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authorAnton Arapov <anton@redhat.com>2012-04-16 10:05:28 +0200
committerAnton Arapov <anton@redhat.com>2012-04-16 10:05:28 +0200
commitb4b6116a13633898cf868f2f103c96a90c4c20f8 (patch)
tree93d1b7e2cfcdf473d8d4ff3ad141fa864f8491f6 /kernel/exit.c
parentedd4be777c953e5faafc80d091d3084b4343f5d3 (diff)
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fedora kernel: d9aad82f3319f3cfd1aebc01234254ef0c37ad84v3.3.2-1
Signed-off-by: Anton Arapov <anton@redhat.com>
Diffstat (limited to 'kernel/exit.c')
-rw-r--r--kernel/exit.c1868
1 files changed, 1868 insertions, 0 deletions
diff --git a/kernel/exit.c b/kernel/exit.c
new file mode 100644
index 00000000000..4b4042f9bc6
--- /dev/null
+++ b/kernel/exit.c
@@ -0,0 +1,1868 @@
+/*
+ * linux/kernel/exit.c
+ *
+ * Copyright (C) 1991, 1992 Linus Torvalds
+ */
+
+#include <linux/mm.h>
+#include <linux/slab.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/security.h>
+#include <linux/cpu.h>
+#include <linux/acct.h>
+#include <linux/tsacct_kern.h>
+#include <linux/file.h>
+#include <linux/fdtable.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/freezer.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/blkdev.h>
+#include <linux/task_io_accounting_ops.h>
+#include <linux/tracehook.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 <asm/uaccess.h>
+#include <asm/unistd.h>
+#include <asm/pgtable.h>
+#include <asm/mmu_context.h>
+
+static void exit_mm(struct task_struct * tsk);
+
+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_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);
+}
+
+/*
+ * 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 *uninitialized_var(tty);
+
+ sighand = rcu_dereference_check(tsk->sighand,
+ lockdep_tasklist_lock_is_held());
+ spin_lock(&sighand->siglock);
+
+ posix_cpu_timers_exit(tsk);
+ if (group_dead) {
+ posix_cpu_timers_exit_group(tsk);
+ tty = sig->tty;
+ sig->tty = NULL;
+ } else {
+ /*
+ * This can only happen if the caller is de_thread().
+ * FIXME: this is the temporary hack, we should teach
+ * posix-cpu-timers to handle this case correctly.
+ */
+ if (unlikely(has_group_leader_pid(tsk)))
+ posix_cpu_timers_exit_group(tsk);
+
+ /*
+ * 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_exit_task);
+
+ if (tsk == sig->curr_target)
+ sig->curr_target = next_thread(tsk);
+ /*
+ * Accumulate here the counters for all threads but the
+ * group leader as they die, so they can be added into
+ * the process-wide totals when those are taken.
+ * The group leader stays around as a zombie as long
+ * as there are other threads. When it gets reaped,
+ * the exit.c code will add its counts into these totals.
+ * We won't ever get here for the group leader, since it
+ * will have been the last reference on the signal_struct.
+ */
+ sig->utime += tsk->utime;
+ sig->stime += tsk->stime;
+ sig->gtime += tsk->gtime;
+ 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);
+
+ /*
+ * 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);
+
+ perf_event_delayed_put(tsk);
+ trace_sched_process_free(tsk);
+ put_task_struct(tsk);
+}
+
+
+void release_task(struct task_struct * p)
+{
+ struct task_struct *leader;
+ 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();
+ atomic_dec(&__task_cred(p)->user->processes);
+ rcu_read_unlock();
+
+ proc_flush_task(p);
+
+ write_lock_irq(&tasklist_lock);
+ ptrace_release_task(p);
+ __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);
+ release_thread(p);
+ call_rcu(&p->rcu, delayed_put_task_struct);
+
+ p = leader;
+ if (unlikely(zap_leader))
+ goto repeat;
+}
+
+/*
+ * This checks not only the pgrp, but falls back on the pid if no
+ * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
+ * without this...
+ *
+ * The caller must hold rcu lock or the tasklist lock.
+ */
+struct pid *session_of_pgrp(struct pid *pgrp)
+{
+ struct task_struct *p;
+ struct pid *sid = NULL;
+
+ p = pid_task(pgrp, PIDTYPE_PGID);
+ if (p == NULL)
+ p = pid_task(pgrp, PIDTYPE_PID);
+ if (p != NULL)
+ sid = task_session(p);
+
+ return sid;
+}
+
+/*
+ * 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);
+ }
+}
+
+/**
+ * reparent_to_kthreadd - Reparent the calling kernel thread to kthreadd
+ *
+ * If a kernel thread is launched as a result of a system call, or if
+ * it ever exits, it should generally reparent itself to kthreadd so it
+ * isn't in the way of other processes and is correctly cleaned up on exit.
