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1 | /* | |
2 | * linux/kernel/exit.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | */ | |
6 | ||
7 | #include <linux/config.h> | |
8 | #include <linux/mm.h> | |
9 | #include <linux/slab.h> | |
10 | #include <linux/interrupt.h> | |
11 | #include <linux/smp_lock.h> | |
12 | #include <linux/module.h> | |
13 | #include <linux/capability.h> | |
14 | #include <linux/completion.h> | |
15 | #include <linux/personality.h> | |
16 | #include <linux/tty.h> | |
17 | #include <linux/namespace.h> | |
18 | #include <linux/key.h> | |
19 | #include <linux/security.h> | |
20 | #include <linux/cpu.h> | |
21 | #include <linux/acct.h> | |
22 | #include <linux/file.h> | |
23 | #include <linux/binfmts.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/cpuset.h> | |
30 | #include <linux/syscalls.h> | |
31 | #include <linux/signal.h> | |
32 | #include <linux/posix-timers.h> | |
33 | #include <linux/cn_proc.h> | |
34 | #include <linux/mutex.h> | |
35 | #include <linux/futex.h> | |
36 | #include <linux/compat.h> | |
37 | #include <linux/pipe_fs_i.h> | |
38 | #include <linux/audit.h> /* for audit_free() */ | |
39 | #include <linux/resource.h> | |
40 | ||
41 | #include <asm/uaccess.h> | |
42 | #include <asm/unistd.h> | |
43 | #include <asm/pgtable.h> | |
44 | #include <asm/mmu_context.h> | |
45 | ||
46 | extern void sem_exit (void); | |
47 | extern struct task_struct *child_reaper; | |
48 | ||
49 | static void exit_mm(struct task_struct * tsk); | |
50 | ||
51 | static void __unhash_process(struct task_struct *p) | |
52 | { | |
53 | nr_threads--; | |
54 | detach_pid(p, PIDTYPE_PID); | |
55 | if (thread_group_leader(p)) { | |
56 | detach_pid(p, PIDTYPE_PGID); | |
57 | detach_pid(p, PIDTYPE_SID); | |
58 | ||
59 | list_del_rcu(&p->tasks); | |
60 | __get_cpu_var(process_counts)--; | |
61 | } | |
62 | list_del_rcu(&p->thread_group); | |
63 | remove_parent(p); | |
64 | } | |
65 | ||
66 | /* | |
67 | * This function expects the tasklist_lock write-locked. | |
68 | */ | |
69 | static void __exit_signal(struct task_struct *tsk) | |
70 | { | |
71 | struct signal_struct *sig = tsk->signal; | |
72 | struct sighand_struct *sighand; | |
73 | ||
74 | BUG_ON(!sig); | |
75 | BUG_ON(!atomic_read(&sig->count)); | |
76 | ||
77 | rcu_read_lock(); | |
78 | sighand = rcu_dereference(tsk->sighand); | |
79 | spin_lock(&sighand->siglock); | |
80 | ||
81 | posix_cpu_timers_exit(tsk); | |
82 | if (atomic_dec_and_test(&sig->count)) | |
83 | posix_cpu_timers_exit_group(tsk); | |
84 | else { | |
85 | /* | |
86 | * If there is any task waiting for the group exit | |
87 | * then notify it: | |
88 | */ | |
89 | if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count) { | |
90 | wake_up_process(sig->group_exit_task); | |
91 | sig->group_exit_task = NULL; | |
92 | } | |
93 | if (tsk == sig->curr_target) | |
94 | sig->curr_target = next_thread(tsk); | |
95 | /* | |
96 | * Accumulate here the counters for all threads but the | |
97 | * group leader as they die, so they can be added into | |
98 | * the process-wide totals when those are taken. | |
99 | * The group leader stays around as a zombie as long | |
100 | * as there are other threads. When it gets reaped, | |
101 | * the exit.c code will add its counts into these totals. | |
102 | * We won't ever get here for the group leader, since it | |
103 | * will have been the last reference on the signal_struct. | |
104 | */ | |
105 | sig->utime = cputime_add(sig->utime, tsk->utime); | |
106 | sig->stime = cputime_add(sig->stime, tsk->stime); | |
107 | sig->min_flt += tsk->min_flt; | |
108 | sig->maj_flt += tsk->maj_flt; | |
109 | sig->nvcsw += tsk->nvcsw; | |
110 | sig->nivcsw += tsk->nivcsw; | |
111 | sig->sched_time += tsk->sched_time; | |
112 | sig = NULL; /* Marker for below. */ | |
113 | } | |
114 | ||
115 | __unhash_process(tsk); | |
116 | ||
117 | tsk->signal = NULL; | |
118 | tsk->sighand = NULL; | |
119 | spin_unlock(&sighand->siglock); | |
120 | rcu_read_unlock(); | |
121 | ||
122 | __cleanup_sighand(sighand); | |
123 | clear_tsk_thread_flag(tsk,TIF_SIGPENDING); | |
124 | flush_sigqueue(&tsk->pending); | |
125 | if (sig) { | |
126 | flush_sigqueue(&sig->shared_pending); | |
127 | __cleanup_signal(sig); | |
128 | } | |
129 | } | |
130 | ||
131 | static void delayed_put_task_struct(struct rcu_head *rhp) | |
132 | { | |
133 | put_task_struct(container_of(rhp, struct task_struct, rcu)); | |
134 | } | |
135 | ||
136 | void release_task(struct task_struct * p) | |
137 | { | |
138 | int zap_leader; | |
139 | task_t *leader; | |
140 | struct dentry *proc_dentry; | |
141 | ||
142 | repeat: | |
143 | atomic_dec(&p->user->processes); | |
144 | spin_lock(&p->proc_lock); | |
145 | proc_dentry = proc_pid_unhash(p); | |
146 | write_lock_irq(&tasklist_lock); | |
147 | ptrace_unlink(p); | |
148 | BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children)); | |
149 | __exit_signal(p); | |
150 | ||
151 | /* | |
152 | * If we are the last non-leader member of the thread | |
153 | * group, and the leader is zombie, then notify the | |
154 | * group leader's parent process. (if it wants notification.) | |
155 | */ | |
156 | zap_leader = 0; | |
157 | leader = p->group_leader; | |
158 | if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) { | |
159 | BUG_ON(leader->exit_signal == -1); | |
160 | do_notify_parent(leader, leader->exit_signal); | |
161 | /* | |
162 | * If we were the last child thread and the leader has | |
163 | * exited already, and the leader's parent ignores SIGCHLD, | |
164 | * then we are the one who should release the leader. | |
165 | * | |
166 | * do_notify_parent() will have marked it self-reaping in | |
167 | * that case. | |
168 | */ | |
169 | zap_leader = (leader->exit_signal == -1); | |
170 | } | |
171 | ||
172 | sched_exit(p); | |
173 | write_unlock_irq(&tasklist_lock); | |
174 | spin_unlock(&p->proc_lock); | |
175 | proc_pid_flush(proc_dentry); | |
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 = -1; | |
193 | ||
194 | read_lock(&tasklist_lock); | |
195 | do_each_task_pid(pgrp, PIDTYPE_PGID, p) { | |
196 | if (p->signal->session > 0) { | |
197 | sid = p->signal->session; | |
198 | goto out; | |
199 | } | |
200 | } while_each_task_pid(pgrp, PIDTYPE_PGID, p); | |
201 | p = find_task_by_pid(pgrp); | |
202 | if (p) | |
203 | sid = p->signal->session; | |
204 | out: | |
205 | read_unlock(&tasklist_lock); | |
206 | ||
207 | return sid; | |
208 | } | |
209 | ||
210 | /* | |
211 | * Determine if a process group is "orphaned", according to the POSIX | |
212 | * definition in 2.2.2.52. Orphaned process groups are not to be affected | |
213 | * by terminal-generated stop signals. Newly orphaned process groups are | |
214 | * to receive a SIGHUP and a SIGCONT. | |
215 | * | |
216 | * "I ask you, have you ever known what it is to be an orphan?" | |
217 | */ | |
218 | static int will_become_orphaned_pgrp(int pgrp, task_t *ignored_task) | |
