| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * linux/kernel/exit.c |
| * |
| * Copyright (C) 1991, 1992 Linus Torvalds |
| */ |
| |
| #include <linux/mm.h> |
| #include <linux/slab.h> |
| #include <linux/sched/autogroup.h> |
| #include <linux/sched/mm.h> |
| #include <linux/sched/stat.h> |
| #include <linux/sched/task.h> |
| #include <linux/sched/task_stack.h> |
| #include <linux/sched/cputime.h> |
| #include <linux/interrupt.h> |
| #include <linux/module.h> |
| #include <linux/capability.h> |
| #include <linux/completion.h> |
| #include <linux/personality.h> |
| #include <linux/tty.h> |
| #include <linux/iocontext.h> |
| #include <linux/key.h> |
| #include <linux/cpu.h> |
| #include <linux/acct.h> |
| #include <linux/tsacct_kern.h> |
| #include <linux/file.h> |
| #include <linux/fdtable.h> |
| #include <linux/freezer.h> |
| #include <linux/binfmts.h> |
| #include <linux/nsproxy.h> |
| #include <linux/pid_namespace.h> |
| #include <linux/ptrace.h> |
| #include <linux/profile.h> |
| #include <linux/mount.h> |
| #include <linux/proc_fs.h> |
| #include <linux/kthread.h> |
| #include <linux/mempolicy.h> |
| #include <linux/taskstats_kern.h> |
| #include <linux/delayacct.h> |
| #include <linux/cgroup.h> |
| #include <linux/syscalls.h> |
| #include <linux/signal.h> |
| #include <linux/posix-timers.h> |
| #include <linux/cn_proc.h> |
| #include <linux/mutex.h> |
| #include <linux/futex.h> |
| #include <linux/pipe_fs_i.h> |
| #include <linux/audit.h> /* for audit_free() */ |
| #include <linux/resource.h> |
| #include <linux/task_io_accounting_ops.h> |
| #include <linux/blkdev.h> |
| #include <linux/task_work.h> |
| #include <linux/fs_struct.h> |
| #include <linux/init_task.h> |
| #include <linux/perf_event.h> |
| #include <trace/events/sched.h> |
| #include <linux/hw_breakpoint.h> |
| #include <linux/oom.h> |
| #include <linux/writeback.h> |
| #include <linux/shm.h> |
| #include <linux/kcov.h> |
| #include <linux/kmsan.h> |
| #include <linux/random.h> |
| #include <linux/rcuwait.h> |
| #include <linux/compat.h> |
| #include <linux/io_uring.h> |
| #include <linux/kprobes.h> |
| #include <linux/rethook.h> |
| #include <linux/sysfs.h> |
| #include <linux/security.h> |
| |
| #include <linux/uaccess.h> |
| #include <asm/unistd.h> |
| #include <asm/mmu_context.h> |
| |
| /* |
| * The default value should be high enough to not crash a system that randomly |
| * crashes its kernel from time to time, but low enough to at least not permit |
| * overflowing 32-bit refcounts or the ldsem writer count. |
| */ |
| static unsigned int oops_limit = 10000; |
| |
| #ifdef CONFIG_SYSCTL |
| static struct ctl_table kern_exit_table[] = { |
| { |
| .procname = "oops_limit", |
| .data = &oops_limit, |
| .maxlen = sizeof(oops_limit), |
| .mode = 0644, |
| .proc_handler = proc_douintvec, |
| }, |
| { } |
| }; |
| |
| static __init int kernel_exit_sysctls_init(void) |
| { |
| register_sysctl_init("kernel", kern_exit_table); |
| return 0; |
| } |
| late_initcall(kernel_exit_sysctls_init); |
| #endif |
| |
| static atomic_t oops_count = ATOMIC_INIT(0); |
| |
| #ifdef CONFIG_SYSFS |
| static ssize_t oops_count_show(struct kobject *kobj, struct kobj_attribute *attr, |
| char *page) |
| { |
| return sysfs_emit(page, "%d\n", atomic_read(&oops_count)); |
| } |
| |
| static struct kobj_attribute oops_count_attr = __ATTR_RO(oops_count); |
| |
| static __init int kernel_exit_sysfs_init(void) |
| { |
| sysfs_add_file_to_group(kernel_kobj, &oops_count_attr.attr, NULL); |
| return 0; |
| } |
| late_initcall(kernel_exit_sysfs_init); |
| #endif |
| |
| static void __unhash_process(struct task_struct *p, bool group_dead) |
| { |
| nr_threads--; |
| detach_pid(p, PIDTYPE_PID); |
| if (group_dead) { |
| detach_pid(p, PIDTYPE_TGID); |
| detach_pid(p, PIDTYPE_PGID); |
| detach_pid(p, PIDTYPE_SID); |
| |
| list_del_rcu(&p->tasks); |
| list_del_init(&p->sibling); |
| __this_cpu_dec(process_counts); |
| } |
| list_del_rcu(&p->thread_group); |
| list_del_rcu(&p->thread_node); |
| } |
| |
| /* |
| * This function expects the tasklist_lock write-locked. |
| */ |
| static void __exit_signal(struct task_struct *tsk) |
| { |
| struct signal_struct *sig = tsk->signal; |
| bool group_dead = thread_group_leader(tsk); |
| struct sighand_struct *sighand; |
| struct tty_struct *tty; |
| u64 utime, stime; |
| |
| sighand = rcu_dereference_check(tsk->sighand, |
| lockdep_tasklist_lock_is_held()); |
| spin_lock(&sighand->siglock); |
| |
| #ifdef CONFIG_POSIX_TIMERS |
| posix_cpu_timers_exit(tsk); |
| if (group_dead) |
| posix_cpu_timers_exit_group(tsk); |
| #endif |
| |
| if (group_dead) { |
| tty = sig->tty; |
| sig->tty = NULL; |
| } else { |
| /* |
| * If there is any task waiting for the group exit |
| * then notify it: |
| */ |
| if (sig->notify_count > 0 && !--sig->notify_count) |
| wake_up_process(sig->group_exec_task); |
| |
| if (tsk == sig->curr_target) |
| sig->curr_target = next_thread(tsk); |
| } |
| |
| add_device_randomness((const void*) &tsk->se.sum_exec_runtime, |
| sizeof(unsigned long long)); |
| |
| /* |
| * Accumulate here the counters for all threads as they die. We could |
| * skip the group leader because it is the last user of signal_struct, |
| * but we want to avoid the race with thread_group_cputime() which can |
| * see the empty ->thread_head list. |
| */ |
| task_cputime(tsk, &utime, &stime); |
| write_seqlock(&sig->stats_lock); |
| sig->utime += utime; |
| sig->stime += stime; |
| sig->gtime += task_gtime(tsk); |
| sig->min_flt += tsk->min_flt; |
| sig->maj_flt += tsk->maj_flt; |
| sig->nvcsw += tsk->nvcsw; |
| sig->nivcsw += tsk->nivcsw; |
| sig->inblock += task_io_get_inblock(tsk); |
| sig->oublock += task_io_get_oublock(tsk); |
| task_io_accounting_add(&sig->ioac, &tsk->ioac); |
| sig->sum_sched_runtime += tsk->se.sum_exec_runtime; |
| sig->nr_threads--; |
| __unhash_process(tsk, group_dead); |
| write_sequnlock(&sig->stats_lock); |
| |
| /* |
| * Do this under ->siglock, we can race with another thread |
| * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals. |
| */ |
| flush_sigqueue(&tsk->pending); |
| tsk->sighand = NULL; |
| spin_unlock(&sighand->siglock); |
| |
| __cleanup_sighand(sighand); |
| clear_tsk_thread_flag(tsk, TIF_SIGPENDING); |
| if (group_dead) { |
| flush_sigqueue(&sig->shared_pending); |
| tty_kref_put(tty); |
| } |
| } |
| |
| static void delayed_put_task_struct(struct rcu_head *rhp) |
| { |
| struct task_struct *tsk = container_of(rhp, struct task_struct, rcu); |
| |
| kprobe_flush_task(tsk); |
| rethook_flush_task(tsk); |
| perf_event_delayed_put(tsk); |
| trace_sched_process_free(tsk); |
| put_task_struct(tsk); |
| } |
| |
| void put_task_struct_rcu_user(struct task_struct *task) |
| { |
