Commit | Line | Data |
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457c8996 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
1da177e4 LT |
2 | /* |
3 | * linux/kernel/exit.c | |
4 | * | |
5 | * Copyright (C) 1991, 1992 Linus Torvalds | |
6 | */ | |
7 | ||
1da177e4 LT |
8 | #include <linux/mm.h> |
9 | #include <linux/slab.h> | |
4eb5aaa3 | 10 | #include <linux/sched/autogroup.h> |
6e84f315 | 11 | #include <linux/sched/mm.h> |
03441a34 | 12 | #include <linux/sched/stat.h> |
29930025 | 13 | #include <linux/sched/task.h> |
68db0cf1 | 14 | #include <linux/sched/task_stack.h> |
32ef5517 | 15 | #include <linux/sched/cputime.h> |
1da177e4 | 16 | #include <linux/interrupt.h> |
1da177e4 | 17 | #include <linux/module.h> |
c59ede7b | 18 | #include <linux/capability.h> |
1da177e4 LT |
19 | #include <linux/completion.h> |
20 | #include <linux/personality.h> | |
21 | #include <linux/tty.h> | |
da9cbc87 | 22 | #include <linux/iocontext.h> |
1da177e4 | 23 | #include <linux/key.h> |
1da177e4 LT |
24 | #include <linux/cpu.h> |
25 | #include <linux/acct.h> | |
8f0ab514 | 26 | #include <linux/tsacct_kern.h> |
1da177e4 | 27 | #include <linux/file.h> |
9f3acc31 | 28 | #include <linux/fdtable.h> |
80d26af8 | 29 | #include <linux/freezer.h> |
1da177e4 | 30 | #include <linux/binfmts.h> |
ab516013 | 31 | #include <linux/nsproxy.h> |
84d73786 | 32 | #include <linux/pid_namespace.h> |
1da177e4 LT |
33 | #include <linux/ptrace.h> |
34 | #include <linux/profile.h> | |
35 | #include <linux/mount.h> | |
36 | #include <linux/proc_fs.h> | |
49d769d5 | 37 | #include <linux/kthread.h> |
1da177e4 | 38 | #include <linux/mempolicy.h> |
c757249a | 39 | #include <linux/taskstats_kern.h> |
ca74e92b | 40 | #include <linux/delayacct.h> |
b4f48b63 | 41 | #include <linux/cgroup.h> |
1da177e4 | 42 | #include <linux/syscalls.h> |
7ed20e1a | 43 | #include <linux/signal.h> |
6a14c5c9 | 44 | #include <linux/posix-timers.h> |
9f46080c | 45 | #include <linux/cn_proc.h> |
de5097c2 | 46 | #include <linux/mutex.h> |
0771dfef | 47 | #include <linux/futex.h> |
b92ce558 | 48 | #include <linux/pipe_fs_i.h> |
fa84cb93 | 49 | #include <linux/audit.h> /* for audit_free() */ |
83cc5ed3 | 50 | #include <linux/resource.h> |
6eaeeaba | 51 | #include <linux/task_io_accounting_ops.h> |
355f841a EB |
52 | #include <linux/blkdev.h> |
53 | #include <linux/task_work.h> | |
5ad4e53b | 54 | #include <linux/fs_struct.h> |
d84f4f99 | 55 | #include <linux/init_task.h> |
cdd6c482 | 56 | #include <linux/perf_event.h> |
ad8d75ff | 57 | #include <trace/events/sched.h> |
24f1e32c | 58 | #include <linux/hw_breakpoint.h> |
3d5992d2 | 59 | #include <linux/oom.h> |
54848d73 | 60 | #include <linux/writeback.h> |
40401530 | 61 | #include <linux/shm.h> |
5c9a8750 | 62 | #include <linux/kcov.h> |
50b5e49c | 63 | #include <linux/kmsan.h> |
53d3eaa3 | 64 | #include <linux/random.h> |
8f95c90c | 65 | #include <linux/rcuwait.h> |
7e95a225 | 66 | #include <linux/compat.h> |
b1b6b5a3 | 67 | #include <linux/io_uring.h> |
670721c7 | 68 | #include <linux/kprobes.h> |
54ecbe6f | 69 | #include <linux/rethook.h> |
9db89b41 | 70 | #include <linux/sysfs.h> |
fd593511 | 71 | #include <linux/user_events.h> |
7c0f6ba6 | 72 | #include <linux/uaccess.h> |
6dfeff09 MWO |
73 | |
74 | #include <uapi/linux/wait.h> | |
75 | ||
1da177e4 | 76 | #include <asm/unistd.h> |
1da177e4 LT |
77 | #include <asm/mmu_context.h> |
78 | ||
2e521a20 JA |
79 | #include "exit.h" |
80 | ||
d4ccd54d JH |
81 | /* |
82 | * The default value should be high enough to not crash a system that randomly | |
83 | * crashes its kernel from time to time, but low enough to at least not permit | |
84 | * overflowing 32-bit refcounts or the ldsem writer count. | |
85 | */ | |
86 | static unsigned int oops_limit = 10000; | |
87 | ||
88 | #ifdef CONFIG_SYSCTL | |
89 | static struct ctl_table kern_exit_table[] = { | |
90 | { | |
91 | .procname = "oops_limit", | |
92 | .data = &oops_limit, | |
93 | .maxlen = sizeof(oops_limit), | |
94 | .mode = 0644, | |
95 | .proc_handler = proc_douintvec, | |
96 | }, | |
d4ccd54d JH |
97 | }; |
98 | ||
99 | static __init int kernel_exit_sysctls_init(void) | |
100 | { | |
101 | register_sysctl_init("kernel", kern_exit_table); | |
102 | return 0; | |
103 | } | |
104 | late_initcall(kernel_exit_sysctls_init); | |
105 | #endif | |
106 | ||
9db89b41 KC |
107 | static atomic_t oops_count = ATOMIC_INIT(0); |
108 | ||
109 | #ifdef CONFIG_SYSFS | |
110 | static ssize_t oops_count_show(struct kobject *kobj, struct kobj_attribute *attr, | |
111 | char *page) | |
112 | { | |
113 | return sysfs_emit(page, "%d\n", atomic_read(&oops_count)); | |
114 | } | |
115 | ||
116 | static struct kobj_attribute oops_count_attr = __ATTR_RO(oops_count); | |
117 | ||
118 | static __init int kernel_exit_sysfs_init(void) | |
119 | { | |
120 | sysfs_add_file_to_group(kernel_kobj, &oops_count_attr.attr, NULL); | |
121 | return 0; | |
122 | } | |
123 | late_initcall(kernel_exit_sysfs_init); | |
124 | #endif | |
125 | ||
d40e48e0 | 126 | static void __unhash_process(struct task_struct *p, bool group_dead) |
1da177e4 LT |
127 | { |
128 | nr_threads--; | |
50d75f8d | 129 | detach_pid(p, PIDTYPE_PID); |
d40e48e0 | 130 | if (group_dead) { |
6883f81a | 131 | detach_pid(p, PIDTYPE_TGID); |
1da177e4 LT |
132 | detach_pid(p, PIDTYPE_PGID); |
133 | detach_pid(p, PIDTYPE_SID); | |
c97d9893 | 134 | |
5e85d4ab | 135 | list_del_rcu(&p->tasks); |
9cd80bbb | 136 | list_del_init(&p->sibling); |
909ea964 | 137 | __this_cpu_dec(process_counts); |
1da177e4 | 138 | } |
0c740d0a | 139 | list_del_rcu(&p->thread_node); |
1da177e4 LT |
140 | } |
141 | ||
6a14c5c9 ON |
142 | /* |
143 | * This function expects the tasklist_lock write-locked. | |
144 | */ | |
145 | static void __exit_signal(struct task_struct *tsk) | |
146 | { | |
147 | struct signal_struct *sig = tsk->signal; | |
d40e48e0 | 148 | bool group_dead = thread_group_leader(tsk); |
6a14c5c9 | 149 | struct sighand_struct *sighand; |
3f649ab7 | 150 | struct tty_struct *tty; |
5613fda9 | 151 | u64 utime, stime; |
6a14c5c9 | 152 | |
d11c563d | 153 | sighand = rcu_dereference_check(tsk->sighand, |
db1466b3 | 154 | lockdep_tasklist_lock_is_held()); |
6a14c5c9 ON |
155 | spin_lock(&sighand->siglock); |
156 | ||
baa73d9e | 157 | #ifdef CONFIG_POSIX_TIMERS |
6a14c5c9 | 158 | posix_cpu_timers_exit(tsk); |
b95e31c0 | 159 | if (group_dead) |
6a14c5c9 | 160 | posix_cpu_timers_exit_group(tsk); |
baa73d9e | 161 | #endif |
e0a70217 | 162 | |
baa73d9e NP |
163 | if (group_dead) { |
164 | tty = sig->tty; | |
165 | sig->tty = NULL; | |
166 | } else { | |
6a14c5c9 ON |
167 | /* |
168 | * If there is any task waiting for the group exit | |
169 | * then notify it: | |
170 | */ | |
d344193a | 171 | if (sig->notify_count > 0 && !--sig->notify_count) |
60700e38 | 172 | wake_up_process(sig->group_exec_task); |
6db840fa | 173 | |
6a14c5c9 ON |
174 | if (tsk == sig->curr_target) |
175 | sig->curr_target = next_thread(tsk); | |
6a14c5c9 ON |
176 | } |
177 | ||
53d3eaa3 NP |
178 | add_device_randomness((const void*) &tsk->se.sum_exec_runtime, |
179 | sizeof(unsigned long long)); | |
180 | ||
90ed9cbe | 181 | /* |
26e75b5c ON |
182 | * Accumulate here the counters for all threads as they die. We could |
183 | * skip the group leader because it is the last user of signal_struct, | |
184 | * but we want to avoid the race with thread_group_cputime() which can | |
185 | * see the empty ->thread_head list. | |
90ed9cbe RR |
186 | */ |
187 | task_cputime(tsk, &utime, &stime); | |
e78c3496 | 188 | write_seqlock(&sig->stats_lock); |
90ed9cbe RR |
189 | sig->utime += utime; |
190 | sig->stime += stime; | |
191 | sig->gtime += task_gtime(tsk); | |
192 | sig->min_flt += tsk->min_flt; | |
193 | sig->maj_flt += tsk->maj_flt; | |
194 | sig->nvcsw += tsk->nvcsw; | |
195 | sig->nivcsw += tsk->nivcsw; | |
196 | sig->inblock += task_io_get_inblock(tsk); | |
197 | sig->oublock += task_io_get_oublock(tsk); | |
198 | task_io_accounting_add(&sig->ioac, &tsk->ioac); | |
199 | sig->sum_sched_runtime += tsk->se.sum_exec_runtime; | |
b3ac022c | 200 | sig->nr_threads--; |
d40e48e0 | 201 | __unhash_process(tsk, group_dead); |
e78c3496 | 202 | write_sequnlock(&sig->stats_lock); |
5876700c | 203 | |
da7978b0 ON |
204 | /* |
205 | * Do this under ->siglock, we can race with another thread | |
206 | * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals. | |
207 | */ | |
208 | flush_sigqueue(&tsk->pending); | |
a7e5328a | 209 | tsk->sighand = NULL; |
6a14c5c9 | 210 | spin_unlock(&sighand->siglock); |
6a14c5c9 | 211 | |
a7e5328a | 212 | __cleanup_sighand(sighand); |
a0be55de | 213 | clear_tsk_thread_flag(tsk, TIF_SIGPENDING); |
d40e48e0 | 214 | if (group_dead) { |
6a14c5c9 | 215 | flush_sigqueue(&sig->shared_pending); |
4ada856f | 216 | tty_kref_put(tty); |
6a14c5c9 ON |
217 | } |
218 | } | |
219 | ||
8c7904a0 EB |
220 | static void delayed_put_task_struct(struct rcu_head *rhp) |
221 | { | |
0a16b607 MD |
222 | struct task_struct *tsk = container_of(rhp, struct task_struct, rcu); |
223 | ||
670721c7 | 224 | kprobe_flush_task(tsk); |
54ecbe6f | 225 | rethook_flush_task(tsk); |
4e231c79 | 226 | perf_event_delayed_put(tsk); |
0a16b607 MD |
227 | trace_sched_process_free(tsk); |
228 | put_task_struct(tsk); | |
8c7904a0 EB |
229 | } |
230 | ||
3fbd7ee2 EB |
