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![Frans Klaver](/assets/img/avatar_default.png)
s,critiera,criteria, While at it, add a comma, because it makes sense grammatically. Signed-off-by: Frans Klaver <fransklaver@gmail.com> Signed-off-by: Jiri Kosina <jkosina@suse.com>
1632 lines
42 KiB
C
1632 lines
42 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/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/freezer.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/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_event.h>
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#include <trace/events/sched.h>
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#include <linux/hw_breakpoint.h>
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#include <linux/oom.h>
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#include <linux/writeback.h>
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#include <linux/shm.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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static void exit_mm(struct task_struct *tsk);
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static void __unhash_process(struct task_struct *p, bool group_dead)
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{
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nr_threads--;
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detach_pid(p, PIDTYPE_PID);
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if (group_dead) {
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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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list_del_init(&p->sibling);
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__this_cpu_dec(process_counts);
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}
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list_del_rcu(&p->thread_group);
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list_del_rcu(&p->thread_node);
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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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bool group_dead = thread_group_leader(tsk);
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struct sighand_struct *sighand;
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struct tty_struct *uninitialized_var(tty);
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cputime_t utime, stime;
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sighand = rcu_dereference_check(tsk->sighand,
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lockdep_tasklist_lock_is_held());
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spin_lock(&sighand->siglock);
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posix_cpu_timers_exit(tsk);
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if (group_dead) {
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posix_cpu_timers_exit_group(tsk);
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tty = sig->tty;
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sig->tty = NULL;
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} else {
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/*
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* This can only happen if the caller is de_thread().
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* FIXME: this is the temporary hack, we should teach
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* posix-cpu-timers to handle this case correctly.
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*/
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if (unlikely(has_group_leader_pid(tsk)))
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posix_cpu_timers_exit_group(tsk);
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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->notify_count > 0 && !--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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/*
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* Accumulate here the counters for all threads as they die. We could
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* skip the group leader because it is the last user of signal_struct,
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* but we want to avoid the race with thread_group_cputime() which can
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* see the empty ->thread_head list.
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*/
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task_cputime(tsk, &utime, &stime);
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write_seqlock(&sig->stats_lock);
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sig->utime += utime;
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sig->stime += stime;
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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->nr_threads--;
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__unhash_process(tsk, group_dead);
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write_sequnlock(&sig->stats_lock);
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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->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 (group_dead) {
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flush_sigqueue(&sig->shared_pending);
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tty_kref_put(tty);
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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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perf_event_delayed_put(tsk);
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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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/* 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. But shut RCU-lockdep up */
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rcu_read_lock();
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atomic_dec(&__task_cred(p)->user->processes);
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rcu_read_unlock();
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proc_flush_task(p);
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write_lock_irq(&tasklist_lock);
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ptrace_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)
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&& leader->exit_state == EXIT_ZOMBIE) {
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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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zap_leader = do_notify_parent(leader, leader->exit_signal);
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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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* 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,
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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 bool has_stopped_jobs(struct pid *pgrp)
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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->signal->flags & SIGNAL_STOP_STOPPED)
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return true;
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} while_each_pid_task(pgrp, PIDTYPE_PGID, p);
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return false;
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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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#ifdef CONFIG_MEMCG
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/*
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* A task is exiting. If it owned this mm, find a new owner for the mm.
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*/
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void mm_update_next_owner(struct mm_struct *mm)
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{
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struct task_struct *c, *g, *p = current;
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retry:
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/*
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* If the exiting or execing task is not the owner, it's
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* someone else's problem.
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*/
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if (mm->owner != p)
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return;
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/*
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* The current owner is exiting/execing and there are no other
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* candidates. Do not leave the mm pointing to a possibly
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* freed task structure.
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*/
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if (atomic_read(&mm->mm_users) <= 1) {
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mm->owner = NULL;
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return;
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}
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read_lock(&tasklist_lock);
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/*
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* Search in the children
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*/
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list_for_each_entry(c, &p->children, sibling) {
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if (c->mm == mm)
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goto assign_new_owner;
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}
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/*
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* Search in the siblings
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*/
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list_for_each_entry(c, &p->real_parent->children, sibling) {
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if (c->mm == mm)
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goto assign_new_owner;
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}
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/*
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* Search through everything else, we should not get here often.