219 | { | |
220 | struct task_struct *p; | |
221 | int ret = 1; | |
222 | ||
223 | do_each_task_pid(pgrp, PIDTYPE_PGID, p) { | |
224 | if (p == ignored_task | |
225 | || p->exit_state | |
226 | || p->real_parent->pid == 1) | |
227 | continue; | |
228 | if (process_group(p->real_parent) != pgrp | |
229 | && p->real_parent->signal->session == p->signal->session) { | |
230 | ret = 0; | |
231 | break; | |
232 | } | |
233 | } while_each_task_pid(pgrp, PIDTYPE_PGID, p); | |
234 | return ret; /* (sighing) "Often!" */ | |
235 | } | |
236 | ||
237 | int is_orphaned_pgrp(int pgrp) | |
238 | { | |
239 | int retval; | |
240 | ||
241 | read_lock(&tasklist_lock); | |
242 | retval = will_become_orphaned_pgrp(pgrp, NULL); | |
243 | read_unlock(&tasklist_lock); | |
244 | ||
245 | return retval; | |
246 | } | |
247 | ||
248 | static int has_stopped_jobs(int pgrp) | |
249 | { | |
250 | int retval = 0; | |
251 | struct task_struct *p; | |
252 | ||
253 | do_each_task_pid(pgrp, PIDTYPE_PGID, p) { | |
254 | if (p->state != TASK_STOPPED) | |
255 | continue; | |
256 | ||
257 | /* If p is stopped by a debugger on a signal that won't | |
258 | stop it, then don't count p as stopped. This isn't | |
259 | perfect but it's a good approximation. */ | |
260 | if (unlikely (p->ptrace) | |
261 | && p->exit_code != SIGSTOP | |
262 | && p->exit_code != SIGTSTP | |
263 | && p->exit_code != SIGTTOU | |
264 | && p->exit_code != SIGTTIN) | |
265 | continue; | |
266 | ||
267 | retval = 1; | |
268 | break; | |
269 | } while_each_task_pid(pgrp, PIDTYPE_PGID, p); | |
270 | return retval; | |
271 | } | |
272 | ||
273 | /** | |
274 | * reparent_to_init - Reparent the calling kernel thread to the init task. | |
275 | * | |
276 | * If a kernel thread is launched as a result of a system call, or if | |
277 | * it ever exits, it should generally reparent itself to init so that | |
278 | * it is correctly cleaned up on exit. | |
279 | * | |
280 | * The various task state such as scheduling policy and priority may have | |
281 | * been inherited from a user process, so we reset them to sane values here. | |
282 | * | |
283 | * NOTE that reparent_to_init() gives the caller full capabilities. | |
284 | */ | |
285 | static void reparent_to_init(void) | |
286 | { | |
287 | write_lock_irq(&tasklist_lock); | |
288 | ||
289 | ptrace_unlink(current); | |
290 | /* Reparent to init */ | |
291 | remove_parent(current); | |
292 | current->parent = child_reaper; | |
293 | current->real_parent = child_reaper; | |
294 | add_parent(current); | |
295 | ||
296 | /* Set the exit signal to SIGCHLD so we signal init on exit */ | |
297 | current->exit_signal = SIGCHLD; | |
298 | ||
299 | if ((current->policy == SCHED_NORMAL || | |
300 | current->policy == SCHED_BATCH) | |
301 | && (task_nice(current) < 0)) | |
302 | set_user_nice(current, 0); | |
303 | /* cpus_allowed? */ | |
304 | /* rt_priority? */ | |
305 | /* signals? */ | |
306 | security_task_reparent_to_init(current); | |
307 | memcpy(current->signal->rlim, init_task.signal->rlim, | |
308 | sizeof(current->signal->rlim)); | |
309 | atomic_inc(&(INIT_USER->__count)); | |
310 | write_unlock_irq(&tasklist_lock); | |
311 | switch_uid(INIT_USER); | |
312 | } | |
313 | ||
314 | void __set_special_pids(pid_t session, pid_t pgrp) | |
315 | { | |
316 | struct task_struct *curr = current->group_leader; | |
317 | ||
318 | if (curr->signal->session != session) { | |
319 | detach_pid(curr, PIDTYPE_SID); | |
320 | curr->signal->session = session; | |
321 | attach_pid(curr, PIDTYPE_SID, session); | |
322 | } | |
323 | if (process_group(curr) != pgrp) { | |
324 | detach_pid(curr, PIDTYPE_PGID); | |
325 | curr->signal->pgrp = pgrp; | |
326 | attach_pid(curr, PIDTYPE_PGID, pgrp); | |
327 | } | |
328 | } | |
329 | ||
330 | void set_special_pids(pid_t session, pid_t pgrp) | |
331 | { | |
332 | write_lock_irq(&tasklist_lock); | |
333 | __set_special_pids(session, pgrp); | |
334 | write_unlock_irq(&tasklist_lock); | |
335 | } | |
336 | ||
337 | /* | |
338 | * Let kernel threads use this to say that they | |
339 | * allow a certain signal (since daemonize() will | |
340 | * have disabled all of them by default). | |
341 | */ | |
342 | int allow_signal(int sig) | |
343 | { | |
344 | if (!valid_signal(sig) || sig < 1) | |
345 | return -EINVAL; | |
346 | ||
347 | spin_lock_irq(¤t->sighand->siglock); | |
348 | sigdelset(¤t->blocked, sig); | |
349 | if (!current->mm) { | |
350 | /* Kernel threads handle their own signals. | |
351 | Let the signal code know it'll be handled, so | |
352 | that they don't get converted to SIGKILL or | |
353 | just silently dropped */ | |
354 | current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2; | |
355 | } | |
356 | recalc_sigpending(); | |
357 | spin_unlock_irq(¤t->sighand->siglock); | |
358 | return 0; | |
359 | } | |
360 | ||
361 | EXPORT_SYMBOL(allow_signal); | |
362 | ||
363 | int disallow_signal(int sig) | |
364 | { | |
365 | if (!valid_signal(sig) || sig < 1) | |
366 | return -EINVAL; | |
367 | ||
368 | spin_lock_irq(¤t->sighand->siglock); | |
369 | sigaddset(¤t->blocked, sig); | |
370 | recalc_sigpending(); | |
371 | spin_unlock_irq(¤t->sighand->siglock); | |
372 | return 0; | |
373 | } | |
374 | ||
375 | EXPORT_SYMBOL(disallow_signal); | |
376 | ||
377 | /* | |
378 | * Put all the gunge required to become a kernel thread without | |
379 | * attached user resources in one place where it belongs. | |
380 | */ | |
381 | ||
382 | void daemonize(const char *name, ...) | |
383 | { | |
384 | va_list args; | |
385 | struct fs_struct *fs; | |
386 | sigset_t blocked; | |
387 | ||
388 | va_start(args, name); | |
389 | vsnprintf(current->comm, sizeof(current->comm), name, args); | |
390 | va_end(args); | |
391 | ||
392 | /* | |
393 | * If we were started as result of loading a module, close all of the | |
394 | * user space pages. We don't need them, and if we didn't close them | |
395 | * they would be locked into memory. | |
396 | */ | |
397 | exit_mm(current); | |
398 | ||
399 | set_special_pids(1, 1); | |
400 | mutex_lock(&tty_mutex); | |
401 | current->signal->tty = NULL; | |
402 | mutex_unlock(&tty_mutex); | |
403 | ||
404 | /* Block and flush all signals */ | |
405 | sigfillset(&blocked); | |
406 | sigprocmask(SIG_BLOCK, &blocked, NULL); | |
407 | flush_signals(current); | |
408 | ||
409 | /* Become as one with the init task */ | |
410 | ||
411 | exit_fs(current); /* current->fs->count--; */ | |
412 | fs = init_task.fs; | |
413 | current->fs = fs; | |
414 | atomic_inc(&fs->count); | |
415 | exit_namespace(current); | |
416 | current->namespace = init_task.namespace; | |
417 | get_namespace(current->namespace); | |
418 | exit_files(current); | |
419 | current->files = init_task.files; | |
420 | atomic_inc(¤t->files->count); | |
421 | ||
422 | reparent_to_init(); | |
423 | } | |
424 | ||
425 | EXPORT_SYMBOL(daemonize); | |
426 | ||
427 | static void close_files(struct files_struct * files) | |