231 | void put_task_struct_rcu_user(struct task_struct *task) |
232 | { | |
233 | if (refcount_dec_and_test(&task->rcu_users)) | |
234 | call_rcu(&task->rcu, delayed_put_task_struct); | |
235 | } | |
f470021a | 236 | |
2be9880d KW |
237 | void __weak release_thread(struct task_struct *dead_task) |
238 | { | |
239 | } | |
240 | ||
a0be55de | 241 | void release_task(struct task_struct *p) |
1da177e4 | 242 | { |
36c8b586 | 243 | struct task_struct *leader; |
7bc3e6e5 | 244 | struct pid *thread_pid; |
1da177e4 | 245 | int zap_leader; |
1f09f974 | 246 | repeat: |
c69e8d9c | 247 | /* don't need to get the RCU readlock here - the process is dead and |
d11c563d PM |
248 | * can't be modifying its own credentials. But shut RCU-lockdep up */ |
249 | rcu_read_lock(); | |
21d1c5e3 | 250 | dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1); |
d11c563d | 251 | rcu_read_unlock(); |
c69e8d9c | 252 | |
6b115bf5 | 253 | cgroup_release(p); |
0203026b | 254 | |
1da177e4 | 255 | write_lock_irq(&tasklist_lock); |
a288eecc | 256 | ptrace_release_task(p); |
7bc3e6e5 | 257 | thread_pid = get_pid(p->thread_pid); |
1da177e4 | 258 | __exit_signal(p); |
35f5cad8 | 259 | |
1da177e4 LT |
260 | /* |
261 | * If we are the last non-leader member of the thread | |
262 | * group, and the leader is zombie, then notify the | |
263 | * group leader's parent process. (if it wants notification.) | |
264 | */ | |
265 | zap_leader = 0; | |
266 | leader = p->group_leader; | |
a0be55de IA |
267 | if (leader != p && thread_group_empty(leader) |
268 | && leader->exit_state == EXIT_ZOMBIE) { | |
1da177e4 LT |
269 | /* |
270 | * If we were the last child thread and the leader has | |
271 | * exited already, and the leader's parent ignores SIGCHLD, | |
272 | * then we are the one who should release the leader. | |
dae33574 | 273 | */ |
86773473 | 274 | zap_leader = do_notify_parent(leader, leader->exit_signal); |
dae33574 RM |
275 | if (zap_leader) |
276 | leader->exit_state = EXIT_DEAD; | |
1da177e4 LT |
277 | } |
278 | ||
1da177e4 | 279 | write_unlock_irq(&tasklist_lock); |
7bc3e6e5 | 280 | proc_flush_pid(thread_pid); |
6ade99ec | 281 | put_pid(thread_pid); |
1da177e4 | 282 | release_thread(p); |
3fbd7ee2 | 283 | put_task_struct_rcu_user(p); |
1da177e4 LT |
284 | |
285 | p = leader; | |
286 | if (unlikely(zap_leader)) | |
287 | goto repeat; | |
288 | } | |
289 | ||
9d9a6ebf | 290 | int rcuwait_wake_up(struct rcuwait *w) |
8f95c90c | 291 | { |
9d9a6ebf | 292 | int ret = 0; |
8f95c90c DB |
293 | struct task_struct *task; |
294 | ||
295 | rcu_read_lock(); | |
296 | ||
297 | /* | |
298 | * Order condition vs @task, such that everything prior to the load | |
299 | * of @task is visible. This is the condition as to why the user called | |
c9d64a1b | 300 | * rcuwait_wake() in the first place. Pairs with set_current_state() |
8f95c90c DB |
301 | * barrier (A) in rcuwait_wait_event(). |
302 | * | |
303 | * WAIT WAKE | |
304 | * [S] tsk = current [S] cond = true | |
305 | * MB (A) MB (B) | |
306 | * [L] cond [L] tsk | |
307 | */ | |
6dc080ee | 308 | smp_mb(); /* (B) */ |
8f95c90c | 309 | |
8f95c90c DB |
310 | task = rcu_dereference(w->task); |
311 | if (task) | |
9d9a6ebf | 312 | ret = wake_up_process(task); |
8f95c90c | 313 | rcu_read_unlock(); |
9d9a6ebf DB |
314 | |
315 | return ret; | |
8f95c90c | 316 | } |
ac8dec42 | 317 | EXPORT_SYMBOL_GPL(rcuwait_wake_up); |
8f95c90c | 318 | |
1da177e4 LT |
319 | /* |
320 | * Determine if a process group is "orphaned", according to the POSIX | |
321 | * definition in 2.2.2.52. Orphaned process groups are not to be affected | |
322 | * by terminal-generated stop signals. Newly orphaned process groups are | |
323 | * to receive a SIGHUP and a SIGCONT. | |
324 | * | |
325 | * "I ask you, have you ever known what it is to be an orphan?" | |
326 | */ | |
a0be55de IA |
327 | static int will_become_orphaned_pgrp(struct pid *pgrp, |
328 | struct task_struct *ignored_task) | |
1da177e4 LT |
329 | { |
330 | struct task_struct *p; | |
1da177e4 | 331 | |
0475ac08 | 332 | do_each_pid_task(pgrp, PIDTYPE_PGID, p) { |
05e83df6 ON |
333 | if ((p == ignored_task) || |
334 | (p->exit_state && thread_group_empty(p)) || | |
335 | is_global_init(p->real_parent)) | |
1da177e4 | 336 | continue; |
05e83df6 | 337 | |
0475ac08 | 338 | if (task_pgrp(p->real_parent) != pgrp && |
05e83df6 ON |
339 | task_session(p->real_parent) == task_session(p)) |
340 | return 0; | |
0475ac08 | 341 | } while_each_pid_task(pgrp, PIDTYPE_PGID, p); |
05e83df6 ON |
342 | |
343 | return 1; | |
1da177e4 LT |
344 | } |
345 | ||
3e7cd6c4 | 346 | int is_current_pgrp_orphaned(void) |
1da177e4 LT |
347 | { |
348 | int retval; | |
349 | ||
350 | read_lock(&tasklist_lock); | |
3e7cd6c4 | 351 | retval = will_become_orphaned_pgrp(task_pgrp(current), NULL); |
1da177e4 LT |
352 | read_unlock(&tasklist_lock); |
353 | ||
354 | return retval; | |
355 | } | |
356 | ||
961c4675 | 357 | static bool has_stopped_jobs(struct pid *pgrp) |
1da177e4 | 358 | { |
1da177e4 LT |
359 | struct task_struct *p; |
360 | ||
0475ac08 | 361 | do_each_pid_task(pgrp, PIDTYPE_PGID, p) { |
961c4675 ON |
362 | if (p->signal->flags & SIGNAL_STOP_STOPPED) |
363 | return true; | |
0475ac08 | 364 | } while_each_pid_task(pgrp, PIDTYPE_PGID, p); |
961c4675 ON |
365 | |
366 | return false; | |
1da177e4 LT |
367 | } |
368 | ||
f49ee505 ON |
369 | /* |
370 | * Check to see if any process groups have become orphaned as | |
371 | * a result of our exiting, and if they have any stopped jobs, | |
372 | * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) | |
373 | */ | |
374 | static void | |
375 | kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent) | |
376 | { | |
377 | struct pid *pgrp = task_pgrp(tsk); | |
378 | struct task_struct *ignored_task = tsk; | |
379 | ||
380 | if (!parent) | |
a0be55de IA |
381 | /* exit: our father is in a different pgrp than |
382 | * we are and we were the only connection outside. | |
383 | */ | |
f49ee505 ON |
384 | parent = tsk->real_parent; |
385 | else | |
386 | /* reparent: our child is in a different pgrp than | |
387 | * we are, and it was the only connection outside. | |
388 | */ | |
389 | ignored_task = NULL; | |
390 | ||
391 | if (task_pgrp(parent) != pgrp && | |
392 | task_session(parent) == task_session(tsk) && | |
393 | will_become_orphaned_pgrp(pgrp, ignored_task) && | |
394 | has_stopped_jobs(pgrp)) { | |
395 | __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp); | |
396 | __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp); | |
397 | } | |
398 | } | |
399 | ||
92307383 | 400 | static void coredump_task_exit(struct task_struct *tsk) |
d67e03e3 EB |
401 | { |
402 | struct core_state *core_state; | |
403 | ||
404 | /* | |
405 | * Serialize with any possible pending coredump. | |
0258b5fd | 406 | * We must hold siglock around checking core_state |
92307383 | 407 | * and setting PF_POSTCOREDUMP. The core-inducing thread |
d67e03e3 | 408 | * will increment ->nr_threads for each thread in the |
92307383 | 409 | * group without PF_POSTCOREDUMP set. |
d67e03e3 | 410 | */ |
0258b5fd | 411 | spin_lock_irq(&tsk->sighand->siglock); |
92307383 | 412 | tsk->flags |= PF_POSTCOREDUMP; |
0258b5fd EB |
413 | core_state = tsk->signal->core_state; |
414 | spin_unlock_irq(&tsk->sighand->siglock); | |
240a1853 | 415 | if (core_state) { |
d67e03e3 EB |
416 | struct core_thread self; |
417 | ||
d67e03e3 EB |
418 | self.task = current; |
419 | if (self.task->flags & PF_SIGNALED) | |
420 | self.next = xchg(&core_state->dumper.next, &self); | |
421 | else | |
422 | self.task = NULL; | |
423 | /* | |
424 | * Implies mb(), the result of xchg() must be visible | |
425 | * to core_state->dumper. | |
426 | */ | |
427 | if (atomic_dec_and_test(&core_state->nr_threads)) | |
428 | complete(&core_state->startup); | |
429 | ||
430 | for (;;) { | |
b8e75312 | 431 | set_current_state(TASK_IDLE|TASK_FREEZABLE); |
d67e03e3 EB |
432 | if (!self.task) /* see coredump_finish() */ |
433 | break; | |
f5d39b02 | 434 | schedule(); |
d67e03e3 EB |
435 | } |
436 | __set_current_state(TASK_RUNNING); | |
d67e03e3 EB |
437 | } |
438 | } | |
439 | ||
f98bafa0 | 440 | #ifdef CONFIG_MEMCG |
2a22b773 | 441 | /* drops tasklist_lock if succeeds */ |
d73d0035 | 442 | static bool __try_to_set_owner(struct task_struct *tsk, struct mm_struct *mm) |
2a22b773 ON |
443 | { |
444 | bool ret = false; | |
445 | ||
446 | task_lock(tsk); | |
447 | if (likely(tsk->mm == mm)) { | |
448 | /* tsk can't pass exit_mm/exec_mmap and exit */ | |
449 | read_unlock(&tasklist_lock); | |
450 | WRITE_ONCE(mm->owner, tsk); | |
451 | lru_gen_migrate_mm(mm); | |
452 | ret = true; | |
453 | } | |
454 | task_unlock(tsk); | |
455 | return ret; | |
456 | } | |
457 | ||
d73d0035 ON |
458 | static bool try_to_set_owner(struct task_struct *g, struct mm_struct *mm) |
459 | { | |
460 | struct task_struct *t; | |
461 | ||
462 | for_each_thread(g, t) { | |
463 | struct mm_struct *t_mm = READ_ONCE(t->mm); | |
464 | if (t_mm == mm) { | |
465 | if (__try_to_set_owner(t, mm)) | |
466 | return true; | |
467 | } else if (t_mm) | |
468 | break; | |
469 | } | |
470 | ||
471 | return false; | |
472 | } | |
473 | ||
cf475ad2 | 474 | /* |
733eda7a | 475 | * A task is exiting. If it owned this mm, find a new owner for the mm. |
cf475ad2 | 476 | */ |
cf475ad2 BS |
477 | void mm_update_next_owner(struct mm_struct *mm) |