| if (refcount_dec_and_test(&task->rcu_users)) |
| call_rcu(&task->rcu, delayed_put_task_struct); |
| } |
| |
| void __weak release_thread(struct task_struct *dead_task) |
| { |
| } |
| |
| void release_task(struct task_struct *p) |
| { |
| struct task_struct *leader; |
| struct pid *thread_pid; |
| int zap_leader; |
| repeat: |
| /* don't need to get the RCU readlock here - the process is dead and |
| * can't be modifying its own credentials. But shut RCU-lockdep up */ |
| rcu_read_lock(); |
| dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1); |
| rcu_read_unlock(); |
| |
| cgroup_release(p); |
| |
| write_lock_irq(&tasklist_lock); |
| ptrace_release_task(p); |
| thread_pid = get_pid(p->thread_pid); |
| __exit_signal(p); |
| |
| /* |
| * If we are the last non-leader member of the thread |
| * group, and the leader is zombie, then notify the |
| * group leader's parent process. (if it wants notification.) |
| */ |
| zap_leader = 0; |
| leader = p->group_leader; |
| if (leader != p && thread_group_empty(leader) |
| && leader->exit_state == EXIT_ZOMBIE) { |
| /* |
| * If we were the last child thread and the leader has |
| * exited already, and the leader's parent ignores SIGCHLD, |
| * then we are the one who should release the leader. |
| */ |
| zap_leader = do_notify_parent(leader, leader->exit_signal); |
| if (zap_leader) |
| leader->exit_state = EXIT_DEAD; |
| } |
| |
| write_unlock_irq(&tasklist_lock); |
| seccomp_filter_release(p); |
| proc_flush_pid(thread_pid); |
| put_pid(thread_pid); |
| release_thread(p); |
| put_task_struct_rcu_user(p); |
| |
| p = leader; |
| if (unlikely(zap_leader)) |
| goto repeat; |
| } |
| |
| int rcuwait_wake_up(struct rcuwait *w) |
| { |
| int ret = 0; |
| struct task_struct *task; |
| |
| rcu_read_lock(); |
| |
| /* |
| * Order condition vs @task, such that everything prior to the load |
| * of @task is visible. This is the condition as to why the user called |
| * rcuwait_wake() in the first place. Pairs with set_current_state() |
| * barrier (A) in rcuwait_wait_event(). |
| * |
| * WAIT WAKE |
| * [S] tsk = current [S] cond = true |
| * MB (A) MB (B) |
| * [L] cond [L] tsk |
| */ |
| smp_mb(); /* (B) */ |
| |
| task = rcu_dereference(w->task); |
| if (task) |
| ret = wake_up_process(task); |
| rcu_read_unlock(); |
| |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(rcuwait_wake_up); |
| |
| /* |
| * Determine if a process group is "orphaned", according to the POSIX |
| * definition in 2.2.2.52. Orphaned process groups are not to be affected |
| * by terminal-generated stop signals. Newly orphaned process groups are |
| * to receive a SIGHUP and a SIGCONT. |
| * |
| * "I ask you, have you ever known what it is to be an orphan?" |
| */ |
| static int will_become_orphaned_pgrp(struct pid *pgrp, |
| struct task_struct *ignored_task) |
| { |
| struct task_struct *p; |
| |
| do_each_pid_task(pgrp, PIDTYPE_PGID, p) { |
| if ((p == ignored_task) || |
| (p->exit_state && thread_group_empty(p)) || |
| is_global_init(p->real_parent)) |
| continue; |
| |
| if (task_pgrp(p->real_parent) != pgrp && |
| task_session(p->real_parent) == task_session(p)) |
| return 0; |
| } while_each_pid_task(pgrp, PIDTYPE_PGID, p); |
| |
| return 1; |
| } |
| |
| int is_current_pgrp_orphaned(void) |
| { |
| int retval; |
| |
| read_lock(&tasklist_lock); |
| retval = will_become_orphaned_pgrp(task_pgrp(current), NULL); |
| read_unlock(&tasklist_lock); |
| |
| return retval; |
| } |
| |
| static bool has_stopped_jobs(struct pid *pgrp) |
| { |
| struct task_struct *p; |
| |
| do_each_pid_task(pgrp, PIDTYPE_PGID, p) { |
| if (p->signal->flags & SIGNAL_STOP_STOPPED) |
| return true; |
| } while_each_pid_task(pgrp, PIDTYPE_PGID, p); |
| |
| return false; |
| } |
| |
| /* |
| * Check to see if any process groups have become orphaned as |
| * a result of our exiting, and if they have any stopped jobs, |
| * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) |
| */ |
| static void |
| kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent) |
| { |
| struct pid *pgrp = task_pgrp(tsk); |
| struct task_struct *ignored_task = tsk; |
| |
| if (!parent) |
| /* exit: our father is in a different pgrp than |
| * we are and we were the only connection outside. |
| */ |
| parent = tsk->real_parent; |
| else |
| /* reparent: our child is in a different pgrp than |
| * we are, and it was the only connection outside. |
| */ |
| ignored_task = NULL; |
| |
| if (task_pgrp(parent) != pgrp && |
| task_session(parent) == task_session(tsk) && |
| will_become_orphaned_pgrp(pgrp, ignored_task) && |
| has_stopped_jobs(pgrp)) { |
| __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp); |
| __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp); |
| } |
| } |
| |
| static void coredump_task_exit(struct task_struct *tsk) |
| { |
| struct core_state *core_state; |
| |
| /* |
| * Serialize with any possible pending coredump. |
| * We must hold siglock around checking core_state |
| * and setting PF_POSTCOREDUMP. The core-inducing thread |
| * will increment ->nr_threads for each thread in the |
| * group without PF_POSTCOREDUMP set. |
| */ |
| spin_lock_irq(&tsk->sighand->siglock); |
| tsk->flags |= PF_POSTCOREDUMP; |
| core_state = tsk->signal->core_state; |
| spin_unlock_irq(&tsk->sighand->siglock); |
| if (core_state) { |
| struct core_thread self; |
| |
| self.task = current; |
| if (self.task->flags & PF_SIGNALED) |
| self.next = xchg(&core_state->dumper.next, &self); |
| else |
| self.task = NULL; |
| /* |
| * Implies mb(), the result of xchg() must be visible |
| * to core_state->dumper. |
| */ |
| if (atomic_dec_and_test(&core_state->nr_threads)) |
| complete(&core_state->startup); |
| |
| for (;;) { |
| set_current_state(TASK_UNINTERRUPTIBLE|TASK_FREEZABLE); |
| if (!self.task) /* see coredump_finish() */ |
| break; |
| schedule(); |
| } |
| __set_current_state(TASK_RUNNING); |
| } |
| } |
| |
| #ifdef CONFIG_MEMCG |
| /* |
| * A task is exiting. If it owned this mm, find a new owner for the mm. |
| */ |
| void mm_update_next_owner(struct mm_struct *mm) |
| { |
| struct task_struct *c, *g, *p = current; |
| |
| retry: |
| /* |
| * If the exiting or execing task is not the owner, it's |
| * someone else's problem. |
| */ |
| if (mm->owner != p) |
| return; |
| /* |
| * The current owner is exiting/execing and there are no other |
| * candidates. Do not leave the mm pointing to a possibly |
| * freed task structure. |
| */ |
| if (atomic_read(&mm->mm_users) <= 1) { |
| WRITE_ONCE(mm->owner, NULL); |
| return; |
| } |
| |
| read_lock(&tasklist_lock); |
| /* |
| * Search in the children |
| */ |
| list_for_each_entry(c, &p->children, sibling) { |
| if (c->mm == mm) |
| goto assign_new_owner; |
