| /* |
| * linux/kernel/exit.c |
| * |
| * Copyright (C) 1991, 1992 Linus Torvalds |
| */ |
| |
| #include <linux/mm.h> |
| #include <linux/slab.h> |
| #include <linux/interrupt.h> |
| #include <linux/module.h> |
| #include <linux/capability.h> |
| #include <linux/completion.h> |
| #include <linux/personality.h> |
| #include <linux/tty.h> |
| #include <linux/mnt_namespace.h> |
| #include <linux/iocontext.h> |
| #include <linux/key.h> |
| #include <linux/security.h> |
| #include <linux/cpu.h> |
| #include <linux/acct.h> |
| #include <linux/tsacct_kern.h> |
| #include <linux/file.h> |
| #include <linux/fdtable.h> |
| #include <linux/binfmts.h> |
| #include <linux/nsproxy.h> |
| #include <linux/pid_namespace.h> |
| #include <linux/ptrace.h> |
| #include <linux/profile.h> |
| #include <linux/mount.h> |
| #include <linux/proc_fs.h> |
| #include <linux/kthread.h> |
| #include <linux/mempolicy.h> |
| #include <linux/taskstats_kern.h> |
| #include <linux/delayacct.h> |
| #include <linux/freezer.h> |
| #include <linux/cgroup.h> |
| #include <linux/syscalls.h> |
| #include <linux/signal.h> |
| #include <linux/posix-timers.h> |
| #include <linux/cn_proc.h> |
| #include <linux/mutex.h> |
| #include <linux/futex.h> |
| #include <linux/pipe_fs_i.h> |
| #include <linux/audit.h> /* for audit_free() */ |
| #include <linux/resource.h> |
| #include <linux/blkdev.h> |
| #include <linux/task_io_accounting_ops.h> |
| #include <linux/tracehook.h> |
| #include <trace/sched.h> |
| |
| #include <asm/uaccess.h> |
| #include <asm/unistd.h> |
| #include <asm/pgtable.h> |
| #include <asm/mmu_context.h> |
| |
| DEFINE_TRACE(sched_process_free); |
| DEFINE_TRACE(sched_process_exit); |
| DEFINE_TRACE(sched_process_wait); |
| |
| static void exit_mm(struct task_struct * tsk); |
| |
| static inline int task_detached(struct task_struct *p) |
| { |
| return p->exit_signal == -1; |
| } |
| |
| static void __unhash_process(struct task_struct *p) |
| { |
| nr_threads--; |
| detach_pid(p, PIDTYPE_PID); |
| if (thread_group_leader(p)) { |
| detach_pid(p, PIDTYPE_PGID); |
| detach_pid(p, PIDTYPE_SID); |
| |
| list_del_rcu(&p->tasks); |
| __get_cpu_var(process_counts)--; |
| } |
| list_del_rcu(&p->thread_group); |
| list_del_init(&p->sibling); |
| } |
| |
| /* |
| * This function expects the tasklist_lock write-locked. |
| */ |
| static void __exit_signal(struct task_struct *tsk) |
| { |
| struct signal_struct *sig = tsk->signal; |
| struct sighand_struct *sighand; |
| |
| BUG_ON(!sig); |
| BUG_ON(!atomic_read(&sig->count)); |
| |
| sighand = rcu_dereference(tsk->sighand); |
| spin_lock(&sighand->siglock); |
| |
| posix_cpu_timers_exit(tsk); |
| if (atomic_dec_and_test(&sig->count)) |
| posix_cpu_timers_exit_group(tsk); |
| else { |
| /* |
| * If there is any task waiting for the group exit |
| * then notify it: |
| */ |
| if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count) |
| wake_up_process(sig->group_exit_task); |
| |
| if (tsk == sig->curr_target) |
| sig->curr_target = next_thread(tsk); |
| /* |
| * Accumulate here the counters for all threads but the |
| * group leader as they die, so they can be added into |
| * the process-wide totals when those are taken. |
| * The group leader stays around as a zombie as long |
| * as there are other threads. When it gets reaped, |
| * the exit.c code will add its counts into these totals. |
| * We won't ever get here for the group leader, since it |
| * will have been the last reference on the signal_struct. |
| */ |
| sig->gtime = cputime_add(sig->gtime, task_gtime(tsk)); |
| sig->min_flt += tsk->min_flt; |
| sig->maj_flt += tsk->maj_flt; |
| sig->nvcsw += tsk->nvcsw; |
| sig->nivcsw += tsk->nivcsw; |
