blob: 16d74f13a3e799c71a644aa594b45194fcdaad3f [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/kernel/exit.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
Linus Torvalds1da177e2005-04-16 15:20:36 -07007#include <linux/mm.h>
8#include <linux/slab.h>
9#include <linux/interrupt.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070010#include <linux/module.h>
Randy.Dunlapc59ede72006-01-11 12:17:46 -080011#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070012#include <linux/completion.h>
13#include <linux/personality.h>
14#include <linux/tty.h>
Kirill Korotaev6b3286e2006-12-08 02:37:56 -080015#include <linux/mnt_namespace.h>
Jens Axboeda9cbc82008-06-30 20:42:08 +020016#include <linux/iocontext.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070017#include <linux/key.h>
18#include <linux/security.h>
19#include <linux/cpu.h>
20#include <linux/acct.h>
Jay Lan8f0ab512006-09-30 23:28:59 -070021#include <linux/tsacct_kern.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070022#include <linux/file.h>
Al Viro9f3acc32008-04-24 07:44:08 -040023#include <linux/fdtable.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070024#include <linux/binfmts.h>
Serge E. Hallynab516012006-10-02 02:18:06 -070025#include <linux/nsproxy.h>
Sukadev Bhattiprolu84d73782006-12-08 02:38:01 -080026#include <linux/pid_namespace.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070027#include <linux/ptrace.h>
28#include <linux/profile.h>
29#include <linux/mount.h>
30#include <linux/proc_fs.h>
Eric W. Biederman49d769d2007-05-09 02:34:33 -070031#include <linux/kthread.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070032#include <linux/mempolicy.h>
Shailabh Nagarc7572492006-07-14 00:24:40 -070033#include <linux/taskstats_kern.h>
Shailabh Nagarca74e922006-07-14 00:24:36 -070034#include <linux/delayacct.h>
Rafael J. Wysocki83144182007-07-17 04:03:35 -070035#include <linux/freezer.h>
Paul Menageb4f48b62007-10-18 23:39:33 -070036#include <linux/cgroup.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070037#include <linux/syscalls.h>
Jesper Juhl7ed20e12005-05-01 08:59:14 -070038#include <linux/signal.h>
Oleg Nesterov6a14c5c2006-03-28 16:11:18 -080039#include <linux/posix-timers.h>
Matt Helsley9f460802005-11-07 00:59:16 -080040#include <linux/cn_proc.h>
Ingo Molnarde5097c2006-01-09 15:59:21 -080041#include <linux/mutex.h>
Ingo Molnar0771dfe2006-03-27 01:16:22 -080042#include <linux/futex.h>
Jens Axboeb92ce552006-04-11 13:52:07 +020043#include <linux/pipe_fs_i.h>
Al Virofa84cb92006-03-29 20:30:19 -050044#include <linux/audit.h> /* for audit_free() */
Adrian Bunk83cc5ed2006-06-25 05:47:41 -070045#include <linux/resource.h>
David Howells0d67a462006-08-29 19:05:56 +010046#include <linux/blkdev.h>
Eric Dumazet6eaeeab2007-05-10 22:22:37 -070047#include <linux/task_io_accounting_ops.h>
Roland McGrath30199f52008-07-25 19:45:46 -070048#include <linux/tracehook.h>
Al Viro5ad4e532009-03-29 19:50:06 -040049#include <linux/fs_struct.h>
David Howellsd84f4f92008-11-14 10:39:23 +110050#include <linux/init_task.h>
Mathieu Desnoyers0a16b602008-07-18 12:16:17 -040051#include <trace/sched.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070052
53#include <asm/uaccess.h>
54#include <asm/unistd.h>
55#include <asm/pgtable.h>
56#include <asm/mmu_context.h>
David Howellsd84f4f92008-11-14 10:39:23 +110057#include "cred-internals.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070058
Mathieu Desnoyers7e066fb2008-11-14 17:47:47 -050059DEFINE_TRACE(sched_process_free);
60DEFINE_TRACE(sched_process_exit);
61DEFINE_TRACE(sched_process_wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -070062
Adrian Bunk408b6642005-05-01 08:59:29 -070063static void exit_mm(struct task_struct * tsk);
64
Linus Torvalds1da177e2005-04-16 15:20:36 -070065static void __unhash_process(struct task_struct *p)
66{
67 nr_threads--;
68 detach_pid(p, PIDTYPE_PID);
Linus Torvalds1da177e2005-04-16 15:20:36 -070069 if (thread_group_leader(p)) {
70 detach_pid(p, PIDTYPE_PGID);
71 detach_pid(p, PIDTYPE_SID);
Oleg Nesterovc97d9892006-03-28 16:11:06 -080072
Eric W. Biederman5e85d4a2006-04-18 22:20:16 -070073 list_del_rcu(&p->tasks);
Oleg Nesterov73b9ebf2006-03-28 16:11:07 -080074 __get_cpu_var(process_counts)--;
Linus Torvalds1da177e2005-04-16 15:20:36 -070075 }
Oleg Nesterov47e65322006-03-28 16:11:25 -080076 list_del_rcu(&p->thread_group);
Roland McGrathf4700212008-03-24 18:36:23 -070077 list_del_init(&p->sibling);
Linus Torvalds1da177e2005-04-16 15:20:36 -070078}
79
Oleg Nesterov6a14c5c2006-03-28 16:11:18 -080080/*
81 * This function expects the tasklist_lock write-locked.
82 */
83static void __exit_signal(struct task_struct *tsk)
84{
85 struct signal_struct *sig = tsk->signal;
86 struct sighand_struct *sighand;
87
88 BUG_ON(!sig);
89 BUG_ON(!atomic_read(&sig->count));
90
Oleg Nesterov6a14c5c2006-03-28 16:11:18 -080091 sighand = rcu_dereference(tsk->sighand);
92 spin_lock(&sighand->siglock);
93
94 posix_cpu_timers_exit(tsk);
95 if (atomic_dec_and_test(&sig->count))
96 posix_cpu_timers_exit_group(tsk);
97 else {
98 /*
99 * If there is any task waiting for the group exit
100 * then notify it:
101 */
Oleg Nesterov6db840f2007-10-16 23:27:23 -0700102 if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count)
Oleg Nesterov6a14c5c2006-03-28 16:11:18 -0800103 wake_up_process(sig->group_exit_task);
Oleg Nesterov6db840f2007-10-16 23:27:23 -0700104
Oleg Nesterov6a14c5c2006-03-28 16:11:18 -0800105 if (tsk == sig->curr_target)
106 sig->curr_target = next_thread(tsk);
107 /*
108 * Accumulate here the counters for all threads but the
109 * group leader as they die, so they can be added into
110 * the process-wide totals when those are taken.
111 * The group leader stays around as a zombie as long
112 * as there are other threads. When it gets reaped,
113 * the exit.c code will add its counts into these totals.
114 * We won't ever get here for the group leader, since it
115 * will have been the last reference on the signal_struct.
116 */
Peter Zijlstra32bd6712009-02-05 12:24:15 +0100117 sig->utime = cputime_add(sig->utime, task_utime(tsk));
118 sig->stime = cputime_add(sig->stime, task_stime(tsk));
Balbir Singh49048622008-09-05 18:12:23 +0200119 sig->gtime = cputime_add(sig->gtime, task_gtime(tsk));
Oleg Nesterov6a14c5c2006-03-28 16:11:18 -0800120 sig->min_flt += tsk->min_flt;
121 sig->maj_flt += tsk->maj_flt;
122 sig->nvcsw += tsk->nvcsw;
123 sig->nivcsw += tsk->nivcsw;
Eric Dumazet6eaeeab2007-05-10 22:22:37 -0700124 sig->inblock += task_io_get_inblock(tsk);
125 sig->oublock += task_io_get_oublock(tsk);
Andrea Righi59954772008-07-27 17:29:15 +0200126 task_io_accounting_add(&sig->ioac, &tsk->ioac);
Peter Zijlstra32bd6712009-02-05 12:24:15 +0100127 sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
Oleg Nesterov6a14c5c2006-03-28 16:11:18 -0800128 sig = NULL; /* Marker for below. */
129 }
130
Peter Zijlstra856d56b2009-05-15 20:45:59 +0200131 /*
132 * Flush inherited counters to the parent - before the parent
133 * gets woken up by child-exit notifications.
134 */
135 perf_counter_exit_task(tsk);
136
Oleg Nesterov58767002006-03-28 16:11:20 -0800137 __unhash_process(tsk);
138
Oleg Nesterovda7978b2008-05-23 13:04:41 -0700139 /*
140 * Do this under ->siglock, we can race with another thread
141 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
142 */
143 flush_sigqueue(&tsk->pending);
144
Oleg Nesterov6a14c5c2006-03-28 16:11:18 -0800145 tsk->signal = NULL;
Oleg Nesterova7e53282006-03-28 16:11:27 -0800146 tsk->sighand = NULL;
Oleg Nesterov6a14c5c2006-03-28 16:11:18 -0800147 spin_unlock(&sighand->siglock);
Oleg Nesterov6a14c5c2006-03-28 16:11:18 -0800148
Oleg Nesterova7e53282006-03-28 16:11:27 -0800149 __cleanup_sighand(sighand);
Oleg Nesterov6a14c5c2006-03-28 16:11:18 -0800150 clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
Oleg Nesterov6a14c5c2006-03-28 16:11:18 -0800151 if (sig) {
152 flush_sigqueue(&sig->shared_pending);
Oleg Nesterov093a8e82006-10-28 10:38:51 -0700153 taskstats_tgid_free(sig);
Oleg Nesterovad474ca2008-11-10 15:39:30 +0100154 /*
155 * Make sure ->signal can't go away under rq->lock,
156 * see account_group_exec_runtime().