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*/
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for_each_process(g) {
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if (g->flags & PF_KTHREAD)
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continue;
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for_each_thread(g, c) {
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if (c->mm == mm)
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goto assign_new_owner;
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if (c->mm)
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break;
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}
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}
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read_unlock(&tasklist_lock);
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/*
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* We found no owner yet mm_users > 1: this implies that we are
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* most likely racing with swapoff (try_to_unuse()) or /proc or
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* ptrace or page migration (get_task_mm()). Mark owner as NULL.
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*/
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mm->owner = NULL;
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return;
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assign_new_owner:
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BUG_ON(c == p);
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get_task_struct(c);
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/*
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* The task_lock protects c->mm from changing.
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* We always want mm->owner->mm == mm
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*/
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task_lock(c);
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/*
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* Delay read_unlock() till we have the task_lock()
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* to ensure that c does not slip away underneath us
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*/
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read_unlock(&tasklist_lock);
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if (c->mm != mm) {
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task_unlock(c);
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put_task_struct(c);
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goto retry;
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}
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mm->owner = c;
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task_unlock(c);
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put_task_struct(c);
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}
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#endif /* CONFIG_MEMCG */
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/*
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* Turn us into a lazy TLB process if we
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* aren't already..
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*/
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static void exit_mm(struct task_struct *tsk)
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{
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struct mm_struct *mm = tsk->mm;
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struct core_state *core_state;
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mm_release(tsk, mm);
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if (!mm)
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return;
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sync_mm_rss(mm);
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/*
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* Serialize with any possible pending coredump.
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* We must hold mmap_sem around checking core_state
|
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* and clearing tsk->mm. The core-inducing thread
|
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* will increment ->nr_threads for each thread in the
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* group with ->mm != NULL.
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*/
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down_read(&mm->mmap_sem);
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core_state = mm->core_state;
|
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if (core_state) {
|
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struct core_thread self;
|
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|
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up_read(&mm->mmap_sem);
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|
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self.task = tsk;
|
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self.next = xchg(&core_state->dumper.next, &self);
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/*
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* Implies mb(), the result of xchg() must be visible
|
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* to core_state->dumper.
|
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*/
|
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if (atomic_dec_and_test(&core_state->nr_threads))
|
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complete(&core_state->startup);
|
|
|
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for (;;) {
|
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set_task_state(tsk, TASK_UNINTERRUPTIBLE);
|
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if (!self.task) /* see coredump_finish() */
|
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break;
|
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freezable_schedule();
|
|
}
|
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__set_task_state(tsk, TASK_RUNNING);
|
|
down_read(&mm->mmap_sem);
|
|
}
|
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atomic_inc(&mm->mm_count);
|
|
BUG_ON(mm != tsk->active_mm);
|
|
/* more a memory barrier than a real lock */
|
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task_lock(tsk);
|
|
tsk->mm = NULL;
|
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up_read(&mm->mmap_sem);
|
|
enter_lazy_tlb(mm, current);
|
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task_unlock(tsk);
|
|
mm_update_next_owner(mm);
|
|
mmput(mm);
|
|
if (test_thread_flag(TIF_MEMDIE))
|
|
exit_oom_victim();
|
|
}
|
|
|
|
static struct task_struct *find_alive_thread(struct task_struct *p)
|
|
{
|
|
struct task_struct *t;
|
|
|
|
for_each_thread(p, t) {
|
|
if (!(t->flags & PF_EXITING))
|
|
return t;
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
static struct task_struct *find_child_reaper(struct task_struct *father)
|
|
__releases(&tasklist_lock)
|
|
__acquires(&tasklist_lock)
|
|
{
|
|
struct pid_namespace *pid_ns = task_active_pid_ns(father);
|
|
struct task_struct *reaper = pid_ns->child_reaper;
|
|
|
|
if (likely(reaper != father))
|
|
return reaper;
|
|
|
|
reaper = find_alive_thread(father);
|
|
if (reaper) {
|
|
pid_ns->child_reaper = reaper;
|
|
return reaper;
|
|
}
|
|
|
|
write_unlock_irq(&tasklist_lock);
|
|
if (unlikely(pid_ns == &init_pid_ns)) {
|
|
panic("Attempted to kill init! exitcode=0x%08x\n",
|
|
father->signal->group_exit_code ?: father->exit_code);
|
|
}
|
|
zap_pid_ns_processes(pid_ns);
|
|
write_lock_irq(&tasklist_lock);
|
|
|
|
return father;
|
|
}
|
|
|
|
/*
|
|
* When we die, we re-parent all our children, and try to:
|
|
* 1. give them to another thread in our thread group, if such a member exists
|
|
* 2. give it to the first ancestor process which prctl'd itself as a
|
|
* child_subreaper for its children (like a service manager)
|
|
* 3. give it to the init process (PID 1) in our pid namespace
|
|
*/
|
|
static struct task_struct *find_new_reaper(struct task_struct *father,
|
|
struct task_struct *child_reaper)
|
|
{
|
|
struct task_struct *thread, *reaper;
|
|
|
|
thread = find_alive_thread(father);
|
|
if (thread)
|
|
return thread;
|
|
|
|
if (father->signal->has_child_subreaper) {
|
|
/*
|
|
* Find the first ->is_child_subreaper ancestor in our pid_ns.