428 | { | |
429 | int i, j; | |
430 | struct fdtable *fdt; | |
431 | ||
432 | j = 0; | |
433 | ||
434 | /* | |
435 | * It is safe to dereference the fd table without RCU or | |
436 | * ->file_lock because this is the last reference to the | |
437 | * files structure. | |
438 | */ | |
439 | fdt = files_fdtable(files); | |
440 | for (;;) { | |
441 | unsigned long set; | |
442 | i = j * __NFDBITS; | |
443 | if (i >= fdt->max_fdset || i >= fdt->max_fds) | |
444 | break; | |
445 | set = fdt->open_fds->fds_bits[j++]; | |
446 | while (set) { | |
447 | if (set & 1) { | |
448 | struct file * file = xchg(&fdt->fd[i], NULL); | |
449 | if (file) | |
450 | filp_close(file, files); | |
451 | } | |
452 | i++; | |
453 | set >>= 1; | |
454 | } | |
455 | } | |
456 | } | |
457 | ||
458 | struct files_struct *get_files_struct(struct task_struct *task) | |
459 | { | |
460 | struct files_struct *files; | |
461 | ||
462 | task_lock(task); | |
463 | files = task->files; | |
464 | if (files) | |
465 | atomic_inc(&files->count); | |
466 | task_unlock(task); | |
467 | ||
468 | return files; | |
469 | } | |
470 | ||
471 | void fastcall put_files_struct(struct files_struct *files) | |
472 | { | |
473 | struct fdtable *fdt; | |
474 | ||
475 | if (atomic_dec_and_test(&files->count)) { | |
476 | close_files(files); | |
477 | /* | |
478 | * Free the fd and fdset arrays if we expanded them. | |
479 | * If the fdtable was embedded, pass files for freeing | |
480 | * at the end of the RCU grace period. Otherwise, | |
481 | * you can free files immediately. | |
482 | */ | |
483 | fdt = files_fdtable(files); | |
484 | if (fdt == &files->fdtab) | |
485 | fdt->free_files = files; | |
486 | else | |
487 | kmem_cache_free(files_cachep, files); | |
488 | free_fdtable(fdt); | |
489 | } | |
490 | } | |
491 | ||
492 | EXPORT_SYMBOL(put_files_struct); | |
493 | ||
494 | static inline void __exit_files(struct task_struct *tsk) | |
495 | { | |
496 | struct files_struct * files = tsk->files; | |
497 | ||
498 | if (files) { | |
499 | task_lock(tsk); | |
500 | tsk->files = NULL; | |
501 | task_unlock(tsk); | |
502 | put_files_struct(files); | |
503 | } | |
504 | } | |
505 | ||
506 | void exit_files(struct task_struct *tsk) | |
507 | { | |
508 | __exit_files(tsk); | |
509 | } | |
510 | ||
511 | static inline void __put_fs_struct(struct fs_struct *fs) | |
512 | { | |
513 | /* No need to hold fs->lock if we are killing it */ | |
514 | if (atomic_dec_and_test(&fs->count)) { | |
515 | dput(fs->root); | |
516 | mntput(fs->rootmnt); | |
517 | dput(fs->pwd); | |
518 | mntput(fs->pwdmnt); | |
519 | if (fs->altroot) { | |
520 | dput(fs->altroot); | |
521 | mntput(fs->altrootmnt); | |
522 | } | |
523 | kmem_cache_free(fs_cachep, fs); | |
524 | } | |
525 | } | |
526 | ||
527 | void put_fs_struct(struct fs_struct *fs) | |
528 | { | |
529 | __put_fs_struct(fs); | |
530 | } | |
531 | ||
532 | static inline void __exit_fs(struct task_struct *tsk) | |
533 | { | |
534 | struct fs_struct * fs = tsk->fs; | |
535 | ||
536 | if (fs) { | |
537 | task_lock(tsk); | |
538 | tsk->fs = NULL; | |
539 | task_unlock(tsk); | |
540 | __put_fs_struct(fs); | |
541 | } | |
542 | } | |
543 | ||
544 | void exit_fs(struct task_struct *tsk) | |
545 | { | |
546 | __exit_fs(tsk); | |
547 | } | |
548 | ||
549 | EXPORT_SYMBOL_GPL(exit_fs); | |
550 | ||
551 | /* | |
552 | * Turn us into a lazy TLB process if we | |
553 | * aren't already.. | |
554 | */ | |
555 | static void exit_mm(struct task_struct * tsk) | |
556 | { | |
557 | struct mm_struct *mm = tsk->mm; | |
558 | ||
559 | mm_release(tsk, mm); | |
560 | if (!mm) | |
561 | return; | |
562 | /* | |
563 | * Serialize with any possible pending coredump. | |
564 | * We must hold mmap_sem around checking core_waiters | |
565 | * and clearing tsk->mm. The core-inducing thread | |
566 | * will increment core_waiters for each thread in the | |
567 | * group with ->mm != NULL. | |
568 | */ | |
569 | down_read(&mm->mmap_sem); | |
570 | if (mm->core_waiters) { | |
571 | up_read(&mm->mmap_sem); | |
572 | down_write(&mm->mmap_sem); | |
573 | if (!--mm->core_waiters) | |
574 | complete(mm->core_startup_done); | |
575 | up_write(&mm->mmap_sem); | |
576 | ||
577 | wait_for_completion(&mm->core_done); | |
578 | down_read(&mm->mmap_sem); | |
579 | } | |
580 | atomic_inc(&mm->mm_count); | |
581 | BUG_ON(mm != tsk->active_mm); | |
582 | /* more a memory barrier than a real lock */ | |
583 | task_lock(tsk); | |
584 | tsk->mm = NULL; | |
585 | up_read(&mm->mmap_sem); | |
586 | enter_lazy_tlb(mm, current); | |
587 | task_unlock(tsk); | |
588 | mmput(mm); | |
589 | } | |
590 | ||
591 | static inline void choose_new_parent(task_t *p, task_t *reaper) | |
592 | { | |
593 | /* | |
594 | * Make sure we're not reparenting to ourselves and that | |
595 | * the parent is not a zombie. | |
596 | */ | |
597 | BUG_ON(p == reaper || reaper->exit_state); | |
598 | p->real_parent = reaper; | |
599 | } | |
600 | ||
601 | static void reparent_thread(task_t *p, task_t *father, int traced) | |
602 | { | |
603 | /* We don't want people slaying init. */ | |
604 | if (p->exit_signal != -1) | |
605 | p->exit_signal = SIGCHLD; | |
606 | ||
607 | if (p->pdeath_signal) | |
608 | /* We already hold the tasklist_lock here. */ | |
609 | group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p); | |
610 | ||
611 | /* Move the child from its dying parent to the new one. */ | |
612 | if (unlikely(traced)) { | |
613 | /* Preserve ptrace links if someone else is tracing this child. */ | |
614 | list_del_init(&p->ptrace_list); | |
615 | if (p->parent != p->real_parent) | |
616 | list_add(&p->ptrace_list, &p->real_parent->ptrace_children); | |
617 | } else { | |
618 | /* If this child is being traced, then we're the one tracing it | |
619 | * anyway, so let go of it. | |
620 | */ | |
621 | p->ptrace = 0; | |
622 | remove_parent(p); | |
623 | p->parent = p->real_parent; | |
624 | add_parent(p); | |
625 | ||
626 | /* If we'd notified the old parent about this child's death, | |
627 | * also notify the new parent. | |
628 | */ | |
629 | if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 && | |
630 | thread_group_empty(p)) | |
631 | do_notify_parent(p, p->exit_signal); | |
632 | else if (p->state == TASK_TRACED) { | |
633 | /* | |
634 | * If it was at a trace stop, turn it into | |
635 | * a normal stop since it's no longer being | |
636 | * traced. | |
637 | */ | |
638 | ptrace_untrace(p); | |
639 | } | |
640 | } | |
641 | ||
642 | /* | |
643 | * process group orphan check | |
644 | * Case ii: Our child is in a different pgrp | |
645 | * than we are, and it was the only connection | |
646 | * outside, so the child pgrp is now orphaned. | |
647 | */ | |
648 | if ((process_group(p) != process_group(father)) && | |
649 | (p->signal->session == father->signal->session)) { | |
650 | int pgrp = process_group(p); | |
651 | ||
652 | if (will_become_orphaned_pgrp(pgrp, NULL) && has_stopped_jobs(pgrp)) { | |
