![Oleg Nesterov](/assets/img/avatar_default.png)
The bug is ancient. If we trace the sub-thread of our natural child and this sub-thread exits, we update parent->signal->cxxx fields. But we should not do this until the whole thread-group exits, otherwise we account this thread (and all other live threads) twice. Add the task_detached() check. No need to check thread_group_empty(), wait_consider_task()->delay_group_leader() already did this. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Roland McGrath <roland@redhat.com> Cc: Stanislaw Gruszka <sgruszka@redhat.com> Cc: Vitaly Mayatskikh <vmayatsk@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1743 lines
43 KiB
C
1743 lines
43 KiB
C
/*
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* linux/kernel/exit.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*/
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/interrupt.h>
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#include <linux/module.h>
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#include <linux/capability.h>
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#include <linux/completion.h>
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#include <linux/personality.h>
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#include <linux/tty.h>
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#include <linux/mnt_namespace.h>
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#include <linux/iocontext.h>
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#include <linux/key.h>
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#include <linux/security.h>
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#include <linux/cpu.h>
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#include <linux/acct.h>
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#include <linux/tsacct_kern.h>
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#include <linux/file.h>
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#include <linux/fdtable.h>
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#include <linux/binfmts.h>
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#include <linux/nsproxy.h>
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#include <linux/pid_namespace.h>
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#include <linux/ptrace.h>
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#include <linux/profile.h>
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#include <linux/mount.h>
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#include <linux/proc_fs.h>
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#include <linux/kthread.h>
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#include <linux/mempolicy.h>
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#include <linux/taskstats_kern.h>
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#include <linux/delayacct.h>
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#include <linux/freezer.h>
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#include <linux/cgroup.h>
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#include <linux/syscalls.h>
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#include <linux/signal.h>
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#include <linux/posix-timers.h>
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#include <linux/cn_proc.h>
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#include <linux/mutex.h>
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#include <linux/futex.h>
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#include <linux/pipe_fs_i.h>
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#include <linux/audit.h> /* for audit_free() */
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#include <linux/resource.h>
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#include <linux/blkdev.h>
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#include <linux/task_io_accounting_ops.h>
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#include <linux/tracehook.h>
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#include <linux/fs_struct.h>
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#include <linux/init_task.h>
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#include <linux/perf_counter.h>
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#include <trace/events/sched.h>
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#include <asm/uaccess.h>
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#include <asm/unistd.h>
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#include <asm/pgtable.h>
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#include <asm/mmu_context.h>
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#include "cred-internals.h"
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static void exit_mm(struct task_struct * tsk);
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static void __unhash_process(struct task_struct *p)
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{
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nr_threads--;
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detach_pid(p, PIDTYPE_PID);
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if (thread_group_leader(p)) {
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detach_pid(p, PIDTYPE_PGID);
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detach_pid(p, PIDTYPE_SID);
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list_del_rcu(&p->tasks);
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__get_cpu_var(process_counts)--;
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}
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list_del_rcu(&p->thread_group);
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list_del_init(&p->sibling);
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}
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/*
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* This function expects the tasklist_lock write-locked.
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*/
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static void __exit_signal(struct task_struct *tsk)
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{
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struct signal_struct *sig = tsk->signal;
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struct sighand_struct *sighand;
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BUG_ON(!sig);
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BUG_ON(!atomic_read(&sig->count));
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sighand = rcu_dereference(tsk->sighand);
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spin_lock(&sighand->siglock);
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posix_cpu_timers_exit(tsk);
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if (atomic_dec_and_test(&sig->count))
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posix_cpu_timers_exit_group(tsk);
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else {
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/*
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* If there is any task waiting for the group exit
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* then notify it:
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*/
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if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count)
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wake_up_process(sig->group_exit_task);
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if (tsk == sig->curr_target)
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sig->curr_target = next_thread(tsk);
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/*
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* Accumulate here the counters for all threads but the
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* group leader as they die, so they can be added into
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* the process-wide totals when those are taken.
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* The group leader stays around as a zombie as long
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* as there are other threads. When it gets reaped,
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* the exit.c code will add its counts into these totals.
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* We won't ever get here for the group leader, since it
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* will have been the last reference on the signal_struct.