|
|
* We start from father to ensure we can not look into another
|
|
* namespace, this is safe because all its threads are dead.
|
|
*/
|
|
for (reaper = father;
|
|
!same_thread_group(reaper, child_reaper);
|
|
reaper = reaper->real_parent) {
|
|
/* call_usermodehelper() descendants need this check */
|
|
if (reaper == &init_task)
|
|
break;
|
|
if (!reaper->signal->is_child_subreaper)
|
|
continue;
|
|
thread = find_alive_thread(reaper);
|
|
if (thread)
|
|
return thread;
|
|
}
|
|
}
|
|
|
|
return child_reaper;
|
|
}
|
|
|
|
/*
|
|
* Any that need to be release_task'd are put on the @dead list.
|
|
*/
|
|
static void reparent_leader(struct task_struct *father, struct task_struct *p,
|
|
struct list_head *dead)
|
|
{
|
|
if (unlikely(p->exit_state == EXIT_DEAD))
|
|
return;
|
|
|
|
/* We don't want people slaying init. */
|
|
p->exit_signal = SIGCHLD;
|
|
|
|
/* If it has exited notify the new parent about this child's death. */
|
|
if (!p->ptrace &&
|
|
p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
|
|
if (do_notify_parent(p, p->exit_signal)) {
|
|
p->exit_state = EXIT_DEAD;
|
|
list_add(&p->ptrace_entry, dead);
|
|
}
|
|
}
|
|
|
|
kill_orphaned_pgrp(p, father);
|
|
}
|
|
|
|
/*
|
|
* This does two things:
|
|
*
|
|
* A. Make init inherit all the child processes
|
|
* B. Check to see if any process groups have become orphaned
|
|
* as a result of our exiting, and if they have any stopped
|
|
* jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
|
|
*/
|
|
static void forget_original_parent(struct task_struct *father,
|
|
struct list_head *dead)
|
|
{
|
|
struct task_struct *p, *t, *reaper;
|
|
|
|
if (unlikely(!list_empty(&father->ptraced)))
|
|
exit_ptrace(father, dead);
|
|
|
|
/* Can drop and reacquire tasklist_lock */
|
|
reaper = find_child_reaper(father);
|
|
if (list_empty(&father->children))
|
|
return;
|
|
|
|
reaper = find_new_reaper(father, reaper);
|
|
list_for_each_entry(p, &father->children, sibling) {
|
|
for_each_thread(p, t) {
|
|
t->real_parent = reaper;
|
|
BUG_ON((!t->ptrace) != (t->parent == father));
|
|
if (likely(!t->ptrace))
|
|
t->parent = t->real_parent;
|
|
if (t->pdeath_signal)
|
|
group_send_sig_info(t->pdeath_signal,
|
|
SEND_SIG_NOINFO, t);
|
|
}
|
|
/*
|
|
* If this is a threaded reparent there is no need to
|
|
* notify anyone anything has happened.
|
|
*/
|
|
if (!same_thread_group(reaper, father))
|
|
reparent_leader(father, p, dead);
|
|
}
|
|
list_splice_tail_init(&father->children, &reaper->children);
|
|
}
|
|
|
|
/*
|
|
* Send signals to all our closest relatives so that they know
|
|
* to properly mourn us..
