blob: 9d3d0f0b27d9a6165384d6af55013488aacfdc72 [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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070016#include <linux/key.h>
17#include <linux/security.h>
18#include <linux/cpu.h>
19#include <linux/acct.h>
Jay Lan8f0ab512006-09-30 23:28:59 -070020#include <linux/tsacct_kern.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070021#include <linux/file.h>
22#include <linux/binfmts.h>
Serge E. Hallynab516012006-10-02 02:18:06 -070023#include <linux/nsproxy.h>
Sukadev Bhattiprolu84d73782006-12-08 02:38:01 -080024#include <linux/pid_namespace.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070025#include <linux/ptrace.h>
26#include <linux/profile.h>
27#include <linux/mount.h>
28#include <linux/proc_fs.h>
Eric W. Biederman49d769d2007-05-09 02:34:33 -070029#include <linux/kthread.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070030#include <linux/mempolicy.h>
Shailabh Nagarc7572492006-07-14 00:24:40 -070031#include <linux/taskstats_kern.h>
Shailabh Nagarca74e922006-07-14 00:24:36 -070032#include <linux/delayacct.h>
Rafael J. Wysocki83144182007-07-17 04:03:35 -070033#include <linux/freezer.h>
Paul Menageb4f48b62007-10-18 23:39:33 -070034#include <linux/cgroup.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070035#include <linux/syscalls.h>
Jesper Juhl7ed20e12005-05-01 08:59:14 -070036#include <linux/signal.h>
Oleg Nesterov6a14c5c2006-03-28 16:11:18 -080037#include <linux/posix-timers.h>
Matt Helsley9f460802005-11-07 00:59:16 -080038#include <linux/cn_proc.h>
Ingo Molnarde5097c2006-01-09 15:59:21 -080039#include <linux/mutex.h>
Ingo Molnar0771dfe2006-03-27 01:16:22 -080040#include <linux/futex.h>
Ingo Molnar34f192c2006-03-27 01:16:24 -080041#include <linux/compat.h>
Jens Axboeb92ce552006-04-11 13:52:07 +020042#include <linux/pipe_fs_i.h>
Al Virofa84cb92006-03-29 20:30:19 -050043#include <linux/audit.h> /* for audit_free() */
Adrian Bunk83cc5ed2006-06-25 05:47:41 -070044#include <linux/resource.h>
David Howells0d67a462006-08-29 19:05:56 +010045#include <linux/blkdev.h>
Eric Dumazet6eaeeab2007-05-10 22:22:37 -070046#include <linux/task_io_accounting_ops.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070047
48#include <asm/uaccess.h>
49#include <asm/unistd.h>
50#include <asm/pgtable.h>
51#include <asm/mmu_context.h>
52
Adrian Bunk408b6642005-05-01 08:59:29 -070053static void exit_mm(struct task_struct * tsk);
54
Linus Torvalds1da177e2005-04-16 15:20:36 -070055static void __unhash_process(struct task_struct *p)
56{
57 nr_threads--;
58 detach_pid(p, PIDTYPE_PID);
Linus Torvalds1da177e2005-04-16 15:20:36 -070059 if (thread_group_leader(p)) {
60 detach_pid(p, PIDTYPE_PGID);
61 detach_pid(p, PIDTYPE_SID);
Oleg Nesterovc97d9892006-03-28 16:11:06 -080062
Eric W. Biederman5e85d4a2006-04-18 22:20:16 -070063 list_del_rcu(&p->tasks);
Oleg Nesterov73b9ebf2006-03-28 16:11:07 -080064 __get_cpu_var(process_counts)--;
Linus Torvalds1da177e2005-04-16 15:20:36 -070065 }
Oleg Nesterov47e65322006-03-28 16:11:25 -080066 list_del_rcu(&p->thread_group);
Oleg Nesterovc97d9892006-03-28 16:11:06 -080067 remove_parent(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -070068}
69
Oleg Nesterov6a14c5c2006-03-28 16:11:18 -080070/*
71 * This function expects the tasklist_lock write-locked.
72 */
73static void __exit_signal(struct task_struct *tsk)
74{
75 struct signal_struct *sig = tsk->signal;
76 struct sighand_struct *sighand;
77
78 BUG_ON(!sig);
79 BUG_ON(!atomic_read(&sig->count));
80
81 rcu_read_lock();
82 sighand = rcu_dereference(tsk->sighand);
83 spin_lock(&sighand->siglock);
84
85 posix_cpu_timers_exit(tsk);
86 if (atomic_dec_and_test(&sig->count))
87 posix_cpu_timers_exit_group(tsk);
88 else {
89 /*
90 * If there is any task waiting for the group exit
91 * then notify it:
92 */
Oleg Nesterov6db840f2007-10-16 23:27:23 -070093 if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count)
Oleg Nesterov6a14c5c2006-03-28 16:11:18 -080094 wake_up_process(sig->group_exit_task);
Oleg Nesterov6db840f2007-10-16 23:27:23 -070095
Oleg Nesterov6a14c5c2006-03-28 16:11:18 -080096 if (tsk == sig->curr_target)
97 sig->curr_target = next_thread(tsk);
98 /*
99 * Accumulate here the counters for all threads but the
100 * group leader as they die, so they can be added into
101 * the process-wide totals when those are taken.
102 * The group leader stays around as a zombie as long
103 * as there are other threads. When it gets reaped,
104 * the exit.c code will add its counts into these totals.
105 * We won't ever get here for the group leader, since it
106 * will have been the last reference on the signal_struct.
107 */
108 sig->utime = cputime_add(sig->utime, tsk->utime);
109 sig->stime = cputime_add(sig->stime, tsk->stime);
Laurent Vivier9ac52312007-10-15 17:00:19 +0200110 sig->gtime = cputime_add(sig->gtime, tsk->gtime);
Oleg Nesterov6a14c5c2006-03-28 16:11:18 -0800111 sig->min_flt += tsk->min_flt;
112 sig->maj_flt += tsk->maj_flt;
113 sig->nvcsw += tsk->nvcsw;
114 sig->nivcsw += tsk->nivcsw;
Eric Dumazet6eaeeab2007-05-10 22:22:37 -0700115 sig->inblock += task_io_get_inblock(tsk);
116 sig->oublock += task_io_get_oublock(tsk);
Balbir Singh172ba842007-07-09 18:52:00 +0200117 sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
Oleg Nesterov6a14c5c2006-03-28 16:11:18 -0800118 sig = NULL; /* Marker for below. */
119 }
120
Oleg Nesterov58767002006-03-28 16:11:20 -0800121 __unhash_process(tsk);
122
Oleg Nesterov6a14c5c2006-03-28 16:11:18 -0800123 tsk->signal = NULL;
Oleg Nesterova7e53282006-03-28 16:11:27 -0800124 tsk->sighand = NULL;
Oleg Nesterov6a14c5c2006-03-28 16:11:18 -0800125 spin_unlock(&sighand->siglock);
126 rcu_read_unlock();
127
Oleg Nesterova7e53282006-03-28 16:11:27 -0800128 __cleanup_sighand(sighand);
Oleg Nesterov6a14c5c2006-03-28 16:11:18 -0800129 clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
130 flush_sigqueue(&tsk->pending);
131 if (sig) {
132 flush_sigqueue(&sig->shared_pending);
Oleg Nesterov093a8e82006-10-28 10:38:51 -0700133 taskstats_tgid_free(sig);
Oleg Nesterov6a14c5c2006-03-28 16:11:18 -0800134 __cleanup_signal(sig);
135 }
136}
137
Eric W. Biederman8c7904a2006-03-31 02:31:37 -0800138static void delayed_put_task_struct(struct rcu_head *rhp)
139{
140 put_task_struct(container_of(rhp, struct task_struct, rcu));
141}
142
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143void release_task(struct task_struct * p)
144{
Ingo Molnar36c8b582006-07-03 00:25:41 -0700145 struct task_struct *leader;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146 int zap_leader;
Oleg Nesterov1f09f972006-03-28 16:11:11 -0800147repeat:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700148 atomic_dec(&p->user->processes);
Pavel Emelyanov60347f62007-10-18 23:40:03 -0700149 proc_flush_task(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150 write_lock_irq(&tasklist_lock);
Oleg Nesterov1f09f972006-03-28 16:11:11 -0800151 ptrace_unlink(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
153 __exit_signal(p);
Oleg Nesterov35f5cad2006-03-28 16:11:19 -0800154
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155 /*
156 * If we are the last non-leader member of the thread
157 * group, and the leader is zombie, then notify the
158 * group leader's parent process. (if it wants notification.)
159 */
160 zap_leader = 0;
161 leader = p->group_leader;
162 if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
163 BUG_ON(leader->exit_signal == -1);
164 do_notify_parent(leader, leader->exit_signal);
165 /*
166 * If we were the last child thread and the leader has
167 * exited already, and the leader's parent ignores SIGCHLD,
168 * then we are the one who should release the leader.
169 *
170 * do_notify_parent() will have marked it self-reaping in
171 * that case.