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*/
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sig->utime = cputime_add(sig->utime, task_utime(tsk));
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sig->stime = cputime_add(sig->stime, task_stime(tsk));
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sig->gtime = cputime_add(sig->gtime, task_gtime(tsk));
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sig->min_flt += tsk->min_flt;
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sig->maj_flt += tsk->maj_flt;
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sig->nvcsw += tsk->nvcsw;
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sig->nivcsw += tsk->nivcsw;
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sig->inblock += task_io_get_inblock(tsk);
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sig->oublock += task_io_get_oublock(tsk);
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task_io_accounting_add(&sig->ioac, &tsk->ioac);
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sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
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sig = NULL; /* Marker for below. */
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}
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__unhash_process(tsk);
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/*
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* Do this under ->siglock, we can race with another thread
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* doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
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*/
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flush_sigqueue(&tsk->pending);
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tsk->signal = NULL;
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tsk->sighand = NULL;
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spin_unlock(&sighand->siglock);
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__cleanup_sighand(sighand);
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clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
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if (sig) {
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flush_sigqueue(&sig->shared_pending);
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taskstats_tgid_free(sig);
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/*
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* Make sure ->signal can't go away under rq->lock,
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* see account_group_exec_runtime().
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*/
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task_rq_unlock_wait(tsk);
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__cleanup_signal(sig);
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}
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}
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static void delayed_put_task_struct(struct rcu_head *rhp)
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{
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struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
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#ifdef CONFIG_PERF_COUNTERS
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WARN_ON_ONCE(tsk->perf_counter_ctxp);
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#endif
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trace_sched_process_free(tsk);
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put_task_struct(tsk);
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}
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void release_task(struct task_struct * p)
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{
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struct task_struct *leader;
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int zap_leader;
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repeat:
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tracehook_prepare_release_task(p);
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/* don't need to get the RCU readlock here - the process is dead and
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* can't be modifying its own credentials */
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atomic_dec(&__task_cred(p)->user->processes);
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proc_flush_task(p);
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write_lock_irq(&tasklist_lock);
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tracehook_finish_release_task(p);
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__exit_signal(p);
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/*
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* If we are the last non-leader member of the thread
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* group, and the leader is zombie, then notify the
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* group leader's parent process. (if it wants notification.)
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*/
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zap_leader = 0;
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leader = p->group_leader;
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if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
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BUG_ON(task_detached(leader));
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do_notify_parent(leader, leader->exit_signal);
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/*
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* If we were the last child thread and the leader has
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* exited already, and the leader's parent ignores SIGCHLD,
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* then we are the one who should release the leader.
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*
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* do_notify_parent() will have marked it self-reaping in
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* that case.
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*/
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zap_leader = task_detached(leader);
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/*
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* This maintains the invariant that release_task()
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* only runs on a task in EXIT_DEAD, just for sanity.
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*/
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if (zap_leader)
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leader->exit_state = EXIT_DEAD;
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}
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write_unlock_irq(&tasklist_lock);
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release_thread(p);
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call_rcu(&p->rcu, delayed_put_task_struct);
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p = leader;
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if (unlikely(zap_leader))
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goto repeat;
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}
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/*
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* This checks not only the pgrp, but falls back on the pid if no
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* satisfactory pgrp is found. I dunno - gdb doesn't work correctly
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* without this...
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*
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* The caller must hold rcu lock or the tasklist lock.
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*/
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struct pid *session_of_pgrp(struct pid *pgrp)
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{
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struct task_struct *p;
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struct pid *sid = NULL;
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p = pid_task(pgrp, PIDTYPE_PGID);
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if (p == NULL)
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p = pid_task(pgrp, PIDTYPE_PID);
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if (p != NULL)
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sid = task_session(p);
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return sid;
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}
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/*
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* Determine if a process group is "orphaned", according to the POSIX
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* definition in 2.2.2.52. Orphaned process groups are not to be affected
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* by terminal-generated stop signals. Newly orphaned process groups are
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* to receive a SIGHUP and a SIGCONT.
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*
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* "I ask you, have you ever known what it is to be an orphan?"
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*/
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static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task)
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{
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struct task_struct *p;
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do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
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if ((p == ignored_task) ||
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(p->exit_state && thread_group_empty(p)) ||
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is_global_init(p->real_parent))
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continue;
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if (task_pgrp(p->real_parent) != pgrp &&
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task_session(p->real_parent) == task_session(p))
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return 0;
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} while_each_pid_task(pgrp, PIDTYPE_PGID, p);
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return 1;
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}
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int is_current_pgrp_orphaned(void)
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{
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int retval;
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read_lock(&tasklist_lock);
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retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
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read_unlock(&tasklist_lock);
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return retval;
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}
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static int has_stopped_jobs(struct pid *pgrp)
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{
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int retval = 0;
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struct task_struct *p;
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do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
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if (!task_is_stopped(p))
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continue;
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retval = 1;
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break;
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} while_each_pid_task(pgrp, PIDTYPE_PGID, p);
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return retval;
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}
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/*
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* Check to see if any process groups have become orphaned as
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* a result of our exiting, and if they have any stopped jobs,
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* send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
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*/
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static void
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kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
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{
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struct pid *pgrp = task_pgrp(tsk);
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struct task_struct *ignored_task = tsk;
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if (!parent)
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/* exit: our father is in a different pgrp than
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* we are and we were the only connection outside.