| sig->inblock += task_io_get_inblock(tsk); |
| sig->oublock += task_io_get_oublock(tsk); |
| task_io_accounting_add(&sig->ioac, &tsk->ioac); |
| sig = NULL; /* Marker for below. */ |
| } |
| |
| __unhash_process(tsk); |
| |
| /* |
| * Do this under ->siglock, we can race with another thread |
| * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals. |
| */ |
| flush_sigqueue(&tsk->pending); |
| |
| tsk->signal = NULL; |
| tsk->sighand = NULL; |
| spin_unlock(&sighand->siglock); |
| |
| __cleanup_sighand(sighand); |
| clear_tsk_thread_flag(tsk,TIF_SIGPENDING); |
| if (sig) { |
| flush_sigqueue(&sig->shared_pending); |
| taskstats_tgid_free(sig); |
| /* |
| * Make sure ->signal can't go away under rq->lock, |
| * see account_group_exec_runtime(). |
| */ |
| task_rq_unlock_wait(tsk); |
| __cleanup_signal(sig); |
| } |
| } |
| |
| static void delayed_put_task_struct(struct rcu_head *rhp) |
| { |
| struct task_struct *tsk = container_of(rhp, struct task_struct, rcu); |
| |
| trace_sched_process_free(tsk); |
| put_task_struct(tsk); |
| } |
| |
| |
| void release_task(struct task_struct * p) |
| { |
| struct task_struct *leader; |
| int zap_leader; |
| repeat: |
| tracehook_prepare_release_task(p); |
| atomic_dec(&p->user->processes); |
| proc_flush_task(p); |
| write_lock_irq(&tasklist_lock); |
| tracehook_finish_release_task(p); |
| __exit_signal(p); |
| |
| /* |
| * If we are the last non-leader member of the thread |
| * group, and the leader is zombie, then notify the |
| * group leader's parent process. (if it wants notification.) |
| */ |
| zap_leader = 0; |
| leader = p->group_leader; |
| if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) { |
| BUG_ON(task_detached(leader)); |
| do_notify_parent(leader, leader->exit_signal); |
| /* |
| * If we were the last child thread and the leader has |
| * exited already, and the leader's parent ignores SIGCHLD, |
| * then we are the one who should release the leader. |
| * |
| * do_notify_parent() will have marked it self-reaping in |
| * that case. |
| */ |
| zap_leader = task_detached(leader); |
| |
| /* |
| * This maintains the invariant that release_task() |
| * only runs on a task in EXIT_DEAD, just for sanity. |
| */ |
| if (zap_leader) |
| leader->exit_state = EXIT_DEAD; |
| } |
| |
| write_unlock_irq(&tasklist_lock); |
| release_thread(p); |
| call_rcu(&p->rcu, delayed_put_task_struct); |
| |
| p = leader; |
| if (unlikely(zap_leader)) |
| goto repeat; |
| } |
| |
| /* |
| * This checks not only the pgrp, but falls back on the pid if no |
| * satisfactory pgrp is found. I dunno - gdb doesn't work correctly |
| * without this... |
| * |
| * The caller must hold rcu lock or the tasklist lock. |
| */ |
| struct pid *session_of_pgrp(struct pid *pgrp) |
| { |
| struct task_struct *p; |
| struct pid *sid = NULL; |
| |
| p = pid_task(pgrp, PIDTYPE_PGID); |
| if (p == NULL) |
| p = pid_task(pgrp, PIDTYPE_PID); |
| if (p != NULL) |
| sid = task_session(p); |
| |
| return sid; |
| } |
| |
| /* |
| * Determine if a process group is "orphaned", according to the POSIX |
| * definition in 2.2.2.52. Orphaned process groups are not to be affected |
| * by terminal-generated stop signals. Newly orphaned process groups are |
| * to receive a SIGHUP and a SIGCONT. |
| * |
| * "I ask you, have you ever known what it is to be an orphan?" |
| */ |
| static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task) |
| { |
| struct task_struct *p; |
| |
| do_each_pid_task(pgrp, PIDTYPE_PGID, p) { |
| if ((p == ignored_task) || |
| (p->exit_state && thread_group_empty(p)) || |
| is_global_init(p->real_parent)) |
| continue; |
| |