653 | __kill_pg_info(SIGHUP, SEND_SIG_PRIV, pgrp); | |
654 | __kill_pg_info(SIGCONT, SEND_SIG_PRIV, pgrp); | |
655 | } | |
656 | } | |
657 | } | |
658 | ||
659 | /* | |
660 | * When we die, we re-parent all our children. | |
661 | * Try to give them to another thread in our thread | |
662 | * group, and if no such member exists, give it to | |
663 | * the global child reaper process (ie "init") | |
664 | */ | |
665 | static void forget_original_parent(struct task_struct * father, | |
666 | struct list_head *to_release) | |
667 | { | |
668 | struct task_struct *p, *reaper = father; | |
669 | struct list_head *_p, *_n; | |
670 | ||
671 | do { | |
672 | reaper = next_thread(reaper); | |
673 | if (reaper == father) { | |
674 | reaper = child_reaper; | |
675 | break; | |
676 | } | |
677 | } while (reaper->exit_state); | |
678 | ||
679 | /* | |
680 | * There are only two places where our children can be: | |
681 | * | |
682 | * - in our child list | |
683 | * - in our ptraced child list | |
684 | * | |
685 | * Search them and reparent children. | |
686 | */ | |
687 | list_for_each_safe(_p, _n, &father->children) { | |
688 | int ptrace; | |
689 | p = list_entry(_p,struct task_struct,sibling); | |
690 | ||
691 | ptrace = p->ptrace; | |
692 | ||
693 | /* if father isn't the real parent, then ptrace must be enabled */ | |
694 | BUG_ON(father != p->real_parent && !ptrace); | |
695 | ||
696 | if (father == p->real_parent) { | |
697 | /* reparent with a reaper, real father it's us */ | |
698 | choose_new_parent(p, reaper); | |
699 | reparent_thread(p, father, 0); | |
700 | } else { | |
701 | /* reparent ptraced task to its real parent */ | |
702 | __ptrace_unlink (p); | |
703 | if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 && | |
704 | thread_group_empty(p)) | |
705 | do_notify_parent(p, p->exit_signal); | |
706 | } | |
707 | ||
708 | /* | |
709 | * if the ptraced child is a zombie with exit_signal == -1 | |
710 | * we must collect it before we exit, or it will remain | |
711 | * zombie forever since we prevented it from self-reap itself | |
712 | * while it was being traced by us, to be able to see it in wait4. | |
713 | */ | |
714 | if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && p->exit_signal == -1)) | |
715 | list_add(&p->ptrace_list, to_release); | |
716 | } | |
717 | list_for_each_safe(_p, _n, &father->ptrace_children) { | |
718 | p = list_entry(_p,struct task_struct,ptrace_list); | |
719 | choose_new_parent(p, reaper); | |
720 | reparent_thread(p, father, 1); | |
721 | } | |
722 | } | |
723 | ||
724 | /* | |
725 | * Send signals to all our closest relatives so that they know | |
726 | * to properly mourn us.. | |
727 | */ | |
728 | static void exit_notify(struct task_struct *tsk) | |
729 | { | |
730 | int state; | |
731 | struct task_struct *t; | |
732 | struct list_head ptrace_dead, *_p, *_n; | |
733 | ||
734 | if (signal_pending(tsk) && !(tsk->signal->flags & SIGNAL_GROUP_EXIT) | |
735 | && !thread_group_empty(tsk)) { | |
736 | /* | |
737 | * This occurs when there was a race between our exit | |
738 | * syscall and a group signal choosing us as the one to | |
739 | * wake up. It could be that we are the only thread | |
740 | * alerted to check for pending signals, but another thread | |
741 | * should be woken now to take the signal since we will not. | |
742 | * Now we'll wake all the threads in the group just to make | |
743 | * sure someone gets all the pending signals. | |
744 | */ | |
745 | read_lock(&tasklist_lock); | |
746 | spin_lock_irq(&tsk->sighand->siglock); | |
747 | for (t = next_thread(tsk); t != tsk; t = next_thread(t)) | |
748 | if (!signal_pending(t) && !(t->flags & PF_EXITING)) { | |
749 | recalc_sigpending_tsk(t); | |
750 | if (signal_pending(t)) | |
751 | signal_wake_up(t, 0); | |
752 | } | |
753 | spin_unlock_irq(&tsk->sighand->siglock); | |
754 | read_unlock(&tasklist_lock); | |
755 | } | |
756 | ||
757 | write_lock_irq(&tasklist_lock); | |
758 | ||
759 | /* | |
760 | * This does two things: | |
761 | * | |
762 | * A. Make init inherit all the child processes | |
763 | * B. Check to see if any process groups have become orphaned | |
764 | * as a result of our exiting, and if they have any stopped | |
765 | * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) | |
766 | */ | |
767 | ||
768 | INIT_LIST_HEAD(&ptrace_dead); | |
769 | forget_original_parent(tsk, &ptrace_dead); | |
770 | BUG_ON(!list_empty(&tsk->children)); | |
771 | BUG_ON(!list_empty(&tsk->ptrace_children)); | |
772 | ||
773 | /* | |
774 | * Check to see if any process groups have become orphaned | |
775 | * as a result of our exiting, and if they have any stopped | |
776 | * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) | |
777 | * | |
778 | * Case i: Our father is in a different pgrp than we are | |
779 | * and we were the only connection outside, so our pgrp | |
780 | * is about to become orphaned. | |
781 | */ | |
782 | ||
783 | t = tsk->real_parent; | |
784 | ||
785 | if ((process_group(t) != process_group(tsk)) && | |
786 | (t->signal->session == tsk->signal->session) && | |
787 | will_become_orphaned_pgrp(process_group(tsk), tsk) && | |
788 | has_stopped_jobs(process_group(tsk))) { | |
789 | __kill_pg_info(SIGHUP, SEND_SIG_PRIV, process_group(tsk)); | |
790 | __kill_pg_info(SIGCONT, SEND_SIG_PRIV, process_group(tsk)); | |
791 | } | |
792 | ||
793 | /* Let father know we died | |
794 | * | |
795 | * Thread signals are configurable, but you aren't going to use | |
796 | * that to send signals to arbitary processes. | |
797 | * That stops right now. | |
798 | * | |
799 | * If the parent exec id doesn't match the exec id we saved | |
800 | * when we started then we know the parent has changed security | |
801 | * domain. | |
802 | * | |
803 | * If our self_exec id doesn't match our parent_exec_id then | |
804 | * we have changed execution domain as these two values started | |
805 | * the same after a fork. | |
806 | * | |
807 | */ | |
808 | ||
809 | if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 && | |
810 | ( tsk->parent_exec_id != t->self_exec_id || | |
811 | tsk->self_exec_id != tsk->parent_exec_id) | |
812 | && !capable(CAP_KILL)) | |
813 | tsk->exit_signal = SIGCHLD; | |
814 | ||
815 | ||
816 | /* If something other than our normal parent is ptracing us, then | |
817 | * send it a SIGCHLD instead of honoring exit_signal. exit_signal | |
818 | * only has special meaning to our real parent. | |
819 | */ | |
820 | if (tsk->exit_signal != -1 && thread_group_empty(tsk)) { | |
821 | int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD; | |
822 | do_notify_parent(tsk, signal); | |
823 | } else if (tsk->ptrace) { | |
824 | do_notify_parent(tsk, SIGCHLD); | |
825 | } | |
826 | ||
827 | state = EXIT_ZOMBIE; | |
828 | if (tsk->exit_signal == -1 && | |
829 | (likely(tsk->ptrace == 0) || | |
830 | unlikely(tsk->parent->signal->flags & SIGNAL_GROUP_EXIT))) | |