+ *
+ * The various task state such as scheduling policy and priority may have
+ * been inherited from a user process, so we reset them to sane values here.
+ *
+ * NOTE that reparent_to_kthreadd() gives the caller full capabilities.
+ */
+static void reparent_to_kthreadd(void)
+{
+ write_lock_irq(&tasklist_lock);
+
+ ptrace_unlink(current);
+ /* Reparent to init */
+ current->real_parent = current->parent = kthreadd_task;
+ list_move_tail(&current->sibling, &current->real_parent->children);
+
+ /* Set the exit signal to SIGCHLD so we signal init on exit */
+ current->exit_signal = SIGCHLD;
+
+ if (task_nice(current) < 0)
+ set_user_nice(current, 0);
+ /* cpus_allowed? */
+ /* rt_priority? */
+ /* signals? */
+ memcpy(current->signal->rlim, init_task.signal->rlim,
+ sizeof(current->signal->rlim));
+
+ atomic_inc(&init_cred.usage);
+ commit_creds(&init_cred);
+ write_unlock_irq(&tasklist_lock);
+}
+
+void __set_special_pids(struct pid *pid)
+{
+ struct task_struct *curr = current->group_leader;
+
+ if (task_session(curr) != pid)
+ change_pid(curr, PIDTYPE_SID, pid);
+
+ if (task_pgrp(curr) != pid)
+ change_pid(curr, PIDTYPE_PGID, pid);
+}
+
+static void set_special_pids(struct pid *pid)
+{
+ write_lock_irq(&tasklist_lock);
+ __set_special_pids(pid);
+ write_unlock_irq(&tasklist_lock);
+}
+
+/*
+ * Let kernel threads use this to say that they allow a certain signal.
+ * Must not be used if kthread was cloned with CLONE_SIGHAND.
+ */
+int allow_signal(int sig)
+{
+ if (!valid_signal(sig) || sig < 1)
+ return -EINVAL;
+
+ spin_lock_irq(&current->sighand->siglock);
+ /* This is only needed for daemonize()'ed kthreads */
+ sigdelset(&current->blocked, sig);
+ /*
+ * Kernel threads handle their own signals. Let the signal code
+ * know it'll be handled, so that they don't get converted to
+ * SIGKILL or just silently dropped.
+ */
+ current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
+ recalc_sigpending();
+ spin_unlock_irq(&current->sighand->siglock);
+ return 0;
+}
+
+EXPORT_SYMBOL(allow_signal);
+
+int disallow_signal(int sig)
+{
+ if (!valid_signal(sig) || sig < 1)
+ return -EINVAL;
+
+ spin_lock_irq(&current->sighand->siglock);
+ current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN;
+ recalc_sigpending();
+ spin_unlock_irq(&current->sighand->siglock);
+ return 0;
+}
+
+EXPORT_SYMBOL(disallow_signal);
+
+/*
+ * Put all the gunge required to become a kernel thread without
+ * attached user resources in one place where it belongs.
+ */
+
+void daemonize(const char *name, ...)
+{
+ va_list args;
+ sigset_t blocked;
+
+ va_start(args, name);
+ vsnprintf(current->comm, sizeof(current->comm), name, args);
+ va_end(args);
+
+ /*
+ * If we were started as result of loading a module, close all of the
+ * user space pages. We don't need them, and if we didn't close them
+ * they would be locked into memory.
+ */
+ exit_mm(current);
+ /*
+ * We don't want to have TIF_FREEZE set if the system-wide hibernation
+ * or suspend transition begins right now.
+ */
+ current->flags |= (PF_NOFREEZE | PF_KTHREAD);
+
+ if (current->nsproxy != &init_nsproxy) {
+ get_nsproxy(&init_nsproxy);
+ switch_task_namespaces(current, &init_nsproxy);
+ }
+ set_special_pids(&init_struct_pid);
+ proc_clear_tty(current);
+
+ /* Block and flush all signals */
+ sigfillset(&blocked);
+ sigprocmask(SIG_BLOCK, &blocked, NULL);
+ flush_signals(current);
+
+ /* Become as one with the init task */
+
+ daemonize_fs_struct();
+ exit_files(current);
+ current->files = init_task.files;
+ atomic_inc(&current->files->count);
+
+ reparent_to_kthreadd();
+}
+
+EXPORT_SYMBOL(daemonize);
+
+static void close_files(struct files_struct * files)
+{
+ int i, j;
+ struct fdtable *fdt;
+
+ j = 0;
+
+ /*
+ * It is safe to dereference the fd table without RCU or
+ * ->file_lock because this is the last reference to the
+ * files structure. But use RCU to shut RCU-lockdep up.