478 | { | |
d73d0035 | 479 | struct task_struct *g, *p = current; |
cf475ad2 | 480 | |
733eda7a KH |
481 | /* |
482 | * If the exiting or execing task is not the owner, it's | |
483 | * someone else's problem. | |
484 | */ | |
485 | if (mm->owner != p) | |
cf475ad2 | 486 | return; |
733eda7a KH |
487 | /* |
488 | * The current owner is exiting/execing and there are no other | |
489 | * candidates. Do not leave the mm pointing to a possibly | |
490 | * freed task structure. | |
491 | */ | |
492 | if (atomic_read(&mm->mm_users) <= 1) { | |
987717e5 | 493 | WRITE_ONCE(mm->owner, NULL); |
733eda7a KH |
494 | return; |
495 | } | |
cf475ad2 BS |
496 | |
497 | read_lock(&tasklist_lock); | |
498 | /* | |
499 | * Search in the children | |
500 | */ | |
d73d0035 ON |
501 | list_for_each_entry(g, &p->children, sibling) { |
502 | if (try_to_set_owner(g, mm)) | |
2a22b773 | 503 | goto ret; |
cf475ad2 | 504 | } |
cf475ad2 BS |
505 | /* |
506 | * Search in the siblings | |
507 | */ | |
d73d0035 ON |
508 | list_for_each_entry(g, &p->real_parent->children, sibling) { |
509 | if (try_to_set_owner(g, mm)) | |
2a22b773 | 510 | goto ret; |
cf475ad2 | 511 | } |
cf475ad2 | 512 | /* |
f87fb599 | 513 | * Search through everything else, we should not get here often. |
cf475ad2 | 514 | */ |
39af1765 | 515 | for_each_process(g) { |
cf3f9a59 JZ |
516 | if (atomic_read(&mm->mm_users) <= 1) |
517 | break; | |
39af1765 ON |
518 | if (g->flags & PF_KTHREAD) |
519 | continue; | |
d73d0035 ON |
520 | if (try_to_set_owner(g, mm)) |
521 | goto ret; | |
f87fb599 | 522 | } |
cf475ad2 | 523 | read_unlock(&tasklist_lock); |
31a78f23 BS |
524 | /* |
525 | * We found no owner yet mm_users > 1: this implies that we are | |
526 | * most likely racing with swapoff (try_to_unuse()) or /proc or | |
e5991371 | 527 | * ptrace or page migration (get_task_mm()). Mark owner as NULL. |
31a78f23 | 528 | */ |
987717e5 | 529 | WRITE_ONCE(mm->owner, NULL); |
2a22b773 | 530 | ret: |
cf475ad2 BS |
531 | return; |
532 | ||
cf475ad2 | 533 | } |
f98bafa0 | 534 | #endif /* CONFIG_MEMCG */ |
cf475ad2 | 535 | |
1da177e4 LT |
536 | /* |
537 | * Turn us into a lazy TLB process if we | |
538 | * aren't already.. | |
539 | */ | |
0039962a | 540 | static void exit_mm(void) |
1da177e4 | 541 | { |
0039962a | 542 | struct mm_struct *mm = current->mm; |
1da177e4 | 543 | |
4610ba7a | 544 | exit_mm_release(current, mm); |
1da177e4 LT |
545 | if (!mm) |
546 | return; | |
d8ed45c5 | 547 | mmap_read_lock(mm); |
aa464ba9 | 548 | mmgrab_lazy_tlb(mm); |
0039962a | 549 | BUG_ON(mm != current->active_mm); |
1da177e4 | 550 | /* more a memory barrier than a real lock */ |
0039962a | 551 | task_lock(current); |
5bc78502 MD |
552 | /* |
553 | * When a thread stops operating on an address space, the loop | |
554 | * in membarrier_private_expedited() may not observe that | |
555 | * tsk->mm, and the loop in membarrier_global_expedited() may | |
556 | * not observe a MEMBARRIER_STATE_GLOBAL_EXPEDITED | |
557 | * rq->membarrier_state, so those would not issue an IPI. | |
558 | * Membarrier requires a memory barrier after accessing | |
559 | * user-space memory, before clearing tsk->mm or the | |
560 | * rq->membarrier_state. | |
561 | */ | |
562 | smp_mb__after_spinlock(); | |
563 | local_irq_disable(); | |
0039962a | 564 | current->mm = NULL; |
5bc78502 | 565 | membarrier_update_current_mm(NULL); |
1da177e4 | 566 | enter_lazy_tlb(mm, current); |
5bc78502 | 567 | local_irq_enable(); |
0039962a | 568 | task_unlock(current); |
5bc78502 | 569 | mmap_read_unlock(mm); |
cf475ad2 | 570 | mm_update_next_owner(mm); |
1da177e4 | 571 | mmput(mm); |
c32b3cbe | 572 | if (test_thread_flag(TIF_MEMDIE)) |
38531201 | 573 | exit_oom_victim(); |
1da177e4 LT |
574 | } |
575 | ||
c9dc05bf ON |
576 | static struct task_struct *find_alive_thread(struct task_struct *p) |
577 | { | |
578 | struct task_struct *t; | |
579 | ||
580 | for_each_thread(p, t) { | |
581 | if (!(t->flags & PF_EXITING)) | |
582 | return t; | |
583 | } | |
584 | return NULL; | |
585 | } | |
586 | ||
8fb335e0 AV |
587 | static struct task_struct *find_child_reaper(struct task_struct *father, |
588 | struct list_head *dead) | |
1109909c ON |
589 | __releases(&tasklist_lock) |
590 | __acquires(&tasklist_lock) | |
591 | { | |
592 | struct pid_namespace *pid_ns = task_active_pid_ns(father); | |
593 | struct task_struct *reaper = pid_ns->child_reaper; | |
8fb335e0 | 594 | struct task_struct *p, *n; |
1109909c ON |
595 | |
596 | if (likely(reaper != father)) | |
597 | return reaper; | |
598 | ||
c9dc05bf ON |
599 | reaper = find_alive_thread(father); |
600 | if (reaper) { | |
1109909c ON |
601 | pid_ns->child_reaper = reaper; |
602 | return reaper; | |
603 | } | |
604 | ||
605 | write_unlock_irq(&tasklist_lock); | |
8fb335e0 AV |
606 | |
607 | list_for_each_entry_safe(p, n, dead, ptrace_entry) { | |
608 | list_del_init(&p->ptrace_entry); | |
609 | release_task(p); | |
610 | } | |
611 | ||
1109909c ON |
612 | zap_pid_ns_processes(pid_ns); |
613 | write_lock_irq(&tasklist_lock); | |
614 | ||
615 | return father; | |
616 | } | |
617 | ||
1da177e4 | 618 | /* |
ebec18a6 LP |
619 | * When we die, we re-parent all our children, and try to: |
620 | * 1. give them to another thread in our thread group, if such a member exists | |
621 | * 2. give it to the first ancestor process which prctl'd itself as a | |
622 | * child_subreaper for its children (like a service manager) | |
623 | * 3. give it to the init process (PID 1) in our pid namespace | |
1da177e4 | 624 | */ |
1109909c ON |
625 | static struct task_struct *find_new_reaper(struct task_struct *father, |
626 | struct task_struct *child_reaper) | |
1da177e4 | 627 | { |
c9dc05bf | 628 | struct task_struct *thread, *reaper; |
1da177e4 | 629 | |
c9dc05bf ON |
630 | thread = find_alive_thread(father); |
631 | if (thread) | |
950bbabb | 632 | return thread; |
1da177e4 | 633 | |
7d24e2df | 634 | if (father->signal->has_child_subreaper) { |
c6c70f44 | 635 | unsigned int ns_level = task_pid(father)->level; |
ebec18a6 | 636 | /* |
175aed3f | 637 | * Find the first ->is_child_subreaper ancestor in our pid_ns. |
c6c70f44 ON |
638 | * We can't check reaper != child_reaper to ensure we do not |
639 | * cross the namespaces, the exiting parent could be injected | |
640 | * by setns() + fork(). | |
641 | * We check pid->level, this is slightly more efficient than | |
642 | * task_active_pid_ns(reaper) != task_active_pid_ns(father). | |
ebec18a6 | 643 | */ |
c6c70f44 ON |
644 | for (reaper = father->real_parent; |
645 | task_pid(reaper)->level == ns_level; | |
ebec18a6 | 646 | reaper = reaper->real_parent) { |
175aed3f | 647 | if (reaper == &init_task) |
ebec18a6 LP |
648 | break; |
649 | if (!reaper->signal->is_child_subreaper) | |
650 | continue; | |
c9dc05bf ON |
651 | thread = find_alive_thread(reaper); |
652 | if (thread) | |
653 | return thread; | |
ebec18a6 | 654 | } |
1da177e4 | 655 | } |
762a24be | 656 | |
1109909c | 657 | return child_reaper; |
950bbabb ON |
658 | } |
659 | ||
5dfc80be ON |
660 | /* |
661 | * Any that need to be release_task'd are put on the @dead list. | |
662 | */ | |
9cd80bbb | 663 | static void reparent_leader(struct task_struct *father, struct task_struct *p, |
5dfc80be ON |
664 | struct list_head *dead) |
665 | { | |
2831096e | 666 | if (unlikely(p->exit_state == EXIT_DEAD)) |
5dfc80be ON |
667 | return; |
668 | ||
abd50b39 | 669 | /* We don't want people slaying init. */ |
5dfc80be ON |
670 | p->exit_signal = SIGCHLD; |
671 | ||
672 | /* If it has exited notify the new parent about this child's death. */ | |
d21142ec | 673 | if (!p->ptrace && |
5dfc80be | 674 | p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) { |
86773473 | 675 | if (do_notify_parent(p, p->exit_signal)) { |
5dfc80be | 676 | p->exit_state = EXIT_DEAD; |
dc2fd4b0 | 677 | list_add(&p->ptrace_entry, dead); |
5dfc80be ON |
678 | } |
679 | } | |
680 | ||
681 | kill_orphaned_pgrp(p, father); | |
682 | } | |
683 | ||
482a3767 ON |
684 | /* |
685 | * This does two things: | |
686 | * | |
687 | * A. Make init inherit all the child processes | |
688 | * B. Check to see if any process groups have become orphaned | |
689 | * as a result of our exiting, and if they have any stopped | |
690 | * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) | |
691 | */ | |
692 | static void forget_original_parent(struct task_struct *father, | |
693 | struct list_head *dead) | |
1da177e4 | 694 | { |
482a3767 | 695 | struct task_struct *p, *t, *reaper; |
762a24be | 696 | |
7c8bd232 | 697 | if (unlikely(!list_empty(&father->ptraced))) |
482a3767 | 698 | exit_ptrace(father, dead); |
f470021a | 699 | |
7c8bd232 | 700 | /* Can drop and reacquire tasklist_lock */ |
8fb335e0 | 701 | reaper = find_child_reaper(father, dead); |
ad9e206a | 702 | if (list_empty(&father->children)) |
482a3767 | 703 | return; |
1109909c ON |
704 | |
705 | reaper = find_new_reaper(father, reaper); | |
2831096e | 706 | list_for_each_entry(p, &father->children, sibling) { |
57a05918 | 707 | for_each_thread(p, t) { |
22a34c6f MB |
708 | RCU_INIT_POINTER(t->real_parent, reaper); |
709 | BUG_ON((!t->ptrace) != (rcu_access_pointer(t->parent) == father)); | |
57a05918 | 710 | if (likely(!t->ptrace)) |
9cd80bbb | 711 | t->parent = t->real_parent; |
9cd80bbb ON |
712 | if (t->pdeath_signal) |