| } |
| |
| /* |
| * Search in the siblings |
| */ |
| list_for_each_entry(c, &p->real_parent->children, sibling) { |
| if (c->mm == mm) |
| goto assign_new_owner; |
| } |
| |
| /* |
| * Search through everything else, we should not get here often. |
| */ |
| for_each_process(g) { |
| if (g->flags & PF_KTHREAD) |
| continue; |
| for_each_thread(g, c) { |
| if (c->mm == mm) |
| goto assign_new_owner; |
| if (c->mm) |
| break; |
| } |
| } |
| read_unlock(&tasklist_lock); |
| /* |
| * We found no owner yet mm_users > 1: this implies that we are |
| * most likely racing with swapoff (try_to_unuse()) or /proc or |
| * ptrace or page migration (get_task_mm()). Mark owner as NULL. |
| */ |
| WRITE_ONCE(mm->owner, NULL); |
| return; |
| |
| assign_new_owner: |
| BUG_ON(c == p); |
| get_task_struct(c); |
| /* |
| * The task_lock protects c->mm from changing. |
| * We always want mm->owner->mm == mm |
| */ |
| task_lock(c); |
| /* |
| * Delay read_unlock() till we have the task_lock() |
| * to ensure that c does not slip away underneath us |
| */ |
| read_unlock(&tasklist_lock); |
| if (c->mm != mm) { |
| task_unlock(c); |
| put_task_struct(c); |
| goto retry; |
| } |
| WRITE_ONCE(mm->owner, c); |
| lru_gen_migrate_mm(mm); |
| task_unlock(c); |
| put_task_struct(c); |
| } |
| #endif /* CONFIG_MEMCG */ |
| |
| /* |
| * Turn us into a lazy TLB process if we |
| * aren't already.. |
| */ |
| static void exit_mm(void) |
| { |
| struct mm_struct *mm = current->mm; |
| |
| exit_mm_release(current, mm); |
| if (!mm) |
| return; |
| sync_mm_rss(mm); |
| mmap_read_lock(mm); |
| mmgrab(mm); |
| BUG_ON(mm != current->active_mm); |
| /* more a memory barrier than a real lock */ |
| task_lock(current); |
| /* |
| * When a thread stops operating on an address space, the loop |
| * in membarrier_private_expedited() may not observe that |
| * tsk->mm, and the loop in membarrier_global_expedited() may |
| * not observe a MEMBARRIER_STATE_GLOBAL_EXPEDITED |
| * rq->membarrier_state, so those would not issue an IPI. |
| * Membarrier requires a memory barrier after accessing |
| * user-space memory, before clearing tsk->mm or the |
| * rq->membarrier_state. |
| */ |
| smp_mb__after_spinlock(); |
| local_irq_disable(); |
| current->mm = NULL; |
| membarrier_update_current_mm(NULL); |
| enter_lazy_tlb(mm, current); |
| local_irq_enable(); |
| task_unlock(current); |
| mmap_read_unlock(mm); |
| mm_update_next_owner(mm); |
| mmput(mm); |
| if (test_thread_flag(TIF_MEMDIE)) |
| exit_oom_victim(); |
| } |
| |
| static struct task_struct *find_alive_thread(struct task_struct *p) |
| { |
| struct task_struct *t; |
| |
| for_each_thread(p, t) { |
| if (!(t->flags & PF_EXITING)) |
| return t; |
| } |
| return NULL; |
| } |
| |
| static struct task_struct *find_child_reaper(struct task_struct *father, |
| struct list_head *dead) |
| __releases(&tasklist_lock) |
| __acquires(&tasklist_lock) |
| { |
| struct pid_namespace *pid_ns = task_active_pid_ns(father); |
| struct task_struct *reaper = pid_ns->child_reaper; |
| struct task_struct *p, *n; |
| |
| if (likely(reaper != father)) |
| return reaper; |
| |
| reaper = find_alive_thread(father); |
| if (reaper) { |
| pid_ns->child_reaper = reaper; |
| return reaper; |
| } |
| |
| write_unlock_irq(&tasklist_lock); |
| |
| list_for_each_entry_safe(p, n, dead, ptrace_entry) { |
| list_del_init(&p->ptrace_entry); |
| release_task(p); |
| } |
| |
| zap_pid_ns_processes(pid_ns); |
| write_lock_irq(&tasklist_lock); |
| |
| return father; |
| } |
| |
| /* |
| * When we die, we re-parent all our children, and try to: |
| * 1. give them to another thread in our thread group, if such a member exists |
| * 2. give it to the first ancestor process which prctl'd itself as a |
| * child_subreaper for its children (like a service manager) |
| * 3. give it to the init process (PID 1) in our pid namespace |
| */ |
| static struct task_struct *find_new_reaper(struct task_struct *father, |
| struct task_struct *child_reaper) |
| { |
| struct task_struct *thread, *reaper; |
| |
| thread = find_alive_thread(father); |
| if (thread) |
| return thread; |
| |
| if (father->signal->has_child_subreaper) { |
| unsigned int ns_level = task_pid(father)->level; |
| /* |
| * Find the first ->is_child_subreaper ancestor in our pid_ns. |
| * We can't check reaper != child_reaper to ensure we do not |
| * cross the namespaces, the exiting parent could be injected |
| * by setns() + fork(). |
| * We check pid->level, this is slightly more efficient than |
| * task_active_pid_ns(reaper) != task_active_pid_ns(father). |
| */ |
| for (reaper = father->real_parent; |
| task_pid(reaper)->level == ns_level; |
| reaper = reaper->real_parent) { |
| if (reaper == &init_task) |
| break; |
| if (!reaper->signal->is_child_subreaper) |
| continue; |
| thread = find_alive_thread(reaper); |
| if (thread) |
| return thread; |
| } |
| } |
| |
| return child_reaper; |
| } |
| |
| /* |
| * Any that need to be release_task'd are put on the @dead list. |
| */ |
| static void reparent_leader(struct task_struct *father, struct task_struct *p, |
| struct list_head *dead) |
| { |
| if (unlikely(p->exit_state == EXIT_DEAD)) |
| return; |
| |
| /* We don't want people slaying init. */ |
| p->exit_signal = SIGCHLD; |
| |
| /* If it has exited notify the new parent about this child's death. */ |
| if (!p->ptrace && |
| p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) { |
| if (do_notify_parent(p, p->exit_signal)) { |
| p->exit_state = EXIT_DEAD; |
| list_add(&p->ptrace_entry, dead); |
| } |
| } |
| |
| kill_orphaned_pgrp(p, father); |
| } |
| |
| /* |
| * This does two things: |
| * |
| * A. Make init inherit all the child processes |
| * B. Check to see if any process groups have become orphaned |
| * as a result of our exiting, and if they have any stopped |
| * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) |
| */ |
| static void forget_original_parent(struct task_struct *father, |
| struct list_head *dead) |
| { |
| struct task_struct *p, *t, *reaper; |
| |
| if (unlikely(!list_empty(&father->ptraced))) |
| exit_ptrace(father, dead); |
| |
| /* Can drop and reacquire tasklist_lock */ |
| reaper = find_child_reaper(father, dead); |
| if (list_empty(&father->children)) |
| return; |
| |
| reaper = find_new_reaper(father, reaper); |
| list_for_each_entry(p, &father->children, sibling) { |
| for_each_thread(p, t) { |
| RCU_INIT_POINTER(t->real_parent, reaper); |
| BUG_ON((!t->ptrace) != (rcu_access_pointer(t->parent) == father)); |
| if (likely(!t->ptrace)) |
| t->parent = t->real_parent; |
| if (t->pdeath_signal) |
| group_send_sig_info(t->pdeath_signal, |
| SEND_SIG_NOINFO, t, |
| PIDTYPE_TGID); |
| } |
| /* |