157 */
158 task_rq_unlock_wait(tsk);
Oleg Nesterov6a14c5c2006-03-28 16:11:18 -0800159 __cleanup_signal(sig);
160 }
161}
162
Eric W. Biederman8c7904a2006-03-31 02:31:37 -0800163static void delayed_put_task_struct(struct rcu_head *rhp)
164{
Mathieu Desnoyers0a16b602008-07-18 12:16:17 -0400165 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
166
Ingo Molnareef6cbf2008-12-19 10:20:42 +0100167#ifdef CONFIG_PERF_COUNTERS
168 WARN_ON_ONCE(!list_empty(&tsk->perf_counter_ctx.counter_list));
169#endif
Mathieu Desnoyers0a16b602008-07-18 12:16:17 -0400170 trace_sched_process_free(tsk);
171 put_task_struct(tsk);
Eric W. Biederman8c7904a2006-03-31 02:31:37 -0800172}
173
Roland McGrathf4700212008-03-24 18:36:23 -0700174
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175void release_task(struct task_struct * p)
176{
Ingo Molnar36c8b582006-07-03 00:25:41 -0700177 struct task_struct *leader;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178 int zap_leader;
Oleg Nesterov1f09f972006-03-28 16:11:11 -0800179repeat:
Roland McGrathdae33572008-07-25 19:45:48 -0700180 tracehook_prepare_release_task(p);
David Howellsc69e8d92008-11-14 10:39:19 +1100181 /* don't need to get the RCU readlock here - the process is dead and
182 * can't be modifying its own credentials */
183 atomic_dec(&__task_cred(p)->user->processes);
184
Pavel Emelyanov60347f62007-10-18 23:40:03 -0700185 proc_flush_task(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186 write_lock_irq(&tasklist_lock);
Roland McGrathdae33572008-07-25 19:45:48 -0700187 tracehook_finish_release_task(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188 __exit_signal(p);
Oleg Nesterov35f5cad2006-03-28 16:11:19 -0800189
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190 /*
191 * If we are the last non-leader member of the thread
192 * group, and the leader is zombie, then notify the
193 * group leader's parent process. (if it wants notification.)
194 */
195 zap_leader = 0;
196 leader = p->group_leader;
197 if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
Oleg Nesterovd839fd42008-04-30 00:53:11 -0700198 BUG_ON(task_detached(leader));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700199 do_notify_parent(leader, leader->exit_signal);
200 /*
201 * If we were the last child thread and the leader has
202 * exited already, and the leader's parent ignores SIGCHLD,
203 * then we are the one who should release the leader.
204 *
205 * do_notify_parent() will have marked it self-reaping in
206 * that case.
207 */
Oleg Nesterovd839fd42008-04-30 00:53:11 -0700208 zap_leader = task_detached(leader);
Roland McGrathdae33572008-07-25 19:45:48 -0700209
210 /*
211 * This maintains the invariant that release_task()
212 * only runs on a task in EXIT_DEAD, just for sanity.
213 */
214 if (zap_leader)
215 leader->exit_state = EXIT_DEAD;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216 }
217
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218 write_unlock_irq(&tasklist_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219 release_thread(p);
Eric W. Biederman8c7904a2006-03-31 02:31:37 -0800220 call_rcu(&p->rcu, delayed_put_task_struct);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221
222 p = leader;
223 if (unlikely(zap_leader))
224 goto repeat;
225}
226
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227/*
228 * This checks not only the pgrp, but falls back on the pid if no
229 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
230 * without this...
Eric W. Biederman04a2e6a2007-02-12 00:52:56 -0800231 *
232 * The caller must hold rcu lock or the tasklist lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700233 */
Eric W. Biederman04a2e6a2007-02-12 00:52:56 -0800234struct pid *session_of_pgrp(struct pid *pgrp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235{
236 struct task_struct *p;
Eric W. Biederman04a2e6a2007-02-12 00:52:56 -0800237 struct pid *sid = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700238
Eric W. Biederman04a2e6a2007-02-12 00:52:56 -0800239 p = pid_task(pgrp, PIDTYPE_PGID);
Oleg Nesterov62dfb552006-12-08 02:38:03 -0800240 if (p == NULL)
Eric W. Biederman04a2e6a2007-02-12 00:52:56 -0800241 p = pid_task(pgrp, PIDTYPE_PID);
Oleg Nesterov62dfb552006-12-08 02:38:03 -0800242 if (p != NULL)
Eric W. Biederman04a2e6a2007-02-12 00:52:56 -0800243 sid = task_session(p);
Oleg Nesterov62dfb552006-12-08 02:38:03 -0800244
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245 return sid;
246}
247
248/*
249 * Determine if a process group is "orphaned", according to the POSIX
250 * definition in 2.2.2.52. Orphaned process groups are not to be affected
251 * by terminal-generated stop signals. Newly orphaned process groups are
252 * to receive a SIGHUP and a SIGCONT.
253 *
254 * "I ask you, have you ever known what it is to be an orphan?"
255 */
Eric W. Biederman0475ac02007-02-12 00:52:57 -0800256static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257{
258 struct task_struct *p;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700259
Eric W. Biederman0475ac02007-02-12 00:52:57 -0800260 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
Oleg Nesterov05e83df2008-03-02 21:44:42 +0300261 if ((p == ignored_task) ||
262 (p->exit_state && thread_group_empty(p)) ||
263 is_global_init(p->real_parent))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700264 continue;
Oleg Nesterov05e83df2008-03-02 21:44:42 +0300265
Eric W. Biederman0475ac02007-02-12 00:52:57 -0800266 if (task_pgrp(p->real_parent) != pgrp &&
Oleg Nesterov05e83df2008-03-02 21:44:42 +0300267 task_session(p->real_parent) == task_session(p))
268 return 0;
Eric W. Biederman0475ac02007-02-12 00:52:57 -0800269 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
Oleg Nesterov05e83df2008-03-02 21:44:42 +0300270
271 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700272}
273
Eric W. Biederman3e7cd6c2007-02-12 00:52:58 -0800274int is_current_pgrp_orphaned(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700275{
276 int retval;
277
278 read_lock(&tasklist_lock);
Eric W. Biederman3e7cd6c2007-02-12 00:52:58 -0800279 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700280 read_unlock(&tasklist_lock);
281
282 return retval;
283}
284
Eric W. Biederman0475ac02007-02-12 00:52:57 -0800285static int has_stopped_jobs(struct pid *pgrp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286{
287 int retval = 0;
288 struct task_struct *p;
289
Eric W. Biederman0475ac02007-02-12 00:52:57 -0800290 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
Matthew Wilcox338077e2007-12-06 11:09:35 -0500291 if (!task_is_stopped(p))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700293 retval = 1;
294 break;
Eric W. Biederman0475ac02007-02-12 00:52:57 -0800295 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296 return retval;
297}
298
Oleg Nesterovf49ee502008-03-02 21:44:40 +0300299/*
300 * Check to see if any process groups have become orphaned as
301 * a result of our exiting, and if they have any stopped jobs,
302 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
303 */
304static void
305kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
306{
307 struct pid *pgrp = task_pgrp(tsk);
308 struct task_struct *ignored_task = tsk;
309
310 if (!parent)
311 /* exit: our father is in a different pgrp than
312 * we are and we were the only connection outside.
313 */
314 parent = tsk->real_parent;
315 else
316 /* reparent: our child is in a different pgrp than
317 * we are, and it was the only connection outside.
318 */
319 ignored_task = NULL;
320
321 if (task_pgrp(parent) != pgrp &&
322 task_session(parent) == task_session(tsk) &&
323 will_become_orphaned_pgrp(pgrp, ignored_task) &&
324 has_stopped_jobs(pgrp)) {
325 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
326 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
327 }
328}
329
Linus Torvalds1da177e2005-04-16 15:20:36 -0700330/**
Eric W. Biederman49d769d2007-05-09 02:34:33 -0700331 * reparent_to_kthreadd - Reparent the calling kernel thread to kthreadd
Linus Torvalds1da177e2005-04-16 15:20:36 -0700332 *
333 * If a kernel thread is launched as a result of a system call, or if
Eric W. Biederman49d769d2007-05-09 02:34:33 -0700334 * it ever exits, it should generally reparent itself to kthreadd so it
335 * isn't in the way of other processes and is correctly cleaned up on exit.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336 *
337 * The various task state such as scheduling policy and priority may have
338 * been inherited from a user process, so we reset them to sane values here.
339 *
Eric W. Biederman49d769d2007-05-09 02:34:33 -0700340 * NOTE that reparent_to_kthreadd() gives the caller full capabilities.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700341 */
Eric W. Biederman49d769d2007-05-09 02:34:33 -0700342static void reparent_to_kthreadd(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343{
344 write_lock_irq(&tasklist_lock);
345
346 ptrace_unlink(current);
347 /* Reparent to init */
Eric W. Biederman49d769d2007-05-09 02:34:33 -0700348 current->real_parent = current->parent = kthreadd_task;
Roland McGrathf4700212008-03-24 18:36:23 -0700349 list_move_tail(&current->sibling, &current->real_parent->children);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350
351 /* Set the exit signal to SIGCHLD so we signal init on exit */
352 current->exit_signal = SIGCHLD;
353
Ingo Molnare05606d2007-07-09 18:51:59 +0200354 if (task_nice(current) < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700355 set_user_nice(current, 0);
356 /* cpus_allowed? */
357 /* rt_priority? */
358 /* signals? */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700359 memcpy(current->signal->rlim, init_task.signal->rlim,
360 sizeof(current->signal->rlim));
David Howellsd84f4f92008-11-14 10:39:23 +1100361
362 atomic_inc(&init_cred.usage);
363 commit_creds(&init_cred);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364 write_unlock_irq(&tasklist_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700365}
366
Oleg Nesterov8520d7c2008-02-08 04:19:09 -0800367void __set_special_pids(struct pid *pid)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368{
Oren Laadane19f2472006-01-08 01:03:58 -0800369 struct task_struct *curr = current->group_leader;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700370
Oleg Nesterov1b0f7ff2009-04-02 16:58:39 -0700371 if (task_session(curr) != pid)
Oleg Nesterov7d8da092008-04-30 00:54:27 -0700372 change_pid(curr, PIDTYPE_SID, pid);
Oleg Nesterov1b0f7ff2009-04-02 16:58:39 -0700373
374 if (task_pgrp(curr) != pid)
Oleg Nesterov7d8da092008-04-30 00:54:27 -0700375 change_pid(curr, PIDTYPE_PGID, pid);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376}
377
Oleg Nesterov8520d7c2008-02-08 04:19:09 -0800378static void set_special_pids(struct pid *pid)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379{
380 write_lock_irq(&tasklist_lock);
Oleg Nesterov8520d7c2008-02-08 04:19:09 -0800381 __set_special_pids(pid);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382 write_unlock_irq(&tasklist_lock);
383}
384
385/*
386 * Let kernel threads use this to say that they
387 * allow a certain signal (since daemonize() will
388 * have disabled all of them by default).
389 */
390int allow_signal(int sig)
391{
Jesper Juhl7ed20e12005-05-01 08:59:14 -0700392 if (!valid_signal(sig) || sig < 1)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700393 return -EINVAL;
394
395 spin_lock_irq(&current->sighand->siglock);
396 sigdelset(&current->blocked, sig);
397 if (!current->mm) {
398 /* Kernel threads handle their own signals.
