. {
  1464. return sys_wait4(pid, stat_addr, options, NULL);
  1465. }
  1466. #endif