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*/
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parent = tsk->real_parent;
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else
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/* reparent: our child is in a different pgrp than
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* we are, and it was the only connection outside.
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*/
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ignored_task = NULL;
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if (task_pgrp(parent) != pgrp &&
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task_session(parent) == task_session(tsk) &&
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will_become_orphaned_pgrp(pgrp, ignored_task) &&
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has_stopped_jobs(pgrp)) {
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__kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
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__kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
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}
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}
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/**
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* reparent_to_kthreadd - Reparent the calling kernel thread to kthreadd
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*
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* If a kernel thread is launched as a result of a system call, or if
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* it ever exits, it should generally reparent itself to kthreadd so it
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* isn't in the way of other processes and is correctly cleaned up on exit.
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*
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* The various task state such as scheduling policy and priority may have
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* been inherited from a user process, so we reset them to sane values here.
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*
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* NOTE that reparent_to_kthreadd() gives the caller full capabilities.
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*/
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static void reparent_to_kthreadd(void)
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{
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write_lock_irq(&tasklist_lock);
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ptrace_unlink(current);
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/* Reparent to init */
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current->real_parent = current->parent = kthreadd_task;
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list_move_tail(¤t->sibling, ¤t->real_parent->children);
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/* Set the exit signal to SIGCHLD so we signal init on exit */
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current->exit_signal = SIGCHLD;
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if (task_nice(current) < 0)
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set_user_nice(current, 0);
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/* cpus_allowed? */
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/* rt_priority? */
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/* signals? */
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memcpy(current->signal->rlim, init_task.signal->rlim,
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sizeof(current->signal->rlim));
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atomic_inc(&init_cred.usage);
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commit_creds(&init_cred);
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write_unlock_irq(&tasklist_lock);
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}
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void __set_special_pids(struct pid *pid)
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{
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struct task_struct *curr = current->group_leader;
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if (task_session(curr) != pid)
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change_pid(curr, PIDTYPE_SID, pid);
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if (task_pgrp(curr) != pid)
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change_pid(curr, PIDTYPE_PGID, pid);
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}
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static void set_special_pids(struct pid *pid)
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{
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write_lock_irq(&tasklist_lock);
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__set_special_pids(pid);
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write_unlock_irq(&tasklist_lock);
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}
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/*
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* Let kernel threads use this to say that they allow a certain signal.
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* Must not be used if kthread was cloned with CLONE_SIGHAND.
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*/
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int allow_signal(int sig)
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{
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if (!valid_signal(sig) || sig < 1)
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return -EINVAL;
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spin_lock_irq(¤t->sighand->siglock);
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/* This is only needed for daemonize()'ed kthreads */
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sigdelset(¤t->blocked, sig);
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/*
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* Kernel threads handle their own signals. Let the signal code
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* know it'll be handled, so that they don't get converted to
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* SIGKILL or just silently dropped.
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*/
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current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
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recalc_sigpending();
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spin_unlock_irq(¤t->sighand->siglock);
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return 0;
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}
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EXPORT_SYMBOL(allow_signal);
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int disallow_signal(int sig)
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{
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if (!valid_signal(sig) || sig < 1)
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return -EINVAL;
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spin_lock_irq(¤t->sighand->siglock);
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current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN;
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recalc_sigpending();
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spin_unlock_irq(¤t->sighand->siglock);
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return 0;
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}
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EXPORT_SYMBOL(disallow_signal);
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/*
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* Put all the gunge required to become a kernel thread without
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* attached user resources in one place where it belongs.
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*/
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void daemonize(const char *name, ...)
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{
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va_list args;
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sigset_t blocked;
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va_start(args, name);
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vsnprintf(current->comm, sizeof(current->comm), name, args);
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va_end(args);
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/*
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* If we were started as result of loading a module, close all of the
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* user space pages. We don't need them, and if we didn't close them
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* they would be locked into memory.