713 | group_send_sig_info(t->pdeath_signal, | |
01024980 EB |
714 | SEND_SIG_NOINFO, t, |
715 | PIDTYPE_TGID); | |
57a05918 | 716 | } |
2831096e ON |
717 | /* |
718 | * If this is a threaded reparent there is no need to | |
719 | * notify anyone anything has happened. | |
720 | */ | |
721 | if (!same_thread_group(reaper, father)) | |
482a3767 | 722 | reparent_leader(father, p, dead); |
1da177e4 | 723 | } |
2831096e | 724 | list_splice_tail_init(&father->children, &reaper->children); |
1da177e4 LT |
725 | } |
726 | ||
727 | /* | |
728 | * Send signals to all our closest relatives so that they know | |
729 | * to properly mourn us.. | |
730 | */ | |
821c7de7 | 731 | static void exit_notify(struct task_struct *tsk, int group_dead) |
1da177e4 | 732 | { |
53c8f9f1 | 733 | bool autoreap; |
482a3767 ON |
734 | struct task_struct *p, *n; |
735 | LIST_HEAD(dead); | |
1da177e4 | 736 | |
762a24be | 737 | write_lock_irq(&tasklist_lock); |
482a3767 ON |
738 | forget_original_parent(tsk, &dead); |
739 | ||
821c7de7 ON |
740 | if (group_dead) |
741 | kill_orphaned_pgrp(tsk->group_leader, NULL); | |
1da177e4 | 742 | |
b191d649 | 743 | tsk->exit_state = EXIT_ZOMBIE; |
64bef697 ON |
744 | /* |
745 | * sub-thread or delay_group_leader(), wake up the | |
746 | * PIDFD_THREAD waiters. | |
747 | */ | |
748 | if (!thread_group_empty(tsk)) | |
749 | do_notify_pidfd(tsk); | |
750 | ||
45cdf5cc ON |
751 | if (unlikely(tsk->ptrace)) { |
752 | int sig = thread_group_leader(tsk) && | |
753 | thread_group_empty(tsk) && | |
754 | !ptrace_reparented(tsk) ? | |
755 | tsk->exit_signal : SIGCHLD; | |
756 | autoreap = do_notify_parent(tsk, sig); | |
757 | } else if (thread_group_leader(tsk)) { | |
758 | autoreap = thread_group_empty(tsk) && | |
759 | do_notify_parent(tsk, tsk->exit_signal); | |
760 | } else { | |
761 | autoreap = true; | |
762 | } | |
1da177e4 | 763 | |
30b692d3 CB |
764 | if (autoreap) { |
765 | tsk->exit_state = EXIT_DEAD; | |
6c66e7db | 766 | list_add(&tsk->ptrace_entry, &dead); |
30b692d3 | 767 | } |
1da177e4 | 768 | |
9c339168 ON |
769 | /* mt-exec, de_thread() is waiting for group leader */ |
770 | if (unlikely(tsk->signal->notify_count < 0)) | |
60700e38 | 771 | wake_up_process(tsk->signal->group_exec_task); |
1da177e4 LT |
772 | write_unlock_irq(&tasklist_lock); |
773 | ||
482a3767 ON |
774 | list_for_each_entry_safe(p, n, &dead, ptrace_entry) { |
775 | list_del_init(&p->ptrace_entry); | |
776 | release_task(p); | |
777 | } | |
1da177e4 LT |
778 | } |
779 | ||
e18eecb8 JD |
780 | #ifdef CONFIG_DEBUG_STACK_USAGE |
781 | static void check_stack_usage(void) | |
782 | { | |
783 | static DEFINE_SPINLOCK(low_water_lock); | |
784 | static int lowest_to_date = THREAD_SIZE; | |
e18eecb8 JD |
785 | unsigned long free; |
786 | ||
7c9f8861 | 787 | free = stack_not_used(current); |
e18eecb8 JD |
788 | |
789 | if (free >= lowest_to_date) | |
790 | return; | |
791 | ||
792 | spin_lock(&low_water_lock); | |
793 | if (free < lowest_to_date) { | |
627393d4 | 794 | pr_info("%s (%d) used greatest stack depth: %lu bytes left\n", |
a0be55de | 795 | current->comm, task_pid_nr(current), free); |
e18eecb8 JD |
796 | lowest_to_date = free; |
797 | } | |
798 | spin_unlock(&low_water_lock); | |
799 | } | |
800 | #else | |
801 | static inline void check_stack_usage(void) {} | |
802 | #endif | |
803 | ||
d80f7d7b EB |
804 | static void synchronize_group_exit(struct task_struct *tsk, long code) |
805 | { | |
806 | struct sighand_struct *sighand = tsk->sighand; | |
807 | struct signal_struct *signal = tsk->signal; | |
808 | ||
809 | spin_lock_irq(&sighand->siglock); | |
810 | signal->quick_threads--; | |
811 | if ((signal->quick_threads == 0) && | |
812 | !(signal->flags & SIGNAL_GROUP_EXIT)) { | |
813 | signal->flags = SIGNAL_GROUP_EXIT; | |
814 | signal->group_exit_code = code; | |
815 | signal->group_stop_count = 0; | |
816 | } | |
817 | spin_unlock_irq(&sighand->siglock); | |
818 | } | |
819 | ||
9af6528e | 820 | void __noreturn do_exit(long code) |
1da177e4 LT |
821 | { |
822 | struct task_struct *tsk = current; | |
823 | int group_dead; | |
824 | ||
001c28e5 NP |
825 | WARN_ON(irqs_disabled()); |
826 | ||
d80f7d7b EB |
827 | synchronize_group_exit(tsk, code); |
828 | ||
b1f866b0 | 829 | WARN_ON(tsk->plug); |
22e2c507 | 830 | |
586b58ca | 831 | kcov_task_exit(tsk); |
50b5e49c | 832 | kmsan_task_exit(tsk); |
586b58ca | 833 | |
92307383 | 834 | coredump_task_exit(tsk); |
a288eecc | 835 | ptrace_event(PTRACE_EVENT_EXIT, code); |
fd593511 | 836 | user_events_exit(tsk); |
1da177e4 | 837 | |
f552a27a | 838 | io_uring_files_cancel(); |
d12619b5 | 839 | exit_signals(tsk); /* sets PF_EXITING */ |
1da177e4 | 840 | |
bfafe5ef AV |
841 | seccomp_filter_release(tsk); |
842 | ||
51229b49 | 843 | acct_update_integrals(tsk); |
1da177e4 | 844 | group_dead = atomic_dec_and_test(&tsk->signal->live); |
c3068951 | 845 | if (group_dead) { |
43cf75d9 | 846 | /* |
847 | * If the last thread of global init has exited, panic | |
848 | * immediately to get a useable coredump. | |
849 | */ | |
850 | if (unlikely(is_global_init(tsk))) | |
851 | panic("Attempted to kill init! exitcode=0x%08x\n", | |
852 | tsk->signal->group_exit_code ?: (int)code); | |
853 | ||
baa73d9e | 854 | #ifdef CONFIG_POSIX_TIMERS |
778e9a9c | 855 | hrtimer_cancel(&tsk->signal->real_timer); |
d5b36a4d | 856 | exit_itimers(tsk); |
baa73d9e | 857 | #endif |
1f10206c JP |
858 | if (tsk->mm) |
859 | setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm); | |
c3068951 | 860 | } |
f6ec29a4 | 861 | acct_collect(code, group_dead); |
522ed776 MT |
862 | if (group_dead) |
863 | tty_audit_exit(); | |
a4ff8dba | 864 | audit_free(tsk); |
115085ea | 865 | |
48d212a2 | 866 | tsk->exit_code = code; |
115085ea | 867 | taskstats_exit(tsk, group_dead); |
c757249a | 868 | |
0039962a | 869 | exit_mm(); |
1da177e4 | 870 | |
0e464814 | 871 | if (group_dead) |
f6ec29a4 | 872 | acct_process(); |
0a16b607 MD |
873 | trace_sched_process_exit(tsk); |
874 | ||
1da177e4 | 875 | exit_sem(tsk); |
b34a6b1d | 876 | exit_shm(tsk); |
1ec7f1dd AV |
877 | exit_files(tsk); |
878 | exit_fs(tsk); | |
c39df5fa ON |
879 | if (group_dead) |
880 | disassociate_ctty(1); | |
8aac6270 | 881 | exit_task_namespaces(tsk); |
ed3e694d | 882 | exit_task_work(tsk); |
e6464694 | 883 | exit_thread(tsk); |
0b3fcf17 SE |
884 | |
885 | /* | |
886 | * Flush inherited counters to the parent - before the parent | |
887 | * gets woken up by child-exit notifications. | |
888 | * | |
889 | * because of cgroup mode, must be called before cgroup_exit() | |
890 | */ | |
891 | perf_event_exit_task(tsk); | |
892 | ||
8e5bfa8c | 893 | sched_autogroup_exit_task(tsk); |
1ec41830 | 894 | cgroup_exit(tsk); |
1da177e4 | 895 | |
24f1e32c FW |
896 | /* |
897 | * FIXME: do that only when needed, using sched_exit tracepoint | |
898 | */ | |
7c8df286 | 899 | flush_ptrace_hw_breakpoint(tsk); |
33b2fb30 | 900 | |
ccdd29ff | 901 | exit_tasks_rcu_start(); |
821c7de7 | 902 | exit_notify(tsk, group_dead); |
ef982393 | 903 | proc_exit_connector(tsk); |
c11600e4 | 904 | mpol_put_task_policy(tsk); |
42b2dd0a | 905 | #ifdef CONFIG_FUTEX |
c87e2837 IM |
906 | if (unlikely(current->pi_state_cache)) |
907 | kfree(current->pi_state_cache); | |
42b2dd0a | 908 | #endif |
de5097c2 | 909 | /* |
9a11b49a | 910 | * Make sure we are holding no locks: |
de5097c2 | 911 | */ |
1b1d2fb4 | 912 | debug_check_no_locks_held(); |
1da177e4 | 913 | |
afc847b7 | 914 | if (tsk->io_context) |
b69f2292 | 915 | exit_io_context(tsk); |
afc847b7 | 916 | |
b92ce558 | 917 | if (tsk->splice_pipe) |
4b8a8f1e | 918 | free_pipe_info(tsk->splice_pipe); |
b92ce558 | 919 | |
5640f768 ED |
920 | if (tsk->task_frag.page) |
921 | put_page(tsk->task_frag.page); | |
922 | ||
1a03d3f1 | 923 | exit_task_stack_account(tsk); |
e0e81739 | 924 | |
4bcb8232 | 925 | check_stack_usage(); |
7407251a | 926 | preempt_disable(); |
54848d73 WF |
927 | if (tsk->nr_dirtied) |
928 | __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied); | |
f41d911f | 929 | exit_rcu(); |
ccdd29ff | 930 | exit_tasks_rcu_finish(); |
b5740f4b | 931 | |
b09be676 | 932 | lockdep_free_task(tsk); |
9af6528e | 933 | do_task_dead(); |
1da177e4 | 934 | } |
012914da | 935 | |
0e25498f EB |
936 | void __noreturn make_task_dead(int signr) |
937 | { | |
938 | /* | |
939 | * Take the task off the cpu after something catastrophic has | |
940 | * happened. | |
05ea0424 EB |
941 | * |
942 | * We can get here from a kernel oops, sometimes with preemption off. | |
943 | * Start by checking for critical errors. | |
944 | * Then fix up important state like USER_DS and preemption. | |
945 | * Then do everything else. | |
0e25498f | 946 | */ |
05ea0424 | 947 | struct task_struct *tsk = current; |
7535b832 | 948 | unsigned int limit; |
05ea0424 EB |
949 | |
950 | if (unlikely(in_interrupt())) | |
951 | panic("Aiee, killing interrupt handler!"); | |
952 | if (unlikely(!tsk->pid)) | |
953 | panic("Attempted to kill the idle task!"); | |
954 | ||
001c28e5 NP |
955 | if (unlikely(irqs_disabled())) { |
956 | pr_info("note: %s[%d] exited with irqs disabled\n", | |
957 | current->comm, task_pid_nr(current)); | |
958 | local_irq_enable(); | |
959 | } | |
05ea0424 EB |
960 | if (unlikely(in_atomic())) { |
961 | pr_info("note: %s[%d] exited with preempt_count %d\n", | |