+ */
+ rcu_read_lock();
+ fdt = files_fdtable(files);
+ rcu_read_unlock();
+ for (;;) {
+ unsigned long set;
+ i = j * __NFDBITS;
+ if (i >= fdt->max_fds)
+ break;
+ set = fdt->open_fds->fds_bits[j++];
+ while (set) {
+ if (set & 1) {
+ struct file * file = xchg(&fdt->fd[i], NULL);
+ if (file) {
+ filp_close(file, files);
+ cond_resched();
+ }
+ }
+ i++;
+ set >>= 1;
+ }
+ }
+}
+
+struct files_struct *get_files_struct(struct task_struct *task)
+{
+ struct files_struct *files;
+
+ task_lock(task);
+ files = task->files;
+ if (files)
+ atomic_inc(&files->count);
+ task_unlock(task);
+
+ return files;
+}
+
+void put_files_struct(struct files_struct *files)
+{
+ struct fdtable *fdt;
+
+ if (atomic_dec_and_test(&files->count)) {
+ close_files(files);
+ /*
+ * Free the fd and fdset arrays if we expanded them.
+ * If the fdtable was embedded, pass files for freeing
+ * at the end of the RCU grace period. Otherwise,
+ * you can free files immediately.
+ */
+ rcu_read_lock();
+ fdt = files_fdtable(files);
+ if (fdt != &files->fdtab)
+ kmem_cache_free(files_cachep, files);
+ free_fdtable(fdt);
+ rcu_read_unlock();
+ }
+}
+
+void reset_files_struct(struct files_struct *files)
+{
+ struct task_struct *tsk = current;
+ struct files_struct *old;
+
+ old = tsk->files;
+ task_lock(tsk);
+ tsk->files = files;
+ task_unlock(tsk);
+ put_files_struct(old);
+}
+
+void exit_files(struct task_struct *tsk)
+{
+ struct files_struct * files = tsk->files;
+
+ if (files) {
+ task_lock(tsk);
+ tsk->files = NULL;
+ task_unlock(tsk);
+ put_files_struct(files);
+ }
+}
+
+#ifdef CONFIG_MM_OWNER
+/*
+ * 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) {
+ 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
+ */
+ do_each_thread(g, c) {
+ if (c->mm == mm)
+ goto assign_new_owner;
+ } while_each_thread(g, c);
+
+ 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.
+ */
+ 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;
+ }
+ mm->owner = c;
+ task_unlock(c);
+ put_task_struct(c);
+}
+#endif /* CONFIG_MM_OWNER */
+
+/*
+ * Turn us into a lazy TLB process if we
+ * aren't already..
+ */
+static void exit_mm(struct task_struct * tsk)
+{
+ struct mm_struct *mm = tsk->mm;
+ struct core_state *core_state;
+
+ mm_release(tsk, mm);
+ if (!mm)
+ return;
+ /*
+ * Serialize with any possible pending coredump.
+ * We must hold mmap_sem around checking core_state
+ * and clearing tsk->mm. The core-inducing thread
+ * will increment ->nr_threads for each thread in the
+ * group with ->mm != NULL.
+ */
+ down_read(&mm->mmap_sem);
+ core_state = mm->core_state;
+ if (core_state) {
+ struct core_thread self;
+ up_read(&mm->mmap_sem);
+
+ self.task = tsk;
+ self.next = xchg(&core_state->dumper.next, &self);
+ /*
+ * 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_task_state(tsk, TASK_UNINTERRUPTIBLE);
+ if (!self.task) /* see coredump_finish() */
+ break;
+ schedule();
+ }
+ __set_task_state(tsk, TASK_RUNNING);
+ down_read(&mm->mmap_sem);
+ }
+ atomic_inc(&mm->mm_count);
+ BUG_ON(mm != tsk->active_mm);
+ /* more a memory barrier than a real lock */
+ task_lock(tsk);
+ tsk->mm = NULL;
+ up_read(&mm->mmap_sem);
+ enter_lazy_tlb(mm, current);
+ task_unlock(tsk);
+ mm_update_next_owner(mm);
+ mmput(mm);
+}
+
+/*
+ * When we die, we re-parent all our children.
+ * Try to give them to another thread in our thread
+ * group, and if no such member exists, give it to
+ * the child reaper process (ie "init") in our pid
+ * space.