|
|
*/
|
|
static void exit_notify(struct task_struct *tsk, int group_dead)
|
|
{
|
|
bool autoreap;
|
|
struct task_struct *p, *n;
|
|
LIST_HEAD(dead);
|
|
|
|
write_lock_irq(&tasklist_lock);
|
|
forget_original_parent(tsk, &dead);
|
|
|
|
if (group_dead)
|
|
kill_orphaned_pgrp(tsk->group_leader, NULL);
|
|
|
|
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;
|
|
if (tsk->exit_state == EXIT_DEAD)
|
|
list_add(&tsk->ptrace_entry, &dead);
|
|
|
|
/* mt-exec, de_thread() is waiting for group leader */
|
|
if (unlikely(tsk->signal->notify_count < 0))
|
|
wake_up_process(tsk->signal->group_exit_task);
|
|
write_unlock_irq(&tasklist_lock);
|
|
|
|
list_for_each_entry_safe(p, n, &dead, ptrace_entry) {
|
|
list_del_init(&p->ptrace_entry);
|
|
release_task(p);
|
|
}
|
|
}
|
|
|
|
#ifdef CONFIG_DEBUG_STACK_USAGE
|
|
static void check_stack_usage(void)
|
|
{
|
|
static DEFINE_SPINLOCK(low_water_lock);
|
|
static int lowest_to_date = THREAD_SIZE;
|
|
unsigned long free;
|
|
|
|
free = stack_not_used(current);
|
|
|
|
if (free >= lowest_to_date)
|
|
return;
|
|
|
|
spin_lock(&low_water_lock);
|
|
if (free < lowest_to_date) {
|
|
pr_warn("%s (%d) used greatest stack depth: %lu bytes left\n",
|
|
current->comm, task_pid_nr(current), free);
|
|
lowest_to_date = free;
|
|
}
|
|
spin_unlock(&low_water_lock);
|
|
}
|
|
#else
|
|
static inline void check_stack_usage(void) {}
|
|
#endif
|
|
|
|
void do_exit(long code)
|
|
{
|
|
struct task_struct *tsk = current;
|
|
int group_dead;
|
|
TASKS_RCU(int tasks_rcu_i);
|
|
|
|
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)) {
|
|
pr_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_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()))
|
|
pr_info("note: %s[%d] exited with preempt_count %d\n",
|
|
current->comm, task_pid_nr(current),
|
|
preempt_count());
|
|
|
|
/* sync mm's RSS info before statistics gathering */
|
|
if (tsk->mm)
|
|
sync_mm_rss(tsk->mm);
|
|
acct_update_integrals(tsk);
|
|
group_dead = atomic_dec_and_test(&tsk->signal->live);
|
|
if (group_dead) {
|
|
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);
|
|
if (group_dead)
|
|
disassociate_ctty(1);
|
|
exit_task_namespaces(tsk);
|
|
exit_task_work(tsk);
|
|
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);
|
|
|
|
/*
|
|
* FIXME: do that only when needed, using sched_exit tracepoint
|
|
*/
|
|
flush_ptrace_hw_breakpoint(tsk);
|
|
|
|
TASKS_RCU(tasks_rcu_i = __srcu_read_lock(&tasks_rcu_exit_srcu));
|
|
exit_notify(tsk, group_dead);
|
|
proc_exit_connector(tsk);
|
|
#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();
|
|
/*
|
|
* 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);
|
|
|
|
if (tsk->task_frag.page)
|
|
put_page(tsk->task_frag.page);
|
|
|
|
validate_creds_for_do_exit(tsk);
|
|
|
|
check_stack_usage();
|
|
preempt_disable();
|
|
if (tsk->nr_dirtied)
|
|
__this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied);
|
|
exit_rcu();
|
|
TASKS_RCU(__srcu_read_unlock(&tasks_rcu_exit_srcu, tasks_rcu_i));
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
int state, retval, status;
|
|
pid_t pid = task_pid_vnr(p);
|
|
uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p));
|
|
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);
|
|
sched_annotate_sleep();
|
|
|
|
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);
|
|
}
|
|
/*
|
|
* Move the task's state to DEAD/TRACE, only one thread can do this.
|
|
*/
|
|
state = (ptrace_reparented(p) && thread_group_leader(p)) ?
|
|
EXIT_TRACE : EXIT_DEAD;
|
|
if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE)
|
|
return 0;
|
|
/*
|
|
* We own this thread, nobody else can reap it.
|
|
*/
|
|
read_unlock(&tasklist_lock);
|
|
sched_annotate_sleep();
|
|
|
|
/*
|
|
* Check thread_group_leader() to exclude the traced sub-threads.