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*/
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exit_mm(current);
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/*
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* We don't want to have TIF_FREEZE set if the system-wide hibernation
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* or suspend transition begins right now.
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*/
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current->flags |= (PF_NOFREEZE | PF_KTHREAD);
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if (current->nsproxy != &init_nsproxy) {
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get_nsproxy(&init_nsproxy);
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switch_task_namespaces(current, &init_nsproxy);
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}
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set_special_pids(&init_struct_pid);
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proc_clear_tty(current);
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/* Block and flush all signals */
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sigfillset(&blocked);
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sigprocmask(SIG_BLOCK, &blocked, NULL);
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flush_signals(current);
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|
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/* Become as one with the init task */
|
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daemonize_fs_struct();
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exit_files(current);
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current->files = init_task.files;
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atomic_inc(¤t->files->count);
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reparent_to_kthreadd();
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}
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|
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EXPORT_SYMBOL(daemonize);
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|
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static void close_files(struct files_struct * files)
|
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{
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int i, j;
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struct fdtable *fdt;
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j = 0;
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|
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/*
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* It is safe to dereference the fd table without RCU or
|
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* ->file_lock because this is the last reference to the
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* files structure.
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*/
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fdt = files_fdtable(files);
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for (;;) {
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unsigned long set;
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i = j * __NFDBITS;
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if (i >= fdt->max_fds)
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break;
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set = fdt->open_fds->fds_bits[j++];
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while (set) {
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if (set & 1) {
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struct file * file = xchg(&fdt->fd[i], NULL);
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if (file) {
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filp_close(file, files);
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cond_resched();
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}
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}
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i++;
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set >>= 1;
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}
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}
|
|
}
|
|
|
|
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.
|
|
*/
|
|
fdt = files_fdtable(files);
|
|
if (fdt != &files->fdtab)
|
|
kmem_cache_free(files_cachep, files);
|
|
free_fdtable(fdt);
|
|
}
|
|
}
|
|
|
|
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
|
|
/*
|
|
* Task p is exiting and it owned mm, lets find a new owner for it
|
|
*/
|
|
static inline int
|
|
mm_need_new_owner(struct mm_struct *mm, struct task_struct *p)
|
|
{
|
|
/*
|
|
* If there are other users of the mm and the owner (us) is exiting
|
|
* we need to find a new owner to take on the responsibility.
|
|
*/
|
|
if (atomic_read(&mm->mm_users) <= 1)
|
|
return 0;
|
|
if (mm->owner != p)
|
|
return 0;
|
|
return 1;
|
|
}
|
|
|
|
void mm_update_next_owner(struct mm_struct *mm)
|
|
{
|
|
struct task_struct *c, *g, *p = current;
|
|
|
|
retry:
|
|
if (!mm_need_new_owner(mm, p))
|
|
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);