172 */
173 zap_leader = (leader->exit_signal == -1);
174 }
175
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176 write_unlock_irq(&tasklist_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177 release_thread(p);
Eric W. Biederman8c7904a2006-03-31 02:31:37 -0800178 call_rcu(&p->rcu, delayed_put_task_struct);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179
180 p = leader;
181 if (unlikely(zap_leader))
182 goto repeat;
183}
184
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185/*
186 * This checks not only the pgrp, but falls back on the pid if no
187 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
188 * without this...
Eric W. Biederman04a2e6a2007-02-12 00:52:56 -0800189 *
190 * The caller must hold rcu lock or the tasklist lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191 */
Eric W. Biederman04a2e6a2007-02-12 00:52:56 -0800192struct pid *session_of_pgrp(struct pid *pgrp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193{
194 struct task_struct *p;
Eric W. Biederman04a2e6a2007-02-12 00:52:56 -0800195 struct pid *sid = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196
Eric W. Biederman04a2e6a2007-02-12 00:52:56 -0800197 p = pid_task(pgrp, PIDTYPE_PGID);
Oleg Nesterov62dfb552006-12-08 02:38:03 -0800198 if (p == NULL)
Eric W. Biederman04a2e6a2007-02-12 00:52:56 -0800199 p = pid_task(pgrp, PIDTYPE_PID);
Oleg Nesterov62dfb552006-12-08 02:38:03 -0800200 if (p != NULL)
Eric W. Biederman04a2e6a2007-02-12 00:52:56 -0800201 sid = task_session(p);
Oleg Nesterov62dfb552006-12-08 02:38:03 -0800202
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203 return sid;
204}
205
206/*
207 * Determine if a process group is "orphaned", according to the POSIX
208 * definition in 2.2.2.52. Orphaned process groups are not to be affected
209 * by terminal-generated stop signals. Newly orphaned process groups are
210 * to receive a SIGHUP and a SIGCONT.
211 *
212 * "I ask you, have you ever known what it is to be an orphan?"
213 */
Eric W. Biederman0475ac02007-02-12 00:52:57 -0800214static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215{
216 struct task_struct *p;
217 int ret = 1;
218
Eric W. Biederman0475ac02007-02-12 00:52:57 -0800219 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700220 if (p == ignored_task
221 || p->exit_state
Serge E. Hallynb460cbc2007-10-18 23:39:52 -0700222 || is_global_init(p->real_parent))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223 continue;
Eric W. Biederman0475ac02007-02-12 00:52:57 -0800224 if (task_pgrp(p->real_parent) != pgrp &&
225 task_session(p->real_parent) == task_session(p)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700226 ret = 0;
227 break;
228 }
Eric W. Biederman0475ac02007-02-12 00:52:57 -0800229 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700230 return ret; /* (sighing) "Often!" */
231}
232
Eric W. Biederman3e7cd6c2007-02-12 00:52:58 -0800233int is_current_pgrp_orphaned(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234{
235 int retval;
236
237 read_lock(&tasklist_lock);
Eric W. Biederman3e7cd6c2007-02-12 00:52:58 -0800238 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239 read_unlock(&tasklist_lock);
240
241 return retval;
242}
243
Eric W. Biederman0475ac02007-02-12 00:52:57 -0800244static int has_stopped_jobs(struct pid *pgrp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245{
246 int retval = 0;
247 struct task_struct *p;
248
Eric W. Biederman0475ac02007-02-12 00:52:57 -0800249 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
Matthew Wilcox338077e2007-12-06 11:09:35 -0500250 if (!task_is_stopped(p))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700252 retval = 1;
253 break;
Eric W. Biederman0475ac02007-02-12 00:52:57 -0800254 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255 return retval;
256}
257
258/**
Eric W. Biederman49d769d2007-05-09 02:34:33 -0700259 * reparent_to_kthreadd - Reparent the calling kernel thread to kthreadd
Linus Torvalds1da177e2005-04-16 15:20:36 -0700260 *
261 * If a kernel thread is launched as a result of a system call, or if
Eric W. Biederman49d769d2007-05-09 02:34:33 -0700262 * it ever exits, it should generally reparent itself to kthreadd so it
263 * isn't in the way of other processes and is correctly cleaned up on exit.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700264 *
265 * The various task state such as scheduling policy and priority may have
266 * been inherited from a user process, so we reset them to sane values here.
267 *
Eric W. Biederman49d769d2007-05-09 02:34:33 -0700268 * NOTE that reparent_to_kthreadd() gives the caller full capabilities.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269 */
Eric W. Biederman49d769d2007-05-09 02:34:33 -0700270static void reparent_to_kthreadd(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271{
272 write_lock_irq(&tasklist_lock);
273
274 ptrace_unlink(current);
275 /* Reparent to init */
Oleg Nesterov9b678ec2006-03-28 16:11:05 -0800276 remove_parent(current);
Eric W. Biederman49d769d2007-05-09 02:34:33 -0700277 current->real_parent = current->parent = kthreadd_task;
Oleg Nesterov9b678ec2006-03-28 16:11:05 -0800278 add_parent(current);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279
280 /* Set the exit signal to SIGCHLD so we signal init on exit */
281 current->exit_signal = SIGCHLD;
282
Ingo Molnare05606d2007-07-09 18:51:59 +0200283 if (task_nice(current) < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284 set_user_nice(current, 0);
285 /* cpus_allowed? */
286 /* rt_priority? */
287 /* signals? */
288 security_task_reparent_to_init(current);
289 memcpy(current->signal->rlim, init_task.signal->rlim,
290 sizeof(current->signal->rlim));
291 atomic_inc(&(INIT_USER->__count));
292 write_unlock_irq(&tasklist_lock);
293 switch_uid(INIT_USER);
294}
295
296void __set_special_pids(pid_t session, pid_t pgrp)
297{
Oren Laadane19f2472006-01-08 01:03:58 -0800298 struct task_struct *curr = current->group_leader;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299
Pavel Emelianova47afb02007-10-18 23:39:46 -0700300 if (task_session_nr(curr) != session) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 detach_pid(curr, PIDTYPE_SID);
Pavel Emelianova47afb02007-10-18 23:39:46 -0700302 set_task_session(curr, session);
Sukadev Bhattiprolue713d0d2007-05-10 22:22:58 -0700303 attach_pid(curr, PIDTYPE_SID, find_pid(session));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700304 }
Pavel Emelianova47afb02007-10-18 23:39:46 -0700305 if (task_pgrp_nr(curr) != pgrp) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700306 detach_pid(curr, PIDTYPE_PGID);
Pavel Emelyanov9a2e7052007-10-18 23:40:39 -0700307 set_task_pgrp(curr, pgrp);
Sukadev Bhattiprolue713d0d2007-05-10 22:22:58 -0700308 attach_pid(curr, PIDTYPE_PGID, find_pid(pgrp));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700309 }
310}
311
Oleg Nesterovae424ae2006-12-08 02:36:08 -0800312static void set_special_pids(pid_t session, pid_t pgrp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700313{
314 write_lock_irq(&tasklist_lock);
315 __set_special_pids(session, pgrp);
316 write_unlock_irq(&tasklist_lock);
317}
318
319/*
320 * Let kernel threads use this to say that they
321 * allow a certain signal (since daemonize() will
322 * have disabled all of them by default).
323 */
324int allow_signal(int sig)
325{
Jesper Juhl7ed20e12005-05-01 08:59:14 -0700326 if (!valid_signal(sig) || sig < 1)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700327 return -EINVAL;
328
329 spin_lock_irq(&current->sighand->siglock);
330 sigdelset(&current->blocked, sig);
331 if (!current->mm) {
332 /* Kernel threads handle their own signals.
333 Let the signal code know it'll be handled, so
334 that they don't get converted to SIGKILL or
335 just silently dropped */
336 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
337 }
338 recalc_sigpending();
339 spin_unlock_irq(&current->sighand->siglock);
340 return 0;
341}
342
343EXPORT_SYMBOL(allow_signal);
344
345int disallow_signal(int sig)
346{
Jesper Juhl7ed20e12005-05-01 08:59:14 -0700347 if (!valid_signal(sig) || sig < 1)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348 return -EINVAL;
349
350 spin_lock_irq(&current->sighand->siglock);
Oleg Nesterov10ab8252007-05-09 02:34:37 -0700351 current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700352 recalc_sigpending();
353 spin_unlock_irq(&current->sighand->siglock);
354 return 0;
355}
356
357EXPORT_SYMBOL(disallow_signal);
358
359/*
360 * Put all the gunge required to become a kernel thread without
361 * attached user resources in one place where it belongs.
362 */
363
364void daemonize(const char *name, ...)
365{
366 va_list args;
367 struct fs_struct *fs;
368 sigset_t blocked;
369
370 va_start(args, name);
371 vsnprintf(current->comm, sizeof(current->comm), name, args);
372 va_end(args);
373
374 /*
375 * If we were started as result of loading a module, close all of the
376 * user space pages. We don't need them, and if we didn't close them
377 * they would be locked into memory.
378 */
379 exit_mm(current);
Rafael J. Wysocki83144182007-07-17 04:03:35 -0700380 /*
381 * We don't want to have TIF_FREEZE set if the system-wide hibernation
382 * or suspend transition begins right now.