399 Let the signal code know it'll be handled, so
400 that they don't get converted to SIGKILL or
401 just silently dropped */
402 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
403 }
404 recalc_sigpending();
405 spin_unlock_irq(&current->sighand->siglock);
406 return 0;
407}
408
409EXPORT_SYMBOL(allow_signal);
410
411int disallow_signal(int sig)
412{
Jesper Juhl7ed20e12005-05-01 08:59:14 -0700413 if (!valid_signal(sig) || sig < 1)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700414 return -EINVAL;
415
416 spin_lock_irq(&current->sighand->siglock);
Oleg Nesterov10ab8252007-05-09 02:34:37 -0700417 current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418 recalc_sigpending();
419 spin_unlock_irq(&current->sighand->siglock);
420 return 0;
421}
422
423EXPORT_SYMBOL(disallow_signal);
424
425/*
426 * Put all the gunge required to become a kernel thread without
427 * attached user resources in one place where it belongs.
428 */
429
430void daemonize(const char *name, ...)
431{
432 va_list args;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700433 sigset_t blocked;
434
435 va_start(args, name);
436 vsnprintf(current->comm, sizeof(current->comm), name, args);
437 va_end(args);
438
439 /*
440 * If we were started as result of loading a module, close all of the
441 * user space pages. We don't need them, and if we didn't close them
442 * they would be locked into memory.
443 */
444 exit_mm(current);
Rafael J. Wysocki83144182007-07-17 04:03:35 -0700445 /*
446 * We don't want to have TIF_FREEZE set if the system-wide hibernation
447 * or suspend transition begins right now.
448 */
Oleg Nesterov7b34e422008-07-25 01:47:37 -0700449 current->flags |= (PF_NOFREEZE | PF_KTHREAD);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700450
Oleg Nesterov8520d7c2008-02-08 04:19:09 -0800451 if (current->nsproxy != &init_nsproxy) {
452 get_nsproxy(&init_nsproxy);
453 switch_task_namespaces(current, &init_nsproxy);
454 }
Oleg Nesterov297bd422008-02-08 04:19:10 -0800455 set_special_pids(&init_struct_pid);
Peter Zijlstra24ec8392006-12-08 02:36:04 -0800456 proc_clear_tty(current);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700457
458 /* Block and flush all signals */
459 sigfillset(&blocked);
460 sigprocmask(SIG_BLOCK, &blocked, NULL);
461 flush_signals(current);
462
463 /* Become as one with the init task */
464
Al Viro3e93cd62009-03-29 19:00:13 -0400465 daemonize_fs_struct();
Daniel Walkerd4c5e412007-10-18 23:39:59 -0700466 exit_files(current);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700467 current->files = init_task.files;
468 atomic_inc(&current->files->count);
469
Eric W. Biederman49d769d2007-05-09 02:34:33 -0700470 reparent_to_kthreadd();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700471}
472
473EXPORT_SYMBOL(daemonize);
474
Arjan van de Ven858119e2006-01-14 13:20:43 -0800475static void close_files(struct files_struct * files)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700476{
477 int i, j;
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700478 struct fdtable *fdt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700479
480 j = 0;
Dipankar Sarma4fb3a532005-09-16 19:28:13 -0700481
482 /*
483 * It is safe to dereference the fd table without RCU or
484 * ->file_lock because this is the last reference to the
485 * files structure.
486 */
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700487 fdt = files_fdtable(files);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700488 for (;;) {
489 unsigned long set;
490 i = j * __NFDBITS;
Vadim Lobanovbbea9f62006-12-10 02:21:12 -0800491 if (i >= fdt->max_fds)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700492 break;
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700493 set = fdt->open_fds->fds_bits[j++];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700494 while (set) {
495 if (set & 1) {
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700496 struct file * file = xchg(&fdt->fd[i], NULL);
Ingo Molnar944be0b2007-02-12 00:52:26 -0800497 if (file) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700498 filp_close(file, files);
Ingo Molnar944be0b2007-02-12 00:52:26 -0800499 cond_resched();
500 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700501 }
502 i++;
503 set >>= 1;
504 }
505 }
506}
507
508struct files_struct *get_files_struct(struct task_struct *task)
509{
510 struct files_struct *files;
511
512 task_lock(task);
513 files = task->files;
514 if (files)
515 atomic_inc(&files->count);
516 task_unlock(task);
517
518 return files;
519}
520
Harvey Harrison7ad5b3a2008-02-08 04:19:53 -0800521void put_files_struct(struct files_struct *files)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700522{
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700523 struct fdtable *fdt;
524
Linus Torvalds1da177e2005-04-16 15:20:36 -0700525 if (atomic_dec_and_test(&files->count)) {
526 close_files(files);
527 /*
528 * Free the fd and fdset arrays if we expanded them.
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -0700529 * If the fdtable was embedded, pass files for freeing
530 * at the end of the RCU grace period. Otherwise,
531 * you can free files immediately.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700532 */
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700533 fdt = files_fdtable(files);
Vadim Lobanov4fd45812006-12-10 02:21:17 -0800534 if (fdt != &files->fdtab)
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -0700535 kmem_cache_free(files_cachep, files);
Vadim Lobanov01b2d932006-12-22 01:10:43 -0800536 free_fdtable(fdt);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700537 }
538}
539
Al Viro3b125382008-04-22 05:31:30 -0400540void reset_files_struct(struct files_struct *files)
Kirill Korotaev3b9b8ab2006-09-29 02:00:05 -0700541{
Al Viro3b125382008-04-22 05:31:30 -0400542 struct task_struct *tsk = current;
Kirill Korotaev3b9b8ab2006-09-29 02:00:05 -0700543 struct files_struct *old;
544
545 old = tsk->files;
546 task_lock(tsk);
547 tsk->files = files;
548 task_unlock(tsk);
549 put_files_struct(old);
550}
Kirill Korotaev3b9b8ab2006-09-29 02:00:05 -0700551
Al Viro1ec7f1d2008-04-22 05:35:42 -0400552void exit_files(struct task_struct *tsk)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700553{
554 struct files_struct * files = tsk->files;
555
556 if (files) {
557 task_lock(tsk);
558 tsk->files = NULL;
559 task_unlock(tsk);
560 put_files_struct(files);
561 }
562}
563
Balbir Singhcf475ad2008-04-29 01:00:16 -0700564#ifdef CONFIG_MM_OWNER
565/*
566 * Task p is exiting and it owned mm, lets find a new owner for it
567 */
568static inline int
569mm_need_new_owner(struct mm_struct *mm, struct task_struct *p)
570{
571 /*
572 * If there are other users of the mm and the owner (us) is exiting
573 * we need to find a new owner to take on the responsibility.
574 */
Balbir Singhcf475ad2008-04-29 01:00:16 -0700575 if (atomic_read(&mm->mm_users) <= 1)
576 return 0;
577 if (mm->owner != p)
578 return 0;
579 return 1;
580}
581
582void mm_update_next_owner(struct mm_struct *mm)
583{
584 struct task_struct *c, *g, *p = current;
585
586retry:
587 if (!mm_need_new_owner(mm, p))
588 return;
589
590 read_lock(&tasklist_lock);
591 /*
592 * Search in the children
593 */
594 list_for_each_entry(c, &p->children, sibling) {
595 if (c->mm == mm)
596 goto assign_new_owner;
597 }
598
599 /*
600 * Search in the siblings
601 */
602 list_for_each_entry(c, &p->parent->children, sibling) {
603 if (c->mm == mm)
604 goto assign_new_owner;
605 }
606
607 /*
608 * Search through everything else. We should not get
609 * here often
610 */
611 do_each_thread(g, c) {
612 if (c->mm == mm)
613 goto assign_new_owner;
614 } while_each_thread(g, c);
615
616 read_unlock(&tasklist_lock);
Balbir Singh31a78f22008-09-28 23:09:31 +0100617 /*
618 * We found no owner yet mm_users > 1: this implies that we are
619 * most likely racing with swapoff (try_to_unuse()) or /proc or
Hugh Dickinse5991372009-01-06 14:39:22 -0800620 * ptrace or page migration (get_task_mm()). Mark owner as NULL.
Balbir Singh31a78f22008-09-28 23:09:31 +0100621 */
Balbir Singh31a78f22008-09-28 23:09:31 +0100622 mm->owner = NULL;
Balbir Singhcf475ad2008-04-29 01:00:16 -0700623 return;
624
625assign_new_owner:
626 BUG_ON(c == p);
627 get_task_struct(c);
628 /*
629 * The task_lock protects c->mm from changing.
630 * We always want mm->owner->mm == mm
631 */
632 task_lock(c);
Hugh Dickinse5991372009-01-06 14:39:22 -0800633 /*
634 * Delay read_unlock() till we have the task_lock()
635 * to ensure that c does not slip away underneath us
636 */
637 read_unlock(&tasklist_lock);
Balbir Singhcf475ad2008-04-29 01:00:16 -0700638 if (c->mm != mm) {
639 task_unlock(c);
640 put_task_struct(c);
641 goto retry;
642 }
Balbir Singhcf475ad2008-04-29 01:00:16 -0700643 mm->owner = c;
644 task_unlock(c);
645 put_task_struct(c);
646}
647#endif /* CONFIG_MM_OWNER */
648
Linus Torvalds1da177e2005-04-16 15:20:36 -0700649/*
650 * Turn us into a lazy TLB process if we
651 * aren't already..
652 */
Adrian Bunk408b6642005-05-01 08:59:29 -0700653static void exit_mm(struct task_struct * tsk)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700654{
655 struct mm_struct *mm = tsk->mm;
Oleg Nesterovb564daf2008-07-25 01:47:44 -0700656 struct core_state *core_state;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700657
658 mm_release(tsk, mm);
659 if (!mm)
660 return;
661 /*
662 * Serialize with any possible pending coredump.
Oleg Nesterov999d9fc2008-07-25 01:47:41 -0700663 * We must hold mmap_sem around checking core_state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700664 * and clearing tsk->mm. The core-inducing thread
Oleg Nesterov999d9fc2008-07-25 01:47:41 -0700665 * will increment ->nr_threads for each thread in the
Linus Torvalds1da177e2005-04-16 15:20:36 -0700666 * group with ->mm != NULL.