+ */
+static struct task_struct *find_new_reaper(struct task_struct *father)
+ __releases(&tasklist_lock)
+ __acquires(&tasklist_lock)
+{
+ struct pid_namespace *pid_ns = task_active_pid_ns(father);
+ struct task_struct *thread;
+
+ thread = father;
+ while_each_thread(father, thread) {
+ if (thread->flags & PF_EXITING)
+ continue;
+ if (unlikely(pid_ns->child_reaper == father))
+ pid_ns->child_reaper = thread;
+ return thread;
+ }
+
+ if (unlikely(pid_ns->child_reaper == father)) {
+ write_unlock_irq(&tasklist_lock);
+ if (unlikely(pid_ns == &init_pid_ns))
+ panic("Attempted to kill init!");
+
+ zap_pid_ns_processes(pid_ns);
+ write_lock_irq(&tasklist_lock);
+ /*
+ * We can not clear ->child_reaper or leave it alone.
+ * There may by stealth EXIT_DEAD tasks on ->children,
+ * forget_original_parent() must move them somewhere.
+ */
+ pid_ns->child_reaper = init_pid_ns.child_reaper;
+ }
+
+ return pid_ns->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)
+{
+ list_move_tail(&p->sibling, &p->real_parent->children);
+
+ if (p->exit_state == EXIT_DEAD)
+ return;
+ /*
+ * If this is a threaded reparent there is no need to
+ * notify anyone anything has happened.
+ */
+ if (same_thread_group(p->real_parent, father))
+ 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_move_tail(&p->sibling, dead);
+ }
+ }
+
+ kill_orphaned_pgrp(p, father);
+}
+
+static void forget_original_parent(struct task_struct *father)
+{
+ struct task_struct *p, *n, *reaper;
+ LIST_HEAD(dead_children);
+
+ write_lock_irq(&tasklist_lock);
+ /*
+ * Note that exit_ptrace() and find_new_reaper() might
+ * drop tasklist_lock and reacquire it.
+ */
+ exit_ptrace(father);
+ reaper = find_new_reaper(father);
+
+ list_for_each_entry_safe(p, n, &father->children, sibling) {
+ struct task_struct *t = p;
+ do {
+ t->real_parent = reaper;
+ if (t->parent == father) {
+ BUG_ON(t->ptrace);
+ t->parent = t->real_parent;
+ }
+ if (t->pdeath_signal)
+ group_send_sig_info(t->pdeath_signal,
+ SEND_SIG_NOINFO, t);
+ } while_each_thread(p, t);
+ reparent_leader(father, p, &dead_children);
+ }
+ write_unlock_irq(&tasklist_lock);
+
+ BUG_ON(!list_empty(&father->children));
+
+ list_for_each_entry_safe(p, n, &dead_children, sibling) {
+ list_del_init(&p->sibling);
+ release_task(p);
+ }
+}
+
+/*
+ * 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;
+
+ /*
+ * 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)
+ */
+ forget_original_parent(tsk);
+ exit_task_namespaces(tsk);
+
+ write_lock_irq(&tasklist_lock);
+ if (group_dead)
+ kill_orphaned_pgrp(tsk->group_leader, NULL);
+
+ /* Let father know we died
+ *
+ * Thread signals are configurable, but you aren't going to use
+ * that to send signals to arbitrary processes.
+ * That stops right now.
+ *
+ * If the parent exec id doesn't match the exec id we saved
+ * when we started then we know the parent has changed security
+ * domain.
+ *
+ * If our self_exec id doesn't match our parent_exec_id then
+ * we have changed execution domain as these two values started
+ * the same after a fork.
+ */
+ if (thread_group_leader(tsk) && tsk->exit_signal != SIGCHLD &&
+ (tsk->parent_exec_id != tsk->real_parent->self_exec_id ||
+ tsk->self_exec_id != tsk->parent_exec_id))
+ tsk->exit_signal = SIGCHLD;
+
+ 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;
+ }
+
+ tsk->exit_state = autoreap ? EXIT_DEAD : EXIT_ZOMBIE;
+
+ /* mt-exec, de_thread() is waiting for group leader */
+ if (unlikely(tsk->signal->notify_count < 0))
+ wake_up_process(tsk->signal->group_exit_task);
+ write_unlock_irq(&tasklist_lock);
+
+ /* If the process is dead, release it - nobody will wait for it */
+ if (autoreap)
+ release_task(tsk);
+}
+
+#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) {
+ printk(KERN_WARNING "%s used greatest stack depth: %lu bytes "
+ "left\n",
+ current->comm, free);
+ lowest_to_date = free;
+ }
+ spin_unlock(&low_water_lock);
+}
+#else
+static inline void check_stack_usage(void) {}
+#endif
+
+void do_exit(long code)
+{
+ struct task_struct *tsk = current;
+ int group_dead;
+
+ profile_task_exit(tsk);
+
+ WARN_ON(blk_needs_flush_plug(tsk));
+
+ if (unlikely(in_interrupt()))
+ panic("Aiee, killing interrupt handler!");
+ if (unlikely(!tsk->pid))
+ panic("Attempted to kill the idle task!");
+
+ /*
+ * If do_exit is called because this processes oopsed, it's possible
+ * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before
+ * continuing. Amongst other possible reasons, this is to prevent
+ * mm_release()->clear_child_tid() from writing to a user-controlled
+ * kernel address.