383 */
384 current->flags |= PF_NOFREEZE;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385
386 set_special_pids(1, 1);
Peter Zijlstra24ec8392006-12-08 02:36:04 -0800387 proc_clear_tty(current);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388
389 /* Block and flush all signals */
390 sigfillset(&blocked);
391 sigprocmask(SIG_BLOCK, &blocked, NULL);
392 flush_signals(current);
393
394 /* Become as one with the init task */
395
396 exit_fs(current); /* current->fs->count--; */
397 fs = init_task.fs;
398 current->fs = fs;
399 atomic_inc(&fs->count);
Serge E. Hallynab516012006-10-02 02:18:06 -0700400
Pavel Emelyanovcf7b7082007-10-18 23:39:54 -0700401 if (current->nsproxy != init_task.nsproxy) {
402 get_nsproxy(init_task.nsproxy);
403 switch_task_namespaces(current, init_task.nsproxy);
404 }
Serge E. Hallynab516012006-10-02 02:18:06 -0700405
Daniel Walkerd4c5e412007-10-18 23:39:59 -0700406 exit_files(current);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700407 current->files = init_task.files;
408 atomic_inc(&current->files->count);
409
Eric W. Biederman49d769d2007-05-09 02:34:33 -0700410 reparent_to_kthreadd();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700411}
412
413EXPORT_SYMBOL(daemonize);
414
Arjan van de Ven858119e2006-01-14 13:20:43 -0800415static void close_files(struct files_struct * files)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416{
417 int i, j;
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700418 struct fdtable *fdt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700419
420 j = 0;
Dipankar Sarma4fb3a532005-09-16 19:28:13 -0700421
422 /*
423 * It is safe to dereference the fd table without RCU or
424 * ->file_lock because this is the last reference to the
425 * files structure.
426 */
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700427 fdt = files_fdtable(files);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700428 for (;;) {
429 unsigned long set;
430 i = j * __NFDBITS;
Vadim Lobanovbbea9f62006-12-10 02:21:12 -0800431 if (i >= fdt->max_fds)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700432 break;
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700433 set = fdt->open_fds->fds_bits[j++];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700434 while (set) {
435 if (set & 1) {
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700436 struct file * file = xchg(&fdt->fd[i], NULL);
Ingo Molnar944be0b2007-02-12 00:52:26 -0800437 if (file) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700438 filp_close(file, files);
Ingo Molnar944be0b2007-02-12 00:52:26 -0800439 cond_resched();
440 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700441 }
442 i++;
443 set >>= 1;
444 }
445 }
446}
447
448struct files_struct *get_files_struct(struct task_struct *task)
449{
450 struct files_struct *files;
451
452 task_lock(task);
453 files = task->files;
454 if (files)
455 atomic_inc(&files->count);
456 task_unlock(task);
457
458 return files;
459}
460
461void fastcall put_files_struct(struct files_struct *files)
462{
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700463 struct fdtable *fdt;
464
Linus Torvalds1da177e2005-04-16 15:20:36 -0700465 if (atomic_dec_and_test(&files->count)) {
466 close_files(files);
467 /*
468 * Free the fd and fdset arrays if we expanded them.
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -0700469 * If the fdtable was embedded, pass files for freeing
470 * at the end of the RCU grace period. Otherwise,
471 * you can free files immediately.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700472 */
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700473 fdt = files_fdtable(files);
Vadim Lobanov4fd45812006-12-10 02:21:17 -0800474 if (fdt != &files->fdtab)
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -0700475 kmem_cache_free(files_cachep, files);
Vadim Lobanov01b2d932006-12-22 01:10:43 -0800476 free_fdtable(fdt);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477 }
478}
479
480EXPORT_SYMBOL(put_files_struct);
481
Kirill Korotaev3b9b8ab2006-09-29 02:00:05 -0700482void reset_files_struct(struct task_struct *tsk, struct files_struct *files)
483{
484 struct files_struct *old;
485
486 old = tsk->files;
487 task_lock(tsk);
488 tsk->files = files;
489 task_unlock(tsk);
490 put_files_struct(old);
491}
492EXPORT_SYMBOL(reset_files_struct);
493
Alexey Dobriyana39bc512007-10-18 23:41:10 -0700494static void __exit_files(struct task_struct *tsk)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700495{
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
506void exit_files(struct task_struct *tsk)
507{
508 __exit_files(tsk);
509}
510
Alexey Dobriyana39bc512007-10-18 23:41:10 -0700511static void __put_fs_struct(struct fs_struct *fs)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700512{
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
527void put_fs_struct(struct fs_struct *fs)
528{
529 __put_fs_struct(fs);
530}
531
Alexey Dobriyana39bc512007-10-18 23:41:10 -0700532static void __exit_fs(struct task_struct *tsk)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700533{
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
544void exit_fs(struct task_struct *tsk)
545{
546 __exit_fs(tsk);
547}
548
549EXPORT_SYMBOL_GPL(exit_fs);
550
551/*
552 * Turn us into a lazy TLB process if we
553 * aren't already..
554 */
Adrian Bunk408b6642005-05-01 08:59:29 -0700555static void exit_mm(struct task_struct * tsk)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556{
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);
Eric Sesterhenn125e1872006-06-23 02:06:06 -0700581 BUG_ON(mm != tsk->active_mm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700582 /* 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);
Rafael J. Wysocki0c1eecf2007-07-19 01:47:33 -0700587 /* We don't want this task to be frozen prematurely */
588 clear_freeze_flag(tsk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700589 task_unlock(tsk);
590 mmput(mm);
591}
592
Ingo Molnar36c8b582006-07-03 00:25:41 -0700593static void
594reparent_thread(struct task_struct *p, struct task_struct *father, int traced)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700595{
Oleg Nesterov241ceee2006-12-24 23:30:44 +0300596 if (p->pdeath_signal)
597 /* We already hold the tasklist_lock here. */
598 group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);
599
Linus Torvalds1da177e2005-04-16 15:20:36 -0700600 /* Move the child from its dying parent to the new one. */
601 if (unlikely(traced)) {
602 /* Preserve ptrace links if someone else is tracing this child. */
603 list_del_init(&p->ptrace_list);
604 if (p->parent != p->real_parent)
605 list_add(&p->ptrace_list, &p->real_parent->ptrace_children);
606 } else {
607 /* If this child is being traced, then we're the one tracing it
608 * anyway, so let go of it.
609 */
610 p->ptrace = 0;
Oleg Nesterov6ac781b2006-03-28 16:11:09 -0800611 remove_parent(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700612 p->parent = p->real_parent;
Oleg Nesterov6ac781b2006-03-28 16:11:09 -0800613 add_parent(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700614
Matthew Wilcox338077e2007-12-06 11:09:35 -0500615 if (task_is_traced(p)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700616 /*
617 * If it was at a trace stop, turn it into
618 * a normal stop since it's no longer being
619 * traced.
620 */
621 ptrace_untrace(p);
622 }
623 }
624
Eric W. Biedermanb2b2cbc2006-12-21 21:28:40 -0700625 /* If this is a threaded reparent there is no need to
626 * notify anyone anything has happened.
627 */
628 if (p->real_parent->group_leader == father->group_leader)
629 return;
630
631 /* We don't want people slaying init. */
632 if (p->exit_signal != -1)
633 p->exit_signal = SIGCHLD;
Eric W. Biedermanb2b2cbc2006-12-21 21:28:40 -0700634
635 /* If we'd notified the old parent about this child's death,
636 * also notify the new parent.
637 */
638 if (!traced && p->exit_state == EXIT_ZOMBIE &&
639 p->exit_signal != -1 && thread_group_empty(p))
640 do_notify_parent(p, p->exit_signal);
641
Linus Torvalds1da177e2005-04-16 15:20:36 -0700642 /*
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 */
Eric W. Biederman0475ac02007-02-12 00:52:57 -0800648 if ((task_pgrp(p) != task_pgrp(father)) &&
649 (task_session(p) == task_session(father))) {
650 struct pid *pgrp = task_pgrp(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700651
Cedric Le Goater937949d2006-12-08 02:37:54 -0800652 if (will_become_orphaned_pgrp(pgrp, NULL) &&
653 has_stopped_jobs(pgrp)) {
Eric W. Biederman0475ac02007-02-12 00:52:57 -0800654 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
655 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700656 }
657 }
658}
659
660/*
661 * When we die, we re-parent all our children.
662 * Try to give them to another thread in our thread
663 * group, and if no such member exists, give it to
Sukadev Bhattiprolu84d73782006-12-08 02:38:01 -0800664 * the child reaper process (ie "init") in our pid
665 * space.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700666 */
Oleg Nesterov762a24b2007-10-18 23:40:00 -0700667static void forget_original_parent(struct task_struct *father)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700668{
Matthias Kaehlcke03ff1792007-10-18 23:39:57 -0700669 struct task_struct *p, *n, *reaper = father;
Oleg Nesterov762a24b2007-10-18 23:40:00 -0700670 struct list_head ptrace_dead;
671
672 INIT_LIST_HEAD(&ptrace_dead);
673
674 write_lock_irq(&tasklist_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700675
676 do {
677 reaper = next_thread(reaper);
678 if (reaper == father) {
Sukadev Bhattiprolu88f21d82007-10-18 23:39:50 -0700679 reaper = task_child_reaper(father);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700680 break;
681 }
Oleg Nesterov762a24b2007-10-18 23:40:00 -0700682 } while (reaper->flags & PF_EXITING);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700683
684 /*
685 * There are only two places where our children can be:
686 *
687 * - in our child list
688 * - in our ptraced child list
689 *
690 * Search them and reparent children.