667 */
668 down_read(&mm->mmap_sem);
Oleg Nesterovb564daf2008-07-25 01:47:44 -0700669 core_state = mm->core_state;
670 if (core_state) {
671 struct core_thread self;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700672 up_read(&mm->mmap_sem);
Oleg Nesterovc5f1cc82008-07-25 01:47:42 -0700673
Oleg Nesterovb564daf2008-07-25 01:47:44 -0700674 self.task = tsk;
675 self.next = xchg(&core_state->dumper.next, &self);
676 /*
677 * Implies mb(), the result of xchg() must be visible
678 * to core_state->dumper.
679 */
680 if (atomic_dec_and_test(&core_state->nr_threads))
681 complete(&core_state->startup);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700682
Oleg Nesterova94e2d42008-07-25 01:47:46 -0700683 for (;;) {
684 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
685 if (!self.task) /* see coredump_finish() */
686 break;
687 schedule();
688 }
689 __set_task_state(tsk, TASK_RUNNING);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700690 down_read(&mm->mmap_sem);
691 }
692 atomic_inc(&mm->mm_count);
Eric Sesterhenn125e1872006-06-23 02:06:06 -0700693 BUG_ON(mm != tsk->active_mm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700694 /* more a memory barrier than a real lock */
695 task_lock(tsk);
696 tsk->mm = NULL;
697 up_read(&mm->mmap_sem);
698 enter_lazy_tlb(mm, current);
Rafael J. Wysocki0c1eecf2007-07-19 01:47:33 -0700699 /* We don't want this task to be frozen prematurely */
700 clear_freeze_flag(tsk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700701 task_unlock(tsk);
Balbir Singhcf475ad2008-04-29 01:00:16 -0700702 mm_update_next_owner(mm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700703 mmput(mm);
704}
705
Roland McGrathf4700212008-03-24 18:36:23 -0700706/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700707 * When we die, we re-parent all our children.
708 * Try to give them to another thread in our thread
709 * group, and if no such member exists, give it to
Sukadev Bhattiprolu84d73782006-12-08 02:38:01 -0800710 * the child reaper process (ie "init") in our pid
711 * space.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700712 */
Oleg Nesterov950bbab2008-09-02 14:35:49 -0700713static struct task_struct *find_new_reaper(struct task_struct *father)
714{
715 struct pid_namespace *pid_ns = task_active_pid_ns(father);
716 struct task_struct *thread;
717
718 thread = father;
719 while_each_thread(father, thread) {
720 if (thread->flags & PF_EXITING)
721 continue;
722 if (unlikely(pid_ns->child_reaper == father))
723 pid_ns->child_reaper = thread;
724 return thread;
725 }
726
727 if (unlikely(pid_ns->child_reaper == father)) {
728 write_unlock_irq(&tasklist_lock);
729 if (unlikely(pid_ns == &init_pid_ns))
730 panic("Attempted to kill init!");
731
732 zap_pid_ns_processes(pid_ns);
733 write_lock_irq(&tasklist_lock);
734 /*
735 * We can not clear ->child_reaper or leave it alone.
736 * There may by stealth EXIT_DEAD tasks on ->children,
737 * forget_original_parent() must move them somewhere.
738 */
739 pid_ns->child_reaper = init_pid_ns.child_reaper;
740 }
741
742 return pid_ns->child_reaper;
743}
744
Oleg Nesterov5dfc80b2009-04-02 16:58:19 -0700745/*
746* Any that need to be release_task'd are put on the @dead list.
747 */
748static void reparent_thread(struct task_struct *father, struct task_struct *p,
749 struct list_head *dead)
750{
751 if (p->pdeath_signal)
752 group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);
753
754 list_move_tail(&p->sibling, &p->real_parent->children);
755
756 if (task_detached(p))
757 return;
758 /*
759 * If this is a threaded reparent there is no need to
760 * notify anyone anything has happened.
761 */
762 if (same_thread_group(p->real_parent, father))
763 return;
764
765 /* We don't want people slaying init. */
766 p->exit_signal = SIGCHLD;
767
768 /* If it has exited notify the new parent about this child's death. */
769 if (!p->ptrace &&
770 p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
771 do_notify_parent(p, p->exit_signal);
772 if (task_detached(p)) {
773 p->exit_state = EXIT_DEAD;
774 list_move_tail(&p->sibling, dead);
775 }
776 }
777
778 kill_orphaned_pgrp(p, father);
779}
780
Oleg Nesterov762a24b2007-10-18 23:40:00 -0700781static void forget_original_parent(struct task_struct *father)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700782{
Oleg Nesterov950bbab2008-09-02 14:35:49 -0700783 struct task_struct *p, *n, *reaper;
Oleg Nesterov5dfc80b2009-04-02 16:58:19 -0700784 LIST_HEAD(dead_children);
Oleg Nesterov762a24b2007-10-18 23:40:00 -0700785
Oleg Nesterov39c626a2009-04-02 16:58:18 -0700786 exit_ptrace(father);
Oleg Nesterov762a24b2007-10-18 23:40:00 -0700787
788 write_lock_irq(&tasklist_lock);
Oleg Nesterov950bbab2008-09-02 14:35:49 -0700789 reaper = find_new_reaper(father);
Roland McGrathf4700212008-03-24 18:36:23 -0700790
Matthias Kaehlcke03ff1792007-10-18 23:39:57 -0700791 list_for_each_entry_safe(p, n, &father->children, sibling) {
Oleg Nesterov84eb6462007-10-16 23:26:49 -0700792 p->real_parent = reaper;
Roland McGrathf4700212008-03-24 18:36:23 -0700793 if (p->parent == father) {
794 BUG_ON(p->ptrace);
795 p->parent = p->real_parent;
796 }
Oleg Nesterov5dfc80b2009-04-02 16:58:19 -0700797 reparent_thread(father, p, &dead_children);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700798 }
Oleg Nesterov762a24b2007-10-18 23:40:00 -0700799 write_unlock_irq(&tasklist_lock);
Oleg Nesterov5dfc80b2009-04-02 16:58:19 -0700800
Oleg Nesterov762a24b2007-10-18 23:40:00 -0700801 BUG_ON(!list_empty(&father->children));
Oleg Nesterov762a24b2007-10-18 23:40:00 -0700802
Oleg Nesterov5dfc80b2009-04-02 16:58:19 -0700803 list_for_each_entry_safe(p, n, &dead_children, sibling) {
804 list_del_init(&p->sibling);
Oleg Nesterov39c626a2009-04-02 16:58:18 -0700805 release_task(p);
806 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700807}
808
809/*
810 * Send signals to all our closest relatives so that they know
811 * to properly mourn us..
812 */
Oleg Nesterov821c7de2008-03-02 21:44:44 +0300813static void exit_notify(struct task_struct *tsk, int group_dead)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700814{
Roland McGrath2b2a1ff2008-07-25 19:45:54 -0700815 int signal;
816 void *cookie;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700817
Linus Torvalds1da177e2005-04-16 15:20:36 -0700818 /*
819 * This does two things:
820 *
821 * A. Make init inherit all the child processes
822 * B. Check to see if any process groups have become orphaned
823 * as a result of our exiting, and if they have any stopped
824 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
825 */
Oleg Nesterov762a24b2007-10-18 23:40:00 -0700826 forget_original_parent(tsk);
Pavel Emelyanov2e4a7072007-10-18 23:40:01 -0700827 exit_task_namespaces(tsk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700828
Oleg Nesterov762a24b2007-10-18 23:40:00 -0700829 write_lock_irq(&tasklist_lock);
Oleg Nesterov821c7de2008-03-02 21:44:44 +0300830 if (group_dead)
831 kill_orphaned_pgrp(tsk->group_leader, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700832
Oleg Nesterov24728442007-08-04 01:04:41 +0400833 /* Let father know we died
Linus Torvalds1da177e2005-04-16 15:20:36 -0700834 *
835 * Thread signals are configurable, but you aren't going to use
Daniel Walkerd4c5e412007-10-18 23:39:59 -0700836 * that to send signals to arbitary processes.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700837 * That stops right now.
838 *
839 * If the parent exec id doesn't match the exec id we saved
840 * when we started then we know the parent has changed security
841 * domain.
842 *
843 * If our self_exec id doesn't match our parent_exec_id then
844 * we have changed execution domain as these two values started
845 * the same after a fork.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700846 */
Oleg Nesterovd839fd42008-04-30 00:53:11 -0700847 if (tsk->exit_signal != SIGCHLD && !task_detached(tsk) &&
Oleg Nesterovf49ee502008-03-02 21:44:40 +0300848 (tsk->parent_exec_id != tsk->real_parent->self_exec_id ||
Oleg Nesterov432870d2009-04-06 16:16:02 +0200849 tsk->self_exec_id != tsk->parent_exec_id))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700850 tsk->exit_signal = SIGCHLD;
851
Roland McGrath2b2a1ff2008-07-25 19:45:54 -0700852 signal = tracehook_notify_death(tsk, &cookie, group_dead);
Roland McGrath5c7edcd2008-07-31 02:04:09 -0700853 if (signal >= 0)
Roland McGrath2b2a1ff2008-07-25 19:45:54 -0700854 signal = do_notify_parent(tsk, signal);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700855
Roland McGrath5c7edcd2008-07-31 02:04:09 -0700856 tsk->exit_state = signal == DEATH_REAP ? EXIT_DEAD : EXIT_ZOMBIE;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700857
Oleg Nesterov2800d8d2008-04-30 00:53:12 -0700858 /* mt-exec, de_thread() is waiting for us */
Oleg Nesterov6db840f2007-10-16 23:27:23 -0700859 if (thread_group_leader(tsk) &&
Steve VanDeBogart2633f0e2008-08-26 15:14:36 -0700860 tsk->signal->group_exit_task &&
861 tsk->signal->notify_count < 0)
Oleg Nesterov6db840f2007-10-16 23:27:23 -0700862 wake_up_process(tsk->signal->group_exit_task);
863
Linus Torvalds1da177e2005-04-16 15:20:36 -0700864 write_unlock_irq(&tasklist_lock);
865
Roland McGrath2b2a1ff2008-07-25 19:45:54 -0700866 tracehook_report_death(tsk, signal, cookie, group_dead);
867
Linus Torvalds1da177e2005-04-16 15:20:36 -0700868 /* If the process is dead, release it - nobody will wait for it */
Roland McGrath5c7edcd2008-07-31 02:04:09 -0700869 if (signal == DEATH_REAP)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700870 release_task(tsk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700871}
872
Jeff Dikee18eecb2007-07-15 23:38:48 -0700873#ifdef CONFIG_DEBUG_STACK_USAGE
874static void check_stack_usage(void)
875{
876 static DEFINE_SPINLOCK(low_water_lock);
877 static int lowest_to_date = THREAD_SIZE;
Jeff Dikee18eecb2007-07-15 23:38:48 -0700878 unsigned long free;
879
Eric Sandeen7c9f8862008-04-22 16:38:23 -0500880 free = stack_not_used(current);
Jeff Dikee18eecb2007-07-15 23:38:48 -0700881
882 if (free >= lowest_to_date)
883 return;
884
885 spin_lock(&low_water_lock);
886 if (free < lowest_to_date) {
887 printk(KERN_WARNING "%s used greatest stack depth: %lu bytes "
888 "left\n",
889 current->comm, free);
890 lowest_to_date = free;
891 }
892 spin_unlock(&low_water_lock);
893}
894#else
895static inline void check_stack_usage(void) {}
896#endif
897
Harvey Harrison7ad5b3a2008-02-08 04:19:53 -0800898NORET_TYPE void do_exit(long code)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700899{
900 struct task_struct *tsk = current;
901 int group_dead;
902
903 profile_task_exit(tsk);
904
Jens Axboe22e2c502005-06-27 10:55:12 +0200905 WARN_ON(atomic_read(&tsk->fs_excl));
906
Linus Torvalds1da177e2005-04-16 15:20:36 -0700907 if (unlikely(in_interrupt()))
908 panic("Aiee, killing interrupt handler!");
909 if (unlikely(!tsk->pid))
910 panic("Attempted to kill the idle task!");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700911
Roland McGrath30199f52008-07-25 19:45:46 -0700912 tracehook_report_exit(&code);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700913
Alexander Nybergdf164db2005-06-23 00:09:13 -0700914 /*
915 * We're taking recursive faults here in do_exit. Safest is to just
916 * leave this task alone and wait for reboot.