+ */
+ set_fs(USER_DS);
+
+ ptrace_event(PTRACE_EVENT_EXIT, code);
+
+ validate_creds_for_do_exit(tsk);
+
+ /*
+ * We're taking recursive faults here in do_exit. Safest is to just
+ * leave this task alone and wait for reboot.
+ */
+ if (unlikely(tsk->flags & PF_EXITING)) {
+ printk(KERN_ALERT
+ "Fixing recursive fault but reboot is needed!\n");
+ /*
+ * We can do this unlocked here. The futex code uses
+ * this flag just to verify whether the pi state
+ * cleanup has been done or not. In the worst case it
+ * loops once more. We pretend that the cleanup was
+ * done as there is no way to return. Either the
+ * OWNER_DIED bit is set by now or we push the blocked
+ * task into the wait for ever nirwana as well.
+ */
+ tsk->flags |= PF_EXITPIDONE;
+ set_current_state(TASK_UNINTERRUPTIBLE);
+ schedule();
+ }
+
+ exit_irq_thread();
+
+ exit_signals(tsk); /* sets PF_EXITING */
+ /*
+ * tsk->flags are checked in the futex code to protect against
+ * an exiting task cleaning up the robust pi futexes.
+ */
+ smp_mb();
+ raw_spin_unlock_wait(&tsk->pi_lock);
+
+ if (unlikely(in_atomic()))
+ printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
+ current->comm, task_pid_nr(current),
+ preempt_count());
+
+ acct_update_integrals(tsk);
+ /* sync mm's RSS info before statistics gathering */
+ if (tsk->mm)
+ sync_mm_rss(tsk, tsk->mm);
+ group_dead = atomic_dec_and_test(&tsk->signal->live);
+ if (group_dead) {
+ hrtimer_cancel(&tsk->signal->real_timer);
+ exit_itimers(tsk->signal);
+ 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(tsk);
+
+ if (group_dead)
+ acct_process();
+ trace_sched_process_exit(tsk);
+
+ exit_sem(tsk);
+ exit_shm(tsk);
+ exit_files(tsk);
+ exit_fs(tsk);
+ check_stack_usage();
+ exit_thread();
+
+ /*
+ * 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);
+
+ cgroup_exit(tsk, 1);
+
+ if (group_dead)
+ disassociate_ctty(1);
+
+ module_put(task_thread_info(tsk)->exec_domain->module);
+
+ proc_exit_connector(tsk);
+
+ /*
+ * FIXME: do that only when needed, using sched_exit tracepoint
+ */
+ ptrace_put_breakpoints(tsk);
+
+ exit_notify(tsk, group_dead);
+#ifdef CONFIG_NUMA
+ task_lock(tsk);
+ mpol_put(tsk->mempolicy);
+ tsk->mempolicy = NULL;
+ task_unlock(tsk);
+#endif
+#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(tsk);
+ /*
+ * We can do this unlocked here. The futex code uses this flag
+ * just to verify whether the pi state cleanup has been done
+ * or not. In the worst case it loops once more.
+ */
+ tsk->flags |= PF_EXITPIDONE;
+
+ if (tsk->io_context)
+ exit_io_context(tsk);
+
+ if (tsk->splice_pipe)
+ __free_pipe_info(tsk->splice_pipe);
+
+ validate_creds_for_do_exit(tsk);
+
+ preempt_disable();
+ if (tsk->nr_dirtied)
+ __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied);
+ exit_rcu();
+
+ /*
+ * The setting of TASK_RUNNING by try_to_wake_up() may be delayed
+ * when the following two conditions become true.
+ * - There is race condition of mmap_sem (It is acquired by
+ * exit_mm()), and
+ * - SMI occurs before setting TASK_RUNINNG.