962 | current->comm, task_pid_nr(current), | |
963 | preempt_count()); | |
964 | preempt_count_set(PREEMPT_ENABLED); | |
965 | } | |
966 | ||
d4ccd54d JH |
967 | /* |
968 | * Every time the system oopses, if the oops happens while a reference | |
969 | * to an object was held, the reference leaks. | |
970 | * If the oops doesn't also leak memory, repeated oopsing can cause | |
971 | * reference counters to wrap around (if they're not using refcount_t). | |
972 | * This means that repeated oopsing can make unexploitable-looking bugs | |
973 | * exploitable through repeated oopsing. | |
974 | * To make sure this can't happen, place an upper bound on how often the | |
975 | * kernel may oops without panic(). | |
976 | */ | |
7535b832 KC |
977 | limit = READ_ONCE(oops_limit); |
978 | if (atomic_inc_return(&oops_count) >= limit && limit) | |
979 | panic("Oopsed too often (kernel.oops_limit is %d)", limit); | |
d4ccd54d | 980 | |
05ea0424 EB |
981 | /* |
982 | * We're taking recursive faults here in make_task_dead. Safest is to just | |
983 | * leave this task alone and wait for reboot. | |
984 | */ | |
985 | if (unlikely(tsk->flags & PF_EXITING)) { | |
986 | pr_alert("Fixing recursive fault but reboot is needed!\n"); | |
987 | futex_exit_recursive(tsk); | |
912616f1 EB |
988 | tsk->exit_state = EXIT_DEAD; |
989 | refcount_inc(&tsk->rcu_users); | |
7f80a2fd | 990 | do_task_dead(); |
05ea0424 EB |
991 | } |
992 | ||
0e25498f EB |
993 | do_exit(signr); |
994 | } | |
995 | ||
754fe8d2 | 996 | SYSCALL_DEFINE1(exit, int, error_code) |
1da177e4 LT |
997 | { |
998 | do_exit((error_code&0xff)<<8); | |
999 | } | |
1000 | ||
1da177e4 LT |
1001 | /* |
1002 | * Take down every thread in the group. This is called by fatal signals | |
1003 | * as well as by sys_exit_group (below). | |
1004 | */ | |
eae654f1 | 1005 | void __noreturn |
1da177e4 LT |
1006 | do_group_exit(int exit_code) |
1007 | { | |
bfc4b089 ON |
1008 | struct signal_struct *sig = current->signal; |
1009 | ||
49697335 | 1010 | if (sig->flags & SIGNAL_GROUP_EXIT) |
bfc4b089 | 1011 | exit_code = sig->group_exit_code; |
49697335 EB |
1012 | else if (sig->group_exec_task) |
1013 | exit_code = 0; | |
cbe9dac3 | 1014 | else { |
1da177e4 | 1015 | struct sighand_struct *const sighand = current->sighand; |
a0be55de | 1016 | |
1da177e4 | 1017 | spin_lock_irq(&sighand->siglock); |
49697335 | 1018 | if (sig->flags & SIGNAL_GROUP_EXIT) |
1da177e4 LT |
1019 | /* Another thread got here before we took the lock. */ |
1020 | exit_code = sig->group_exit_code; | |
49697335 EB |
1021 | else if (sig->group_exec_task) |
1022 | exit_code = 0; | |
1da177e4 | 1023 | else { |
1da177e4 | 1024 | sig->group_exit_code = exit_code; |
ed5d2cac | 1025 | sig->flags = SIGNAL_GROUP_EXIT; |
1da177e4 LT |
1026 | zap_other_threads(current); |
1027 | } | |
1028 | spin_unlock_irq(&sighand->siglock); | |
1da177e4 LT |
1029 | } |
1030 | ||
1031 | do_exit(exit_code); | |
1032 | /* NOTREACHED */ | |
1033 | } | |
1034 | ||
1035 | /* | |
1036 | * this kills every thread in the thread group. Note that any externally | |
1037 | * wait4()-ing process will get the correct exit code - even if this | |
1038 | * thread is not the thread group leader. | |
1039 | */ | |
754fe8d2 | 1040 | SYSCALL_DEFINE1(exit_group, int, error_code) |
1da177e4 LT |
1041 | { |
1042 | do_group_exit((error_code & 0xff) << 8); | |
2ed7c03e HC |
1043 | /* NOTREACHED */ |
1044 | return 0; | |
1da177e4 LT |
1045 | } |
1046 | ||
989264f4 | 1047 | static int eligible_pid(struct wait_opts *wo, struct task_struct *p) |
1da177e4 | 1048 | { |
5c01ba49 ON |
1049 | return wo->wo_type == PIDTYPE_MAX || |
1050 | task_pid_type(p, wo->wo_type) == wo->wo_pid; | |
1051 | } | |
1da177e4 | 1052 | |
bf959931 ON |
1053 | static int |
1054 | eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p) | |
5c01ba49 ON |
1055 | { |
1056 | if (!eligible_pid(wo, p)) | |
1057 | return 0; | |
bf959931 ON |
1058 | |
1059 | /* | |
1060 | * Wait for all children (clone and not) if __WALL is set or | |
1061 | * if it is traced by us. | |
1062 | */ | |
1063 | if (ptrace || (wo->wo_flags & __WALL)) | |
1064 | return 1; | |
1065 | ||
1066 | /* | |
1067 | * Otherwise, wait for clone children *only* if __WCLONE is set; | |
1068 | * otherwise, wait for non-clone children *only*. | |
1069 | * | |
1070 | * Note: a "clone" child here is one that reports to its parent | |
1071 | * using a signal other than SIGCHLD, or a non-leader thread which | |
1072 | * we can only see if it is traced by us. | |
1073 | */ | |
1074 | if ((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE)) | |
1da177e4 | 1075 | return 0; |
1da177e4 | 1076 | |
14dd0b81 | 1077 | return 1; |
1da177e4 LT |
1078 | } |
1079 | ||
1da177e4 LT |
1080 | /* |
1081 | * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold | |
1082 | * read_lock(&tasklist_lock) on entry. If we return zero, we still hold | |
1083 | * the lock and this task is uninteresting. If we return nonzero, we have | |
1084 | * released the lock and the system call should return. | |
1085 | */ | |
9e8ae01d | 1086 | static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) |
1da177e4 | 1087 | { |
67d7ddde | 1088 | int state, status; |
6c5f3e7b | 1089 | pid_t pid = task_pid_vnr(p); |
43e13cc1 | 1090 | uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p)); |
67d7ddde | 1091 | struct waitid_info *infop; |
1da177e4 | 1092 | |
9e8ae01d | 1093 | if (!likely(wo->wo_flags & WEXITED)) |
98abed02 RM |
1094 | return 0; |
1095 | ||
9e8ae01d | 1096 | if (unlikely(wo->wo_flags & WNOWAIT)) { |
907c311f EB |
1097 | status = (p->signal->flags & SIGNAL_GROUP_EXIT) |
1098 | ? p->signal->group_exit_code : p->exit_code; | |
1da177e4 LT |
1099 | get_task_struct(p); |
1100 | read_unlock(&tasklist_lock); | |
1029a2b5 | 1101 | sched_annotate_sleep(); |
e61a2502 AV |
1102 | if (wo->wo_rusage) |
1103 | getrusage(p, RUSAGE_BOTH, wo->wo_rusage); | |
bb380ec3 | 1104 | put_task_struct(p); |
76d9871e | 1105 | goto out_info; |
1da177e4 | 1106 | } |
1da177e4 | 1107 | /* |
abd50b39 | 1108 | * Move the task's state to DEAD/TRACE, only one thread can do this. |
1da177e4 | 1109 | */ |
f6507f83 ON |
1110 | state = (ptrace_reparented(p) && thread_group_leader(p)) ? |
1111 | EXIT_TRACE : EXIT_DEAD; | |
abd50b39 | 1112 | if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE) |
1da177e4 | 1113 | return 0; |
986094df ON |
1114 | /* |
1115 | * We own this thread, nobody else can reap it. | |
1116 | */ | |
1117 | read_unlock(&tasklist_lock); | |
1118 | sched_annotate_sleep(); | |
f6507f83 | 1119 | |
befca967 | 1120 | /* |
f6507f83 | 1121 | * Check thread_group_leader() to exclude the traced sub-threads. |
befca967 | 1122 | */ |
f6507f83 | 1123 | if (state == EXIT_DEAD && thread_group_leader(p)) { |
f953ccd0 ON |
1124 | struct signal_struct *sig = p->signal; |
1125 | struct signal_struct *psig = current->signal; | |
1f10206c | 1126 | unsigned long maxrss; |
5613fda9 | 1127 | u64 tgutime, tgstime; |
3795e161 | 1128 | |
1da177e4 LT |
1129 | /* |
1130 | * The resource counters for the group leader are in its | |
1131 | * own task_struct. Those for dead threads in the group | |
1132 | * are in its signal_struct, as are those for the child | |
1133 | * processes it has previously reaped. All these | |
1134 | * accumulate in the parent's signal_struct c* fields. | |
1135 | * | |
1136 | * We don't bother to take a lock here to protect these | |
f953ccd0 ON |
1137 | * p->signal fields because the whole thread group is dead |
1138 | * and nobody can change them. | |
1139 | * | |
dcca3475 | 1140 | * psig->stats_lock also protects us from our sub-threads |
c1be35a1 | 1141 | * which can reap other children at the same time. |
0cf55e1e | 1142 | * |
a0be55de IA |
1143 | * We use thread_group_cputime_adjusted() to get times for |
1144 | * the thread group, which consolidates times for all threads | |
1145 | * in the group including the group leader. | |
1da177e4 | 1146 | */ |
e80d0a1a | 1147 | thread_group_cputime_adjusted(p, &tgutime, &tgstime); |
c1be35a1 | 1148 | write_seqlock_irq(&psig->stats_lock); |
64861634 MS |
1149 | psig->cutime += tgutime + sig->cutime; |
1150 | psig->cstime += tgstime + sig->cstime; | |
6fac4829 | 1151 | psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime; |
3795e161 JJ |
1152 | psig->cmin_flt += |
1153 | p->min_flt + sig->min_flt + sig->cmin_flt; | |
1154 | psig->cmaj_flt += | |
1155 | p->maj_flt + sig->maj_flt + sig->cmaj_flt; | |
1156 | psig->cnvcsw += | |
1157 | p->nvcsw + sig->nvcsw + sig->cnvcsw; | |
1158 | psig->cnivcsw += | |
1159 | p->nivcsw + sig->nivcsw + sig->cnivcsw; | |
6eaeeaba ED |
1160 | psig->cinblock += |
1161 | task_io_get_inblock(p) + | |
1162 | sig->inblock + sig->cinblock; | |
1163 | psig->coublock += | |
1164 | task_io_get_oublock(p) + | |
1165 | sig->oublock + sig->coublock; | |
1f10206c JP |
1166 | maxrss = max(sig->maxrss, sig->cmaxrss); |
1167 | if (psig->cmaxrss < maxrss) | |
1168 | psig->cmaxrss = maxrss; | |
5995477a AR |
1169 | task_io_accounting_add(&psig->ioac, &p->ioac); |
1170 | task_io_accounting_add(&psig->ioac, &sig->ioac); | |
c1be35a1 | 1171 | write_sequnlock_irq(&psig->stats_lock); |
1da177e4 LT |
1172 | } |
1173 | ||
ce72a16f AV |
1174 | if (wo->wo_rusage) |
1175 | getrusage(p, RUSAGE_BOTH, wo->wo_rusage); | |
1da177e4 LT |
1176 | status = (p->signal->flags & SIGNAL_GROUP_EXIT) |