831 | state = EXIT_DEAD; | |
832 | tsk->exit_state = state; | |
833 | ||
834 | write_unlock_irq(&tasklist_lock); | |
835 | ||
836 | list_for_each_safe(_p, _n, &ptrace_dead) { | |
837 | list_del_init(_p); | |
838 | t = list_entry(_p,struct task_struct,ptrace_list); | |
839 | release_task(t); | |
840 | } | |
841 | ||
842 | /* If the process is dead, release it - nobody will wait for it */ | |
843 | if (state == EXIT_DEAD) | |
844 | release_task(tsk); | |
845 | } | |
846 | ||
847 | fastcall NORET_TYPE void do_exit(long code) | |
848 | { | |
849 | struct task_struct *tsk = current; | |
850 | int group_dead; | |
851 | ||
852 | profile_task_exit(tsk); | |
853 | ||
854 | WARN_ON(atomic_read(&tsk->fs_excl)); | |
855 | ||
856 | if (unlikely(in_interrupt())) | |
857 | panic("Aiee, killing interrupt handler!"); | |
858 | if (unlikely(!tsk->pid)) | |
859 | panic("Attempted to kill the idle task!"); | |
860 | if (unlikely(tsk == child_reaper)) | |
861 | panic("Attempted to kill init!"); | |
862 | ||
863 | if (unlikely(current->ptrace & PT_TRACE_EXIT)) { | |
864 | current->ptrace_message = code; | |
865 | ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP); | |
866 | } | |
867 | ||
868 | /* | |
869 | * We're taking recursive faults here in do_exit. Safest is to just | |
870 | * leave this task alone and wait for reboot. | |
871 | */ | |
872 | if (unlikely(tsk->flags & PF_EXITING)) { | |
873 | printk(KERN_ALERT | |
874 | "Fixing recursive fault but reboot is needed!\n"); | |
875 | if (tsk->io_context) | |
876 | exit_io_context(); | |
877 | set_current_state(TASK_UNINTERRUPTIBLE); | |
878 | schedule(); | |
879 | } | |
880 | ||
881 | tsk->flags |= PF_EXITING; | |
882 | ||
883 | if (unlikely(in_atomic())) | |
884 | printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n", | |
885 | current->comm, current->pid, | |
886 | preempt_count()); | |
887 | ||
888 | acct_update_integrals(tsk); | |
889 | if (tsk->mm) { | |
890 | update_hiwater_rss(tsk->mm); | |
891 | update_hiwater_vm(tsk->mm); | |
892 | } | |
893 | group_dead = atomic_dec_and_test(&tsk->signal->live); | |
894 | if (group_dead) { | |
895 | hrtimer_cancel(&tsk->signal->real_timer); | |
896 | exit_itimers(tsk->signal); | |
897 | acct_process(code); | |
898 | } | |
899 | if (unlikely(tsk->robust_list)) | |
900 | exit_robust_list(tsk); | |
901 | #if defined(CONFIG_FUTEX) && defined(CONFIG_COMPAT) | |
902 | if (unlikely(tsk->compat_robust_list)) | |
903 | compat_exit_robust_list(tsk); | |
904 | #endif | |
905 | if (unlikely(tsk->audit_context)) | |
906 | audit_free(tsk); | |
907 | exit_mm(tsk); | |
908 | ||
909 | exit_sem(tsk); | |
910 | __exit_files(tsk); | |
911 | __exit_fs(tsk); | |
912 | exit_namespace(tsk); | |
913 | exit_thread(); | |
914 | cpuset_exit(tsk); | |
915 | exit_keys(tsk); | |
916 | ||
917 | if (group_dead && tsk->signal->leader) | |
918 | disassociate_ctty(1); | |
919 | ||
920 | module_put(task_thread_info(tsk)->exec_domain->module); | |
921 | if (tsk->binfmt) | |
922 | module_put(tsk->binfmt->module); | |
923 | ||
924 | tsk->exit_code = code; | |
925 | proc_exit_connector(tsk); | |
926 | exit_notify(tsk); | |
927 | #ifdef CONFIG_NUMA | |
928 | mpol_free(tsk->mempolicy); | |
929 | tsk->mempolicy = NULL; | |
930 | #endif | |
931 | /* | |
932 | * If DEBUG_MUTEXES is on, make sure we are holding no locks: | |
933 | */ | |
934 | mutex_debug_check_no_locks_held(tsk); | |
935 | ||
936 | if (tsk->io_context) | |
937 | exit_io_context(); | |
938 | ||
939 | if (tsk->splice_pipe) | |
940 | __free_pipe_info(tsk->splice_pipe); | |
941 | ||
942 | /* PF_DEAD causes final put_task_struct after we schedule. */ | |
943 | preempt_disable(); | |
944 | BUG_ON(tsk->flags & PF_DEAD); | |
945 | tsk->flags |= PF_DEAD; | |
946 | ||
947 | schedule(); | |
948 | BUG(); | |
949 | /* Avoid "noreturn function does return". */ | |
950 | for (;;) ; | |
951 | } | |
952 | ||
953 | EXPORT_SYMBOL_GPL(do_exit); | |
954 | ||
955 | NORET_TYPE void complete_and_exit(struct completion *comp, long code) | |
956 | { | |
957 | if (comp) | |
958 | complete(comp); | |
959 | ||
960 | do_exit(code); | |
961 | } | |
962 | ||
963 | EXPORT_SYMBOL(complete_and_exit); | |
964 | ||
965 | asmlinkage long sys_exit(int error_code) | |
966 | { | |
967 | do_exit((error_code&0xff)<<8); | |
968 | } | |
969 | ||
970 | /* | |
971 | * Take down every thread in the group. This is called by fatal signals | |
972 | * as well as by sys_exit_group (below). | |
973 | */ | |
974 | NORET_TYPE void | |
975 | do_group_exit(int exit_code) | |
976 | { | |
977 | BUG_ON(exit_code & 0x80); /* core dumps don't get here */ | |
978 | ||
979 | if (current->signal->flags & SIGNAL_GROUP_EXIT) | |
980 | exit_code = current->signal->group_exit_code; | |
981 | else if (!thread_group_empty(current)) { | |
982 | struct signal_struct *const sig = current->signal; | |
983 | struct sighand_struct *const sighand = current->sighand; | |
984 | spin_lock_irq(&sighand->siglock); | |
985 | if (sig->flags & SIGNAL_GROUP_EXIT) | |
986 | /* Another thread got here before we took the lock. */ | |
987 | exit_code = sig->group_exit_code; | |
988 | else { | |
989 | sig->group_exit_code = exit_code; | |
990 | zap_other_threads(current); | |
991 | } | |
992 | spin_unlock_irq(&sighand->siglock); | |
993 | } | |
994 | ||
995 | do_exit(exit_code); | |
996 | /* NOTREACHED */ | |
997 | } | |
998 | ||
999 | /* | |
1000 | * this kills every thread in the thread group. Note that any externally | |
1001 | * wait4()-ing process will get the correct exit code - even if this | |
1002 | * thread is not the thread group leader. | |
1003 | */ | |
1004 | asmlinkage void sys_exit_group(int error_code) | |
1005 | { | |
1006 | do_group_exit((error_code & 0xff) << 8); | |
1007 | } | |
1008 | ||
1009 | static int eligible_child(pid_t pid, int options, task_t *p) | |
1010 | { | |
1011 | if (pid > 0) { | |
1012 | if (p->pid != pid) | |
1013 | return 0; | |
1014 | } else if (!pid) { | |
1015 | if (process_group(p) != process_group(current)) | |
1016 | return 0; | |
1017 | } else if (pid != -1) { | |
1018 | if (process_group(p) != -pid) | |
1019 | return 0; | |
1020 | } | |
1021 | ||
1022 | /* | |
1023 | * Do not consider detached threads that are | |
1024 | * not ptraced: | |
1025 | */ | |
1026 | if (p->exit_signal == -1 && !p->ptrace) | |
1027 | return 0; | |
1028 | ||
1029 | /* Wait for all children (clone and not) if __WALL is set; | |
1030 | * otherwise, wait for clone children *only* if __WCLONE is | |
1031 | * set; otherwise, wait for non-clone children *only*. (Note: | |
1032 | * A "clone" child here is one that reports to its parent | |
1033 | * using a signal other than SIGCHLD.) */ | |
1034 | if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0)) | |
1035 | && !(options & __WALL)) | |
1036 | return 0; | |
1037 | /* | |
1038 | * Do not consider thread group leaders that are | |
1039 | * in a non-empty thread group: | |
1040 | */ | |