| * If this is a threaded reparent there is no need to |
| * notify anyone anything has happened. |
| */ |
| if (!same_thread_group(reaper, father)) |
| reparent_leader(father, p, dead); |
| } |
| list_splice_tail_init(&father->children, &reaper->children); |
| } |
| |
| /* |
| * Send signals to all our closest relatives so that they know |
| * to properly mourn us.. |
| */ |
| static void exit_notify(struct task_struct *tsk, int group_dead) |
| { |
| bool autoreap; |
| struct task_struct *p, *n; |
| LIST_HEAD(dead); |
| |
| write_lock_irq(&tasklist_lock); |
| forget_original_parent(tsk, &dead); |
| |
| if (group_dead) |
| kill_orphaned_pgrp(tsk->group_leader, NULL); |
| |
| tsk->exit_state = EXIT_ZOMBIE; |
| if (unlikely(tsk->ptrace)) { |
| int sig = thread_group_leader(tsk) && |
| thread_group_empty(tsk) && |
| !ptrace_reparented(tsk) ? |
| tsk->exit_signal : SIGCHLD; |
| autoreap = do_notify_parent(tsk, sig); |
| } else if (thread_group_leader(tsk)) { |
| autoreap = thread_group_empty(tsk) && |
| do_notify_parent(tsk, tsk->exit_signal); |
| } else { |
| autoreap = true; |
| } |
| |
| if (autoreap) { |
| tsk->exit_state = EXIT_DEAD; |
| list_add(&tsk->ptrace_entry, &dead); |
| } |
| |
| /* mt-exec, de_thread() is waiting for group leader */ |
| if (unlikely(tsk->signal->notify_count < 0)) |
| wake_up_process(tsk->signal->group_exec_task); |
| write_unlock_irq(&tasklist_lock); |
| |
| list_for_each_entry_safe(p, n, &dead, ptrace_entry) { |
| list_del_init(&p->ptrace_entry); |
| release_task(p); |
| } |
| } |
| |
| #ifdef CONFIG_DEBUG_STACK_USAGE |
| static void check_stack_usage(void) |
| { |
| static DEFINE_SPINLOCK(low_water_lock); |
| static int lowest_to_date = THREAD_SIZE; |
| unsigned long free; |
| |
| free = stack_not_used(current); |
| |
| if (free >= lowest_to_date) |
| return; |
| |
| spin_lock(&low_water_lock); |
| if (free < lowest_to_date) { |
| pr_info("%s (%d) used greatest stack depth: %lu bytes left\n", |
| current->comm, task_pid_nr(current), free); |
| lowest_to_date = free; |
| } |
| spin_unlock(&low_water_lock); |
| } |
| #else |
| static inline void check_stack_usage(void) {} |
| #endif |
| |
| static void synchronize_group_exit(struct task_struct *tsk, long code) |
| { |
| struct sighand_struct *sighand = tsk->sighand; |
| struct signal_struct *signal = tsk->signal; |
| |
| spin_lock_irq(&sighand->siglock); |
| signal->quick_threads--; |
| if ((signal->quick_threads == 0) && |
| !(signal->flags & SIGNAL_GROUP_EXIT)) { |
| signal->flags = SIGNAL_GROUP_EXIT; |
| signal->group_exit_code = code; |
| signal->group_stop_count = 0; |
| } |
| spin_unlock_irq(&sighand->siglock); |
| } |
| |
| void __noreturn do_exit(long code) |
| { |
| struct task_struct *tsk = current; |
| int group_dead; |
| |
| WARN_ON(irqs_disabled()); |
| |
| synchronize_group_exit(tsk, code); |
| |
| WARN_ON(tsk->plug); |
| |
| kcov_task_exit(tsk); |
| kmsan_task_exit(tsk); |
| |
| coredump_task_exit(tsk); |
| ptrace_event(PTRACE_EVENT_EXIT, code); |
| |
| validate_creds_for_do_exit(tsk); |
| |
| io_uring_files_cancel(); |
| exit_signals(tsk); /* sets PF_EXITING */ |
| |
| /* sync mm's RSS info before statistics gathering */ |
| if (tsk->mm) |
| sync_mm_rss(tsk->mm); |
| acct_update_integrals(tsk); |
| group_dead = atomic_dec_and_test(&tsk->signal->live); |
| if (group_dead) { |
| /* |
| * If the last thread of global init has exited, panic |
| * immediately to get a useable coredump. |
| */ |
| if (unlikely(is_global_init(tsk))) |
| panic("Attempted to kill init! exitcode=0x%08x\n", |
| tsk->signal->group_exit_code ?: (int)code); |
| |
| #ifdef CONFIG_POSIX_TIMERS |
| hrtimer_cancel(&tsk->signal->real_timer); |
| exit_itimers(tsk); |
| #endif |
| if (tsk->mm) |
| setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm); |
| |
| security_task_exit(tsk); |
| } |
| acct_collect(code, group_dead); |
| if (group_dead) |
| tty_audit_exit(); |
| audit_free(tsk); |
| |
| tsk->exit_code = code; |
| taskstats_exit(tsk, group_dead); |
| |
| exit_mm(); |
| |
| if (group_dead) |
| acct_process(); |
| trace_sched_process_exit(tsk); |
| |
| exit_sem(tsk); |
| exit_shm(tsk); |
| exit_files(tsk); |
| exit_fs(tsk); |
| if (group_dead) |
| disassociate_ctty(1); |
| exit_task_namespaces(tsk); |
| exit_task_work(tsk); |
| exit_thread(tsk); |
| |
| /* |
| * Flush inherited counters to the parent - before the parent |
| * gets woken up by child-exit notifications. |
| * |
| * because of cgroup mode, must be called before cgroup_exit() |
| */ |
| perf_event_exit_task(tsk); |
| |
| sched_autogroup_exit_task(tsk); |
| cgroup_exit(tsk); |
| |
| /* |
| * FIXME: do that only when needed, using sched_exit tracepoint |
| */ |
| flush_ptrace_hw_breakpoint(tsk); |
| |
| exit_tasks_rcu_start(); |
| exit_notify(tsk, group_dead); |
| proc_exit_connector(tsk); |
| mpol_put_task_policy(tsk); |
| #ifdef CONFIG_FUTEX |
| if (unlikely(current->pi_state_cache)) |
| kfree(current->pi_state_cache); |
| #endif |
| /* |
| * Make sure we are holding no locks: |
| */ |
| debug_check_no_locks_held(); |
| |
| if (tsk->io_context) |
| exit_io_context(tsk); |
| |
| if (tsk->splice_pipe) |
| free_pipe_info(tsk->splice_pipe); |
| |
| if (tsk->task_frag.page) |
| put_page(tsk->task_frag.page); |
| |
| validate_creds_for_do_exit(tsk); |
| exit_task_stack_account(tsk); |
| |
| check_stack_usage(); |
| preempt_disable(); |
| if (tsk->nr_dirtied) |
| __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied); |
| exit_rcu(); |
| exit_tasks_rcu_finish(); |
| |
| lockdep_free_task(tsk); |
| do_task_dead(); |
| } |
| |
| void __noreturn make_task_dead(int signr) |
| { |
| /* |
| * Take the task off the cpu after something catastrophic has |
| * happened. |
| * |
| * We can get here from a kernel oops, sometimes with preemption off. |
| * Start by checking for critical errors. |
| * Then fix up important state like USER_DS and preemption. |
| * Then do everything else. |
| */ |
| struct task_struct *tsk = current; |
| unsigned int limit; |
| |
| if (unlikely(in_interrupt())) |
| panic("Aiee, killing interrupt handler!"); |
| if (unlikely(!tsk->pid)) |
| panic("Attempted to kill the idle task!"); |
| |
| if (unlikely(irqs_disabled())) { |
| pr_info("note: %s[%d] exited with irqs disabled\n", |
| current->comm, task_pid_nr(current)); |
| local_irq_enable(); |
| } |
| if (unlikely(in_atomic())) { |
| pr_info("note: %s[%d] exited with preempt_count %d\n", |
| current->comm, task_pid_nr(current), |
| preempt_count()); |
| preempt_count_set(PREEMPT_ENABLED); |
| } |
| |
| /* |
| * Every time the system oopses, if the oops happens while a reference |
| * to an object was held, the reference leaks. |
| * If the oops doesn't also leak memory, repeated oopsing can cause |
