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-rw-r--r--kernel/exit.c1924
1 files changed, 1924 insertions, 0 deletions
diff --git a/kernel/exit.c b/kernel/exit.c
new file mode 100644
index 0000000000..21a59a6e1f
--- /dev/null
+++ b/kernel/exit.c
@@ -0,0 +1,1924 @@
+// 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/user_events.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);
+
+ /* The vhost_worker does not particpate in coredumps */
+ if (core_state &&
+ ((tsk->flags & (PF_IO_WORKER | PF_USER_WORKER)) != PF_USER_WORKER)) {
+ 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_lazy_tlb(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);
+ user_events_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);
+ }
+ 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);
+
+ 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(&current->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(&current->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(&current->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(&current->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);