1041 | if (current->tgid != p->tgid && delay_group_leader(p)) | |
1042 | return 2; | |
1043 | ||
1044 | if (security_task_wait(p)) | |
1045 | return 0; | |
1046 | ||
1047 | return 1; | |
1048 | } | |
1049 | ||
1050 | static int wait_noreap_copyout(task_t *p, pid_t pid, uid_t uid, | |
1051 | int why, int status, | |
1052 | struct siginfo __user *infop, | |
1053 | struct rusage __user *rusagep) | |
1054 | { | |
1055 | int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0; | |
1056 | put_task_struct(p); | |
1057 | if (!retval) | |
1058 | retval = put_user(SIGCHLD, &infop->si_signo); | |
1059 | if (!retval) | |
1060 | retval = put_user(0, &infop->si_errno); | |
1061 | if (!retval) | |
1062 | retval = put_user((short)why, &infop->si_code); | |
1063 | if (!retval) | |
1064 | retval = put_user(pid, &infop->si_pid); | |
1065 | if (!retval) | |
1066 | retval = put_user(uid, &infop->si_uid); | |
1067 | if (!retval) | |
1068 | retval = put_user(status, &infop->si_status); | |
1069 | if (!retval) | |
1070 | retval = pid; | |
1071 | return retval; | |
1072 | } | |
1073 | ||
1074 | /* | |
1075 | * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold | |
1076 | * read_lock(&tasklist_lock) on entry. If we return zero, we still hold | |
1077 | * the lock and this task is uninteresting. If we return nonzero, we have | |
1078 | * released the lock and the system call should return. | |
1079 | */ | |
1080 | static int wait_task_zombie(task_t *p, int noreap, | |
1081 | struct siginfo __user *infop, | |
1082 | int __user *stat_addr, struct rusage __user *ru) | |
1083 | { | |
1084 | unsigned long state; | |
1085 | int retval; | |
1086 | int status; | |
1087 | ||
1088 | if (unlikely(noreap)) { | |
1089 | pid_t pid = p->pid; | |
1090 | uid_t uid = p->uid; | |
1091 | int exit_code = p->exit_code; | |
1092 | int why, status; | |
1093 | ||
1094 | if (unlikely(p->exit_state != EXIT_ZOMBIE)) | |
1095 | return 0; | |
1096 | if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) | |
1097 | return 0; | |
1098 | get_task_struct(p); | |
1099 | read_unlock(&tasklist_lock); | |
1100 | if ((exit_code & 0x7f) == 0) { | |
1101 | why = CLD_EXITED; | |
1102 | status = exit_code >> 8; | |
1103 | } else { | |
1104 | why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED; | |
1105 | status = exit_code & 0x7f; | |
1106 | } | |
1107 | return wait_noreap_copyout(p, pid, uid, why, | |
1108 | status, infop, ru); | |
1109 | } | |
1110 | ||
1111 | /* | |
1112 | * Try to move the task's state to DEAD | |
1113 | * only one thread is allowed to do this: | |
1114 | */ | |
1115 | state = xchg(&p->exit_state, EXIT_DEAD); | |
1116 | if (state != EXIT_ZOMBIE) { | |
1117 | BUG_ON(state != EXIT_DEAD); | |
1118 | return 0; | |
1119 | } | |
1120 | if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) { | |
1121 | /* | |
1122 | * This can only happen in a race with a ptraced thread | |
1123 | * dying on another processor. | |
1124 | */ | |
1125 | return 0; | |
1126 | } | |
1127 | ||
1128 | if (likely(p->real_parent == p->parent) && likely(p->signal)) { | |
1129 | struct signal_struct *psig; | |
1130 | struct signal_struct *sig; | |
1131 | ||
1132 | /* | |
1133 | * The resource counters for the group leader are in its | |
1134 | * own task_struct. Those for dead threads in the group | |
1135 | * are in its signal_struct, as are those for the child | |
1136 | * processes it has previously reaped. All these | |
1137 | * accumulate in the parent's signal_struct c* fields. | |
1138 | * | |
1139 | * We don't bother to take a lock here to protect these | |
1140 | * p->signal fields, because they are only touched by | |
1141 | * __exit_signal, which runs with tasklist_lock | |
1142 | * write-locked anyway, and so is excluded here. We do | |
1143 | * need to protect the access to p->parent->signal fields, | |
1144 | * as other threads in the parent group can be right | |
1145 | * here reaping other children at the same time. | |
1146 | */ | |
1147 | spin_lock_irq(&p->parent->sighand->siglock); | |
1148 | psig = p->parent->signal; | |
1149 | sig = p->signal; | |
1150 | psig->cutime = | |
1151 | cputime_add(psig->cutime, | |
1152 | cputime_add(p->utime, | |
1153 | cputime_add(sig->utime, | |
1154 | sig->cutime))); | |
1155 | psig->cstime = | |
1156 | cputime_add(psig->cstime, | |
1157 | cputime_add(p->stime, | |
1158 | cputime_add(sig->stime, | |
1159 | sig->cstime))); | |
1160 | psig->cmin_flt += | |
1161 | p->min_flt + sig->min_flt + sig->cmin_flt; | |
1162 | psig->cmaj_flt += | |
1163 | p->maj_flt + sig->maj_flt + sig->cmaj_flt; | |
1164 | psig->cnvcsw += | |
1165 | p->nvcsw + sig->nvcsw + sig->cnvcsw; | |
1166 | psig->cnivcsw += | |
1167 | p->nivcsw + sig->nivcsw + sig->cnivcsw; | |
1168 | spin_unlock_irq(&p->parent->sighand->siglock); | |
1169 | } | |
1170 | ||
1171 | /* | |
1172 | * Now we are sure this task is interesting, and no other | |
1173 | * thread can reap it because we set its state to EXIT_DEAD. | |
1174 | */ | |
1175 | read_unlock(&tasklist_lock); | |
1176 | ||
1177 | retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0; | |
1178 | status = (p->signal->flags & SIGNAL_GROUP_EXIT) | |
1179 | ? p->signal->group_exit_code : p->exit_code; | |
1180 | if (!retval && stat_addr) | |
1181 | retval = put_user(status, stat_addr); | |
1182 | if (!retval && infop) | |
1183 | retval = put_user(SIGCHLD, &infop->si_signo); | |
1184 | if (!retval && infop) | |
1185 | retval = put_user(0, &infop->si_errno); | |
1186 | if (!retval && infop) { | |
1187 | int why; | |
1188 | ||
1189 | if ((status & 0x7f) == 0) { | |
1190 | why = CLD_EXITED; | |
1191 | status >>= 8; | |
1192 | } else { | |
1193 | why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED; | |
1194 | status &= 0x7f; | |
1195 | } | |
1196 | retval = put_user((short)why, &infop->si_code); | |
1197 | if (!retval) | |
1198 | retval = put_user(status, &infop->si_status); | |
1199 | } | |
1200 | if (!retval && infop) | |
1201 | retval = put_user(p->pid, &infop->si_pid); | |
1202 | if (!retval && infop) | |
1203 | retval = put_user(p->uid, &infop->si_uid); | |
1204 | if (retval) { | |
1205 | // TODO: is this safe? | |
1206 | p->exit_state = EXIT_ZOMBIE; | |
1207 | return retval; | |
1208 | } | |
1209 | retval = p->pid; | |
1210 | if (p->real_parent != p->parent) { | |
1211 | write_lock_irq(&tasklist_lock); | |
1212 | /* Double-check with lock held. */ | |
1213 | if (p->real_parent != p->parent) { | |
1214 | __ptrace_unlink(p); | |
1215 | // TODO: is this safe? | |
1216 | p->exit_state = EXIT_ZOMBIE; | |
1217 | /* | |
1218 | * If this is not a detached task, notify the parent. | |
1219 | * If it's still not detached after that, don't release | |
1220 | * it now. | |
1221 | */ | |
1222 | if (p->exit_signal != -1) { | |
1223 | do_notify_parent(p, p->exit_signal); | |
1224 | if (p->exit_signal != -1) | |
1225 | p = NULL; | |
1226 | } | |
1227 | } | |
1228 | write_unlock_irq(&tasklist_lock); | |