691 */
Matthias Kaehlcke03ff1792007-10-18 23:39:57 -0700692 list_for_each_entry_safe(p, n, &father->children, sibling) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700693 int ptrace;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700694
695 ptrace = p->ptrace;
696
697 /* if father isn't the real parent, then ptrace must be enabled */
698 BUG_ON(father != p->real_parent && !ptrace);
699
700 if (father == p->real_parent) {
701 /* reparent with a reaper, real father it's us */
Oleg Nesterov84eb6462007-10-16 23:26:49 -0700702 p->real_parent = reaper;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700703 reparent_thread(p, father, 0);
704 } else {
705 /* reparent ptraced task to its real parent */
706 __ptrace_unlink (p);
707 if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
708 thread_group_empty(p))
709 do_notify_parent(p, p->exit_signal);
710 }
711
712 /*
713 * if the ptraced child is a zombie with exit_signal == -1
714 * we must collect it before we exit, or it will remain
715 * zombie forever since we prevented it from self-reap itself
716 * while it was being traced by us, to be able to see it in wait4.
717 */
718 if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && p->exit_signal == -1))
Oleg Nesterov762a24b2007-10-18 23:40:00 -0700719 list_add(&p->ptrace_list, &ptrace_dead);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700720 }
Oleg Nesterov762a24b2007-10-18 23:40:00 -0700721
Matthias Kaehlcke03ff1792007-10-18 23:39:57 -0700722 list_for_each_entry_safe(p, n, &father->ptrace_children, ptrace_list) {
Oleg Nesterov84eb6462007-10-16 23:26:49 -0700723 p->real_parent = reaper;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700724 reparent_thread(p, father, 1);
725 }
Oleg Nesterov762a24b2007-10-18 23:40:00 -0700726
727 write_unlock_irq(&tasklist_lock);
728 BUG_ON(!list_empty(&father->children));
729 BUG_ON(!list_empty(&father->ptrace_children));
730
731 list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_list) {
732 list_del_init(&p->ptrace_list);
733 release_task(p);
734 }
735
Linus Torvalds1da177e2005-04-16 15:20:36 -0700736}
737
738/*
739 * Send signals to all our closest relatives so that they know
740 * to properly mourn us..
741 */
742static void exit_notify(struct task_struct *tsk)
743{
744 int state;
745 struct task_struct *t;
Eric W. Biederman0475ac02007-02-12 00:52:57 -0800746 struct pid *pgrp;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700747
748 if (signal_pending(tsk) && !(tsk->signal->flags & SIGNAL_GROUP_EXIT)
749 && !thread_group_empty(tsk)) {
750 /*
751 * This occurs when there was a race between our exit
752 * syscall and a group signal choosing us as the one to
753 * wake up. It could be that we are the only thread
754 * alerted to check for pending signals, but another thread
755 * should be woken now to take the signal since we will not.
756 * Now we'll wake all the threads in the group just to make
757 * sure someone gets all the pending signals.
758 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700759 spin_lock_irq(&tsk->sighand->siglock);
760 for (t = next_thread(tsk); t != tsk; t = next_thread(t))
Roland McGrath7bb44ad2007-05-23 13:57:44 -0700761 if (!signal_pending(t) && !(t->flags & PF_EXITING))
762 recalc_sigpending_and_wake(t);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700763 spin_unlock_irq(&tsk->sighand->siglock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700764 }
765
Linus Torvalds1da177e2005-04-16 15:20:36 -0700766 /*
767 * This does two things:
768 *
769 * A. Make init inherit all the child processes
770 * B. Check to see if any process groups have become orphaned
771 * as a result of our exiting, and if they have any stopped
772 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
773 */
Oleg Nesterov762a24b2007-10-18 23:40:00 -0700774 forget_original_parent(tsk);
Pavel Emelyanov2e4a7072007-10-18 23:40:01 -0700775 exit_task_namespaces(tsk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700776
Oleg Nesterov762a24b2007-10-18 23:40:00 -0700777 write_lock_irq(&tasklist_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700778 /*
779 * Check to see if any process groups have become orphaned
780 * as a result of our exiting, and if they have any stopped
781 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
782 *
783 * Case i: Our father is in a different pgrp than we are
784 * and we were the only connection outside, so our pgrp
785 * is about to become orphaned.
786 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700787 t = tsk->real_parent;
Oleg Nesterov3ae4cba2007-10-16 23:26:58 -0700788
Eric W. Biederman0475ac02007-02-12 00:52:57 -0800789 pgrp = task_pgrp(tsk);
790 if ((task_pgrp(t) != pgrp) &&
Eric W. Biederman14e9d572007-03-28 23:38:16 -0600791 (task_session(t) == task_session(tsk)) &&
Eric W. Biederman0475ac02007-02-12 00:52:57 -0800792 will_become_orphaned_pgrp(pgrp, tsk) &&
793 has_stopped_jobs(pgrp)) {
794 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
795 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700796 }
797
Oleg Nesterov24728442007-08-04 01:04:41 +0400798 /* Let father know we died
Linus Torvalds1da177e2005-04-16 15:20:36 -0700799 *
800 * Thread signals are configurable, but you aren't going to use
Daniel Walkerd4c5e412007-10-18 23:39:59 -0700801 * that to send signals to arbitary processes.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700802 * That stops right now.
803 *
804 * If the parent exec id doesn't match the exec id we saved
805 * when we started then we know the parent has changed security
806 * domain.
807 *
808 * If our self_exec id doesn't match our parent_exec_id then
809 * we have changed execution domain as these two values started
810 * the same after a fork.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700811 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700812 if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 &&
813 ( tsk->parent_exec_id != t->self_exec_id ||
814 tsk->self_exec_id != tsk->parent_exec_id)
815 && !capable(CAP_KILL))
816 tsk->exit_signal = SIGCHLD;
817
818
819 /* If something other than our normal parent is ptracing us, then
820 * send it a SIGCHLD instead of honoring exit_signal. exit_signal
821 * only has special meaning to our real parent.
822 */
823 if (tsk->exit_signal != -1 && thread_group_empty(tsk)) {
824 int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD;
825 do_notify_parent(tsk, signal);
826 } else if (tsk->ptrace) {
827 do_notify_parent(tsk, SIGCHLD);
828 }
829
830 state = EXIT_ZOMBIE;
Oleg Nesterov24728442007-08-04 01:04:41 +0400831 if (tsk->exit_signal == -1 && likely(!tsk->ptrace))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700832 state = EXIT_DEAD;
833 tsk->exit_state = state;
834
Oleg Nesterov6db840f2007-10-16 23:27:23 -0700835 if (thread_group_leader(tsk) &&
836 tsk->signal->notify_count < 0 &&
837 tsk->signal->group_exit_task)
838 wake_up_process(tsk->signal->group_exit_task);
839
Linus Torvalds1da177e2005-04-16 15:20:36 -0700840 write_unlock_irq(&tasklist_lock);
841
Linus Torvalds1da177e2005-04-16 15:20:36 -0700842 /* If the process is dead, release it - nobody will wait for it */
843 if (state == EXIT_DEAD)
844 release_task(tsk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700845}
846
Jeff Dikee18eecb2007-07-15 23:38:48 -0700847#ifdef CONFIG_DEBUG_STACK_USAGE
848static void check_stack_usage(void)
849{
850 static DEFINE_SPINLOCK(low_water_lock);
851 static int lowest_to_date = THREAD_SIZE;
852 unsigned long *n = end_of_stack(current);
853 unsigned long free;
854
855 while (*n == 0)
856 n++;
857 free = (unsigned long)n - (unsigned long)end_of_stack(current);
858
859 if (free >= lowest_to_date)
860 return;
861
862 spin_lock(&low_water_lock);
863 if (free < lowest_to_date) {
864 printk(KERN_WARNING "%s used greatest stack depth: %lu bytes "
865 "left\n",
866 current->comm, free);
867 lowest_to_date = free;
868 }
869 spin_unlock(&low_water_lock);
870}
871#else
872static inline void check_stack_usage(void) {}
873#endif
874
Oleg Nesterov84eb6462007-10-16 23:26:49 -0700875static inline void exit_child_reaper(struct task_struct *tsk)
876{
Sukadev Bhattiprolu88f21d82007-10-18 23:39:50 -0700877 if (likely(tsk->group_leader != task_child_reaper(tsk)))
Oleg Nesterov84eb6462007-10-16 23:26:49 -0700878 return;
879
Sukadev Bhattiprolu3eb07c82007-10-18 23:40:13 -0700880 if (tsk->nsproxy->pid_ns == &init_pid_ns)
881 panic("Attempted to kill init!");
882
883 /*
884 * @tsk is the last thread in the 'cgroup-init' and is exiting.
885 * Terminate all remaining processes in the namespace and reap them
886 * before exiting @tsk.
887 *
888 * Note that @tsk (last thread of cgroup-init) may not necessarily
889 * be the child-reaper (i.e main thread of cgroup-init) of the
890 * namespace i.e the child_reaper may have already exited.