| * reference counters to wrap around (if they're not using refcount_t). |
| * This means that repeated oopsing can make unexploitable-looking bugs |
| * exploitable through repeated oopsing. |
| * To make sure this can't happen, place an upper bound on how often the |
| * kernel may oops without panic(). |
| */ |
| limit = READ_ONCE(oops_limit); |
| if (atomic_inc_return(&oops_count) >= limit && limit) |
| panic("Oopsed too often (kernel.oops_limit is %d)", limit); |
| |
| /* |
| * We're taking recursive faults here in make_task_dead. Safest is to just |
| * leave this task alone and wait for reboot. |
| */ |
| if (unlikely(tsk->flags & PF_EXITING)) { |
| pr_alert("Fixing recursive fault but reboot is needed!\n"); |
| futex_exit_recursive(tsk); |
| tsk->exit_state = EXIT_DEAD; |
| refcount_inc(&tsk->rcu_users); |
| do_task_dead(); |
| } |
| |
| do_exit(signr); |
| } |
| |
| SYSCALL_DEFINE1(exit, int, error_code) |
| { |
| do_exit((error_code&0xff)<<8); |
| } |
| |
| /* |
| * Take down every thread in the group. This is called by fatal signals |
| * as well as by sys_exit_group (below). |
| */ |
| void __noreturn |
| do_group_exit(int exit_code) |
| { |
| struct signal_struct *sig = current->signal; |
| |
| if (sig->flags & SIGNAL_GROUP_EXIT) |
| exit_code = sig->group_exit_code; |
| else if (sig->group_exec_task) |
| exit_code = 0; |
| else { |
| struct sighand_struct *const sighand = current->sighand; |
| |
| spin_lock_irq(&sighand->siglock); |
| if (sig->flags & SIGNAL_GROUP_EXIT) |
| /* Another thread got here before we took the lock. */ |
| exit_code = sig->group_exit_code; |
| else if (sig->group_exec_task) |
| exit_code = 0; |
| else { |
| sig->group_exit_code = exit_code; |
| sig->flags = SIGNAL_GROUP_EXIT; |
| zap_other_threads(current); |
| } |
| spin_unlock_irq(&sighand->siglock); |
| } |
| |
| do_exit(exit_code); |
| /* NOTREACHED */ |
| } |
| |
| /* |
| * this kills every thread in the thread group. Note that any externally |
| * wait4()-ing process will get the correct exit code - even if this |
| * thread is not the thread group leader. |
| */ |
| SYSCALL_DEFINE1(exit_group, int, error_code) |
| { |
| do_group_exit((error_code & 0xff) << 8); |
| /* NOTREACHED */ |
| return 0; |
| } |
| |
| struct waitid_info { |
| pid_t pid; |
| uid_t uid; |
| int status; |
| int cause; |
| }; |
| |
| struct wait_opts { |
| enum pid_type wo_type; |
| int wo_flags; |
| struct pid *wo_pid; |
| |
| struct waitid_info *wo_info; |
| int wo_stat; |
| struct rusage *wo_rusage; |
| |
| wait_queue_entry_t child_wait; |
| int notask_error; |
| }; |
| |
| static int eligible_pid(struct wait_opts *wo, struct task_struct *p) |
| { |
| return wo->wo_type == PIDTYPE_MAX || |
| task_pid_type(p, wo->wo_type) == wo->wo_pid; |
| } |
| |
| static int |
| eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p) |
| { |
| if (!eligible_pid(wo, p)) |
| return 0; |
| |
| /* |
| * Wait for all children (clone and not) if __WALL is set or |
| * if it is traced by us. |
| */ |
| if (ptrace || (wo->wo_flags & __WALL)) |
| return 1; |
| |
| /* |
| * Otherwise, wait for clone children *only* if __WCLONE is set; |
| * otherwise, wait for non-clone children *only*. |
| * |
| * Note: a "clone" child here is one that reports to its parent |
| * using a signal other than SIGCHLD, or a non-leader thread which |
| * we can only see if it is traced by us. |
| */ |
| if ((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE)) |
| return 0; |
| |
| return 1; |
| } |
| |
| /* |
| * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold |
| * read_lock(&tasklist_lock) on entry. If we return zero, we still hold |
| * the lock and this task is uninteresting. If we return nonzero, we have |
| * released the lock and the system call should return. |
| */ |
| static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) |
| { |
| int state, status; |
| pid_t pid = task_pid_vnr(p); |
| uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p)); |
| struct waitid_info *infop; |
| |
| if (!likely(wo->wo_flags & WEXITED)) |
| return 0; |
| |
| if (unlikely(wo->wo_flags & WNOWAIT)) { |
| status = (p->signal->flags & SIGNAL_GROUP_EXIT) |
| ? p->signal->group_exit_code : p->exit_code; |
| get_task_struct(p); |
| read_unlock(&tasklist_lock); |
| sched_annotate_sleep(); |
| if (wo->wo_rusage) |
| getrusage(p, RUSAGE_BOTH, wo->wo_rusage); |
| put_task_struct(p); |
| goto out_info; |
| } |
| /* |
| * Move the task's state to DEAD/TRACE, only one thread can do this. |
| */ |
| state = (ptrace_reparented(p) && thread_group_leader(p)) ? |
| EXIT_TRACE : EXIT_DEAD; |
| if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE) |
| return 0; |
| /* |
| * We own this thread, nobody else can reap it. |
| */ |
| read_unlock(&tasklist_lock); |
| sched_annotate_sleep(); |
| |
| /* |
| * Check thread_group_leader() to exclude the traced sub-threads. |
| */ |
| if (state == EXIT_DEAD && thread_group_leader(p)) { |
| struct signal_struct *sig = p->signal; |
| struct signal_struct *psig = current->signal; |
| unsigned long maxrss; |
| u64 tgutime, tgstime; |
| |
| /* |
| * The resource counters for the group leader are in its |
| * own task_struct. Those for dead threads in the group |
| * are in its signal_struct, as are those for the child |
| * processes it has previously reaped. All these |
| * accumulate in the parent's signal_struct c* fields. |
| * |
| * We don't bother to take a lock here to protect these |
| * p->signal fields because the whole thread group is dead |
| * and nobody can change them. |
| * |
| * psig->stats_lock also protects us from our sub-threads |
| * which can reap other children at the same time. Until |
| * we change k_getrusage()-like users to rely on this lock |
| * we have to take ->siglock as well. |
| * |
| * We use thread_group_cputime_adjusted() to get times for |
| * the thread group, which consolidates times for all threads |
| * in the group including the group leader. |
| */ |
| thread_group_cputime_adjusted(p, &tgutime, &tgstime); |
| spin_lock_irq(¤t->sighand->siglock); |
| write_seqlock(&psig->stats_lock); |
| psig->cutime += tgutime + sig->cutime; |
| psig->cstime += tgstime + sig->cstime; |
| psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime; |
| psig->cmin_flt += |
| p->min_flt + sig->min_flt + sig->cmin_flt; |
| psig->cmaj_flt += |
| p->maj_flt + sig->maj_flt + sig->cmaj_flt; |
| psig->cnvcsw += |
| p->nvcsw + sig->nvcsw + sig->cnvcsw; |
| psig->cnivcsw += |
| p->nivcsw + sig->nivcsw + sig->cnivcsw; |
| psig->cinblock += |
| task_io_get_inblock(p) + |
| sig->inblock + sig->cinblock; |
| psig->coublock += |
| task_io_get_oublock(p) + |
| sig->oublock + sig->coublock; |
| maxrss = max(sig->maxrss, sig->cmaxrss); |