|
|
*/
|
|
if (state == EXIT_DEAD && thread_group_leader(p)) {
|
|
struct signal_struct *sig = p->signal;
|
|
struct signal_struct *psig = current->signal;
|
|
unsigned long maxrss;
|
|
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 the whole thread group is dead
|
|
* and nobody can change them.
|
|
*
|
|
* psig->stats_lock also protects us from our sub-theads
|
|
* which can reap other children at the same time. Until
|
|
* we change k_getrusage()-like users to rely on this lock
|
|
* we have to take ->siglock as well.
|
|
*
|
|
* We use thread_group_cputime_adjusted() to get times for
|
|
* the thread group, which consolidates times for all threads
|
|
* in the group including the group leader.
|
|
*/
|
|
thread_group_cputime_adjusted(p, &tgutime, &tgstime);
|
|
spin_lock_irq(¤t->sighand->siglock);
|
|
write_seqlock(&psig->stats_lock);
|
|
psig->cutime += tgutime + sig->cutime;
|
|
psig->cstime += tgstime + sig->cstime;
|
|
psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime;
|
|
psig->cmin_flt +=
|
|
p->min_flt + sig->min_flt + sig->cmin_flt;
|
|
psig->cmaj_flt +=
|
|
p->maj_flt + sig->maj_flt + sig->cmaj_flt;
|
|
psig->cnvcsw +=
|
|
p->nvcsw + sig->nvcsw + sig->cnvcsw;
|
|
psig->cnivcsw +=
|
|
p->nivcsw + sig->nivcsw + sig->cnivcsw;
|
|
psig->cinblock +=
|
|
task_io_get_inblock(p) +
|
|
sig->inblock + sig->cinblock;
|
|
psig->coublock +=
|
|
task_io_get_oublock(p) +
|
|
sig->oublock + sig->coublock;
|
|
maxrss = max(sig->maxrss, sig->cmaxrss);
|
|
if (psig->cmaxrss < maxrss)
|
|
psig->cmaxrss = maxrss;
|
|
task_io_accounting_add(&psig->ioac, &p->ioac);
|
|
task_io_accounting_add(&psig->ioac, &sig->ioac);
|
|
write_sequnlock(&psig->stats_lock);
|
|
spin_unlock_irq(¤t->sighand->siglock);
|
|
}
|
|
|
|
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 (state == EXIT_TRACE) {
|
|
write_lock_irq(&tasklist_lock);
|
|
/* We dropped tasklist, ptracer could die and untrace */
|
|
ptrace_unlink(p);
|
|
|
|
/* If parent wants a zombie, don't release it now */
|
|
state = EXIT_ZOMBIE;
|
|
if (do_notify_parent(p, p->exit_signal))
|
|
state = EXIT_DEAD;
|
|
p->exit_state = state;
|
|
write_unlock_irq(&tasklist_lock);
|
|
}
|
|
if (state == EXIT_DEAD)
|
|
release_task(p);
|
|
|
|
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 = from_kuid_munged(current_user_ns(), task_uid(p));
|
|
unlock_sig:
|
|
spin_unlock_irq(&p->sighand->siglock);
|
|
if (!exit_code)
|
|
return 0;
|
|
|
|
/*
|
|
* Now we are pretty sure this task is interesting.
|
|
* Make sure it doesn't get reaped out from under us while we
|
|
* give up the lock and then examine it below. We don't want to
|
|
* keep holding onto the tasklist_lock while we call getrusage and
|
|
* possibly take page faults for user memory.
|
|
*/
|
|
get_task_struct(p);
|
|
pid = task_pid_vnr(p);
|
|
why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
|
|
read_unlock(&tasklist_lock);
|
|
sched_annotate_sleep();
|
|
|
|
if (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 = from_kuid_munged(current_user_ns(), task_uid(p));
|
|
spin_unlock_irq(&p->sighand->siglock);
|
|
|
|
pid = task_pid_vnr(p);
|
|
get_task_struct(p);
|
|
read_unlock(&tasklist_lock);
|
|
sched_annotate_sleep();
|
|
|
|
if (!wo->wo_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)
|
|
{
|
|
/*
|
|
* We can race with wait_task_zombie() from another thread.
|
|
* Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition
|
|
* can't confuse the checks below.