891 *
892 * Even after a child_reaper exits, we let it inherit orphaned children,
893 * because, pid_ns->child_reaper remains valid as long as there is
894 * at least one living sub-thread in the cgroup init.
895
896 * This living sub-thread of the cgroup-init will be notified when
897 * a child inherited by the 'child-reaper' exits (do_notify_parent()
898 * uses __group_send_sig_info()). Further, when reaping child processes,
899 * do_wait() iterates over children of all living sub threads.
900
901 * i.e even though 'child_reaper' thread is listed as the parent of the
902 * orphaned children, any living sub-thread in the cgroup-init can
903 * perform the role of the child_reaper.
904 */
905 zap_pid_ns_processes(tsk->nsproxy->pid_ns);
Oleg Nesterov84eb6462007-10-16 23:26:49 -0700906}
907
Linus Torvalds1da177e2005-04-16 15:20:36 -0700908fastcall NORET_TYPE void do_exit(long code)
909{
910 struct task_struct *tsk = current;
911 int group_dead;
912
913 profile_task_exit(tsk);
914
Jens Axboe22e2c502005-06-27 10:55:12 +0200915 WARN_ON(atomic_read(&tsk->fs_excl));
916
Linus Torvalds1da177e2005-04-16 15:20:36 -0700917 if (unlikely(in_interrupt()))
918 panic("Aiee, killing interrupt handler!");
919 if (unlikely(!tsk->pid))
920 panic("Attempted to kill the idle task!");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700921
922 if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
923 current->ptrace_message = code;
924 ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP);
925 }
926
Alexander Nybergdf164db2005-06-23 00:09:13 -0700927 /*
928 * We're taking recursive faults here in do_exit. Safest is to just
929 * leave this task alone and wait for reboot.
930 */
931 if (unlikely(tsk->flags & PF_EXITING)) {
932 printk(KERN_ALERT
933 "Fixing recursive fault but reboot is needed!\n");
Alexey Kuznetsov778e9a92007-06-08 13:47:00 -0700934 /*
935 * We can do this unlocked here. The futex code uses
936 * this flag just to verify whether the pi state
937 * cleanup has been done or not. In the worst case it
938 * loops once more. We pretend that the cleanup was
939 * done as there is no way to return. Either the
940 * OWNER_DIED bit is set by now or we push the blocked
941 * task into the wait for ever nirwana as well.
942 */
943 tsk->flags |= PF_EXITPIDONE;
Al Viroafc847b2006-02-28 12:51:55 -0500944 if (tsk->io_context)
945 exit_io_context();
Alexander Nybergdf164db2005-06-23 00:09:13 -0700946 set_current_state(TASK_UNINTERRUPTIBLE);
947 schedule();
948 }
949
Oleg Nesterovd2ee7192007-10-16 23:26:47 -0700950 tsk->flags |= PF_EXITING;
Alexey Kuznetsov778e9a92007-06-08 13:47:00 -0700951 /*
952 * tsk->flags are checked in the futex code to protect against
953 * an exiting task cleaning up the robust pi futexes.
954 */
Oleg Nesterovd2ee7192007-10-16 23:26:47 -0700955 smp_mb();
956 spin_unlock_wait(&tsk->pi_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700957
Linus Torvalds1da177e2005-04-16 15:20:36 -0700958 if (unlikely(in_atomic()))
959 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -0700960 current->comm, task_pid_nr(current),
Linus Torvalds1da177e2005-04-16 15:20:36 -0700961 preempt_count());
962
963 acct_update_integrals(tsk);
Hugh Dickins365e9c872005-10-29 18:16:18 -0700964 if (tsk->mm) {
965 update_hiwater_rss(tsk->mm);
966 update_hiwater_vm(tsk->mm);
967 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700968 group_dead = atomic_dec_and_test(&tsk->signal->live);
Andrew Mortonc3068952005-08-04 16:49:32 -0700969 if (group_dead) {
Oleg Nesterov84eb6462007-10-16 23:26:49 -0700970 exit_child_reaper(tsk);
Alexey Kuznetsov778e9a92007-06-08 13:47:00 -0700971 hrtimer_cancel(&tsk->signal->real_timer);
Roland McGrath25f407f2005-10-21 15:03:29 -0700972 exit_itimers(tsk->signal);
Andrew Mortonc3068952005-08-04 16:49:32 -0700973 }
KaiGai Koheif6ec29a2006-06-25 05:49:25 -0700974 acct_collect(code, group_dead);
Alexey Dobriyan42b2dd02007-10-16 23:27:30 -0700975#ifdef CONFIG_FUTEX
Ingo Molnar0771dfe2006-03-27 01:16:22 -0800976 if (unlikely(tsk->robust_list))
977 exit_robust_list(tsk);
Alexey Dobriyan42b2dd02007-10-16 23:27:30 -0700978#ifdef CONFIG_COMPAT
Ingo Molnar34f192c2006-03-27 01:16:24 -0800979 if (unlikely(tsk->compat_robust_list))
980 compat_exit_robust_list(tsk);
981#endif
Alexey Dobriyan42b2dd02007-10-16 23:27:30 -0700982#endif
Miloslav Trmac522ed772007-07-15 23:40:56 -0700983 if (group_dead)
984 tty_audit_exit();
Al Virofa84cb92006-03-29 20:30:19 -0500985 if (unlikely(tsk->audit_context))
986 audit_free(tsk);
Oleg Nesterov115085e2006-12-06 20:36:51 -0800987
Jonathan Limf2ab6d82007-08-30 23:56:23 -0700988 tsk->exit_code = code;
Oleg Nesterov115085e2006-12-06 20:36:51 -0800989 taskstats_exit(tsk, group_dead);
Shailabh Nagarc7572492006-07-14 00:24:40 -0700990
Linus Torvalds1da177e2005-04-16 15:20:36 -0700991 exit_mm(tsk);
992
KaiGai Kohei0e464812006-06-25 05:49:24 -0700993 if (group_dead)
KaiGai Koheif6ec29a2006-06-25 05:49:25 -0700994 acct_process();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700995 exit_sem(tsk);
996 __exit_files(tsk);
997 __exit_fs(tsk);
Jeff Dikee18eecb2007-07-15 23:38:48 -0700998 check_stack_usage();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700999 exit_thread();
Paul Menageb4f48b62007-10-18 23:39:33 -07001000 cgroup_exit(tsk, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001001 exit_keys(tsk);
1002
1003 if (group_dead && tsk->signal->leader)
1004 disassociate_ctty(1);
1005
Al Viroa1261f52005-11-13 16:06:55 -08001006 module_put(task_thread_info(tsk)->exec_domain->module);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001007 if (tsk->binfmt)
1008 module_put(tsk->binfmt->module);
1009
Matt Helsley9f460802005-11-07 00:59:16 -08001010 proc_exit_connector(tsk);
Serge E. Hallyn0f245282007-01-30 15:28:23 -06001011 exit_notify(tsk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001012#ifdef CONFIG_NUMA
1013 mpol_free(tsk->mempolicy);
1014 tsk->mempolicy = NULL;
1015#endif
Alexey Dobriyan42b2dd02007-10-16 23:27:30 -07001016#ifdef CONFIG_FUTEX
Ingo Molnarde5097c2006-01-09 15:59:21 -08001017 /*
Ingo Molnarc87e2832006-06-27 02:54:58 -07001018 * This must happen late, after the PID is not
1019 * hashed anymore:
1020 */
1021 if (unlikely(!list_empty(&tsk->pi_state_list)))
1022 exit_pi_state_list(tsk);
1023 if (unlikely(current->pi_state_cache))
1024 kfree(current->pi_state_cache);
Alexey Dobriyan42b2dd02007-10-16 23:27:30 -07001025#endif
Ingo Molnarc87e2832006-06-27 02:54:58 -07001026 /*
Ingo Molnar9a11b49a2006-07-03 00:24:33 -07001027 * Make sure we are holding no locks:
Ingo Molnarde5097c2006-01-09 15:59:21 -08001028 */
Ingo Molnar9a11b49a2006-07-03 00:24:33 -07001029 debug_check_no_locks_held(tsk);
Alexey Kuznetsov778e9a92007-06-08 13:47:00 -07001030 /*
1031 * We can do this unlocked here. The futex code uses this flag
1032 * just to verify whether the pi state cleanup has been done
1033 * or not. In the worst case it loops once more.