1229 | } | |
1230 | if (p != NULL) | |
1231 | release_task(p); | |
1232 | BUG_ON(!retval); | |
1233 | return retval; | |
1234 | } | |
1235 | ||
1236 | /* | |
1237 | * Handle sys_wait4 work for one task in state TASK_STOPPED. We hold | |
1238 | * read_lock(&tasklist_lock) on entry. If we return zero, we still hold | |
1239 | * the lock and this task is uninteresting. If we return nonzero, we have | |
1240 | * released the lock and the system call should return. | |
1241 | */ | |
1242 | static int wait_task_stopped(task_t *p, int delayed_group_leader, int noreap, | |
1243 | struct siginfo __user *infop, | |
1244 | int __user *stat_addr, struct rusage __user *ru) | |
1245 | { | |
1246 | int retval, exit_code; | |
1247 | ||
1248 | if (!p->exit_code) | |
1249 | return 0; | |
1250 | if (delayed_group_leader && !(p->ptrace & PT_PTRACED) && | |
1251 | p->signal && p->signal->group_stop_count > 0) | |
1252 | /* | |
1253 | * A group stop is in progress and this is the group leader. | |
1254 | * We won't report until all threads have stopped. | |
1255 | */ | |
1256 | return 0; | |
1257 | ||
1258 | /* | |
1259 | * Now we are pretty sure this task is interesting. | |
1260 | * Make sure it doesn't get reaped out from under us while we | |
1261 | * give up the lock and then examine it below. We don't want to | |
1262 | * keep holding onto the tasklist_lock while we call getrusage and | |
1263 | * possibly take page faults for user memory. | |
1264 | */ | |
1265 | get_task_struct(p); | |
1266 | read_unlock(&tasklist_lock); | |
1267 | ||
1268 | if (unlikely(noreap)) { | |
1269 | pid_t pid = p->pid; | |
1270 | uid_t uid = p->uid; | |
1271 | int why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED; | |
1272 | ||
1273 | exit_code = p->exit_code; | |
1274 | if (unlikely(!exit_code) || | |
1275 | unlikely(p->state & TASK_TRACED)) | |
1276 | goto bail_ref; | |
1277 | return wait_noreap_copyout(p, pid, uid, | |
1278 | why, (exit_code << 8) | 0x7f, | |
1279 | infop, ru); | |
1280 | } | |
1281 | ||
1282 | write_lock_irq(&tasklist_lock); | |
1283 | ||
1284 | /* | |
1285 | * This uses xchg to be atomic with the thread resuming and setting | |
1286 | * it. It must also be done with the write lock held to prevent a | |
1287 | * race with the EXIT_ZOMBIE case. | |
1288 | */ | |
1289 | exit_code = xchg(&p->exit_code, 0); | |
1290 | if (unlikely(p->exit_state)) { | |
1291 | /* | |
1292 | * The task resumed and then died. Let the next iteration | |
1293 | * catch it in EXIT_ZOMBIE. Note that exit_code might | |
1294 | * already be zero here if it resumed and did _exit(0). | |
1295 | * The task itself is dead and won't touch exit_code again; | |
1296 | * other processors in this function are locked out. | |
1297 | */ | |
1298 | p->exit_code = exit_code; | |
1299 | exit_code = 0; | |
1300 | } | |
1301 | if (unlikely(exit_code == 0)) { | |
1302 | /* | |
1303 | * Another thread in this function got to it first, or it | |
1304 | * resumed, or it resumed and then died. | |
1305 | */ | |
1306 | write_unlock_irq(&tasklist_lock); | |
1307 | bail_ref: | |
1308 | put_task_struct(p); | |
1309 | /* | |
1310 | * We are returning to the wait loop without having successfully | |
1311 | * removed the process and having released the lock. We cannot | |
1312 | * continue, since the "p" task pointer is potentially stale. | |
1313 | * | |
1314 | * Return -EAGAIN, and do_wait() will restart the loop from the | |
1315 | * beginning. Do _not_ re-acquire the lock. | |
1316 | */ | |
1317 | return -EAGAIN; | |
1318 | } | |
1319 | ||
1320 | /* move to end of parent's list to avoid starvation */ | |
1321 | remove_parent(p); | |
1322 | add_parent(p); | |
1323 | ||
1324 | write_unlock_irq(&tasklist_lock); | |
1325 | ||
1326 | retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0; | |
1327 | if (!retval && stat_addr) | |
1328 | retval = put_user((exit_code << 8) | 0x7f, stat_addr); | |
1329 | if (!retval && infop) | |
1330 | retval = put_user(SIGCHLD, &infop->si_signo); | |
1331 | if (!retval && infop) | |
1332 | retval = put_user(0, &infop->si_errno); | |
1333 | if (!retval && infop) | |
1334 | retval = put_user((short)((p->ptrace & PT_PTRACED) | |
1335 | ? CLD_TRAPPED : CLD_STOPPED), | |
1336 | &infop->si_code); | |
1337 | if (!retval && infop) | |
1338 | retval = put_user(exit_code, &infop->si_status); | |
1339 | if (!retval && infop) | |
1340 | retval = put_user(p->pid, &infop->si_pid); | |
1341 | if (!retval && infop) | |
1342 | retval = put_user(p->uid, &infop->si_uid); | |
1343 | if (!retval) | |
1344 | retval = p->pid; | |
1345 | put_task_struct(p); | |
1346 | ||
1347 | BUG_ON(!retval); | |
1348 | return retval; | |
1349 | } | |
1350 | ||
1351 | /* | |
1352 | * Handle do_wait work for one task in a live, non-stopped state. | |
1353 | * read_lock(&tasklist_lock) on entry. If we return zero, we still hold | |
1354 | * the lock and this task is uninteresting. If we return nonzero, we have | |
1355 | * released the lock and the system call should return. | |
1356 | */ | |
1357 | static int wait_task_continued(task_t *p, int noreap, | |
1358 | struct siginfo __user *infop, | |
1359 | int __user *stat_addr, struct rusage __user *ru) | |
1360 | { | |
1361 | int retval; | |
1362 | pid_t pid; | |
1363 | uid_t uid; | |
1364 | ||
1365 | if (unlikely(!p->signal)) | |
1366 | return 0; | |
1367 | ||
1368 | if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) | |
1369 | return 0; | |
1370 | ||
1371 | spin_lock_irq(&p->sighand->siglock); | |
1372 | /* Re-check with the lock held. */ | |
1373 | if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) { | |
1374 | spin_unlock_irq(&p->sighand->siglock); | |
1375 | return 0; | |
1376 | } | |
1377 | if (!noreap) | |
1378 | p->signal->flags &= ~SIGNAL_STOP_CONTINUED; | |
1379 | spin_unlock_irq(&p->sighand->siglock); | |
1380 | ||
1381 | pid = p->pid; | |
1382 | uid = p->uid; | |
1383 | get_task_struct(p); | |
1384 | read_unlock(&tasklist_lock); | |
1385 | ||
1386 | if (!infop) { | |
1387 | retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0; | |
1388 | put_task_struct(p); | |
1389 | if (!retval && stat_addr) | |
1390 | retval = put_user(0xffff, stat_addr); | |
1391 | if (!retval) | |
1392 | retval = p->pid; | |
1393 | } else { | |
1394 | retval = wait_noreap_copyout(p, pid, uid, | |
1395 | CLD_CONTINUED, SIGCONT, | |
1396 | infop, ru); | |
1397 | BUG_ON(retval == 0); | |
1398 | } | |
1399 | ||
1400 | return retval; | |
1401 | } | |
1402 | ||
1403 | ||
1404 | static inline int my_ptrace_child(struct task_struct *p) | |
1405 | { | |
1406 | if (!(p->ptrace & PT_PTRACED)) | |
1407 | return 0; | |
1408 | if (!(p->ptrace & PT_ATTACHED)) | |
1409 | return 1; | |
1410 | /* | |
1411 | * This child was PTRACE_ATTACH'd. We should be seeing it only if | |
1412 | * we are the attacher. If we are the real parent, this is a race | |
1413 | * inside ptrace_attach. It is waiting for the tasklist_lock, | |