|
|
/* We don't want this task to be frozen prematurely */
|
|
clear_freeze_flag(tsk);
|
|
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)
|
|
{
|
|
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_thread(struct task_struct *father, struct task_struct *p,
|
|
struct list_head *dead)
|
|
{
|
|
if (p->pdeath_signal)
|
|
group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);
|
|
|
|
list_move_tail(&p->sibling, &p->real_parent->children);
|
|
|
|
if (task_detached(p))
|
|
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 (!task_ptrace(p) &&
|
|
p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
|
|
do_notify_parent(p, p->exit_signal);
|
|
if (task_detached(p)) {
|
|
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);
|
|
|
|
exit_ptrace(father);
|
|
|
|
write_lock_irq(&tasklist_lock);
|
|
reaper = find_new_reaper(father);
|
|
|
|
list_for_each_entry_safe(p, n, &father->children, sibling) {
|
|
p->real_parent = reaper;
|
|
if (p->parent == father) {
|
|
BUG_ON(task_ptrace(p));
|
|
p->parent = p->real_parent;
|
|
}
|
|
reparent_thread(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)
|
|
{
|
|
int signal;
|
|
void *cookie;
|
|
|
|
/*
|
|
* 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 arbitary 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 (tsk->exit_signal != SIGCHLD && !task_detached(tsk) &&
|
|
(tsk->parent_exec_id != tsk->real_parent->self_exec_id ||
|
|
tsk->self_exec_id != tsk->parent_exec_id))
|
|
tsk->exit_signal = SIGCHLD;
|
|
|
|
signal = tracehook_notify_death(tsk, &cookie, group_dead);
|
|
if (signal >= 0)
|
|
signal = do_notify_parent(tsk, signal);
|
|
|
|
tsk->exit_state = signal == DEATH_REAP ? EXIT_DEAD : EXIT_ZOMBIE;
|
|
|
|
/* mt-exec, de_thread() is waiting for us */
|
|
if (thread_group_leader(tsk) &&
|
|
tsk->signal->group_exit_task &&
|
|
tsk->signal->notify_count < 0)
|
|
wake_up_process(tsk->signal->group_exit_task);
|
|
|
|
write_unlock_irq(&tasklist_lock);
|
|
|
|
tracehook_report_death(tsk, signal, cookie, group_dead);
|
|
|
|
/* If the process is dead, release it - nobody will wait for it */
|
|
if (signal == DEATH_REAP)
|
|
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
|
|
|
|
NORET_TYPE void do_exit(long code)
|
|
{
|
|
struct task_struct *tsk = current;
|
|
int group_dead;
|
|
|
|
profile_task_exit(tsk);
|
|
|
|
WARN_ON(atomic_read(&tsk->fs_excl));
|
|
|
|
if (unlikely(in_interrupt()))
|
|
panic("Aiee, killing interrupt handler!");
|
|
if (unlikely(!tsk->pid))
|
|
panic("Attempted to kill the idle task!");
|
|
|
|
tracehook_report_exit(&code);
|
|
|
|
/*
|
|
* 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();
|
|
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);
|
|
|
|
group_dead = atomic_dec_and_test(&tsk->signal->live);
|
|
if (group_dead) {
|
|
hrtimer_cancel(&tsk->signal->real_timer);
|
|
exit_itimers(tsk->signal);
|
|
}
|
|
acct_collect(code, group_dead);
|
|
if (group_dead)
|
|
tty_audit_exit();
|
|
if (unlikely(tsk->audit_context))
|
|
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_files(tsk);
|
|
exit_fs(tsk);
|
|
check_stack_usage();
|
|
exit_thread();
|
|
cgroup_exit(tsk, 1);
|
|
|
|
if (group_dead && tsk->signal->leader)
|
|
disassociate_ctty(1);
|
|
|
|
module_put(task_thread_info(tsk)->exec_domain->module);
|
|
if (tsk->binfmt)
|
|
module_put(tsk->binfmt->module);
|
|
|
|
proc_exit_connector(tsk);
|
|
|
|
/*
|
|
* Flush inherited counters to the parent - before the parent
|
|
* gets woken up by child-exit notifications.
|
|
*/
|
|
perf_counter_exit_task(tsk);
|
|
|
|
exit_notify(tsk, group_dead);
|
|
#ifdef CONFIG_NUMA
|
|
mpol_put(tsk->mempolicy);
|
|
tsk->mempolicy = NULL;
|
|
#endif
|
|
#ifdef CONFIG_FUTEX
|
|
if (unlikely(!list_empty(&tsk->pi_state_list)))
|
|
exit_pi_state_list(tsk);
|
|
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();
|
|
|
|
if (tsk->splice_pipe)
|
|
__free_pipe_info(tsk->splice_pipe);
|
|
|
|
preempt_disable();
|
|
/* causes final put_task_struct in finish_task_switch(). */
|
|
tsk->state = TASK_DEAD;
|
|
schedule();
|
|
BUG();
|
|
/* Avoid "noreturn function does return". */
|
|
for (;;)
|
|
cpu_relax(); /* For when BUG is null */
|
|
}
|
|
|
|
EXPORT_SYMBOL_GPL(do_exit);
|
|
|
|
NORET_TYPE 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).
|
|
*/
|
|
NORET_TYPE 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;
|
|
|
|
int notask_error;
|
|
};
|
|
|
|
static struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
|
|
{
|
|
struct pid *pid = NULL;
|
|
if (type == PIDTYPE_PID)
|
|
pid = task->pids[type].pid;
|
|
else if (type < PIDTYPE_MAX)
|
|
pid = task->group_leader->pids[type].pid;
|
|
return pid;
|
|
}
|
|
|
|
static int eligible_child(struct wait_opts *wo, struct task_struct *p)
|
|
{
|
|
int err;
|
|
|
|
if (wo->wo_type < PIDTYPE_MAX) {
|
|
if (task_pid_type(p, wo->wo_type) != wo->wo_pid)
|
|
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;
|
|
|
|
err = security_task_wait(p);
|
|
if (err)
|
|
return err;
|
|
|
|
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 (!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, status;
|
|
|
|
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
|
|
* !task_detached() to filter out sub-threads.