| if (psig->cmaxrss < maxrss) |
| psig->cmaxrss = maxrss; |
| task_io_accounting_add(&psig->ioac, &p->ioac); |
| task_io_accounting_add(&psig->ioac, &sig->ioac); |
| write_sequnlock(&psig->stats_lock); |
| spin_unlock_irq(¤t->sighand->siglock); |
| } |
| |
| if (wo->wo_rusage) |
| getrusage(p, RUSAGE_BOTH, wo->wo_rusage); |
| status = (p->signal->flags & SIGNAL_GROUP_EXIT) |
| ? p->signal->group_exit_code : p->exit_code; |
| wo->wo_stat = status; |
| |
| if (state == EXIT_TRACE) { |
| write_lock_irq(&tasklist_lock); |
| /* We dropped tasklist, ptracer could die and untrace */ |
| ptrace_unlink(p); |
| |
| /* If parent wants a zombie, don't release it now */ |
| state = EXIT_ZOMBIE; |
| if (do_notify_parent(p, p->exit_signal)) |
| state = EXIT_DEAD; |
| p->exit_state = state; |
| write_unlock_irq(&tasklist_lock); |
| } |
| if (state == EXIT_DEAD) |
| release_task(p); |
| |
| out_info: |
| infop = wo->wo_info; |
| if (infop) { |
| if ((status & 0x7f) == 0) { |
| infop->cause = CLD_EXITED; |
| infop->status = status >> 8; |
| } else { |
| infop->cause = (status & 0x80) ? CLD_DUMPED : CLD_KILLED; |
| infop->status = status & 0x7f; |
| } |
| infop->pid = pid; |
| infop->uid = uid; |
| } |
| |
| return pid; |
| } |
| |
| static int *task_stopped_code(struct task_struct *p, bool ptrace) |
| { |
| if (ptrace) { |
| if (task_is_traced(p) && !(p->jobctl & JOBCTL_LISTENING)) |
| return &p->exit_code; |
| } else { |
| if (p->signal->flags & SIGNAL_STOP_STOPPED) |
| return &p->signal->group_exit_code; |
| } |
| return NULL; |
| } |
| |
| /** |
| * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED |
| * @wo: wait options |
| * @ptrace: is the wait for ptrace |
| * @p: task to wait for |
| * |
| * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED. |
| * |
| * CONTEXT: |
| * read_lock(&tasklist_lock), which is released if return value is |
| * non-zero. Also, grabs and releases @p->sighand->siglock. |
| * |
| * RETURNS: |
| * 0 if wait condition didn't exist and search for other wait conditions |
| * should continue. Non-zero return, -errno on failure and @p's pid on |
| * success, implies that tasklist_lock is released and wait condition |
| * search should terminate. |
| */ |
| static int wait_task_stopped(struct wait_opts *wo, |
| int ptrace, struct task_struct *p) |
| { |
| struct waitid_info *infop; |
| int exit_code, *p_code, why; |
| uid_t uid = 0; /* unneeded, required by compiler */ |
| pid_t pid; |
| |
| /* |
| * Traditionally we see ptrace'd stopped tasks regardless of options. |
| */ |
| if (!ptrace && !(wo->wo_flags & WUNTRACED)) |
| return 0; |
| |
| if (!task_stopped_code(p, ptrace)) |
| return 0; |
| |
| exit_code = 0; |
| spin_lock_irq(&p->sighand->siglock); |
| |
| p_code = task_stopped_code(p, ptrace); |
| if (unlikely(!p_code)) |
| goto unlock_sig; |
| |
| exit_code = *p_code; |
| if (!exit_code) |
| goto unlock_sig; |
| |
| if (!unlikely(wo->wo_flags & WNOWAIT)) |
| *p_code = 0; |
| |
| uid = from_kuid_munged(current_user_ns(), task_uid(p)); |
| unlock_sig: |
| spin_unlock_irq(&p->sighand->siglock); |
| if (!exit_code) |
| return 0; |
| |
| /* |
| * Now we are pretty sure this task is interesting. |
| * Make sure it doesn't get reaped out from under us while we |
| * give up the lock and then examine it below. We don't want to |
| * keep holding onto the tasklist_lock while we call getrusage and |
| * possibly take page faults for user memory. |
| */ |
| get_task_struct(p); |
| pid = task_pid_vnr(p); |
| why = ptrace ? CLD_TRAPPED : CLD_STOPPED; |
| read_unlock(&tasklist_lock); |
| sched_annotate_sleep(); |
| if (wo->wo_rusage) |
| getrusage(p, RUSAGE_BOTH, wo->wo_rusage); |
| put_task_struct(p); |
| |
| if (likely(!(wo->wo_flags & WNOWAIT))) |
| wo->wo_stat = (exit_code << 8) | 0x7f; |
| |
| infop = wo->wo_info; |
| if (infop) { |
| infop->cause = why; |
| infop->status = exit_code; |
| infop->pid = pid; |
| infop->uid = uid; |
| } |
| return pid; |
| } |
| |
| /* |
| * Handle do_wait work for one task in a live, non-stopped state. |
| * read_lock(&tasklist_lock) on entry. If we return zero, we still hold |
| * the lock and this task is uninteresting. If we return nonzero, we have |
| * released the lock and the system call should return. |
| */ |
| static int wait_task_continued(struct wait_opts *wo, struct task_struct *p) |
| { |
| struct waitid_info *infop; |
| pid_t pid; |
| uid_t uid; |
| |
| if (!unlikely(wo->wo_flags & WCONTINUED)) |
| return 0; |
| |
| if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) |
| return 0; |
| |
| spin_lock_irq(&p->sighand->siglock); |
| /* Re-check with the lock held. */ |
| if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) { |
| spin_unlock_irq(&p->sighand->siglock); |
| return 0; |
| } |
| if (!unlikely(wo->wo_flags & WNOWAIT)) |
| p->signal->flags &= ~SIGNAL_STOP_CONTINUED; |
| uid = from_kuid_munged(current_user_ns(), task_uid(p)); |
| spin_unlock_irq(&p->sighand->siglock); |
| |
| pid = task_pid_vnr(p); |
| get_task_struct(p); |
| read_unlock(&tasklist_lock); |
| sched_annotate_sleep(); |
| if (wo->wo_rusage) |
| getrusage(p, RUSAGE_BOTH, wo->wo_rusage); |
| put_task_struct(p); |
| |
| infop = wo->wo_info; |
| if (!infop) { |
| wo->wo_stat = 0xffff; |
| } else { |
| infop->cause = CLD_CONTINUED; |
| infop->pid = pid; |
| infop->uid = uid; |
| infop->status = SIGCONT; |
| } |
| return pid; |
| } |
| |
| /* |
| * Consider @p for a wait by @parent. |
| * |
| * -ECHILD should be in ->notask_error before the first call. |
| * Returns nonzero for a final return, when we have unlocked tasklist_lock. |
| * Returns zero if the search for a child should continue; |
| * then ->notask_error is 0 if @p is an eligible child, |
| * or still -ECHILD. |
| */ |
| static int wait_consider_task(struct wait_opts *wo, int ptrace, |
| struct task_struct *p) |
| { |
| /* |
| * We can race with wait_task_zombie() from another thread. |
| * Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition |
| * can't confuse the checks below. |
| */ |
| int exit_state = READ_ONCE(p->exit_state); |
| int ret; |
| |
| if (unlikely(exit_state == EXIT_DEAD)) |
| return 0; |
| |
| ret = eligible_child(wo, ptrace, p); |
| if (!ret) |
| return ret; |
| |
| if (unlikely(exit_state == EXIT_TRACE)) { |
| /* |
| * ptrace == 0 means we are the natural parent. In this case |
| * we should clear notask_error, debugger will notify us. |
| */ |
| if (likely(!ptrace)) |
| wo->notask_error = 0; |
| return 0; |
| } |
| |
| if (likely(!ptrace) && unlikely(p->ptrace)) { |
| /* |
| * If it is traced by its real parent's group, just pretend |
| * the caller is ptrace_do_wait() and reap this child if it |
| * is zombie. |
| * |
| * This also hides group stop state from real parent; otherwise |