1177 | ? p->signal->group_exit_code : p->exit_code; | |
359566fa | 1178 | wo->wo_stat = status; |
2f4e6e2a | 1179 | |
b4360690 | 1180 | if (state == EXIT_TRACE) { |
1da177e4 | 1181 | write_lock_irq(&tasklist_lock); |
2f4e6e2a ON |
1182 | /* We dropped tasklist, ptracer could die and untrace */ |
1183 | ptrace_unlink(p); | |
b4360690 ON |
1184 | |
1185 | /* If parent wants a zombie, don't release it now */ | |
1186 | state = EXIT_ZOMBIE; | |
1187 | if (do_notify_parent(p, p->exit_signal)) | |
1188 | state = EXIT_DEAD; | |
abd50b39 | 1189 | p->exit_state = state; |
1da177e4 LT |
1190 | write_unlock_irq(&tasklist_lock); |
1191 | } | |
abd50b39 | 1192 | if (state == EXIT_DEAD) |
1da177e4 | 1193 | release_task(p); |
2f4e6e2a | 1194 | |
76d9871e AV |
1195 | out_info: |
1196 | infop = wo->wo_info; | |
1197 | if (infop) { | |
1198 | if ((status & 0x7f) == 0) { | |
1199 | infop->cause = CLD_EXITED; | |
1200 | infop->status = status >> 8; | |
1201 | } else { | |
1202 | infop->cause = (status & 0x80) ? CLD_DUMPED : CLD_KILLED; | |
1203 | infop->status = status & 0x7f; | |
1204 | } | |
1205 | infop->pid = pid; | |
1206 | infop->uid = uid; | |
1207 | } | |
1208 | ||
67d7ddde | 1209 | return pid; |
1da177e4 LT |
1210 | } |
1211 | ||
90bc8d8b ON |
1212 | static int *task_stopped_code(struct task_struct *p, bool ptrace) |
1213 | { | |
1214 | if (ptrace) { | |
570ac933 | 1215 | if (task_is_traced(p) && !(p->jobctl & JOBCTL_LISTENING)) |
90bc8d8b ON |
1216 | return &p->exit_code; |
1217 | } else { | |
1218 | if (p->signal->flags & SIGNAL_STOP_STOPPED) | |
1219 | return &p->signal->group_exit_code; | |
1220 | } | |
1221 | return NULL; | |
1222 | } | |
1223 | ||
19e27463 TH |
1224 | /** |
1225 | * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED | |
1226 | * @wo: wait options | |
1227 | * @ptrace: is the wait for ptrace | |
1228 | * @p: task to wait for | |
1229 | * | |
1230 | * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED. | |
1231 | * | |
1232 | * CONTEXT: | |
1233 | * read_lock(&tasklist_lock), which is released if return value is | |
1234 | * non-zero. Also, grabs and releases @p->sighand->siglock. | |
1235 | * | |
1236 | * RETURNS: | |
1237 | * 0 if wait condition didn't exist and search for other wait conditions | |
1238 | * should continue. Non-zero return, -errno on failure and @p's pid on | |
1239 | * success, implies that tasklist_lock is released and wait condition | |
1240 | * search should terminate. | |
1da177e4 | 1241 | */ |
9e8ae01d ON |
1242 | static int wait_task_stopped(struct wait_opts *wo, |
1243 | int ptrace, struct task_struct *p) | |
1da177e4 | 1244 | { |
67d7ddde AV |
1245 | struct waitid_info *infop; |
1246 | int exit_code, *p_code, why; | |
ee7c82da | 1247 | uid_t uid = 0; /* unneeded, required by compiler */ |
c8950783 | 1248 | pid_t pid; |
1da177e4 | 1249 | |
47918025 ON |
1250 | /* |
1251 | * Traditionally we see ptrace'd stopped tasks regardless of options. | |
1252 | */ | |
9e8ae01d | 1253 | if (!ptrace && !(wo->wo_flags & WUNTRACED)) |
98abed02 RM |
1254 | return 0; |
1255 | ||
19e27463 TH |
1256 | if (!task_stopped_code(p, ptrace)) |
1257 | return 0; | |
1258 | ||
ee7c82da ON |
1259 | exit_code = 0; |
1260 | spin_lock_irq(&p->sighand->siglock); | |
1261 | ||
90bc8d8b ON |
1262 | p_code = task_stopped_code(p, ptrace); |
1263 | if (unlikely(!p_code)) | |
ee7c82da ON |
1264 | goto unlock_sig; |
1265 | ||
90bc8d8b | 1266 | exit_code = *p_code; |
ee7c82da ON |
1267 | if (!exit_code) |
1268 | goto unlock_sig; | |
1269 | ||
9e8ae01d | 1270 | if (!unlikely(wo->wo_flags & WNOWAIT)) |
90bc8d8b | 1271 | *p_code = 0; |
ee7c82da | 1272 | |
8ca937a6 | 1273 | uid = from_kuid_munged(current_user_ns(), task_uid(p)); |
ee7c82da ON |
1274 | unlock_sig: |
1275 | spin_unlock_irq(&p->sighand->siglock); | |
1276 | if (!exit_code) | |
1da177e4 LT |
1277 | return 0; |
1278 | ||
1279 | /* | |
1280 | * Now we are pretty sure this task is interesting. | |
1281 | * Make sure it doesn't get reaped out from under us while we | |
1282 | * give up the lock and then examine it below. We don't want to | |
1283 | * keep holding onto the tasklist_lock while we call getrusage and | |
1284 | * possibly take page faults for user memory. | |
1285 | */ | |
1286 | get_task_struct(p); | |
6c5f3e7b | 1287 | pid = task_pid_vnr(p); |
f470021a | 1288 | why = ptrace ? CLD_TRAPPED : CLD_STOPPED; |
1da177e4 | 1289 | read_unlock(&tasklist_lock); |
1029a2b5 | 1290 | sched_annotate_sleep(); |
e61a2502 AV |
1291 | if (wo->wo_rusage) |
1292 | getrusage(p, RUSAGE_BOTH, wo->wo_rusage); | |
bb380ec3 | 1293 | put_task_struct(p); |
1da177e4 | 1294 | |
bb380ec3 AV |
1295 | if (likely(!(wo->wo_flags & WNOWAIT))) |
1296 | wo->wo_stat = (exit_code << 8) | 0x7f; | |
1da177e4 | 1297 | |
9e8ae01d | 1298 | infop = wo->wo_info; |
67d7ddde AV |
1299 | if (infop) { |
1300 | infop->cause = why; | |
1301 | infop->status = exit_code; | |
1302 | infop->pid = pid; | |
1303 | infop->uid = uid; | |
1304 | } | |
67d7ddde | 1305 | return pid; |
1da177e4 LT |
1306 | } |
1307 | ||
1308 | /* | |
1309 | * Handle do_wait work for one task in a live, non-stopped state. | |
1310 | * read_lock(&tasklist_lock) on entry. If we return zero, we still hold | |
1311 | * the lock and this task is uninteresting. If we return nonzero, we have | |
1312 | * released the lock and the system call should return. | |
1313 | */ | |
9e8ae01d | 1314 | static int wait_task_continued(struct wait_opts *wo, struct task_struct *p) |
1da177e4 | 1315 | { |
bb380ec3 | 1316 | struct waitid_info *infop; |
1da177e4 LT |
1317 | pid_t pid; |
1318 | uid_t uid; | |
1319 | ||
9e8ae01d | 1320 | if (!unlikely(wo->wo_flags & WCONTINUED)) |
98abed02 RM |
1321 | return 0; |
1322 | ||
1da177e4 LT |
1323 | if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) |
1324 | return 0; | |
1325 | ||
1326 | spin_lock_irq(&p->sighand->siglock); | |
1327 | /* Re-check with the lock held. */ | |
1328 | if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) { | |
1329 | spin_unlock_irq(&p->sighand->siglock); | |
1330 | return 0; | |
1331 | } | |
9e8ae01d | 1332 | if (!unlikely(wo->wo_flags & WNOWAIT)) |
1da177e4 | 1333 | p->signal->flags &= ~SIGNAL_STOP_CONTINUED; |
8ca937a6 | 1334 | uid = from_kuid_munged(current_user_ns(), task_uid(p)); |
1da177e4 LT |
1335 | spin_unlock_irq(&p->sighand->siglock); |
1336 | ||
6c5f3e7b | 1337 | pid = task_pid_vnr(p); |
1da177e4 LT |
1338 | get_task_struct(p); |
1339 | read_unlock(&tasklist_lock); | |
1029a2b5 | 1340 | sched_annotate_sleep(); |
e61a2502 AV |
1341 | if (wo->wo_rusage) |
1342 | getrusage(p, RUSAGE_BOTH, wo->wo_rusage); | |
bb380ec3 | 1343 | put_task_struct(p); |
1da177e4 | 1344 | |
bb380ec3 AV |
1345 | infop = wo->wo_info; |
1346 | if (!infop) { | |
359566fa | 1347 | wo->wo_stat = 0xffff; |
1da177e4 | 1348 | } else { |
bb380ec3 AV |
1349 | infop->cause = CLD_CONTINUED; |
1350 | infop->pid = pid; | |
1351 | infop->uid = uid; | |
1352 | infop->status = SIGCONT; | |
1da177e4 | 1353 | } |
bb380ec3 | 1354 | return pid; |
1da177e4 LT |
1355 | } |
1356 | ||
98abed02 RM |
1357 | /* |
1358 | * Consider @p for a wait by @parent. | |
1359 | * | |
9e8ae01d | 1360 | * -ECHILD should be in ->notask_error before the first call. |
98abed02 RM |
1361 | * Returns nonzero for a final return, when we have unlocked tasklist_lock. |
1362 | * Returns zero if the search for a child should continue; | |
9e8ae01d | 1363 | * then ->notask_error is 0 if @p is an eligible child, |
3a2f5a59 | 1364 | * or still -ECHILD. |
98abed02 | 1365 | */ |
b6e763f0 ON |
1366 | static int wait_consider_task(struct wait_opts *wo, int ptrace, |
1367 | struct task_struct *p) | |
98abed02 | 1368 | { |
3245d6ac ON |
1369 | /* |
1370 | * We can race with wait_task_zombie() from another thread. | |
1371 | * Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition | |
1372 | * can't confuse the checks below. | |
1373 | */ | |
6aa7de05 | 1374 | int exit_state = READ_ONCE(p->exit_state); |
b3ab0316 ON |
1375 | int ret; |
1376 | ||
3245d6ac | 1377 | if (unlikely(exit_state == EXIT_DEAD)) |
b3ab0316 ON |
1378 | return 0; |
1379 | ||
bf959931 | 1380 | ret = eligible_child(wo, ptrace, p); |
14dd0b81 | 1381 | if (!ret) |
98abed02 RM |
1382 | return ret; |
1383 | ||
3245d6ac | 1384 | if (unlikely(exit_state == EXIT_TRACE)) { |
50b8d257 | 1385 | /* |
abd50b39 ON |
1386 | * ptrace == 0 means we are the natural parent. In this case |
1387 | * we should clear notask_error, debugger will notify us. | |
50b8d257 | 1388 | */ |
abd50b39 | 1389 | if (likely(!ptrace)) |
50b8d257 | 1390 | wo->notask_error = 0; |
823b018e | 1391 | return 0; |
50b8d257 | 1392 | } |
823b018e | 1393 | |
377d75da ON |
1394 | if (likely(!ptrace) && unlikely(p->ptrace)) { |
1395 | /* | |
1396 | * If it is traced by its real parent's group, just pretend | |
1397 | * the caller is ptrace_do_wait() and reap this child if it | |
1398 | * is zombie. | |
1399 | * | |
1400 | * This also hides group stop state from real parent; otherwise | |
1401 | * a single stop can be reported twice as group and ptrace stop. | |
1402 | * If a ptracer wants to distinguish these two events for its | |
1403 | * own children it should create a separate process which takes | |
1404 | * the role of real parent. | |
1405 | */ | |
1406 | if (!ptrace_reparented(p)) | |