+ * (or hypervisor of virtual machine switches to other guest)
+ * As a result, we may become TASK_RUNNING after becoming TASK_DEAD
+ *
+ * To avoid it, we have to wait for releasing tsk->pi_lock which
+ * is held by try_to_wake_up()
+ */
+ smp_mb();
+ raw_spin_unlock_wait(&tsk->pi_lock);
+
+ /* causes final put_task_struct in finish_task_switch(). */
+ tsk->state = TASK_DEAD;
+ tsk->flags |= PF_NOFREEZE; /* tell freezer to ignore us */
+ schedule();
+ BUG();
+ /* Avoid "noreturn function does return". */
+ for (;;)
+ cpu_relax(); /* For when BUG is null */
+}
+
+EXPORT_SYMBOL_GPL(do_exit);
+
+void complete_and_exit(struct completion *comp, long code)
+{
+ if (comp)
+ complete(comp);
+
+ do_exit(code);
+}
+
+EXPORT_SYMBOL(complete_and_exit);
+
+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
+do_group_exit(int exit_code)
+{
+ struct signal_struct *sig = current->signal;
+
+ BUG_ON(exit_code & 0x80); /* core dumps don't get here */
+
+ if (signal_group_exit(sig))
+ exit_code = sig->group_exit_code;
+ else if (!thread_group_empty(current)) {
+ struct sighand_struct *const sighand = current->sighand;
+ spin_lock_irq(&sighand->siglock);
+ if (signal_group_exit(sig))
+ /* Another thread got here before we took the lock. */
+ exit_code = sig->group_exit_code;
+ 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 wait_opts {
+ enum pid_type wo_type;
+ int wo_flags;
+ struct pid *wo_pid;
+
+ struct siginfo __user *wo_info;
+ int __user *wo_stat;
+ struct rusage __user *wo_rusage;
+
+ wait_queue_t child_wait;
+ int notask_error;
+};
+
+static inline
+struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
+{
+ if (type != PIDTYPE_PID)
+ task = task->group_leader;
+ return task->pids[type].pid;
+}
+
+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, struct task_struct *p)
+{
+ if (!eligible_pid(wo, p))
+ return 0;
+ /* Wait for all children (clone and not) if __WALL is set;
+ * 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.) */
+ if (((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))
+ && !(wo->wo_flags & __WALL))
+ return 0;
+
+ return 1;
+}
+
+static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p,
+ pid_t pid, uid_t uid, int why, int status)
+{
+ struct siginfo __user *infop;
+ int retval = wo->wo_rusage
+ ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
+
+ put_task_struct(p);
+ infop = wo->wo_info;
+ if (infop) {
+ if (!retval)
+ retval = put_user(SIGCHLD, &infop->si_signo);
+ if (!retval)
+ retval = put_user(0, &infop->si_errno);
+ if (!retval)
+ retval = put_user((short)why, &infop->si_code);
+ if (!retval)
+ retval = put_user(pid, &infop->si_pid);
+ if (!retval)
+ retval = put_user(uid, &infop->si_uid);
+ if (!retval)
+ retval = put_user(status, &infop->si_status);
+ }
+ if (!retval)
+ retval = pid;
+ return retval;
+}
+
+/*
+ * 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)
+{
+ unsigned long state;
+ int retval, status, traced;
+ pid_t pid = task_pid_vnr(p);
+ uid_t uid = __task_cred(p)->uid;
+ struct siginfo __user *infop;
+
+ if (!likely(wo->wo_flags & WEXITED))
+ return 0;
+
+ if (unlikely(wo->wo_flags & WNOWAIT)) {
+ int exit_code = p->exit_code;
+ int why;
+
+ get_task_struct(p);
+ read_unlock(&tasklist_lock);
+ if ((exit_code & 0x7f) == 0) {
+ why = CLD_EXITED;
+ status = exit_code >> 8;
+ } else {
+ why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
+ status = exit_code & 0x7f;
+ }
+ return wait_noreap_copyout(wo, p, pid, uid, why, status);
+ }
+
+ /*
+ * Try to move the task's state to DEAD
+ * only one thread is allowed to do this:
+ */
+ state = xchg(&p->exit_state, EXIT_DEAD);
+ if (state != EXIT_ZOMBIE) {
+ BUG_ON(state != EXIT_DEAD);
+ return 0;
+ }
+
+ traced = ptrace_reparented(p);
+ /*
+ * It can be ptraced but not reparented, check
+ * thread_group_leader() to filter out sub-threads.
+ */
+ if (likely(!traced) && thread_group_leader(p)) {
+ struct signal_struct *psig;
+ struct signal_struct *sig;
+ unsigned long maxrss;
+ cputime_t 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 they are only touched by
+ * __exit_signal, which runs with tasklist_lock
+ * write-locked anyway, and so is excluded here. We do
+ * need to protect the access to parent->signal fields,
+ * as other threads in the parent group can be right
+ * here reaping other children at the same time.