917 */
918 if (unlikely(tsk->flags & PF_EXITING)) {
919 printk(KERN_ALERT
920 "Fixing recursive fault but reboot is needed!\n");
Alexey Kuznetsov778e9a92007-06-08 13:47:00 -0700921 /*
922 * We can do this unlocked here. The futex code uses
923 * this flag just to verify whether the pi state
924 * cleanup has been done or not. In the worst case it
925 * loops once more. We pretend that the cleanup was
926 * done as there is no way to return. Either the
927 * OWNER_DIED bit is set by now or we push the blocked
928 * task into the wait for ever nirwana as well.
929 */
930 tsk->flags |= PF_EXITPIDONE;
Alexander Nybergdf164db2005-06-23 00:09:13 -0700931 set_current_state(TASK_UNINTERRUPTIBLE);
932 schedule();
933 }
934
Thomas Gleixner3aa551c2009-03-23 18:28:15 +0100935 exit_irq_thread();
936
Oleg Nesterovd12619b2008-02-08 04:19:12 -0800937 exit_signals(tsk); /* sets PF_EXITING */
Alexey Kuznetsov778e9a92007-06-08 13:47:00 -0700938 /*
939 * tsk->flags are checked in the futex code to protect against
940 * an exiting task cleaning up the robust pi futexes.
941 */
Oleg Nesterovd2ee7192007-10-16 23:26:47 -0700942 smp_mb();
943 spin_unlock_wait(&tsk->pi_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700944
Linus Torvalds1da177e2005-04-16 15:20:36 -0700945 if (unlikely(in_atomic()))
946 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -0700947 current->comm, task_pid_nr(current),
Linus Torvalds1da177e2005-04-16 15:20:36 -0700948 preempt_count());
949
950 acct_update_integrals(tsk);
Oleg Nesterov901608d2009-01-06 14:40:29 -0800951
Linus Torvalds1da177e2005-04-16 15:20:36 -0700952 group_dead = atomic_dec_and_test(&tsk->signal->live);
Andrew Mortonc3068952005-08-04 16:49:32 -0700953 if (group_dead) {
Alexey Kuznetsov778e9a92007-06-08 13:47:00 -0700954 hrtimer_cancel(&tsk->signal->real_timer);
Roland McGrath25f407f2005-10-21 15:03:29 -0700955 exit_itimers(tsk->signal);
Andrew Mortonc3068952005-08-04 16:49:32 -0700956 }
KaiGai Koheif6ec29a2006-06-25 05:49:25 -0700957 acct_collect(code, group_dead);
Miloslav Trmac522ed772007-07-15 23:40:56 -0700958 if (group_dead)
959 tty_audit_exit();
Al Virofa84cb92006-03-29 20:30:19 -0500960 if (unlikely(tsk->audit_context))
961 audit_free(tsk);
Oleg Nesterov115085e2006-12-06 20:36:51 -0800962
Jonathan Limf2ab6d82007-08-30 23:56:23 -0700963 tsk->exit_code = code;
Oleg Nesterov115085e2006-12-06 20:36:51 -0800964 taskstats_exit(tsk, group_dead);
Shailabh Nagarc7572492006-07-14 00:24:40 -0700965
Linus Torvalds1da177e2005-04-16 15:20:36 -0700966 exit_mm(tsk);
967
KaiGai Kohei0e464812006-06-25 05:49:24 -0700968 if (group_dead)
KaiGai Koheif6ec29a2006-06-25 05:49:25 -0700969 acct_process();
Mathieu Desnoyers0a16b602008-07-18 12:16:17 -0400970 trace_sched_process_exit(tsk);
971
Linus Torvalds1da177e2005-04-16 15:20:36 -0700972 exit_sem(tsk);
Al Viro1ec7f1d2008-04-22 05:35:42 -0400973 exit_files(tsk);
974 exit_fs(tsk);
Jeff Dikee18eecb2007-07-15 23:38:48 -0700975 check_stack_usage();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700976 exit_thread();
Paul Menageb4f48b62007-10-18 23:39:33 -0700977 cgroup_exit(tsk, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700978
979 if (group_dead && tsk->signal->leader)
980 disassociate_ctty(1);
981
Al Viroa1261f52005-11-13 16:06:55 -0800982 module_put(task_thread_info(tsk)->exec_domain->module);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700983 if (tsk->binfmt)
984 module_put(tsk->binfmt->module);
985
Matt Helsley9f460802005-11-07 00:59:16 -0800986 proc_exit_connector(tsk);
Oleg Nesterov821c7de2008-03-02 21:44:44 +0300987 exit_notify(tsk, group_dead);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700988#ifdef CONFIG_NUMA
Lee Schermerhornf0be3d32008-04-28 02:13:08 -0700989 mpol_put(tsk->mempolicy);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700990 tsk->mempolicy = NULL;
991#endif
Ingo Molnar9b51f662008-12-12 13:49:45 +0100992#ifdef CONFIG_FUTEX
Ingo Molnarc87e2832006-06-27 02:54:58 -0700993 if (unlikely(!list_empty(&tsk->pi_state_list)))
994 exit_pi_state_list(tsk);
995 if (unlikely(current->pi_state_cache))
996 kfree(current->pi_state_cache);
Alexey Dobriyan42b2dd02007-10-16 23:27:30 -0700997#endif
Ingo Molnarc87e2832006-06-27 02:54:58 -0700998 /*
Ingo Molnar9a11b49a2006-07-03 00:24:33 -0700999 * Make sure we are holding no locks:
Ingo Molnarde5097c2006-01-09 15:59:21 -08001000 */
Ingo Molnar9a11b49a2006-07-03 00:24:33 -07001001 debug_check_no_locks_held(tsk);
Alexey Kuznetsov778e9a92007-06-08 13:47:00 -07001002 /*
1003 * We can do this unlocked here. The futex code uses this flag
1004 * just to verify whether the pi state cleanup has been done
1005 * or not. In the worst case it loops once more.
1006 */
1007 tsk->flags |= PF_EXITPIDONE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001008
Al Viroafc847b2006-02-28 12:51:55 -05001009 if (tsk->io_context)
1010 exit_io_context();
1011
Jens Axboeb92ce552006-04-11 13:52:07 +02001012 if (tsk->splice_pipe)
1013 __free_pipe_info(tsk->splice_pipe);
1014
Coywolf Qi Hunt74072512005-10-30 15:02:47 -08001015 preempt_disable();
Oleg Nesterov55a101f2006-09-29 02:01:10 -07001016 /* causes final put_task_struct in finish_task_switch(). */
Oleg Nesterovc394cc92006-09-29 02:01:11 -07001017 tsk->state = TASK_DEAD;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001018 schedule();
1019 BUG();
1020 /* Avoid "noreturn function does return". */
Alan Cox54306cf2006-09-29 02:00:42 -07001021 for (;;)
1022 cpu_relax(); /* For when BUG is null */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001023}
1024
Russ Anderson012914d2005-04-23 00:08:00 -07001025EXPORT_SYMBOL_GPL(do_exit);
1026
Linus Torvalds1da177e2005-04-16 15:20:36 -07001027NORET_TYPE void complete_and_exit(struct completion *comp, long code)
1028{
1029 if (comp)
1030 complete(comp);
Oleg Nesterov55a101f2006-09-29 02:01:10 -07001031
Linus Torvalds1da177e2005-04-16 15:20:36 -07001032 do_exit(code);
1033}
1034
1035EXPORT_SYMBOL(complete_and_exit);
1036
Heiko Carstens754fe8d2009-01-14 14:14:09 +01001037SYSCALL_DEFINE1(exit, int, error_code)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001038{
1039 do_exit((error_code&0xff)<<8);
1040}
1041
Linus Torvalds1da177e2005-04-16 15:20:36 -07001042/*
1043 * Take down every thread in the group. This is called by fatal signals
1044 * as well as by sys_exit_group (below).
1045 */
1046NORET_TYPE void
1047do_group_exit(int exit_code)
1048{
Oleg Nesterovbfc4b082008-04-30 00:52:36 -07001049 struct signal_struct *sig = current->signal;
1050
Linus Torvalds1da177e2005-04-16 15:20:36 -07001051 BUG_ON(exit_code & 0x80); /* core dumps don't get here */
1052
Oleg Nesterovbfc4b082008-04-30 00:52:36 -07001053 if (signal_group_exit(sig))
1054 exit_code = sig->group_exit_code;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001055 else if (!thread_group_empty(current)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001056 struct sighand_struct *const sighand = current->sighand;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001057 spin_lock_irq(&sighand->siglock);
Oleg Nesteroved5d2ca2008-02-04 22:27:24 -08001058 if (signal_group_exit(sig))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001059 /* Another thread got here before we took the lock. */
1060 exit_code = sig->group_exit_code;
1061 else {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001062 sig->group_exit_code = exit_code;
Oleg Nesteroved5d2ca2008-02-04 22:27:24 -08001063 sig->flags = SIGNAL_GROUP_EXIT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001064 zap_other_threads(current);
1065 }
1066 spin_unlock_irq(&sighand->siglock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001067 }
1068
1069 do_exit(exit_code);
1070 /* NOTREACHED */
1071}
1072
1073/*
1074 * this kills every thread in the thread group. Note that any externally
1075 * wait4()-ing process will get the correct exit code - even if this
1076 * thread is not the thread group leader.