1407 | ptrace = 1; | |
1408 | } | |
1409 | ||
45cb24a1 | 1410 | /* slay zombie? */ |
3245d6ac | 1411 | if (exit_state == EXIT_ZOMBIE) { |
9b84cca2 | 1412 | /* we don't reap group leaders with subthreads */ |
7c733eb3 ON |
1413 | if (!delay_group_leader(p)) { |
1414 | /* | |
1415 | * A zombie ptracee is only visible to its ptracer. | |
1416 | * Notification and reaping will be cascaded to the | |
1417 | * real parent when the ptracer detaches. | |
1418 | */ | |
1419 | if (unlikely(ptrace) || likely(!p->ptrace)) | |
1420 | return wait_task_zombie(wo, p); | |
1421 | } | |
98abed02 | 1422 | |
f470021a | 1423 | /* |
9b84cca2 TH |
1424 | * Allow access to stopped/continued state via zombie by |
1425 | * falling through. Clearing of notask_error is complex. | |
1426 | * | |
1427 | * When !@ptrace: | |
1428 | * | |
1429 | * If WEXITED is set, notask_error should naturally be | |
1430 | * cleared. If not, subset of WSTOPPED|WCONTINUED is set, | |
1431 | * so, if there are live subthreads, there are events to | |
1432 | * wait for. If all subthreads are dead, it's still safe | |
1433 | * to clear - this function will be called again in finite | |
1434 | * amount time once all the subthreads are released and | |
1435 | * will then return without clearing. | |
1436 | * | |
1437 | * When @ptrace: | |
1438 | * | |
1439 | * Stopped state is per-task and thus can't change once the | |
1440 | * target task dies. Only continued and exited can happen. | |
1441 | * Clear notask_error if WCONTINUED | WEXITED. | |
1442 | */ | |
1443 | if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED))) | |
1444 | wo->notask_error = 0; | |
1445 | } else { | |
1446 | /* | |
1447 | * @p is alive and it's gonna stop, continue or exit, so | |
1448 | * there always is something to wait for. | |
f470021a | 1449 | */ |
9e8ae01d | 1450 | wo->notask_error = 0; |
f470021a RM |
1451 | } |
1452 | ||
98abed02 | 1453 | /* |
45cb24a1 TH |
1454 | * Wait for stopped. Depending on @ptrace, different stopped state |
1455 | * is used and the two don't interact with each other. | |
98abed02 | 1456 | */ |
19e27463 TH |
1457 | ret = wait_task_stopped(wo, ptrace, p); |
1458 | if (ret) | |
1459 | return ret; | |
98abed02 RM |
1460 | |
1461 | /* | |
45cb24a1 TH |
1462 | * Wait for continued. There's only one continued state and the |
1463 | * ptracer can consume it which can confuse the real parent. Don't | |
1464 | * use WCONTINUED from ptracer. You don't need or want it. | |
98abed02 | 1465 | */ |
9e8ae01d | 1466 | return wait_task_continued(wo, p); |
98abed02 RM |
1467 | } |
1468 | ||
1469 | /* | |
1470 | * Do the work of do_wait() for one thread in the group, @tsk. | |
1471 | * | |
9e8ae01d | 1472 | * -ECHILD should be in ->notask_error before the first call. |
98abed02 RM |
1473 | * Returns nonzero for a final return, when we have unlocked tasklist_lock. |
1474 | * Returns zero if the search for a child should continue; then | |
9e8ae01d | 1475 | * ->notask_error is 0 if there were any eligible children, |
3a2f5a59 | 1476 | * or still -ECHILD. |
98abed02 | 1477 | */ |
9e8ae01d | 1478 | static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk) |
98abed02 RM |
1479 | { |
1480 | struct task_struct *p; | |
1481 | ||
1482 | list_for_each_entry(p, &tsk->children, sibling) { | |
9cd80bbb | 1483 | int ret = wait_consider_task(wo, 0, p); |
a0be55de | 1484 | |
9cd80bbb ON |
1485 | if (ret) |
1486 | return ret; | |
98abed02 RM |
1487 | } |
1488 | ||
1489 | return 0; | |
1490 | } | |
1491 | ||
9e8ae01d | 1492 | static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk) |
98abed02 RM |
1493 | { |
1494 | struct task_struct *p; | |
1495 | ||
f470021a | 1496 | list_for_each_entry(p, &tsk->ptraced, ptrace_entry) { |
b6e763f0 | 1497 | int ret = wait_consider_task(wo, 1, p); |
a0be55de | 1498 | |
f470021a | 1499 | if (ret) |
98abed02 | 1500 | return ret; |
98abed02 RM |
1501 | } |
1502 | ||
1503 | return 0; | |
1504 | } | |
1505 | ||
2e521a20 | 1506 | bool pid_child_should_wake(struct wait_opts *wo, struct task_struct *p) |
9d900d4e JA |
1507 | { |
1508 | if (!eligible_pid(wo, p)) | |
1509 | return false; | |
1510 | ||
1511 | if ((wo->wo_flags & __WNOTHREAD) && wo->child_wait.private != p->parent) | |
1512 | return false; | |
1513 | ||
1514 | return true; | |
1515 | } | |
1516 | ||
ac6424b9 | 1517 | static int child_wait_callback(wait_queue_entry_t *wait, unsigned mode, |
0b7570e7 ON |
1518 | int sync, void *key) |
1519 | { | |
1520 | struct wait_opts *wo = container_of(wait, struct wait_opts, | |
1521 | child_wait); | |
1522 | struct task_struct *p = key; | |
1523 | ||
9d900d4e JA |
1524 | if (pid_child_should_wake(wo, p)) |
1525 | return default_wake_function(wait, mode, sync, key); | |
0b7570e7 | 1526 | |
9d900d4e | 1527 | return 0; |
0b7570e7 ON |
1528 | } |
1529 | ||
a7f0765e ON |
1530 | void __wake_up_parent(struct task_struct *p, struct task_struct *parent) |
1531 | { | |
0b7570e7 | 1532 | __wake_up_sync_key(&parent->signal->wait_chldexit, |
ce4dd442 | 1533 | TASK_INTERRUPTIBLE, p); |
a7f0765e ON |
1534 | } |
1535 | ||
5449162a JN |
1536 | static bool is_effectively_child(struct wait_opts *wo, bool ptrace, |
1537 | struct task_struct *target) | |
1538 | { | |
1539 | struct task_struct *parent = | |
1540 | !ptrace ? target->real_parent : target->parent; | |
1541 | ||
1542 | return current == parent || (!(wo->wo_flags & __WNOTHREAD) && | |
1543 | same_thread_group(current, parent)); | |
1544 | } | |
1545 | ||
1546 | /* | |
1547 | * Optimization for waiting on PIDTYPE_PID. No need to iterate through child | |
1548 | * and tracee lists to find the target task. | |
1549 | */ | |
1550 | static int do_wait_pid(struct wait_opts *wo) | |
1551 | { | |
1552 | bool ptrace; | |
1553 | struct task_struct *target; | |
1554 | int retval; | |
1555 | ||
1556 | ptrace = false; | |
1557 | target = pid_task(wo->wo_pid, PIDTYPE_TGID); | |
1558 | if (target && is_effectively_child(wo, ptrace, target)) { | |
1559 | retval = wait_consider_task(wo, ptrace, target); | |
1560 | if (retval) | |
1561 | return retval; | |
1562 | } | |
1563 | ||
1564 | ptrace = true; | |
1565 | target = pid_task(wo->wo_pid, PIDTYPE_PID); | |
1566 | if (target && target->ptrace && | |
1567 | is_effectively_child(wo, ptrace, target)) { | |
1568 | retval = wait_consider_task(wo, ptrace, target); | |
1569 | if (retval) | |
1570 | return retval; | |
1571 | } | |
1572 | ||
1573 | return 0; | |
1574 | } | |
1575 | ||
2e521a20 | 1576 | long __do_wait(struct wait_opts *wo) |
1da177e4 | 1577 | { |
06a101ca | 1578 | long retval; |
0a16b607 | 1579 | |
98abed02 | 1580 | /* |
3da56d16 | 1581 | * If there is nothing that can match our criteria, just get out. |
9e8ae01d ON |
1582 | * We will clear ->notask_error to zero if we see any child that |
1583 | * might later match our criteria, even if we are not able to reap | |
1584 | * it yet. | |
98abed02 | 1585 | */ |
64a16caf | 1586 | wo->notask_error = -ECHILD; |
9e8ae01d | 1587 | if ((wo->wo_type < PIDTYPE_MAX) && |
1722c14a | 1588 | (!wo->wo_pid || !pid_has_task(wo->wo_pid, wo->wo_type))) |
64a16caf | 1589 | goto notask; |
161550d7 | 1590 | |
1da177e4 | 1591 | read_lock(&tasklist_lock); |
9e8ae01d | 1592 | |
5449162a JN |
1593 | if (wo->wo_type == PIDTYPE_PID) { |
1594 | retval = do_wait_pid(wo); | |
64a16caf | 1595 | if (retval) |
06a101ca | 1596 | return retval; |
5449162a JN |
1597 | } else { |
1598 | struct task_struct *tsk = current; | |
1599 | ||
1600 | do { | |
1601 | retval = do_wait_thread(wo, tsk); | |
1602 | if (retval) | |
06a101ca | 1603 | return retval; |
98abed02 | 1604 | |
5449162a JN |
1605 | retval = ptrace_do_wait(wo, tsk); |
1606 | if (retval) | |
06a101ca | 1607 | return retval; |
5449162a JN |
1608 | |
1609 | if (wo->wo_flags & __WNOTHREAD) | |
1610 | break; | |
1611 | } while_each_thread(current, tsk); | |
1612 | } | |
1da177e4 | 1613 | read_unlock(&tasklist_lock); |
f2cc3eb1 | 1614 | |
64a16caf | 1615 | notask: |
9e8ae01d | 1616 | retval = wo->notask_error; |
06a101ca JA |
1617 | if (!retval && !(wo->wo_flags & WNOHANG)) |
1618 | return -ERESTARTSYS; | |
1619 | ||
1620 | return retval; | |
1621 | } | |
1622 | ||
1623 | static long do_wait(struct wait_opts *wo) | |
1624 | { | |
1625 | int retval; | |
1626 | ||
1627 | trace_sched_process_wait(wo->wo_pid); | |
1628 | ||
1629 | init_waitqueue_func_entry(&wo->child_wait, child_wait_callback); | |
1630 | wo->child_wait.private = current; | |
1631 | add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); | |
1632 | ||
1633 | do { | |
1634 | set_current_state(TASK_INTERRUPTIBLE); | |
1635 | retval = __do_wait(wo); | |
1636 | if (retval != -ERESTARTSYS) | |
1637 | break; | |
1638 | if (signal_pending(current)) | |
1639 | break; | |
1640 | schedule(); | |
1641 | } while (1); | |
1642 | ||
f95d39d1 | 1643 | __set_current_state(TASK_RUNNING); |
0b7570e7 | 1644 | remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); |
1da177e4 LT |
1645 | return retval; |
1646 | } | |
1647 | ||
2e521a20 JA |
1648 | int kernel_waitid_prepare(struct wait_opts *wo, int which, pid_t upid, |
1649 | struct waitid_info *infop, int options, | |
1650 | struct rusage *ru) | |
1da177e4 | 1651 | { |
eda7e9d4 | 1652 | unsigned int f_flags = 0; |
161550d7 EB |
1653 | struct pid *pid = NULL; |
1654 | enum pid_type type; | |
1da177e4 | 1655 | |
91c4e8ea ON |