|
|
*/
|
|
if (likely(!traced) && likely(!task_detached(p))) {
|
|
struct signal_struct *psig;
|
|
struct signal_struct *sig;
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
spin_lock_irq(&p->real_parent->sighand->siglock);
|
|
psig = p->real_parent->signal;
|
|
sig = p->signal;
|
|
psig->cutime =
|
|
cputime_add(psig->cutime,
|
|
cputime_add(p->utime,
|
|
cputime_add(sig->utime,
|
|
sig->cutime)));
|
|
psig->cstime =
|
|
cputime_add(psig->cstime,
|
|
cputime_add(p->stime,
|
|
cputime_add(sig->stime,
|
|
sig->cstime)));
|
|
psig->cgtime =
|
|
cputime_add(psig->cgtime,
|
|
cputime_add(p->gtime,
|
|
cputime_add(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;
|
|
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 detached task, notify the parent.
|
|
* If it's still not detached after that, don't release
|
|
* it now.
|
|
*/
|
|
if (!task_detached(p)) {
|
|
do_notify_parent(p, p->exit_signal);
|
|
if (!task_detached(p)) {
|
|
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))
|
|
return &p->exit_code;
|
|
} else {
|
|
if (p->signal->flags & SIGNAL_STOP_STOPPED)
|
|
return &p->signal->group_exit_code;
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Handle sys_wait4 work for one task in state TASK_STOPPED. 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_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;
|
|
|
|
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;
|
|
|
|
/* don't need the RCU readlock here as we're holding a spinlock */
|
|
uid = __task_cred(p)->uid;
|
|
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_cred(p)->uid;
|
|
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, struct task_struct *parent,
|
|
int ptrace, struct task_struct *p)
|
|
{
|
|
int ret = eligible_child(wo, p);
|
|
if (!ret)
|
|
return ret;
|
|
|
|
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;
|
|
}
|
|
|
|
if (likely(!ptrace) && unlikely(task_ptrace(p))) {
|
|
/*
|
|
* This child is hidden by ptrace.
|
|
* We aren't allowed to see it now, but eventually we will.
|
|
*/
|
|
wo->notask_error = 0;
|
|
return 0;
|
|
}
|
|
|
|
if (p->exit_state == EXIT_DEAD)
|
|
return 0;
|
|
|
|
/*
|
|
* We don't reap group leaders with subthreads.
|
|
*/
|
|
if (p->exit_state == EXIT_ZOMBIE && !delay_group_leader(p))
|
|
return wait_task_zombie(wo, p);
|
|
|
|
/*
|
|
* It's stopped or running now, so it might
|
|
* later continue, exit, or stop again.
|
|
*/
|
|
wo->notask_error = 0;
|
|
|
|
if (task_stopped_code(p, ptrace))
|
|
return wait_task_stopped(wo, ptrace, p);
|
|
|
|
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) {
|
|
/*
|
|
* Do not consider detached threads.
|
|
*/
|
|
if (!task_detached(p)) {
|
|
int ret = wait_consider_task(wo, tsk, 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, tsk, 1, p);
|
|
if (ret)
|
|
return ret;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static long do_wait(struct wait_opts *wo)
|
|
{
|
|
DECLARE_WAITQUEUE(wait, current);
|
|
struct task_struct *tsk;
|
|
int retval;
|
|
|
|
trace_sched_process_wait(wo->wo_pid);
|
|
|
|
add_wait_queue(¤t->signal->wait_chldexit,&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(¤t->signal->wait_chldexit,&wait);
|
|
if (wo->wo_info) {
|
|
struct siginfo __user *infop = wo->wo_info;
|
|
|
|
if (retval > 0)
|
|
retval = 0;
|
|
else {
|
|
/*
|
|
* For a WNOHANG return, clear out all the fields
|
|
* we would set so the user can easily tell the
|
|
* difference.
|
|
*/
|
|
if (!retval)
|
|
retval = put_user(0, &infop->si_signo);
|
|
if (!retval)
|
|
retval = put_user(0, &infop->si_errno);
|
|
if (!retval)
|
|
retval = put_user(0, &infop->si_code);
|
|
if (!retval)
|
|
retval = put_user(0, &infop->si_pid);
|
|
if (!retval)
|
|
retval = put_user(0, &infop->si_uid);
|
|
if (!retval)
|
|
retval = put_user(0, &infop->si_status);
|
|
}
|
|
}
|
|
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);
|
|
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
|