1077 */
Heiko Carstens754fe8d2009-01-14 14:14:09 +01001078SYSCALL_DEFINE1(exit_group, int, error_code)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001079{
1080 do_group_exit((error_code & 0xff) << 8);
Heiko Carstens2ed7c032009-01-14 14:13:54 +01001081 /* NOTREACHED */
1082 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001083}
1084
Eric W. Biederman161550d2008-02-08 04:19:14 -08001085static struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
1086{
1087 struct pid *pid = NULL;
1088 if (type == PIDTYPE_PID)
1089 pid = task->pids[type].pid;
1090 else if (type < PIDTYPE_MAX)
1091 pid = task->group_leader->pids[type].pid;
1092 return pid;
1093}
1094
1095static int eligible_child(enum pid_type type, struct pid *pid, int options,
1096 struct task_struct *p)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001097{
Roland McGrath73243282007-05-06 14:50:20 -07001098 int err;
1099
Eric W. Biederman161550d2008-02-08 04:19:14 -08001100 if (type < PIDTYPE_MAX) {
1101 if (task_pid_type(p, type) != pid)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001102 return 0;
1103 }
1104
Linus Torvalds1da177e2005-04-16 15:20:36 -07001105 /* Wait for all children (clone and not) if __WALL is set;
1106 * otherwise, wait for clone children *only* if __WCLONE is
1107 * set; otherwise, wait for non-clone children *only*. (Note:
1108 * A "clone" child here is one that reports to its parent
1109 * using a signal other than SIGCHLD.) */
1110 if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
1111 && !(options & __WALL))
1112 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001113
Roland McGrath73243282007-05-06 14:50:20 -07001114 err = security_task_wait(p);
Roland McGrath14dd0b82008-03-30 18:41:25 -07001115 if (err)
1116 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001117
Roland McGrath14dd0b82008-03-30 18:41:25 -07001118 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001119}
1120
Ingo Molnar36c8b582006-07-03 00:25:41 -07001121static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001122 int why, int status,
1123 struct siginfo __user *infop,
1124 struct rusage __user *rusagep)
1125{
1126 int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
Ingo Molnar36c8b582006-07-03 00:25:41 -07001127
Linus Torvalds1da177e2005-04-16 15:20:36 -07001128 put_task_struct(p);
1129 if (!retval)
1130 retval = put_user(SIGCHLD, &infop->si_signo);
1131 if (!retval)
1132 retval = put_user(0, &infop->si_errno);
1133 if (!retval)
1134 retval = put_user((short)why, &infop->si_code);
1135 if (!retval)
1136 retval = put_user(pid, &infop->si_pid);
1137 if (!retval)
1138 retval = put_user(uid, &infop->si_uid);
1139 if (!retval)
1140 retval = put_user(status, &infop->si_status);
1141 if (!retval)
1142 retval = pid;
1143 return retval;
1144}
1145
1146/*
1147 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
1148 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1149 * the lock and this task is uninteresting. If we return nonzero, we have
1150 * released the lock and the system call should return.
1151 */
Roland McGrath98abed02008-03-19 19:24:59 -07001152static int wait_task_zombie(struct task_struct *p, int options,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001153 struct siginfo __user *infop,
1154 int __user *stat_addr, struct rusage __user *ru)
1155{
1156 unsigned long state;
Oleg Nesterov2f4e6e22007-10-16 23:26:58 -07001157 int retval, status, traced;
Pavel Emelyanov6c5f3e72008-02-08 04:19:20 -08001158 pid_t pid = task_pid_vnr(p);
David Howellsc69e8d92008-11-14 10:39:19 +11001159 uid_t uid = __task_cred(p)->uid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001160
Roland McGrath98abed02008-03-19 19:24:59 -07001161 if (!likely(options & WEXITED))
1162 return 0;
1163
1164 if (unlikely(options & WNOWAIT)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001165 int exit_code = p->exit_code;
1166 int why, status;
1167
Linus Torvalds1da177e2005-04-16 15:20:36 -07001168 get_task_struct(p);
1169 read_unlock(&tasklist_lock);
1170 if ((exit_code & 0x7f) == 0) {
1171 why = CLD_EXITED;
1172 status = exit_code >> 8;
1173 } else {
1174 why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1175 status = exit_code & 0x7f;
1176 }
1177 return wait_noreap_copyout(p, pid, uid, why,
1178 status, infop, ru);
1179 }
1180
1181 /*
1182 * Try to move the task's state to DEAD
1183 * only one thread is allowed to do this:
1184 */
1185 state = xchg(&p->exit_state, EXIT_DEAD);
1186 if (state != EXIT_ZOMBIE) {
1187 BUG_ON(state != EXIT_DEAD);
1188 return 0;
1189 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001190
Oleg Nesterov53b6f9f2008-04-30 00:53:13 -07001191 traced = ptrace_reparented(p);
Oleg Nesterov2f4e6e22007-10-16 23:26:58 -07001192
1193 if (likely(!traced)) {
Jesper Juhl3795e162006-01-09 20:54:39 -08001194 struct signal_struct *psig;
1195 struct signal_struct *sig;
Frank Mayharf06febc2008-09-12 09:54:39 -07001196 struct task_cputime cputime;
Jesper Juhl3795e162006-01-09 20:54:39 -08001197
Linus Torvalds1da177e2005-04-16 15:20:36 -07001198 /*
1199 * The resource counters for the group leader are in its
1200 * own task_struct. Those for dead threads in the group
1201 * are in its signal_struct, as are those for the child
1202 * processes it has previously reaped. All these
1203 * accumulate in the parent's signal_struct c* fields.
1204 *
1205 * We don't bother to take a lock here to protect these
1206 * p->signal fields, because they are only touched by
1207 * __exit_signal, which runs with tasklist_lock
1208 * write-locked anyway, and so is excluded here. We do
1209 * need to protect the access to p->parent->signal fields,
1210 * as other threads in the parent group can be right
1211 * here reaping other children at the same time.
Frank Mayharf06febc2008-09-12 09:54:39 -07001212 *
1213 * We use thread_group_cputime() to get times for the thread
1214 * group, which consolidates times for all threads in the
1215 * group including the group leader.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001216 */
Oleg Nesterov2b5fe6d2008-11-17 15:40:08 +01001217 thread_group_cputime(p, &cputime);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001218 spin_lock_irq(&p->parent->sighand->siglock);
Jesper Juhl3795e162006-01-09 20:54:39 -08001219 psig = p->parent->signal;
1220 sig = p->signal;
1221 psig->cutime =
1222 cputime_add(psig->cutime,
Frank Mayharf06febc2008-09-12 09:54:39 -07001223 cputime_add(cputime.utime,
1224 sig->cutime));
Jesper Juhl3795e162006-01-09 20:54:39 -08001225 psig->cstime =
1226 cputime_add(psig->cstime,
Frank Mayharf06febc2008-09-12 09:54:39 -07001227 cputime_add(cputime.stime,
1228 sig->cstime));
Laurent Vivier9ac52312007-10-15 17:00:19 +02001229 psig->cgtime =
1230 cputime_add(psig->cgtime,
1231 cputime_add(p->gtime,
1232 cputime_add(sig->gtime,
1233 sig->cgtime)));
Jesper Juhl3795e162006-01-09 20:54:39 -08001234 psig->cmin_flt +=
1235 p->min_flt + sig->min_flt + sig->cmin_flt;
1236 psig->cmaj_flt +=
1237 p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1238 psig->cnvcsw +=
1239 p->nvcsw + sig->nvcsw + sig->cnvcsw;
1240 psig->cnivcsw +=
1241 p->nivcsw + sig->nivcsw + sig->cnivcsw;
Eric Dumazet6eaeeab2007-05-10 22:22:37 -07001242 psig->cinblock +=
1243 task_io_get_inblock(p) +
1244 sig->inblock + sig->cinblock;
1245 psig->coublock +=
1246 task_io_get_oublock(p) +
1247 sig->oublock + sig->coublock;
Andrea Righi59954772008-07-27 17:29:15 +02001248 task_io_accounting_add(&psig->ioac, &p->ioac);
1249 task_io_accounting_add(&psig->ioac, &sig->ioac);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001250 spin_unlock_irq(&p->parent->sighand->siglock);
1251 }
1252
1253 /*
1254 * Now we are sure this task is interesting, and no other
1255 * thread can reap it because we set its state to EXIT_DEAD.
1256 */
1257 read_unlock(&tasklist_lock);
1258
Ingo Molnareef6cbf2008-12-19 10:20:42 +01001259 /*
1260 * Flush inherited counters to the parent - before the parent
1261 * gets woken up by child-exit notifications.
1262 */
1263 perf_counter_exit_task(p);
1264
Linus Torvalds1da177e2005-04-16 15:20:36 -07001265 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1266 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1267 ? p->signal->group_exit_code : p->exit_code;
1268 if (!retval && stat_addr)
1269 retval = put_user(status, stat_addr);
1270 if (!retval && infop)
1271 retval = put_user(SIGCHLD, &infop->si_signo);
1272 if (!retval && infop)
1273 retval = put_user(0, &infop->si_errno);
1274 if (!retval && infop) {
1275 int why;
1276
1277 if ((status & 0x7f) == 0) {
1278 why = CLD_EXITED;
1279 status >>= 8;
1280 } else {
1281 why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1282 status &= 0x7f;
1283 }
1284 retval = put_user((short)why, &infop->si_code);
1285 if (!retval)
1286 retval = put_user(status, &infop->si_status);
1287 }
1288 if (!retval && infop)
Oleg Nesterov3a515e42008-02-08 04:19:07 -08001289 retval = put_user(pid, &infop->si_pid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001290 if (!retval && infop)
David Howellsc69e8d92008-11-14 10:39:19 +11001291 retval = put_user(uid, &infop->si_uid);
Oleg Nesterov2f4e6e22007-10-16 23:26:58 -07001292 if (!retval)
Oleg Nesterov3a515e42008-02-08 04:19:07 -08001293 retval = pid;
Oleg Nesterov2f4e6e22007-10-16 23:26:58 -07001294
1295 if (traced) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001296 write_lock_irq(&tasklist_lock);
Oleg Nesterov2f4e6e22007-10-16 23:26:58 -07001297 /* We dropped tasklist, ptracer could die and untrace */
1298 ptrace_unlink(p);
1299 /*
1300 * If this is not a detached task, notify the parent.