1414 | * which we have to switch the parent links, but has already set | |
1415 | * the flags in p->ptrace. | |
1416 | */ | |
1417 | return (p->parent != p->real_parent); | |
1418 | } | |
1419 | ||
1420 | static long do_wait(pid_t pid, int options, struct siginfo __user *infop, | |
1421 | int __user *stat_addr, struct rusage __user *ru) | |
1422 | { | |
1423 | DECLARE_WAITQUEUE(wait, current); | |
1424 | struct task_struct *tsk; | |
1425 | int flag, retval; | |
1426 | ||
1427 | add_wait_queue(¤t->signal->wait_chldexit,&wait); | |
1428 | repeat: | |
1429 | /* | |
1430 | * We will set this flag if we see any child that might later | |
1431 | * match our criteria, even if we are not able to reap it yet. | |
1432 | */ | |
1433 | flag = 0; | |
1434 | current->state = TASK_INTERRUPTIBLE; | |
1435 | read_lock(&tasklist_lock); | |
1436 | tsk = current; | |
1437 | do { | |
1438 | struct task_struct *p; | |
1439 | struct list_head *_p; | |
1440 | int ret; | |
1441 | ||
1442 | list_for_each(_p,&tsk->children) { | |
1443 | p = list_entry(_p,struct task_struct,sibling); | |
1444 | ||
1445 | ret = eligible_child(pid, options, p); | |
1446 | if (!ret) | |
1447 | continue; | |
1448 | ||
1449 | switch (p->state) { | |
1450 | case TASK_TRACED: | |
1451 | /* | |
1452 | * When we hit the race with PTRACE_ATTACH, | |
1453 | * we will not report this child. But the | |
1454 | * race means it has not yet been moved to | |
1455 | * our ptrace_children list, so we need to | |
1456 | * set the flag here to avoid a spurious ECHILD | |
1457 | * when the race happens with the only child. | |
1458 | */ | |
1459 | flag = 1; | |
1460 | if (!my_ptrace_child(p)) | |
1461 | continue; | |
1462 | /*FALLTHROUGH*/ | |
1463 | case TASK_STOPPED: | |
1464 | /* | |
1465 | * It's stopped now, so it might later | |
1466 | * continue, exit, or stop again. | |
1467 | */ | |
1468 | flag = 1; | |
1469 | if (!(options & WUNTRACED) && | |
1470 | !my_ptrace_child(p)) | |
1471 | continue; | |
1472 | retval = wait_task_stopped(p, ret == 2, | |
1473 | (options & WNOWAIT), | |
1474 | infop, | |
1475 | stat_addr, ru); | |
1476 | if (retval == -EAGAIN) | |
1477 | goto repeat; | |
1478 | if (retval != 0) /* He released the lock. */ | |
1479 | goto end; | |
1480 | break; | |
1481 | default: | |
1482 | // case EXIT_DEAD: | |
1483 | if (p->exit_state == EXIT_DEAD) | |
1484 | continue; | |
1485 | // case EXIT_ZOMBIE: | |
1486 | if (p->exit_state == EXIT_ZOMBIE) { | |
1487 | /* | |
1488 | * Eligible but we cannot release | |
1489 | * it yet: | |
1490 | */ | |
1491 | if (ret == 2) | |
1492 | goto check_continued; | |
1493 | if (!likely(options & WEXITED)) | |
1494 | continue; | |
1495 | retval = wait_task_zombie( | |
1496 | p, (options & WNOWAIT), | |
1497 | infop, stat_addr, ru); | |
1498 | /* He released the lock. */ | |
1499 | if (retval != 0) | |
1500 | goto end; | |
1501 | break; | |
1502 | } | |
1503 | check_continued: | |
1504 | /* | |
1505 | * It's running now, so it might later | |
1506 | * exit, stop, or stop and then continue. | |
1507 | */ | |
1508 | flag = 1; | |
1509 | if (!unlikely(options & WCONTINUED)) | |
1510 | continue; | |
1511 | retval = wait_task_continued( | |
1512 | p, (options & WNOWAIT), | |
1513 | infop, stat_addr, ru); | |
1514 | if (retval != 0) /* He released the lock. */ | |
1515 | goto end; | |
1516 | break; | |
1517 | } | |
1518 | } | |
1519 | if (!flag) { | |
1520 | list_for_each(_p, &tsk->ptrace_children) { | |
1521 | p = list_entry(_p, struct task_struct, | |
1522 | ptrace_list); | |
1523 | if (!eligible_child(pid, options, p)) | |
1524 | continue; | |
1525 | flag = 1; | |
1526 | break; | |
1527 | } | |
1528 | } | |
1529 | if (options & __WNOTHREAD) | |
1530 | break; | |
1531 | tsk = next_thread(tsk); | |
1532 | BUG_ON(tsk->signal != current->signal); | |
1533 | } while (tsk != current); | |
1534 | ||
1535 | read_unlock(&tasklist_lock); | |
1536 | if (flag) { | |
1537 | retval = 0; | |
1538 | if (options & WNOHANG) | |
1539 | goto end; | |
1540 | retval = -ERESTARTSYS; | |
1541 | if (signal_pending(current)) | |
1542 | goto end; | |
1543 | schedule(); | |
1544 | goto repeat; | |
1545 | } | |
1546 | retval = -ECHILD; | |
1547 | end: | |
1548 | current->state = TASK_RUNNING; | |
1549 | remove_wait_queue(¤t->signal->wait_chldexit,&wait); | |
1550 | if (infop) { | |
1551 | if (retval > 0) | |
1552 | retval = 0; | |
1553 | else { | |
1554 | /* | |
1555 | * For a WNOHANG return, clear out all the fields | |
1556 | * we would set so the user can easily tell the | |
1557 | * difference. | |
1558 | */ | |
1559 | if (!retval) | |
1560 | retval = put_user(0, &infop->si_signo); | |
1561 | if (!retval) | |
1562 | retval = put_user(0, &infop->si_errno); | |
1563 | if (!retval) | |
1564 | retval = put_user(0, &infop->si_code); | |
1565 | if (!retval) | |
1566 | retval = put_user(0, &infop->si_pid); | |
1567 | if (!retval) | |
1568 | retval = put_user(0, &infop->si_uid); | |
1569 | if (!retval) | |
1570 | retval = put_user(0, &infop->si_status); | |
1571 | } | |
1572 | } | |
1573 | return retval; | |
1574 | } | |
1575 | ||
1576 | asmlinkage long sys_waitid(int which, pid_t pid, | |
1577 | struct siginfo __user *infop, int options, | |
1578 | struct rusage __user *ru) | |
1579 | { | |
1580 | long ret; | |
1581 | ||
1582 | if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED)) | |
1583 | return -EINVAL; | |
1584 | if (!(options & (WEXITED|WSTOPPED|WCONTINUED))) | |
1585 | return -EINVAL; | |
1586 | ||
1587 | switch (which) { | |
1588 | case P_ALL: | |
1589 | pid = -1; | |
1590 | break; | |
1591 | case P_PID: | |
1592 | if (pid <= 0) | |
1593 | return -EINVAL; | |
1594 | break; | |
1595 | case P_PGID: | |
1596 | if (pid <= 0) | |
1597 | return -EINVAL; | |
1598 | pid = -pid; | |
1599 | break; | |
1600 | default: | |
1601 | return -EINVAL; | |
1602 | } | |
1603 | ||
1604 | ret = do_wait(pid, options, infop, NULL, ru); | |
1605 | ||
1606 | /* avoid REGPARM breakage on x86: */ | |
1607 | prevent_tail_call(ret); | |
1608 | return ret; | |
1609 | } | |
1610 | ||
1611 | asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr, | |
1612 | int options, struct rusage __user *ru) | |
1613 | { | |
1614 | long ret; | |
1615 | ||
1616 | if (options & ~(WNOHANG|WUNTRACED|WCONTINUED| | |
1617 | __WNOTHREAD|__WCLONE|__WALL)) | |
1618 | return -EINVAL; | |
1619 | ret = do_wait(pid, options | WEXITED, NULL, stat_addr, ru); | |
1620 | ||
1621 | /* avoid REGPARM breakage on x86: */ | |
1622 | prevent_tail_call(ret); | |
1623 | return ret; | |
1624 | } | |
1625 | ||
1626 | #ifdef __ARCH_WANT_SYS_WAITPID | |
1627 | ||
1628 | /* | |
1629 | * sys_waitpid() remains for compatibility. waitpid() should be | |
1630 | * implemented by calling sys_wait4() from libc.a. | |
1631 | */ | |
1632 | asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options) | |
1633 | { | |
1634 | return sys_wait4(pid, stat_addr, options, NULL); | |
1635 | } | |
1636 | ||
1637 | #endif |