1034 */
1035 tsk->flags |= PF_EXITPIDONE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001036
Al Viroafc847b2006-02-28 12:51:55 -05001037 if (tsk->io_context)
1038 exit_io_context();
1039
Jens Axboeb92ce552006-04-11 13:52:07 +02001040 if (tsk->splice_pipe)
1041 __free_pipe_info(tsk->splice_pipe);
1042
Coywolf Qi Hunt74072512005-10-30 15:02:47 -08001043 preempt_disable();
Oleg Nesterov55a101f2006-09-29 02:01:10 -07001044 /* causes final put_task_struct in finish_task_switch(). */
Oleg Nesterovc394cc92006-09-29 02:01:11 -07001045 tsk->state = TASK_DEAD;
Coywolf Qi Hunt74072512005-10-30 15:02:47 -08001046
Linus Torvalds1da177e2005-04-16 15:20:36 -07001047 schedule();
1048 BUG();
1049 /* Avoid "noreturn function does return". */
Alan Cox54306cf2006-09-29 02:00:42 -07001050 for (;;)
1051 cpu_relax(); /* For when BUG is null */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001052}
1053
Russ Anderson012914d2005-04-23 00:08:00 -07001054EXPORT_SYMBOL_GPL(do_exit);
1055
Linus Torvalds1da177e2005-04-16 15:20:36 -07001056NORET_TYPE void complete_and_exit(struct completion *comp, long code)
1057{
1058 if (comp)
1059 complete(comp);
Oleg Nesterov55a101f2006-09-29 02:01:10 -07001060
Linus Torvalds1da177e2005-04-16 15:20:36 -07001061 do_exit(code);
1062}
1063
1064EXPORT_SYMBOL(complete_and_exit);
1065
1066asmlinkage long sys_exit(int error_code)
1067{
1068 do_exit((error_code&0xff)<<8);
1069}
1070
Linus Torvalds1da177e2005-04-16 15:20:36 -07001071/*
1072 * Take down every thread in the group. This is called by fatal signals
1073 * as well as by sys_exit_group (below).
1074 */
1075NORET_TYPE void
1076do_group_exit(int exit_code)
1077{
1078 BUG_ON(exit_code & 0x80); /* core dumps don't get here */
1079
1080 if (current->signal->flags & SIGNAL_GROUP_EXIT)
1081 exit_code = current->signal->group_exit_code;
1082 else if (!thread_group_empty(current)) {
1083 struct signal_struct *const sig = current->signal;
1084 struct sighand_struct *const sighand = current->sighand;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001085 spin_lock_irq(&sighand->siglock);
Oleg Nesteroved5d2ca2008-02-04 22:27:24 -08001086 if (signal_group_exit(sig))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001087 /* Another thread got here before we took the lock. */
1088 exit_code = sig->group_exit_code;
1089 else {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001090 sig->group_exit_code = exit_code;
Oleg Nesteroved5d2ca2008-02-04 22:27:24 -08001091 sig->flags = SIGNAL_GROUP_EXIT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001092 zap_other_threads(current);
1093 }
1094 spin_unlock_irq(&sighand->siglock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001095 }
1096
1097 do_exit(exit_code);
1098 /* NOTREACHED */
1099}
1100
1101/*
1102 * this kills every thread in the thread group. Note that any externally
1103 * wait4()-ing process will get the correct exit code - even if this
1104 * thread is not the thread group leader.
1105 */
1106asmlinkage void sys_exit_group(int error_code)
1107{
1108 do_group_exit((error_code & 0xff) << 8);
1109}
1110
Ingo Molnar36c8b582006-07-03 00:25:41 -07001111static int eligible_child(pid_t pid, int options, struct task_struct *p)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001112{
Roland McGrath73243282007-05-06 14:50:20 -07001113 int err;
Pavel Emelyanovb4888932007-10-18 23:40:14 -07001114 struct pid_namespace *ns;
Roland McGrath73243282007-05-06 14:50:20 -07001115
Pavel Emelyanovb4888932007-10-18 23:40:14 -07001116 ns = current->nsproxy->pid_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001117 if (pid > 0) {
Pavel Emelyanovb4888932007-10-18 23:40:14 -07001118 if (task_pid_nr_ns(p, ns) != pid)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001119 return 0;
1120 } else if (!pid) {
Pavel Emelyanovb4888932007-10-18 23:40:14 -07001121 if (task_pgrp_nr_ns(p, ns) != task_pgrp_vnr(current))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001122 return 0;
1123 } else if (pid != -1) {
Pavel Emelyanovb4888932007-10-18 23:40:14 -07001124 if (task_pgrp_nr_ns(p, ns) != -pid)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001125 return 0;
1126 }
1127
1128 /*
1129 * Do not consider detached threads that are
1130 * not ptraced:
1131 */
1132 if (p->exit_signal == -1 && !p->ptrace)
1133 return 0;
1134
1135 /* Wait for all children (clone and not) if __WALL is set;
1136 * otherwise, wait for clone children *only* if __WCLONE is
1137 * set; otherwise, wait for non-clone children *only*. (Note:
1138 * A "clone" child here is one that reports to its parent
1139 * using a signal other than SIGCHLD.) */
1140 if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
1141 && !(options & __WALL))
1142 return 0;
1143 /*
1144 * Do not consider thread group leaders that are
1145 * in a non-empty thread group:
1146 */
Oleg Nesterov3b6362b2006-09-02 21:22:16 +04001147 if (delay_group_leader(p))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001148 return 2;
1149
Roland McGrath73243282007-05-06 14:50:20 -07001150 err = security_task_wait(p);
1151 if (err)
1152 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001153
1154 return 1;
1155}
1156
Ingo Molnar36c8b582006-07-03 00:25:41 -07001157static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001158 int why, int status,
1159 struct siginfo __user *infop,
1160 struct rusage __user *rusagep)
1161{
1162 int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
Ingo Molnar36c8b582006-07-03 00:25:41 -07001163
Linus Torvalds1da177e2005-04-16 15:20:36 -07001164 put_task_struct(p);
1165 if (!retval)
1166 retval = put_user(SIGCHLD, &infop->si_signo);
1167 if (!retval)
1168 retval = put_user(0, &infop->si_errno);
1169 if (!retval)
1170 retval = put_user((short)why, &infop->si_code);
1171 if (!retval)
1172 retval = put_user(pid, &infop->si_pid);
1173 if (!retval)
1174 retval = put_user(uid, &infop->si_uid);
1175 if (!retval)
1176 retval = put_user(status, &infop->si_status);
1177 if (!retval)
1178 retval = pid;
1179 return retval;
1180}
1181
1182/*
1183 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
1184 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1185 * the lock and this task is uninteresting. If we return nonzero, we have
1186 * released the lock and the system call should return.
1187 */
Ingo Molnar36c8b582006-07-03 00:25:41 -07001188static int wait_task_zombie(struct task_struct *p, int noreap,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001189 struct siginfo __user *infop,
1190 int __user *stat_addr, struct rusage __user *ru)
1191{
1192 unsigned long state;
Oleg Nesterov2f4e6e22007-10-16 23:26:58 -07001193 int retval, status, traced;
Pavel Emelyanovb4888932007-10-18 23:40:14 -07001194 struct pid_namespace *ns;
1195
1196 ns = current->nsproxy->pid_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001197
1198 if (unlikely(noreap)) {
Pavel Emelyanovb4888932007-10-18 23:40:14 -07001199 pid_t pid = task_pid_nr_ns(p, ns);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001200 uid_t uid = p->uid;
1201 int exit_code = p->exit_code;
1202 int why, status;
1203
1204 if (unlikely(p->exit_state != EXIT_ZOMBIE))
1205 return 0;
1206 if (unlikely(p->exit_signal == -1 && p->ptrace == 0))
1207 return 0;
1208 get_task_struct(p);
1209 read_unlock(&tasklist_lock);
1210 if ((exit_code & 0x7f) == 0) {
1211 why = CLD_EXITED;
1212 status = exit_code >> 8;
1213 } else {
1214 why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1215 status = exit_code & 0x7f;
1216 }
1217 return wait_noreap_copyout(p, pid, uid, why,
1218 status, infop, ru);
1219 }
1220
1221 /*
1222 * Try to move the task's state to DEAD
1223 * only one thread is allowed to do this:
1224 */
1225 state = xchg(&p->exit_state, EXIT_DEAD);
1226 if (state != EXIT_ZOMBIE) {
1227 BUG_ON(state != EXIT_DEAD);
1228 return 0;
1229 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001230
Oleg Nesterov2f4e6e22007-10-16 23:26:58 -07001231 /* traced means p->ptrace, but not vice versa */
1232 traced = (p->real_parent != p->parent);
1233
1234 if (likely(!traced)) {
Jesper Juhl3795e162006-01-09 20:54:39 -08001235 struct signal_struct *psig;
1236 struct signal_struct *sig;
1237
Linus Torvalds1da177e2005-04-16 15:20:36 -07001238 /*
1239 * The resource counters for the group leader are in its
1240 * own task_struct. Those for dead threads in the group
1241 * are in its signal_struct, as are those for the child
1242 * processes it has previously reaped. All these
1243 * accumulate in the parent's signal_struct c* fields.
1244 *
1245 * We don't bother to take a lock here to protect these
1246 * p->signal fields, because they are only touched by
1247 * __exit_signal, which runs with tasklist_lock
1248 * write-locked anyway, and so is excluded here. We do
1249 * need to protect the access to p->parent->signal fields,
1250 * as other threads in the parent group can be right
1251 * here reaping other children at the same time.