| * a single stop can be reported twice as group and ptrace stop. |
| * If a ptracer wants to distinguish these two events for its |
| * own children it should create a separate process which takes |
| * the role of real parent. |
| */ |
| if (!ptrace_reparented(p)) |
| ptrace = 1; |
| } |
| |
| /* slay zombie? */ |
| if (exit_state == EXIT_ZOMBIE) { |
| /* we don't reap group leaders with subthreads */ |
| if (!delay_group_leader(p)) { |
| /* |
| * A zombie ptracee is only visible to its ptracer. |
| * Notification and reaping will be cascaded to the |
| * real parent when the ptracer detaches. |
| */ |
| if (unlikely(ptrace) || likely(!p->ptrace)) |
| return wait_task_zombie(wo, p); |
| } |
| |
| /* |
| * Allow access to stopped/continued state via zombie by |
| * falling through. Clearing of notask_error is complex. |
| * |
| * When !@ptrace: |
| * |
| * If WEXITED is set, notask_error should naturally be |
| * cleared. If not, subset of WSTOPPED|WCONTINUED is set, |
| * so, if there are live subthreads, there are events to |
| * wait for. If all subthreads are dead, it's still safe |
| * to clear - this function will be called again in finite |
| * amount time once all the subthreads are released and |
| * will then return without clearing. |
| * |
| * When @ptrace: |
| * |
| * Stopped state is per-task and thus can't change once the |
| * target task dies. Only continued and exited can happen. |
| * Clear notask_error if WCONTINUED | WEXITED. |
| */ |
| if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED))) |
| wo->notask_error = 0; |
| } else { |
| /* |
| * @p is alive and it's gonna stop, continue or exit, so |
| * there always is something to wait for. |
| */ |
| wo->notask_error = 0; |
| } |
| |
| /* |
| * Wait for stopped. Depending on @ptrace, different stopped state |
| * is used and the two don't interact with each other. |
| */ |
| ret = wait_task_stopped(wo, ptrace, p); |
| if (ret) |
| return ret; |
| |
| /* |
| * Wait for continued. There's only one continued state and the |
| * ptracer can consume it which can confuse the real parent. Don't |
| * use WCONTINUED from ptracer. You don't need or want it. |
| */ |
| return wait_task_continued(wo, p); |
| } |
| |
| /* |
| * Do the work of do_wait() for one thread in the group, @tsk. |
| * |
| * -ECHILD should be in ->notask_error before the first call. |
| * Returns nonzero for a final return, when we have unlocked tasklist_lock. |
| * Returns zero if the search for a child should continue; then |
| * ->notask_error is 0 if there were any eligible children, |
| * or still -ECHILD. |
| */ |
| static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk) |
| { |
| struct task_struct *p; |
| |
| list_for_each_entry(p, &tsk->children, sibling) { |
| int ret = wait_consider_task(wo, 0, p); |
| |
| if (ret) |
| return ret; |
| } |
| |
| return 0; |
| } |
| |
| static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk) |
| { |
| struct task_struct *p; |
| |
| list_for_each_entry(p, &tsk->ptraced, ptrace_entry) { |
| int ret = wait_consider_task(wo, 1, p); |
| |
| if (ret) |
| return ret; |
| } |
| |
| return 0; |
| } |
| |
| static int child_wait_callback(wait_queue_entry_t *wait, unsigned mode, |
| int sync, void *key) |
| { |
| struct wait_opts *wo = container_of(wait, struct wait_opts, |
| child_wait); |
| struct task_struct *p = key; |
| |
| if (!eligible_pid(wo, p)) |
| return 0; |
| |
| if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent) |
| return 0; |
| |
| return default_wake_function(wait, mode, sync, key); |
| } |
| |
| void __wake_up_parent(struct task_struct *p, struct task_struct *parent) |
| { |
| __wake_up_sync_key(&parent->signal->wait_chldexit, |
| TASK_INTERRUPTIBLE, p); |
| } |
| |
| static bool is_effectively_child(struct wait_opts *wo, bool ptrace, |
| struct task_struct *target) |
| { |
| struct task_struct *parent = |
| !ptrace ? target->real_parent : target->parent; |
| |
| return current == parent || (!(wo->wo_flags & __WNOTHREAD) && |
| same_thread_group(current, parent)); |
| } |
| |
| /* |
| * Optimization for waiting on PIDTYPE_PID. No need to iterate through child |
| * and tracee lists to find the target task. |
| */ |
| static int do_wait_pid(struct wait_opts *wo) |
| { |
| bool ptrace; |
| struct task_struct *target; |
| int retval; |
| |
| ptrace = false; |
| target = pid_task(wo->wo_pid, PIDTYPE_TGID); |
| if (target && is_effectively_child(wo, ptrace, target)) { |
| retval = wait_consider_task(wo, ptrace, target); |
| if (retval) |
| return retval; |
| } |
| |
| ptrace = true; |
| target = pid_task(wo->wo_pid, PIDTYPE_PID); |
| if (target && target->ptrace && |
| is_effectively_child(wo, ptrace, target)) { |
| retval = wait_consider_task(wo, ptrace, target); |
| if (retval) |
| return retval; |
| } |
| |
| return 0; |
| } |
| |
| static long do_wait(struct wait_opts *wo) |
| { |
| int retval; |
| |
| trace_sched_process_wait(wo->wo_pid); |
| |
| init_waitqueue_func_entry(&wo->child_wait, child_wait_callback); |
| wo->child_wait.private = current; |
| add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); |
| repeat: |
| /* |
| * If there is nothing that can match our criteria, just get out. |
| * We will clear ->notask_error to zero if we see any child that |
| * might later match our criteria, even if we are not able to reap |
| * it yet. |
| */ |
| wo->notask_error = -ECHILD; |
| if ((wo->wo_type < PIDTYPE_MAX) && |
| (!wo->wo_pid || !pid_has_task(wo->wo_pid, wo->wo_type))) |
| goto notask; |
| |
| set_current_state(TASK_INTERRUPTIBLE); |
| read_lock(&tasklist_lock); |
| |
| if (wo->wo_type == PIDTYPE_PID) { |
| retval = do_wait_pid(wo); |
| if (retval) |
| goto end; |
| } else { |
| struct task_struct *tsk = current; |
| |
| do { |
| retval = do_wait_thread(wo, tsk); |
| if (retval) |
| goto end; |
| |
| retval = ptrace_do_wait(wo, tsk); |
| if (retval) |
| goto end; |
| |
| if (wo->wo_flags & __WNOTHREAD) |
| break; |
| } while_each_thread(current, tsk); |
| } |
| read_unlock(&tasklist_lock); |
| |
| notask: |
| retval = wo->notask_error; |
| if (!retval && !(wo->wo_flags & WNOHANG)) { |
| retval = -ERESTARTSYS; |
| if (!signal_pending(current)) { |
| schedule(); |
| goto repeat; |
| } |
| } |
| end: |
| __set_current_state(TASK_RUNNING); |
| remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); |
| return retval; |
| } |
| |
| static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop, |
| int options, struct rusage *ru) |
| { |
| struct wait_opts wo; |
| struct pid *pid = NULL; |
| enum pid_type type; |
| long ret; |
| unsigned int f_flags = 0; |
| |
| if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED| |
| __WNOTHREAD|__WCLONE|__WALL)) |
| return -EINVAL; |