1301 * If it's still not detached after that, don't release
1302 * it now.
1303 */
Oleg Nesterovd839fd42008-04-30 00:53:11 -07001304 if (!task_detached(p)) {
Oleg Nesterov2f4e6e22007-10-16 23:26:58 -07001305 do_notify_parent(p, p->exit_signal);
Oleg Nesterovd839fd42008-04-30 00:53:11 -07001306 if (!task_detached(p)) {
Oleg Nesterov2f4e6e22007-10-16 23:26:58 -07001307 p->exit_state = EXIT_ZOMBIE;
1308 p = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001309 }
1310 }
1311 write_unlock_irq(&tasklist_lock);
1312 }
1313 if (p != NULL)
1314 release_task(p);
Oleg Nesterov2f4e6e22007-10-16 23:26:58 -07001315
Linus Torvalds1da177e2005-04-16 15:20:36 -07001316 return retval;
1317}
1318
Oleg Nesterov90bc8d82009-04-02 16:57:58 -07001319static int *task_stopped_code(struct task_struct *p, bool ptrace)
1320{
1321 if (ptrace) {
1322 if (task_is_stopped_or_traced(p))
1323 return &p->exit_code;
1324 } else {
1325 if (p->signal->flags & SIGNAL_STOP_STOPPED)
1326 return &p->signal->group_exit_code;
1327 }
1328 return NULL;
1329}
1330
Linus Torvalds1da177e2005-04-16 15:20:36 -07001331/*
1332 * Handle sys_wait4 work for one task in state TASK_STOPPED. We hold
1333 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1334 * the lock and this task is uninteresting. If we return nonzero, we have
1335 * released the lock and the system call should return.
1336 */
Roland McGrathf4700212008-03-24 18:36:23 -07001337static int wait_task_stopped(int ptrace, struct task_struct *p,
Roland McGrath98abed02008-03-19 19:24:59 -07001338 int options, struct siginfo __user *infop,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001339 int __user *stat_addr, struct rusage __user *ru)
1340{
Oleg Nesterov90bc8d82009-04-02 16:57:58 -07001341 int retval, exit_code, *p_code, why;
Oleg Nesterovee7c82d2008-02-08 04:19:01 -08001342 uid_t uid = 0; /* unneeded, required by compiler */
Oleg Nesterovc8950782007-11-28 16:21:24 -08001343 pid_t pid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001344
Roland McGrathf4700212008-03-24 18:36:23 -07001345 if (!(options & WUNTRACED))
Roland McGrath98abed02008-03-19 19:24:59 -07001346 return 0;
1347
Oleg Nesterovee7c82d2008-02-08 04:19:01 -08001348 exit_code = 0;
1349 spin_lock_irq(&p->sighand->siglock);
1350
Oleg Nesterov90bc8d82009-04-02 16:57:58 -07001351 p_code = task_stopped_code(p, ptrace);
1352 if (unlikely(!p_code))
Oleg Nesterovee7c82d2008-02-08 04:19:01 -08001353 goto unlock_sig;
1354
Oleg Nesterov90bc8d82009-04-02 16:57:58 -07001355 exit_code = *p_code;
Oleg Nesterovee7c82d2008-02-08 04:19:01 -08001356 if (!exit_code)
1357 goto unlock_sig;
1358
Roland McGrath98abed02008-03-19 19:24:59 -07001359 if (!unlikely(options & WNOWAIT))
Oleg Nesterov90bc8d82009-04-02 16:57:58 -07001360 *p_code = 0;
Oleg Nesterovee7c82d2008-02-08 04:19:01 -08001361
David Howellsc69e8d92008-11-14 10:39:19 +11001362 /* don't need the RCU readlock here as we're holding a spinlock */
1363 uid = __task_cred(p)->uid;
Oleg Nesterovee7c82d2008-02-08 04:19:01 -08001364unlock_sig:
1365 spin_unlock_irq(&p->sighand->siglock);
1366 if (!exit_code)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001367 return 0;
1368
1369 /*
1370 * Now we are pretty sure this task is interesting.
1371 * Make sure it doesn't get reaped out from under us while we
1372 * give up the lock and then examine it below. We don't want to
1373 * keep holding onto the tasklist_lock while we call getrusage and
1374 * possibly take page faults for user memory.
1375 */
1376 get_task_struct(p);
Pavel Emelyanov6c5f3e72008-02-08 04:19:20 -08001377 pid = task_pid_vnr(p);
Roland McGrathf4700212008-03-24 18:36:23 -07001378 why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001379 read_unlock(&tasklist_lock);
1380
Roland McGrath98abed02008-03-19 19:24:59 -07001381 if (unlikely(options & WNOWAIT))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001382 return wait_noreap_copyout(p, pid, uid,
Scott James Remnante6ceb322007-11-28 16:22:07 -08001383 why, exit_code,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001384 infop, ru);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001385
1386 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1387 if (!retval && stat_addr)
1388 retval = put_user((exit_code << 8) | 0x7f, stat_addr);
1389 if (!retval && infop)
1390 retval = put_user(SIGCHLD, &infop->si_signo);
1391 if (!retval && infop)
1392 retval = put_user(0, &infop->si_errno);
1393 if (!retval && infop)
Roland McGrath6efcae42008-03-08 11:41:22 -08001394 retval = put_user((short)why, &infop->si_code);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001395 if (!retval && infop)
1396 retval = put_user(exit_code, &infop->si_status);
1397 if (!retval && infop)
Oleg Nesterovc8950782007-11-28 16:21:24 -08001398 retval = put_user(pid, &infop->si_pid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001399 if (!retval && infop)
Oleg Nesterovee7c82d2008-02-08 04:19:01 -08001400 retval = put_user(uid, &infop->si_uid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001401 if (!retval)
Oleg Nesterovc8950782007-11-28 16:21:24 -08001402 retval = pid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001403 put_task_struct(p);
1404
1405 BUG_ON(!retval);
1406 return retval;
1407}
1408
1409/*
1410 * Handle do_wait work for one task in a live, non-stopped state.
1411 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1412 * the lock and this task is uninteresting. If we return nonzero, we have
1413 * released the lock and the system call should return.
1414 */
Roland McGrath98abed02008-03-19 19:24:59 -07001415static int wait_task_continued(struct task_struct *p, int options,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001416 struct siginfo __user *infop,
1417 int __user *stat_addr, struct rusage __user *ru)
1418{
1419 int retval;
1420 pid_t pid;
1421 uid_t uid;
1422
Roland McGrath98abed02008-03-19 19:24:59 -07001423 if (!unlikely(options & WCONTINUED))
1424 return 0;
1425
Linus Torvalds1da177e2005-04-16 15:20:36 -07001426 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1427 return 0;
1428
1429 spin_lock_irq(&p->sighand->siglock);
1430 /* Re-check with the lock held. */
1431 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1432 spin_unlock_irq(&p->sighand->siglock);
1433 return 0;
1434 }
Roland McGrath98abed02008-03-19 19:24:59 -07001435 if (!unlikely(options & WNOWAIT))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001436 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
David Howellsc69e8d92008-11-14 10:39:19 +11001437 uid = __task_cred(p)->uid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001438 spin_unlock_irq(&p->sighand->siglock);
1439
Pavel Emelyanov6c5f3e72008-02-08 04:19:20 -08001440 pid = task_pid_vnr(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001441 get_task_struct(p);
1442 read_unlock(&tasklist_lock);
1443
1444 if (!infop) {
1445 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1446 put_task_struct(p);
1447 if (!retval && stat_addr)
1448 retval = put_user(0xffff, stat_addr);
1449 if (!retval)
Oleg Nesterov3a515e42008-02-08 04:19:07 -08001450 retval = pid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001451 } else {
1452 retval = wait_noreap_copyout(p, pid, uid,
1453 CLD_CONTINUED, SIGCONT,
1454 infop, ru);
1455 BUG_ON(retval == 0);
1456 }
1457
1458 return retval;
1459}
1460
Roland McGrath98abed02008-03-19 19:24:59 -07001461/*
1462 * Consider @p for a wait by @parent.
1463 *
1464 * -ECHILD should be in *@notask_error before the first call.
1465 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1466 * Returns zero if the search for a child should continue;
Roland McGrath14dd0b82008-03-30 18:41:25 -07001467 * then *@notask_error is 0 if @p is an eligible child,
1468 * or another error from security_task_wait(), or still -ECHILD.
Roland McGrath98abed02008-03-19 19:24:59 -07001469 */
Roland McGrathf4700212008-03-24 18:36:23 -07001470static int wait_consider_task(struct task_struct *parent, int ptrace,
Roland McGrath98abed02008-03-19 19:24:59 -07001471 struct task_struct *p, int *notask_error,
1472 enum pid_type type, struct pid *pid, int options,
1473 struct siginfo __user *infop,
1474 int __user *stat_addr, struct rusage __user *ru)
1475{
1476 int ret = eligible_child(type, pid, options, p);
Roland McGrath14dd0b82008-03-30 18:41:25 -07001477 if (!ret)
Roland McGrath98abed02008-03-19 19:24:59 -07001478 return ret;
1479
Roland McGrath14dd0b82008-03-30 18:41:25 -07001480 if (unlikely(ret < 0)) {
1481 /*
1482 * If we have not yet seen any eligible child,
1483 * then let this error code replace -ECHILD.
1484 * A permission error will give the user a clue
1485 * to look for security policy problems, rather
1486 * than for mysterious wait bugs.
1487 */
1488 if (*notask_error)
1489 *notask_error = ret;
1490 }
1491
Roland McGrathf4700212008-03-24 18:36:23 -07001492 if (likely(!ptrace) && unlikely(p->ptrace)) {
1493 /*
1494 * This child is hidden by ptrace.
1495 * We aren't allowed to see it now, but eventually we will.
1496 */
1497 *notask_error = 0;
1498 return 0;
1499 }
1500
Roland McGrath98abed02008-03-19 19:24:59 -07001501 if (p->exit_state == EXIT_DEAD)
1502 return 0;
1503
1504 /*
1505 * We don't reap group leaders with subthreads.