|
|
*/
|
|
int exit_state = ACCESS_ONCE(p->exit_state);
|
|
int ret;
|
|
|
|
if (unlikely(exit_state == EXIT_DEAD))
|
|
return 0;
|
|
|
|
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;
|
|
}
|
|
|
|
if (unlikely(exit_state == EXIT_TRACE)) {
|
|
/*
|
|
* ptrace == 0 means we are the natural parent. In this case
|
|
* we should clear notask_error, debugger will notify us.
|
|
*/
|
|
if (likely(!ptrace))
|
|
wo->notask_error = 0;
|
|
return 0;
|
|
}
|
|
|
|
if (likely(!ptrace) && unlikely(p->ptrace)) {
|
|
/*
|
|
* If it is traced by its real parent's group, just pretend
|
|
* the caller is ptrace_do_wait() and reap this child if it
|
|
* is zombie.
|
|
*
|
|
* This also hides group stop state from real parent; otherwise
|
|
* a single stop can be reported twice as group and ptrace stop.
|
|
* If a ptracer wants to distinguish these two events for its
|
|
* own children it should create a separate process which takes
|
|
* the role of real parent.
|
|
*/
|
|
if (!ptrace_reparented(p))
|
|
ptrace = 1;
|
|
}
|
|
|
|
/* slay zombie? */
|
|
if (exit_state == EXIT_ZOMBIE) {
|
|
/* we don't reap group leaders with subthreads */
|
|
if (!delay_group_leader(p)) {
|
|
/*
|
|
* A zombie ptracee is only visible to its ptracer.
|
|
* Notification and reaping will be cascaded to the
|
|
* real parent when the ptracer detaches.
|
|
*/
|
|
if (unlikely(ptrace) || likely(!p->ptrace))
|
|
return wait_task_zombie(wo, p);
|
|
}
|
|
|
|
/*
|
|
* Allow access to stopped/continued state via zombie by
|
|
* falling through. Clearing of notask_error is complex.
|
|
*
|
|
* When !@ptrace:
|
|
*
|
|
* If WEXITED is set, notask_error should naturally be
|
|
* cleared. If not, subset of WSTOPPED|WCONTINUED is set,
|
|
* so, if there are live subthreads, there are events to
|
|
* wait for. If all subthreads are dead, it's still safe
|
|
* to clear - this function will be called again in finite
|
|
* amount time once all the subthreads are released and
|
|
* will then return without clearing.
|
|
*
|
|
* When @ptrace:
|
|
*
|
|
* Stopped state is per-task and thus can't change once the
|
|
* target task dies. Only continued and exited can happen.
|
|
* Clear notask_error if WCONTINUED | WEXITED.
|
|
*/
|
|
if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED)))
|
|
wo->notask_error = 0;
|
|
} else {
|
|
/*
|
|
* @p is alive and it's gonna stop, continue or exit, so
|
|
* there always is something to wait for.
|
|
*/
|
|
wo->notask_error = 0;
|
|
}
|
|
|
|
/*
|
|
* Wait for stopped. Depending on @ptrace, different stopped state
|
|
* is used and the two don't interact with each other.
|
|
*/
|
|
ret = wait_task_stopped(wo, ptrace, p);
|
|
if (ret)
|
|
return ret;
|
|
|
|
/*
|
|
* Wait for continued. There's only one continued state and the
|
|
* ptracer can consume it which can confuse the real parent. Don't
|
|
* use WCONTINUED from ptracer. You don't need or want it.
|
|
*/
|
|
return wait_task_continued(wo, p);
|
|
}
|
|
|
|
/*
|
|
* Do the work of do_wait() for one thread in the group, @tsk.
|
|
*
|
|
* -ECHILD should be in ->notask_error before the first call.
|
|
* Returns nonzero for a final return, when we have unlocked tasklist_lock.
|
|
* Returns zero if the search for a child should continue; then
|
|
* ->notask_error is 0 if there were any eligible children,
|
|
* or 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(¤t->signal->wait_chldexit, &wo->child_wait);
|
|
repeat:
|
|
/*
|
|
* If there is nothing that can match our criteria, just get out.
|
|
* We will clear ->notask_error to zero if we see any child that
|
|
* might later match our criteria, even if we are not able to reap
|
|
* it yet.
|
|
*/
|
|
wo->notask_error = -ECHILD;
|
|
if ((wo->wo_type < PIDTYPE_MAX) &&
|
|
(!wo->wo_pid || 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, &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);
|
|
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);
|
|
|
|
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
|