1252 */
1253 spin_lock_irq(&p->parent->sighand->siglock);
Jesper Juhl3795e162006-01-09 20:54:39 -08001254 psig = p->parent->signal;
1255 sig = p->signal;
1256 psig->cutime =
1257 cputime_add(psig->cutime,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001258 cputime_add(p->utime,
Jesper Juhl3795e162006-01-09 20:54:39 -08001259 cputime_add(sig->utime,
1260 sig->cutime)));
1261 psig->cstime =
1262 cputime_add(psig->cstime,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001263 cputime_add(p->stime,
Jesper Juhl3795e162006-01-09 20:54:39 -08001264 cputime_add(sig->stime,
1265 sig->cstime)));
Laurent Vivier9ac52312007-10-15 17:00:19 +02001266 psig->cgtime =
1267 cputime_add(psig->cgtime,
1268 cputime_add(p->gtime,
1269 cputime_add(sig->gtime,
1270 sig->cgtime)));
Jesper Juhl3795e162006-01-09 20:54:39 -08001271 psig->cmin_flt +=
1272 p->min_flt + sig->min_flt + sig->cmin_flt;
1273 psig->cmaj_flt +=
1274 p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1275 psig->cnvcsw +=
1276 p->nvcsw + sig->nvcsw + sig->cnvcsw;
1277 psig->cnivcsw +=
1278 p->nivcsw + sig->nivcsw + sig->cnivcsw;
Eric Dumazet6eaeeab2007-05-10 22:22:37 -07001279 psig->cinblock +=
1280 task_io_get_inblock(p) +
1281 sig->inblock + sig->cinblock;
1282 psig->coublock +=
1283 task_io_get_oublock(p) +
1284 sig->oublock + sig->coublock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001285 spin_unlock_irq(&p->parent->sighand->siglock);
1286 }
1287
1288 /*
1289 * Now we are sure this task is interesting, and no other
1290 * thread can reap it because we set its state to EXIT_DEAD.
1291 */
1292 read_unlock(&tasklist_lock);
1293
1294 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1295 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1296 ? p->signal->group_exit_code : p->exit_code;
1297 if (!retval && stat_addr)
1298 retval = put_user(status, stat_addr);
1299 if (!retval && infop)
1300 retval = put_user(SIGCHLD, &infop->si_signo);
1301 if (!retval && infop)
1302 retval = put_user(0, &infop->si_errno);
1303 if (!retval && infop) {
1304 int why;
1305
1306 if ((status & 0x7f) == 0) {
1307 why = CLD_EXITED;
1308 status >>= 8;
1309 } else {
1310 why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1311 status &= 0x7f;
1312 }
1313 retval = put_user((short)why, &infop->si_code);
1314 if (!retval)
1315 retval = put_user(status, &infop->si_status);
1316 }
1317 if (!retval && infop)
Pavel Emelyanovb4888932007-10-18 23:40:14 -07001318 retval = put_user(task_pid_nr_ns(p, ns), &infop->si_pid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001319 if (!retval && infop)
1320 retval = put_user(p->uid, &infop->si_uid);
Oleg Nesterov2f4e6e22007-10-16 23:26:58 -07001321 if (!retval)
Pavel Emelyanovb4888932007-10-18 23:40:14 -07001322 retval = task_pid_nr_ns(p, ns);
Oleg Nesterov2f4e6e22007-10-16 23:26:58 -07001323
1324 if (traced) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001325 write_lock_irq(&tasklist_lock);
Oleg Nesterov2f4e6e22007-10-16 23:26:58 -07001326 /* We dropped tasklist, ptracer could die and untrace */
1327 ptrace_unlink(p);
1328 /*
1329 * If this is not a detached task, notify the parent.
1330 * If it's still not detached after that, don't release
1331 * it now.
1332 */
1333 if (p->exit_signal != -1) {
1334 do_notify_parent(p, p->exit_signal);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001335 if (p->exit_signal != -1) {
Oleg Nesterov2f4e6e22007-10-16 23:26:58 -07001336 p->exit_state = EXIT_ZOMBIE;
1337 p = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001338 }
1339 }
1340 write_unlock_irq(&tasklist_lock);
1341 }
1342 if (p != NULL)
1343 release_task(p);
Oleg Nesterov2f4e6e22007-10-16 23:26:58 -07001344
Linus Torvalds1da177e2005-04-16 15:20:36 -07001345 return retval;
1346}
1347
1348/*
1349 * Handle sys_wait4 work for one task in state TASK_STOPPED. We hold
1350 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1351 * the lock and this task is uninteresting. If we return nonzero, we have
1352 * released the lock and the system call should return.
1353 */
Ingo Molnar36c8b582006-07-03 00:25:41 -07001354static int wait_task_stopped(struct task_struct *p, int delayed_group_leader,
1355 int noreap, struct siginfo __user *infop,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001356 int __user *stat_addr, struct rusage __user *ru)
1357{
1358 int retval, exit_code;
Oleg Nesterovc8950782007-11-28 16:21:24 -08001359 pid_t pid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001360
1361 if (!p->exit_code)
1362 return 0;
1363 if (delayed_group_leader && !(p->ptrace & PT_PTRACED) &&
Oleg Nesterov715015e2007-10-16 23:27:00 -07001364 p->signal->group_stop_count > 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001365 /*
1366 * A group stop is in progress and this is the group leader.
1367 * We won't report until all threads have stopped.
1368 */
1369 return 0;
1370
1371 /*
1372 * Now we are pretty sure this task is interesting.
1373 * Make sure it doesn't get reaped out from under us while we
1374 * give up the lock and then examine it below. We don't want to
1375 * keep holding onto the tasklist_lock while we call getrusage and
1376 * possibly take page faults for user memory.
1377 */
Oleg Nesterovc8950782007-11-28 16:21:24 -08001378 pid = task_pid_nr_ns(p, current->nsproxy->pid_ns);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001379 get_task_struct(p);
1380 read_unlock(&tasklist_lock);
1381
1382 if (unlikely(noreap)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001383 uid_t uid = p->uid;
1384 int why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
1385
1386 exit_code = p->exit_code;
Roland McGratha3474222007-11-13 22:11:50 -08001387 if (unlikely(!exit_code) || unlikely(p->exit_state))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001388 goto bail_ref;
1389 return wait_noreap_copyout(p, pid, uid,
Scott James Remnante6ceb322007-11-28 16:22:07 -08001390 why, exit_code,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001391 infop, ru);
1392 }
1393
1394 write_lock_irq(&tasklist_lock);
1395
1396 /*
1397 * This uses xchg to be atomic with the thread resuming and setting
1398 * it. It must also be done with the write lock held to prevent a
1399 * race with the EXIT_ZOMBIE case.
1400 */
1401 exit_code = xchg(&p->exit_code, 0);
1402 if (unlikely(p->exit_state)) {
1403 /*
1404 * The task resumed and then died. Let the next iteration
1405 * catch it in EXIT_ZOMBIE. Note that exit_code might
1406 * already be zero here if it resumed and did _exit(0).
1407 * The task itself is dead and won't touch exit_code again;
1408 * other processors in this function are locked out.
1409 */
1410 p->exit_code = exit_code;
1411 exit_code = 0;
1412 }
1413 if (unlikely(exit_code == 0)) {
1414 /*
1415 * Another thread in this function got to it first, or it
1416 * resumed, or it resumed and then died.
1417 */
1418 write_unlock_irq(&tasklist_lock);
1419bail_ref:
1420 put_task_struct(p);
1421 /*
1422 * We are returning to the wait loop without having successfully
1423 * removed the process and having released the lock. We cannot
1424 * continue, since the "p" task pointer is potentially stale.
1425 *
1426 * Return -EAGAIN, and do_wait() will restart the loop from the
1427 * beginning. Do _not_ re-acquire the lock.
1428 */
1429 return -EAGAIN;
1430 }
1431
1432 /* move to end of parent's list to avoid starvation */
1433 remove_parent(p);
Oleg Nesterov8fafabd2006-03-28 16:11:05 -08001434 add_parent(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001435
1436 write_unlock_irq(&tasklist_lock);
1437
1438 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1439 if (!retval && stat_addr)
1440 retval = put_user((exit_code << 8) | 0x7f, stat_addr);
1441 if (!retval && infop)
1442 retval = put_user(SIGCHLD, &infop->si_signo);
1443 if (!retval && infop)
1444 retval = put_user(0, &infop->si_errno);
1445 if (!retval && infop)
1446 retval = put_user((short)((p->ptrace & PT_PTRACED)
1447 ? CLD_TRAPPED : CLD_STOPPED),
1448 &infop->si_code);
1449 if (!retval && infop)
1450 retval = put_user(exit_code, &infop->si_status);
1451 if (!retval && infop)
Oleg Nesterovc8950782007-11-28 16:21:24 -08001452 retval = put_user(pid, &infop->si_pid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001453 if (!retval && infop)
1454 retval = put_user(p->uid, &infop->si_uid);
1455 if (!retval)
Oleg Nesterovc8950782007-11-28 16:21:24 -08001456 retval = pid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001457 put_task_struct(p);
1458
1459 BUG_ON(!retval);
1460 return retval;
1461}
1462
1463/*
1464 * Handle do_wait work for one task in a live, non-stopped state.
1465 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1466 * the lock and this task is uninteresting. If we return nonzero, we have
1467 * released the lock and the system call should return.