1506 */
1507 if (p->exit_state == EXIT_ZOMBIE && !delay_group_leader(p))
1508 return wait_task_zombie(p, options, infop, stat_addr, ru);
1509
1510 /*
1511 * It's stopped or running now, so it might
1512 * later continue, exit, or stop again.
1513 */
1514 *notask_error = 0;
1515
Oleg Nesterov90bc8d82009-04-02 16:57:58 -07001516 if (task_stopped_code(p, ptrace))
Roland McGrathf4700212008-03-24 18:36:23 -07001517 return wait_task_stopped(ptrace, p, options,
1518 infop, stat_addr, ru);
Roland McGrath98abed02008-03-19 19:24:59 -07001519
1520 return wait_task_continued(p, options, infop, stat_addr, ru);
1521}
1522
1523/*
1524 * Do the work of do_wait() for one thread in the group, @tsk.
1525 *
1526 * -ECHILD should be in *@notask_error before the first call.
1527 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1528 * Returns zero if the search for a child should continue; then
Roland McGrath14dd0b82008-03-30 18:41:25 -07001529 * *@notask_error is 0 if there were any eligible children,
1530 * or another error from security_task_wait(), or still -ECHILD.
Roland McGrath98abed02008-03-19 19:24:59 -07001531 */
1532static int do_wait_thread(struct task_struct *tsk, int *notask_error,
1533 enum pid_type type, struct pid *pid, int options,
1534 struct siginfo __user *infop, int __user *stat_addr,
1535 struct rusage __user *ru)
1536{
1537 struct task_struct *p;
1538
1539 list_for_each_entry(p, &tsk->children, sibling) {
Roland McGrathf4700212008-03-24 18:36:23 -07001540 /*
1541 * Do not consider detached threads.
1542 */
1543 if (!task_detached(p)) {
1544 int ret = wait_consider_task(tsk, 0, p, notask_error,
1545 type, pid, options,
1546 infop, stat_addr, ru);
1547 if (ret)
1548 return ret;
1549 }
Roland McGrath98abed02008-03-19 19:24:59 -07001550 }
1551
1552 return 0;
1553}
1554
1555static int ptrace_do_wait(struct task_struct *tsk, int *notask_error,
1556 enum pid_type type, struct pid *pid, int options,
1557 struct siginfo __user *infop, int __user *stat_addr,
1558 struct rusage __user *ru)
1559{
1560 struct task_struct *p;
1561
1562 /*
Roland McGrathf4700212008-03-24 18:36:23 -07001563 * Traditionally we see ptrace'd stopped tasks regardless of options.
Roland McGrath98abed02008-03-19 19:24:59 -07001564 */
Roland McGrathf4700212008-03-24 18:36:23 -07001565 options |= WUNTRACED;
Roland McGrath98abed02008-03-19 19:24:59 -07001566
Roland McGrathf4700212008-03-24 18:36:23 -07001567 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
1568 int ret = wait_consider_task(tsk, 1, p, notask_error,
1569 type, pid, options,
1570 infop, stat_addr, ru);
1571 if (ret)
Roland McGrath98abed02008-03-19 19:24:59 -07001572 return ret;
Roland McGrath98abed02008-03-19 19:24:59 -07001573 }
1574
1575 return 0;
1576}
1577
Eric W. Biederman161550d2008-02-08 04:19:14 -08001578static long do_wait(enum pid_type type, struct pid *pid, int options,
1579 struct siginfo __user *infop, int __user *stat_addr,
1580 struct rusage __user *ru)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001581{
1582 DECLARE_WAITQUEUE(wait, current);
1583 struct task_struct *tsk;
Roland McGrath98abed02008-03-19 19:24:59 -07001584 int retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001585
Mathieu Desnoyers0a16b602008-07-18 12:16:17 -04001586 trace_sched_process_wait(pid);
1587
Linus Torvalds1da177e2005-04-16 15:20:36 -07001588 add_wait_queue(&current->signal->wait_chldexit,&wait);
1589repeat:
Roland McGrath98abed02008-03-19 19:24:59 -07001590 /*
1591 * If there is nothing that can match our critiera just get out.
1592 * We will clear @retval to zero if we see any child that might later
1593 * match our criteria, even if we are not able to reap it yet.
1594 */
Eric W. Biederman161550d2008-02-08 04:19:14 -08001595 retval = -ECHILD;
1596 if ((type < PIDTYPE_MAX) && (!pid || hlist_empty(&pid->tasks[type])))
1597 goto end;
1598
Linus Torvalds1da177e2005-04-16 15:20:36 -07001599 current->state = TASK_INTERRUPTIBLE;
1600 read_lock(&tasklist_lock);
1601 tsk = current;
1602 do {
Roland McGrath98abed02008-03-19 19:24:59 -07001603 int tsk_result = do_wait_thread(tsk, &retval,
1604 type, pid, options,
1605 infop, stat_addr, ru);
1606 if (!tsk_result)
1607 tsk_result = ptrace_do_wait(tsk, &retval,
1608 type, pid, options,
1609 infop, stat_addr, ru);
1610 if (tsk_result) {
1611 /*
1612 * tasklist_lock is unlocked and we have a final result.
1613 */
1614 retval = tsk_result;
1615 goto end;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001616 }
Roland McGrath98abed02008-03-19 19:24:59 -07001617
Linus Torvalds1da177e2005-04-16 15:20:36 -07001618 if (options & __WNOTHREAD)
1619 break;
1620 tsk = next_thread(tsk);
Eric Sesterhenn125e1872006-06-23 02:06:06 -07001621 BUG_ON(tsk->signal != current->signal);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001622 } while (tsk != current);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001623 read_unlock(&tasklist_lock);
Oleg Nesterovf2cc3eb2008-02-08 04:19:06 -08001624
Roland McGrath98abed02008-03-19 19:24:59 -07001625 if (!retval && !(options & WNOHANG)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001626 retval = -ERESTARTSYS;
Roland McGrath98abed02008-03-19 19:24:59 -07001627 if (!signal_pending(current)) {
1628 schedule();
1629 goto repeat;
1630 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001631 }
Roland McGrath98abed02008-03-19 19:24:59 -07001632
Linus Torvalds1da177e2005-04-16 15:20:36 -07001633end:
1634 current->state = TASK_RUNNING;
1635 remove_wait_queue(&current->signal->wait_chldexit,&wait);
1636 if (infop) {
1637 if (retval > 0)
Oleg Nesterov9cbab812008-02-08 04:19:02 -08001638 retval = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001639 else {
1640 /*
1641 * For a WNOHANG return, clear out all the fields
1642 * we would set so the user can easily tell the
1643 * difference.
1644 */
1645 if (!retval)
1646 retval = put_user(0, &infop->si_signo);
1647 if (!retval)
1648 retval = put_user(0, &infop->si_errno);
1649 if (!retval)
1650 retval = put_user(0, &infop->si_code);
1651 if (!retval)
1652 retval = put_user(0, &infop->si_pid);
1653 if (!retval)
1654 retval = put_user(0, &infop->si_uid);
1655 if (!retval)
1656 retval = put_user(0, &infop->si_status);
1657 }
1658 }
1659 return retval;
1660}
1661
Heiko Carstens17da2bd2009-01-14 14:14:10 +01001662SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
1663 infop, int, options, struct rusage __user *, ru)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001664{
Eric W. Biederman161550d2008-02-08 04:19:14 -08001665 struct pid *pid = NULL;
1666 enum pid_type type;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001667 long ret;
1668
1669 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1670 return -EINVAL;
1671 if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1672 return -EINVAL;
1673
1674 switch (which) {
1675 case P_ALL:
Eric W. Biederman161550d2008-02-08 04:19:14 -08001676 type = PIDTYPE_MAX;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001677 break;
1678 case P_PID:
Eric W. Biederman161550d2008-02-08 04:19:14 -08001679 type = PIDTYPE_PID;
1680 if (upid <= 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001681 return -EINVAL;
1682 break;
1683 case P_PGID:
Eric W. Biederman161550d2008-02-08 04:19:14 -08001684 type = PIDTYPE_PGID;
1685 if (upid <= 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001686 return -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001687 break;
1688 default:
1689 return -EINVAL;
1690 }
1691
Eric W. Biederman161550d2008-02-08 04:19:14 -08001692 if (type < PIDTYPE_MAX)
1693 pid = find_get_pid(upid);
1694 ret = do_wait(type, pid, options, infop, NULL, ru);
1695 put_pid(pid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001696
1697 /* avoid REGPARM breakage on x86: */
Roland McGrath54a01512008-04-10 15:37:38 -07001698 asmlinkage_protect(5, ret, which, upid, infop, options, ru);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001699 return ret;
1700}
1701
Heiko Carstens754fe8d2009-01-14 14:14:09 +01001702SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
1703 int, options, struct rusage __user *, ru)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001704{
Eric W. Biederman161550d2008-02-08 04:19:14 -08001705 struct pid *pid = NULL;
1706 enum pid_type type;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001707 long ret;
1708
1709 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1710 __WNOTHREAD|__WCLONE|__WALL))
1711 return -EINVAL;
Eric W. Biederman161550d2008-02-08 04:19:14 -08001712
1713 if (upid == -1)
1714 type = PIDTYPE_MAX;
1715 else if (upid < 0) {
1716 type = PIDTYPE_PGID;
1717 pid = find_get_pid(-upid);
1718 } else if (upid == 0) {
1719 type = PIDTYPE_PGID;
Oleg Nesterov2ae448e2009-04-02 16:58:36 -07001720 pid = get_task_pid(current, PIDTYPE_PGID);
Eric W. Biederman161550d2008-02-08 04:19:14 -08001721 } else /* upid > 0 */ {
1722 type = PIDTYPE_PID;
1723 pid = find_get_pid(upid);
1724 }
1725
1726 ret = do_wait(type, pid, options | WEXITED, NULL, stat_addr, ru);
1727 put_pid(pid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001728
1729 /* avoid REGPARM breakage on x86: */
Roland McGrath54a01512008-04-10 15:37:38 -07001730 asmlinkage_protect(4, ret, upid, stat_addr, options, ru);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001731 return ret;
1732}
1733
1734#ifdef __ARCH_WANT_SYS_WAITPID
1735
1736/*
1737 * sys_waitpid() remains for compatibility. waitpid() should be
1738 * implemented by calling sys_wait4() from libc.a.
1739 */
Heiko Carstens17da2bd2009-01-14 14:14:10 +01001740SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001741{
1742 return sys_wait4(pid, stat_addr, options, NULL);
1743}
1744
1745#endif