+ *
+ * We use thread_group_times() to get times for the thread
+ * group, which consolidates times for all threads in the
+ * group including the group leader.
+ */
+ thread_group_times(p, &tgutime, &tgstime);
+ spin_lock_irq(&p->real_parent->sighand->siglock);
+ psig = p->real_parent->signal;
+ sig = p->signal;
+ psig->cutime += tgutime + sig->cutime;
+ psig->cstime += tgstime + sig->cstime;
+ psig->cgtime += p->gtime + 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);
+ spin_unlock_irq(&p->real_parent->sighand->siglock);
+ }
+
+ /*
+ * Now we are sure this task is interesting, and no other
+ * thread can reap it because we set its state to EXIT_DEAD.
+ */
+ read_unlock(&tasklist_lock);
+
+ retval = wo->wo_rusage
+ ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
+ status = (p->signal->flags & SIGNAL_GROUP_EXIT)
+ ? p->signal->group_exit_code : p->exit_code;
+ if (!retval && wo->wo_stat)
+ retval = put_user(status, wo->wo_stat);
+
+ infop = wo->wo_info;
+ if (!retval && infop)
+ retval = put_user(SIGCHLD, &infop->si_signo);
+ if (!retval && infop)
+ retval = put_user(0, &infop->si_errno);
+ if (!retval && infop) {
+ int why;
+
+ if ((status & 0x7f) == 0) {
+ why = CLD_EXITED;
+ status >>= 8;
+ } else {
+ why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
+ status &= 0x7f;
+ }
+ retval = put_user((short)why, &infop->si_code);
+ if (!retval)
+ retval = put_user(status, &infop->si_status);
+ }
+ if (!retval && infop)
+ retval = put_user(pid, &infop->si_pid);
+ if (!retval && infop)
+ retval = put_user(uid, &infop->si_uid);
+ if (!retval)
+ retval = pid;
+
+ if (traced) {
+ write_lock_irq(&tasklist_lock);
+ /* We dropped tasklist, ptracer could die and untrace */
+ ptrace_unlink(p);
+ /*
+ * If this is not a sub-thread, notify the parent.
+ * If parent wants a zombie, don't release it now.
+ */
+ if (thread_group_leader(p) &&
+ !do_notify_parent(p, p->exit_signal)) {
+ p->exit_state = EXIT_ZOMBIE;
+ p = NULL;
+ }
+ write_unlock_irq(&tasklist_lock);
+ }
+ if (p != NULL)
+ release_task(p);
+
+ return retval;
+}
+
+static int *task_stopped_code(struct task_struct *p, bool ptrace)
+{
+ if (ptrace) {
+ if (task_is_stopped_or_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 siginfo __user *infop;
+ int retval, 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 = 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);
+
+ if (unlikely(wo->wo_flags & WNOWAIT))
+ return wait_noreap_copyout(wo, p, pid, uid, why, exit_code);
+
+ retval = wo->wo_rusage
+ ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
+ if (!retval && wo->wo_stat)
+ retval = put_user((exit_code << 8) | 0x7f, wo->wo_stat);
+
+ infop = wo->wo_info;
+ if (!retval && infop)
+ retval = put_user(SIGCHLD, &infop->si_signo);
+ if (!retval && infop)
+ retval = put_user(0, &infop->si_errno);
+ if (!retval && infop)
+ retval = put_user((short)why, &infop->si_code);
+ if (!retval && infop)
+ retval = put_user(exit_code, &infop->si_status);
+ if (!retval && infop)
+ retval = put_user(pid, &infop->si_pid);
+ if (!retval && infop)
+ retval = put_user(uid, &infop->si_uid);
+ if (!retval)
+ retval = pid;
+ put_task_struct(p);
+
+ BUG_ON(!retval);
+ return retval;
+}
+
+/*
+ * 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)
+{
+ int retval;
+ 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 = task_uid(p);
+ spin_unlock_irq(&p->sighand->siglock);
+
+ pid = task_pid_vnr(p);
+ get_task_struct(p);
+ read_unlock(&tasklist_lock);
+
+ if (!wo->wo_info) {
+ retval = wo->wo_rusage
+ ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
+ put_task_struct(p);
+ if (!retval && wo->wo_stat)
+ retval = put_user(0xffff, wo->wo_stat);
+ if (!retval)
+ retval = pid;
+ } else {
+ retval = wait_noreap_copyout(wo, p, pid, uid,
+ CLD_CONTINUED, SIGCONT);
+ BUG_ON(retval == 0);
+ }
+
+ return retval;
+}
+
+/*
+ * 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 another error from security_task_wait(), or still -ECHILD.