| if (!(options & (WEXITED|WSTOPPED|WCONTINUED))) |
| return -EINVAL; |
| |
| switch (which) { |
| case P_ALL: |
| type = PIDTYPE_MAX; |
| break; |
| case P_PID: |
| type = PIDTYPE_PID; |
| if (upid <= 0) |
| return -EINVAL; |
| |
| pid = find_get_pid(upid); |
| break; |
| case P_PGID: |
| type = PIDTYPE_PGID; |
| if (upid < 0) |
| return -EINVAL; |
| |
| if (upid) |
| pid = find_get_pid(upid); |
| else |
| pid = get_task_pid(current, PIDTYPE_PGID); |
| break; |
| case P_PIDFD: |
| type = PIDTYPE_PID; |
| if (upid < 0) |
| return -EINVAL; |
| |
| pid = pidfd_get_pid(upid, &f_flags); |
| if (IS_ERR(pid)) |
| return PTR_ERR(pid); |
| |
| break; |
| default: |
| return -EINVAL; |
| } |
| |
| wo.wo_type = type; |
| wo.wo_pid = pid; |
| wo.wo_flags = options; |
| wo.wo_info = infop; |
| wo.wo_rusage = ru; |
| if (f_flags & O_NONBLOCK) |
| wo.wo_flags |= WNOHANG; |
| |
| ret = do_wait(&wo); |
| if (!ret && !(options & WNOHANG) && (f_flags & O_NONBLOCK)) |
| ret = -EAGAIN; |
| |
| put_pid(pid); |
| return ret; |
| } |
| |
| SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, |
| infop, int, options, struct rusage __user *, ru) |
| { |
| struct rusage r; |
| struct waitid_info info = {.status = 0}; |
| long err = kernel_waitid(which, upid, &info, options, ru ? &r : NULL); |
| int signo = 0; |
| |
| if (err > 0) { |
| signo = SIGCHLD; |
| err = 0; |
| if (ru && copy_to_user(ru, &r, sizeof(struct rusage))) |
| return -EFAULT; |
| } |
| if (!infop) |
| return err; |
| |
| if (!user_write_access_begin(infop, sizeof(*infop))) |
| return -EFAULT; |
| |
| unsafe_put_user(signo, &infop->si_signo, Efault); |
| unsafe_put_user(0, &infop->si_errno, Efault); |
| unsafe_put_user(info.cause, &infop->si_code, Efault); |
| unsafe_put_user(info.pid, &infop->si_pid, Efault); |
| unsafe_put_user(info.uid, &infop->si_uid, Efault); |
| unsafe_put_user(info.status, &infop->si_status, Efault); |
| user_write_access_end(); |
| return err; |
| Efault: |
| user_write_access_end(); |
| return -EFAULT; |
| } |
| |
| long kernel_wait4(pid_t upid, int __user *stat_addr, int options, |
| struct rusage *ru) |
| { |
| struct wait_opts wo; |
| struct pid *pid = NULL; |
| enum pid_type type; |
| long ret; |
| |
| if (options & ~(WNOHANG|WUNTRACED|WCONTINUED| |
| __WNOTHREAD|__WCLONE|__WALL)) |
| return -EINVAL; |
| |
| /* -INT_MIN is not defined */ |
| if (upid == INT_MIN) |
| return -ESRCH; |
| |
| if (upid == -1) |
| type = PIDTYPE_MAX; |
| else if (upid < 0) { |
| type = PIDTYPE_PGID; |
| pid = find_get_pid(-upid); |
| } else if (upid == 0) { |
| type = PIDTYPE_PGID; |
| pid = get_task_pid(current, PIDTYPE_PGID); |
| } else /* upid > 0 */ { |
| type = PIDTYPE_PID; |
| pid = find_get_pid(upid); |
| } |
| |
| wo.wo_type = type; |
| wo.wo_pid = pid; |
| wo.wo_flags = options | WEXITED; |
| wo.wo_info = NULL; |
| wo.wo_stat = 0; |
| wo.wo_rusage = ru; |
| ret = do_wait(&wo); |
| put_pid(pid); |
| if (ret > 0 && stat_addr && put_user(wo.wo_stat, stat_addr)) |
| ret = -EFAULT; |
| |
| return ret; |
| } |
| |
| int kernel_wait(pid_t pid, int *stat) |
| { |
| struct wait_opts wo = { |
| .wo_type = PIDTYPE_PID, |
| .wo_pid = find_get_pid(pid), |
| .wo_flags = WEXITED, |
| }; |
| int ret; |
| |
| ret = do_wait(&wo); |
| if (ret > 0 && wo.wo_stat) |
| *stat = wo.wo_stat; |
| put_pid(wo.wo_pid); |
| return ret; |
| } |
| |
| SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr, |
| int, options, struct rusage __user *, ru) |
| { |
| struct rusage r; |
| long err = kernel_wait4(upid, stat_addr, options, ru ? &r : NULL); |
| |
| if (err > 0) { |
| if (ru && copy_to_user(ru, &r, sizeof(struct rusage))) |
| return -EFAULT; |
| } |
| return err; |
| } |
| |
| #ifdef __ARCH_WANT_SYS_WAITPID |
| |
| /* |
| * sys_waitpid() remains for compatibility. waitpid() should be |
| * implemented by calling sys_wait4() from libc.a. |
| */ |
| SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options) |
| { |
| return kernel_wait4(pid, stat_addr, options, NULL); |
| } |
| |
| #endif |
| |
| #ifdef CONFIG_COMPAT |
| COMPAT_SYSCALL_DEFINE4(wait4, |
| compat_pid_t, pid, |
| compat_uint_t __user *, stat_addr, |
| int, options, |
| struct compat_rusage __user *, ru) |
| { |
| struct rusage r; |
| long err = kernel_wait4(pid, stat_addr, options, ru ? &r : NULL); |
| if (err > 0) { |
| if (ru && put_compat_rusage(&r, ru)) |
| return -EFAULT; |
| } |
| return err; |
| } |
| |
| COMPAT_SYSCALL_DEFINE5(waitid, |
| int, which, compat_pid_t, pid, |
| struct compat_siginfo __user *, infop, int, options, |
| struct compat_rusage __user *, uru) |
| { |
| struct rusage ru; |
| struct waitid_info info = {.status = 0}; |
| long err = kernel_waitid(which, pid, &info, options, uru ? &ru : NULL); |
| int signo = 0; |
| if (err > 0) { |
| signo = SIGCHLD; |
| err = 0; |
| if (uru) { |
| /* kernel_waitid() overwrites everything in ru */ |
| if (COMPAT_USE_64BIT_TIME) |
| err = copy_to_user(uru, &ru, sizeof(ru)); |
| else |
| err = put_compat_rusage(&ru, uru); |
| if (err) |
| return -EFAULT; |
| } |
| } |
| |
| if (!infop) |
| return err; |
| |
| if (!user_write_access_begin(infop, sizeof(*infop))) |
| return -EFAULT; |
| |
| unsafe_put_user(signo, &infop->si_signo, Efault); |
| unsafe_put_user(0, &infop->si_errno, Efault); |
| unsafe_put_user(info.cause, &infop->si_code, Efault); |
| unsafe_put_user(info.pid, &infop->si_pid, Efault); |
| unsafe_put_user(info.uid, &infop->si_uid, Efault); |
| unsafe_put_user(info.status, &infop->si_status, Efault); |
| user_write_access_end(); |
| return err; |
| Efault: |
| user_write_access_end(); |
| return -EFAULT; |
| } |
| #endif |
| |
| /** |
| * thread_group_exited - check that a thread group has exited |
| * @pid: tgid of thread group to be checked. |
| * |
| * Test if the thread group represented by tgid has exited (all |
| * threads are zombies, dead or completely gone). |
| * |
| * Return: true if the thread group has exited. false otherwise. |
| */ |
| bool thread_group_exited(struct pid *pid) |
| { |
| struct task_struct *task; |
| bool exited; |
| |
| rcu_read_lock(); |
| task = pid_task(pid, PIDTYPE_PID); |
| exited = !task || |
| (READ_ONCE(task->exit_state) && thread_group_empty(task)); |
| rcu_read_unlock(); |
| |
| return exited; |
| } |
| EXPORT_SYMBOL(thread_group_exited); |
| |
| /* |
| * This needs to be __function_aligned as GCC implicitly makes any |
| * implementation of abort() cold and drops alignment specified by |
| * -falign-functions=N. |
| * |
| * See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88345#c11 |
| */ |
| __weak __function_aligned void abort(void) |
| { |
| BUG(); |
| |
| /* if that doesn't kill us, halt */ |
| panic("Oops failed to kill thread"); |
| } |
| EXPORT_SYMBOL(abort); |