1468 */
Ingo Molnar36c8b582006-07-03 00:25:41 -07001469static int wait_task_continued(struct task_struct *p, int noreap,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001470 struct siginfo __user *infop,
1471 int __user *stat_addr, struct rusage __user *ru)
1472{
1473 int retval;
1474 pid_t pid;
1475 uid_t uid;
Pavel Emelyanovb4888932007-10-18 23:40:14 -07001476 struct pid_namespace *ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001477
Linus Torvalds1da177e2005-04-16 15:20:36 -07001478 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1479 return 0;
1480
1481 spin_lock_irq(&p->sighand->siglock);
1482 /* Re-check with the lock held. */
1483 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1484 spin_unlock_irq(&p->sighand->siglock);
1485 return 0;
1486 }
1487 if (!noreap)
1488 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1489 spin_unlock_irq(&p->sighand->siglock);
1490
Pavel Emelyanovb4888932007-10-18 23:40:14 -07001491 ns = current->nsproxy->pid_ns;
1492 pid = task_pid_nr_ns(p, ns);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001493 uid = p->uid;
1494 get_task_struct(p);
1495 read_unlock(&tasklist_lock);
1496
1497 if (!infop) {
1498 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1499 put_task_struct(p);
1500 if (!retval && stat_addr)
1501 retval = put_user(0xffff, stat_addr);
1502 if (!retval)
Pavel Emelyanovb4888932007-10-18 23:40:14 -07001503 retval = task_pid_nr_ns(p, ns);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001504 } else {
1505 retval = wait_noreap_copyout(p, pid, uid,
1506 CLD_CONTINUED, SIGCONT,
1507 infop, ru);
1508 BUG_ON(retval == 0);
1509 }
1510
1511 return retval;
1512}
1513
1514
1515static inline int my_ptrace_child(struct task_struct *p)
1516{
1517 if (!(p->ptrace & PT_PTRACED))
1518 return 0;
1519 if (!(p->ptrace & PT_ATTACHED))
1520 return 1;
1521 /*
1522 * This child was PTRACE_ATTACH'd. We should be seeing it only if
1523 * we are the attacher. If we are the real parent, this is a race
1524 * inside ptrace_attach. It is waiting for the tasklist_lock,
1525 * which we have to switch the parent links, but has already set
1526 * the flags in p->ptrace.
1527 */
1528 return (p->parent != p->real_parent);
1529}
1530
1531static long do_wait(pid_t pid, int options, struct siginfo __user *infop,
1532 int __user *stat_addr, struct rusage __user *ru)
1533{
1534 DECLARE_WAITQUEUE(wait, current);
1535 struct task_struct *tsk;
1536 int flag, retval;
Roland McGrath73243282007-05-06 14:50:20 -07001537 int allowed, denied;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001538
1539 add_wait_queue(&current->signal->wait_chldexit,&wait);
1540repeat:
1541 /*
1542 * We will set this flag if we see any child that might later
1543 * match our criteria, even if we are not able to reap it yet.
1544 */
1545 flag = 0;
Roland McGrath73243282007-05-06 14:50:20 -07001546 allowed = denied = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001547 current->state = TASK_INTERRUPTIBLE;
1548 read_lock(&tasklist_lock);
1549 tsk = current;
1550 do {
1551 struct task_struct *p;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001552 int ret;
1553
Matthias Kaehlcke03ff1792007-10-18 23:39:57 -07001554 list_for_each_entry(p, &tsk->children, sibling) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001555 ret = eligible_child(pid, options, p);
1556 if (!ret)
1557 continue;
1558
Roland McGrath73243282007-05-06 14:50:20 -07001559 if (unlikely(ret < 0)) {
1560 denied = ret;
1561 continue;
1562 }
1563 allowed = 1;
1564
Matthew Wilcox338077e2007-12-06 11:09:35 -05001565 if (task_is_stopped_or_traced(p)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001566 /*
1567 * It's stopped now, so it might later
1568 * continue, exit, or stop again.
Matthew Wilcox338077e2007-12-06 11:09:35 -05001569 *
1570 * When we hit the race with PTRACE_ATTACH, we
1571 * will not report this child. But the race
1572 * means it has not yet been moved to our
1573 * ptrace_children list, so we need to set the
1574 * flag here to avoid a spurious ECHILD when
1575 * the race happens with the only child.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001576 */
1577 flag = 1;
Matthew Wilcox338077e2007-12-06 11:09:35 -05001578
1579 if (!my_ptrace_child(p)) {
1580 if (task_is_traced(p))
1581 continue;
1582 if (!(options & WUNTRACED))
1583 continue;
1584 }
1585
Linus Torvalds1da177e2005-04-16 15:20:36 -07001586 retval = wait_task_stopped(p, ret == 2,
Matthew Wilcox338077e2007-12-06 11:09:35 -05001587 (options & WNOWAIT), infop,
1588 stat_addr, ru);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001589 if (retval == -EAGAIN)
1590 goto repeat;
1591 if (retval != 0) /* He released the lock. */
1592 goto end;
Matthew Wilcox338077e2007-12-06 11:09:35 -05001593 } else if (p->exit_state == EXIT_DEAD) {
1594 continue;
1595 } else if (p->exit_state == EXIT_ZOMBIE) {
1596 /*
1597 * Eligible but we cannot release it yet:
1598 */
1599 if (ret == 2)
1600 goto check_continued;
1601 if (!likely(options & WEXITED))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001602 continue;
Matthew Wilcox338077e2007-12-06 11:09:35 -05001603 retval = wait_task_zombie(p,
1604 (options & WNOWAIT), infop,
1605 stat_addr, ru);
1606 /* He released the lock. */
1607 if (retval != 0)
1608 goto end;
1609 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001610check_continued:
1611 /*
1612 * It's running now, so it might later
1613 * exit, stop, or stop and then continue.
1614 */
1615 flag = 1;
1616 if (!unlikely(options & WCONTINUED))
1617 continue;
Matthew Wilcox338077e2007-12-06 11:09:35 -05001618 retval = wait_task_continued(p,
1619 (options & WNOWAIT), infop,
1620 stat_addr, ru);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001621 if (retval != 0) /* He released the lock. */
1622 goto end;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001623 }
1624 }
1625 if (!flag) {
Matthias Kaehlcke03ff1792007-10-18 23:39:57 -07001626 list_for_each_entry(p, &tsk->ptrace_children,
1627 ptrace_list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001628 if (!eligible_child(pid, options, p))
1629 continue;
1630 flag = 1;
1631 break;
1632 }
1633 }
1634 if (options & __WNOTHREAD)
1635 break;
1636 tsk = next_thread(tsk);
Eric Sesterhenn125e1872006-06-23 02:06:06 -07001637 BUG_ON(tsk->signal != current->signal);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001638 } while (tsk != current);
1639
1640 read_unlock(&tasklist_lock);
1641 if (flag) {
1642 retval = 0;
1643 if (options & WNOHANG)
1644 goto end;
1645 retval = -ERESTARTSYS;
1646 if (signal_pending(current))
1647 goto end;
1648 schedule();
1649 goto repeat;
1650 }
1651 retval = -ECHILD;
Roland McGrath73243282007-05-06 14:50:20 -07001652 if (unlikely(denied) && !allowed)
1653 retval = denied;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001654end:
1655 current->state = TASK_RUNNING;
1656 remove_wait_queue(&current->signal->wait_chldexit,&wait);
1657 if (infop) {
1658 if (retval > 0)
1659 retval = 0;
1660 else {
1661 /*
1662 * For a WNOHANG return, clear out all the fields
1663 * we would set so the user can easily tell the
1664 * difference.
1665 */
1666 if (!retval)
1667 retval = put_user(0, &infop->si_signo);
1668 if (!retval)
1669 retval = put_user(0, &infop->si_errno);
1670 if (!retval)
1671 retval = put_user(0, &infop->si_code);
1672 if (!retval)
1673 retval = put_user(0, &infop->si_pid);
1674 if (!retval)
1675 retval = put_user(0, &infop->si_uid);
1676 if (!retval)
1677 retval = put_user(0, &infop->si_status);
1678 }
1679 }
1680 return retval;
1681}
1682
1683asmlinkage long sys_waitid(int which, pid_t pid,
1684 struct siginfo __user *infop, int options,
1685 struct rusage __user *ru)
1686{
1687 long ret;
1688
1689 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1690 return -EINVAL;
1691 if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1692 return -EINVAL;
1693
1694 switch (which) {
1695 case P_ALL:
1696 pid = -1;
1697 break;
1698 case P_PID:
1699 if (pid <= 0)
1700 return -EINVAL;
1701 break;
1702 case P_PGID:
1703 if (pid <= 0)
1704 return -EINVAL;
1705 pid = -pid;
1706 break;
1707 default:
1708 return -EINVAL;
1709 }
1710
1711 ret = do_wait(pid, options, infop, NULL, ru);
1712
1713 /* avoid REGPARM breakage on x86: */
1714 prevent_tail_call(ret);
1715 return ret;
1716}
1717
1718asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr,
1719 int options, struct rusage __user *ru)
1720{
1721 long ret;
1722
1723 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1724 __WNOTHREAD|__WCLONE|__WALL))
1725 return -EINVAL;
1726 ret = do_wait(pid, options | WEXITED, NULL, stat_addr, ru);
1727
1728 /* avoid REGPARM breakage on x86: */
1729 prevent_tail_call(ret);
1730 return ret;
1731}
1732
1733#ifdef __ARCH_WANT_SYS_WAITPID
1734
1735/*
1736 * sys_waitpid() remains for compatibility. waitpid() should be
1737 * implemented by calling sys_wait4() from libc.a.
1738 */
1739asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options)
1740{
1741 return sys_wait4(pid, stat_addr, options, NULL);
1742}
1743
1744#endif