+ */
+static int wait_consider_task(struct wait_opts *wo, int ptrace,
+ struct task_struct *p)
+{
+ int ret = eligible_child(wo, p);
+ if (!ret)
+ return ret;
+
+ ret = security_task_wait(p);
+ if (unlikely(ret < 0)) {
+ /*
+ * If we have not yet seen any eligible child,
+ * then let this error code replace -ECHILD.
+ * A permission error will give the user a clue
+ * to look for security policy problems, rather
+ * than for mysterious wait bugs.
+ */
+ if (wo->notask_error)
+ wo->notask_error = ret;
+ return 0;
+ }
+
+ /* dead body doesn't have much to contribute */
+ if (unlikely(p->exit_state == EXIT_DEAD)) {
+ /*
+ * But do not ignore this task until the tracer does
+ * wait_task_zombie()->do_notify_parent().
+ */
+ if (likely(!ptrace) && unlikely(ptrace_reparented(p)))
+ wo->notask_error = 0;
+ return 0;
+ }
+
+ /* slay zombie? */
+ if (p->exit_state == EXIT_ZOMBIE) {
+ /*
+ * A zombie ptracee is only visible to its ptracer.
+ * Notification and reaping will be cascaded to the real
+ * parent when the ptracer detaches.
+ */
+ if (likely(!ptrace) && unlikely(p->ptrace)) {
+ /* it will become visible, clear notask_error */
+ wo->notask_error = 0;
+ return 0;
+ }
+
+ /* we don't reap group leaders with subthreads */
+ if (!delay_group_leader(p))
+ 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 {
+ /*
+ * If @p is ptraced by a task in its real parent's group,
+ * hide group stop/continued state when looking at @p as
+ * the real parent; otherwise, a single stop can be
+ * reported twice as group and ptrace stops.
+ *
+ * If a ptracer wants to distinguish the two events for its
+ * own children, it should create a separate process which
+ * takes the role of real parent.
+ */
+ if (likely(!ptrace) && p->ptrace && !ptrace_reparented(p))
+ return 0;
+
+ /*
+ * @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 another error from security_task_wait(), 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_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, 1, p);
+}
+
+static long do_wait(struct wait_opts *wo)
+{
+ struct task_struct *tsk;
+ 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 critiera 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 || hlist_empty(&wo->wo_pid->tasks[wo->wo_type])))
+ goto notask;
+
+ set_current_state(TASK_INTERRUPTIBLE);
+ read_lock(&tasklist_lock);
+ 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;
+}
+
+SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
+ infop, int, options, struct rusage __user *, ru)
+{
+ struct wait_opts wo;
+ struct pid *pid = NULL;
+ enum pid_type type;
+ long ret;
+
+ if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
+ 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;
+ break;
+ case P_PGID:
+ type = PIDTYPE_PGID;
+ if (upid <= 0)
+ return -EINVAL;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ if (type < PIDTYPE_MAX)
+ pid = find_get_pid(upid);
+
+ wo.wo_type = type;
+ wo.wo_pid = pid;
+ wo.wo_flags = options;
+ wo.wo_info = infop;
+ wo.wo_stat = NULL;
+ wo.wo_rusage = ru;
+ ret = do_wait(&wo);
+
+ if (ret > 0) {
+ ret = 0;
+ } else if (infop) {
+ /*
+ * For a WNOHANG return, clear out all the fields
+ * we would set so the user can easily tell the
+ * difference.
+ */
+ if (!ret)
+ ret = put_user(0, &infop->si_signo);
+ if (!ret)
+ ret = put_user(0, &infop->si_errno);
+ if (!ret)
+ ret = put_user(0, &infop->si_code);
+ if (!ret)
+ ret = put_user(0, &infop->si_pid);
+ if (!ret)
+ ret = put_user(0, &infop->si_uid);
+ if (!ret)
+ ret = put_user(0, &infop->si_status);
+ }
+
+ put_pid(pid);
+
+ /* avoid REGPARM breakage on x86: */
+ asmlinkage_protect(5, ret, which, upid, infop, options, ru);
+ return ret;
+}
+
+SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
+ int, options, struct rusage __user *, 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;
+
+ 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 = stat_addr;
+ wo.wo_rusage = ru;
+ ret = do_wait(&wo);
+ put_pid(pid);
+
+ /* avoid REGPARM breakage on x86: */
+ asmlinkage_protect(4, ret, upid, stat_addr, options, ru);
+ return ret;
+}
+
+#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 sys_wait4(pid, stat_addr, options, NULL);
+}
+
+#endif