1656 | if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED| |
1657 | __WNOTHREAD|__WCLONE|__WALL)) | |
1da177e4 LT |
1658 | return -EINVAL; |
1659 | if (!(options & (WEXITED|WSTOPPED|WCONTINUED))) | |
1660 | return -EINVAL; | |
1661 | ||
1662 | switch (which) { | |
1663 | case P_ALL: | |
161550d7 | 1664 | type = PIDTYPE_MAX; |
1da177e4 LT |
1665 | break; |
1666 | case P_PID: | |
161550d7 EB |
1667 | type = PIDTYPE_PID; |
1668 | if (upid <= 0) | |
1da177e4 | 1669 | return -EINVAL; |
3695eae5 CB |
1670 | |
1671 | pid = find_get_pid(upid); | |
1da177e4 LT |
1672 | break; |
1673 | case P_PGID: | |
161550d7 | 1674 | type = PIDTYPE_PGID; |
821cc7b0 | 1675 | if (upid < 0) |
1da177e4 | 1676 | return -EINVAL; |
3695eae5 | 1677 | |
821cc7b0 EB |
1678 | if (upid) |
1679 | pid = find_get_pid(upid); | |
1680 | else | |
1681 | pid = get_task_pid(current, PIDTYPE_PGID); | |
3695eae5 CB |
1682 | break; |
1683 | case P_PIDFD: | |
1684 | type = PIDTYPE_PID; | |
1685 | if (upid < 0) | |
1da177e4 | 1686 | return -EINVAL; |
3695eae5 | 1687 | |
ba7d25f3 | 1688 | pid = pidfd_get_pid(upid, &f_flags); |
3695eae5 CB |
1689 | if (IS_ERR(pid)) |
1690 | return PTR_ERR(pid); | |
ba7d25f3 | 1691 | |
1da177e4 LT |
1692 | break; |
1693 | default: | |
1694 | return -EINVAL; | |
1695 | } | |
1696 | ||
eda7e9d4 JA |
1697 | wo->wo_type = type; |
1698 | wo->wo_pid = pid; | |
1699 | wo->wo_flags = options; | |
1700 | wo->wo_info = infop; | |
1701 | wo->wo_rusage = ru; | |
ba7d25f3 | 1702 | if (f_flags & O_NONBLOCK) |
eda7e9d4 JA |
1703 | wo->wo_flags |= WNOHANG; |
1704 | ||
1705 | return 0; | |
1706 | } | |
1707 | ||
1708 | static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop, | |
1709 | int options, struct rusage *ru) | |
1710 | { | |
1711 | struct wait_opts wo; | |
1712 | long ret; | |
1713 | ||
1714 | ret = kernel_waitid_prepare(&wo, which, upid, infop, options, ru); | |
1715 | if (ret) | |
1716 | return ret; | |
ba7d25f3 | 1717 | |
9e8ae01d | 1718 | ret = do_wait(&wo); |
eda7e9d4 | 1719 | if (!ret && !(options & WNOHANG) && (wo.wo_flags & WNOHANG)) |
ba7d25f3 | 1720 | ret = -EAGAIN; |
dfe16dfa | 1721 | |
eda7e9d4 | 1722 | put_pid(wo.wo_pid); |
1da177e4 LT |
1723 | return ret; |
1724 | } | |
1725 | ||
ce72a16f AV |
1726 | SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, |
1727 | infop, int, options, struct rusage __user *, ru) | |
1728 | { | |
1729 | struct rusage r; | |
67d7ddde AV |
1730 | struct waitid_info info = {.status = 0}; |
1731 | long err = kernel_waitid(which, upid, &info, options, ru ? &r : NULL); | |
634a8160 | 1732 | int signo = 0; |
6c85501f | 1733 | |
634a8160 AV |
1734 | if (err > 0) { |
1735 | signo = SIGCHLD; | |
1736 | err = 0; | |
ce72a16f AV |
1737 | if (ru && copy_to_user(ru, &r, sizeof(struct rusage))) |
1738 | return -EFAULT; | |
1739 | } | |
67d7ddde AV |
1740 | if (!infop) |
1741 | return err; | |
1742 | ||
41cd7805 | 1743 | if (!user_write_access_begin(infop, sizeof(*infop))) |
1c9fec47 | 1744 | return -EFAULT; |
96ca579a | 1745 | |
634a8160 | 1746 | unsafe_put_user(signo, &infop->si_signo, Efault); |
4c48abe9 | 1747 | unsafe_put_user(0, &infop->si_errno, Efault); |
cc731525 | 1748 | unsafe_put_user(info.cause, &infop->si_code, Efault); |
4c48abe9 AV |
1749 | unsafe_put_user(info.pid, &infop->si_pid, Efault); |
1750 | unsafe_put_user(info.uid, &infop->si_uid, Efault); | |
1751 | unsafe_put_user(info.status, &infop->si_status, Efault); | |
41cd7805 | 1752 | user_write_access_end(); |
ce72a16f | 1753 | return err; |
4c48abe9 | 1754 | Efault: |
41cd7805 | 1755 | user_write_access_end(); |
4c48abe9 | 1756 | return -EFAULT; |
ce72a16f AV |
1757 | } |
1758 | ||
92ebce5a AV |
1759 | long kernel_wait4(pid_t upid, int __user *stat_addr, int options, |
1760 | struct rusage *ru) | |
1da177e4 | 1761 | { |
9e8ae01d | 1762 | struct wait_opts wo; |
161550d7 EB |
1763 | struct pid *pid = NULL; |
1764 | enum pid_type type; | |
1da177e4 LT |
1765 | long ret; |
1766 | ||
1767 | if (options & ~(WNOHANG|WUNTRACED|WCONTINUED| | |
1768 | __WNOTHREAD|__WCLONE|__WALL)) | |
1769 | return -EINVAL; | |
161550d7 | 1770 | |
dd83c161 | 1771 | /* -INT_MIN is not defined */ |
1772 | if (upid == INT_MIN) | |
1773 | return -ESRCH; | |
1774 | ||
161550d7 EB |
1775 | if (upid == -1) |
1776 | type = PIDTYPE_MAX; | |
1777 | else if (upid < 0) { | |
1778 | type = PIDTYPE_PGID; | |
1779 | pid = find_get_pid(-upid); | |
1780 | } else if (upid == 0) { | |
1781 | type = PIDTYPE_PGID; | |
2ae448ef | 1782 | pid = get_task_pid(current, PIDTYPE_PGID); |
161550d7 EB |
1783 | } else /* upid > 0 */ { |
1784 | type = PIDTYPE_PID; | |
1785 | pid = find_get_pid(upid); | |
1786 | } | |
1787 | ||
9e8ae01d ON |
1788 | wo.wo_type = type; |
1789 | wo.wo_pid = pid; | |
1790 | wo.wo_flags = options | WEXITED; | |
1791 | wo.wo_info = NULL; | |
359566fa | 1792 | wo.wo_stat = 0; |
9e8ae01d ON |
1793 | wo.wo_rusage = ru; |
1794 | ret = do_wait(&wo); | |
161550d7 | 1795 | put_pid(pid); |
359566fa AV |
1796 | if (ret > 0 && stat_addr && put_user(wo.wo_stat, stat_addr)) |
1797 | ret = -EFAULT; | |
1da177e4 | 1798 | |
1da177e4 LT |
1799 | return ret; |
1800 | } | |
1801 | ||
8043fc14 CH |
1802 | int kernel_wait(pid_t pid, int *stat) |
1803 | { | |
1804 | struct wait_opts wo = { | |
1805 | .wo_type = PIDTYPE_PID, | |
1806 | .wo_pid = find_get_pid(pid), | |
1807 | .wo_flags = WEXITED, | |
1808 | }; | |
1809 | int ret; | |
1810 | ||
1811 | ret = do_wait(&wo); | |
1812 | if (ret > 0 && wo.wo_stat) | |
1813 | *stat = wo.wo_stat; | |
1814 | put_pid(wo.wo_pid); | |
1815 | return ret; | |
1816 | } | |
1817 | ||
ce72a16f AV |
1818 | SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr, |
1819 | int, options, struct rusage __user *, ru) | |
1820 | { | |
1821 | struct rusage r; | |
1822 | long err = kernel_wait4(upid, stat_addr, options, ru ? &r : NULL); | |
1823 | ||
1824 | if (err > 0) { | |
1825 | if (ru && copy_to_user(ru, &r, sizeof(struct rusage))) | |
1826 | return -EFAULT; | |
1827 | } | |
1828 | return err; | |
1829 | } | |
1830 | ||
1da177e4 LT |
1831 | #ifdef __ARCH_WANT_SYS_WAITPID |
1832 | ||
1833 | /* | |
1834 | * sys_waitpid() remains for compatibility. waitpid() should be | |
1835 | * implemented by calling sys_wait4() from libc.a. | |
1836 | */ | |
17da2bd9 | 1837 | SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options) |
1da177e4 | 1838 | { |
d300b610 | 1839 | return kernel_wait4(pid, stat_addr, options, NULL); |
1da177e4 LT |
1840 | } |
1841 | ||
1842 | #endif | |
7e95a225 AV |
1843 | |
1844 | #ifdef CONFIG_COMPAT | |
1845 | COMPAT_SYSCALL_DEFINE4(wait4, | |
1846 | compat_pid_t, pid, | |
1847 | compat_uint_t __user *, stat_addr, | |
1848 | int, options, | |
1849 | struct compat_rusage __user *, ru) | |
1850 | { | |
ce72a16f AV |
1851 | struct rusage r; |
1852 | long err = kernel_wait4(pid, stat_addr, options, ru ? &r : NULL); | |
1853 | if (err > 0) { | |
1854 | if (ru && put_compat_rusage(&r, ru)) | |
1855 | return -EFAULT; | |
7e95a225 | 1856 | } |
ce72a16f | 1857 | return err; |
7e95a225 AV |
1858 | } |
1859 | ||
1860 | COMPAT_SYSCALL_DEFINE5(waitid, | |
1861 | int, which, compat_pid_t, pid, | |
1862 | struct compat_siginfo __user *, infop, int, options, | |
1863 | struct compat_rusage __user *, uru) | |
1864 | { | |
7e95a225 | 1865 | struct rusage ru; |
67d7ddde AV |
1866 | struct waitid_info info = {.status = 0}; |
1867 | long err = kernel_waitid(which, pid, &info, options, uru ? &ru : NULL); | |
634a8160 AV |
1868 | int signo = 0; |
1869 | if (err > 0) { | |
1870 | signo = SIGCHLD; | |
1871 | err = 0; | |
6c85501f AV |
1872 | if (uru) { |
1873 | /* kernel_waitid() overwrites everything in ru */ | |
1874 | if (COMPAT_USE_64BIT_TIME) | |
1875 | err = copy_to_user(uru, &ru, sizeof(ru)); | |
1876 | else | |
1877 | err = put_compat_rusage(&ru, uru); | |
1878 | if (err) | |
1879 | return -EFAULT; | |
1880 | } | |
7e95a225 AV |
1881 | } |
1882 | ||
4c48abe9 AV |
1883 | if (!infop) |
1884 | return err; | |
1885 | ||
41cd7805 | 1886 | if (!user_write_access_begin(infop, sizeof(*infop))) |
1c9fec47 | 1887 | return -EFAULT; |
96ca579a | 1888 | |
634a8160 | 1889 | unsafe_put_user(signo, &infop->si_signo, Efault); |
4c48abe9 | 1890 | unsafe_put_user(0, &infop->si_errno, Efault); |
cc731525 | 1891 | unsafe_put_user(info.cause, &infop->si_code, Efault); |
4c48abe9 AV |
1892 | unsafe_put_user(info.pid, &infop->si_pid, Efault); |
1893 | unsafe_put_user(info.uid, &infop->si_uid, Efault); | |
1894 | unsafe_put_user(info.status, &infop->si_status, Efault); | |
41cd7805 | 1895 | user_write_access_end(); |
67d7ddde | 1896 | return err; |
4c48abe9 | 1897 | Efault: |
41cd7805 | 1898 | user_write_access_end(); |
4c48abe9 | 1899 | return -EFAULT; |
7e95a225 AV |
1900 | } |
1901 | #endif | |
7c2c11b2 | 1902 | |
c27cd083 MR |
1903 | /* |
1904 | * This needs to be __function_aligned as GCC implicitly makes any | |
1905 | * implementation of abort() cold and drops alignment specified by | |
1906 | * -falign-functions=N. | |
1907 | * | |
1908 | * See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88345#c11 | |
1909 | */ | |
1910 | __weak __function_aligned void abort(void) | |
7c2c11b2 SM |
1911 | { |
1912 | BUG(); | |
1913 | ||
1914 | /* if that doesn't kill us, halt */ | |
1915 | panic("Oops failed to kill thread"); | |
1916 | } | |
dc8635b7 | 1917 | EXPORT_SYMBOL(abort); |