| if (task_pgrp(p->real_parent) != pgrp && |
| task_session(p->real_parent) == task_session(p)) |
| return 0; |
| } while_each_pid_task(pgrp, PIDTYPE_PGID, p); |
| |
| return 1; |
| } |
| |
| int is_current_pgrp_orphaned(void) |
| { |
| int retval; |
| |
| read_lock(&tasklist_lock); |
| retval = will_become_orphaned_pgrp(task_pgrp(current), NULL); |
| read_unlock(&tasklist_lock); |
| |
| return retval; |
| } |
| |
| static int has_stopped_jobs(struct pid *pgrp) |
| { |
| int retval = 0; |
| struct task_struct *p; |
| |
| do_each_pid_task(pgrp, PIDTYPE_PGID, p) { |
| if (!task_is_stopped(p)) |
| continue; |
| retval = 1; |
| break; |
| } while_each_pid_task(pgrp, PIDTYPE_PGID, p); |
| return retval; |
| } |
| |
| /* |
| * Check to see if any process groups have become orphaned as |
| * a result of our exiting, and if they have any stopped jobs, |
| * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) |
| */ |
| static void |
| kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent) |
| { |
| struct pid *pgrp = task_pgrp(tsk); |
| struct task_struct *ignored_task = tsk; |
| |
| if (!parent) |
| /* exit: our father is in a different pgrp than |
| * we are and we were the only connection outside. |
| */ |
| parent = tsk->real_parent; |
| else |
| /* reparent: our child is in a different pgrp than |
| * we are, and it was the only connection outside. |
| */ |
| ignored_task = NULL; |
| |
| if (task_pgrp(parent) != pgrp && |
| task_session(parent) == task_session(tsk) && |
| will_become_orphaned_pgrp(pgrp, ignored_task) && |
| has_stopped_jobs(pgrp)) { |
| __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp); |
| __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp); |
| } |
| } |
| |
| /** |
| * reparent_to_kthreadd - Reparent the calling kernel thread to kthreadd |
| * |
| * If a kernel thread is launched as a result of a system call, or if |
| * it ever exits, it should generally reparent itself to kthreadd so it |
| * isn't in the way of other processes and is correctly cleaned up on exit. |
| * |
| * The various task state such as scheduling policy and priority may have |
| * been inherited from a user process, so we reset them to sane values here. |
| * |
| * NOTE that reparent_to_kthreadd() gives the caller full capabilities. |
| */ |
| static void reparent_to_kthreadd(void) |
| { |
| write_lock_irq(&tasklist_lock); |
| |
| ptrace_unlink(current); |
| /* Reparent to init */ |
| current->real_parent = current->parent = kthreadd_task; |
| list_move_tail(¤t->sibling, ¤t->real_parent->children); |
| |
| /* Set the exit signal to SIGCHLD so we signal init on exit */ |
| current->exit_signal = SIGCHLD; |
| |
| if (task_nice(current) < 0) |
| set_user_nice(current, 0); |
| /* cpus_allowed? */ |
| /* rt_priority? */ |
| /* signals? */ |
| security_task_reparent_to_init(current); |
| memcpy(current->signal->rlim, init_task.signal->rlim, |
| sizeof(current->signal->rlim)); |
| atomic_inc(&(INIT_USER->__count)); |
| write_unlock_irq(&tasklist_lock); |
| switch_uid(INIT_USER); |
| } |
| |
| void __set_special_pids(struct pid *pid) |
| { |
| struct task_struct *curr = current->group_leader; |
| pid_t nr = pid_nr(pid); |
| |
| if (task_session(curr) != pid) { |
| change_pid(curr, PIDTYPE_SID, pid); |
| set_task_session(curr, nr); |
| } |
| if (task_pgrp(curr) != pid) { |
| change_pid(curr, PIDTYPE_PGID, pid); |
| set_task_pgrp(curr, nr); |
| } |
| } |
| |
| static void set_special_pids(struct pid *pid) |
| { |
| write_lock_irq(&tasklist_lock); |
| __set_special_pids(pid); |
| write_unlock_irq(&tasklist_lock); |
| } |
| |
| /* |
| * Let kernel threads use this to say that they |
| * allow a certain signal (since daemonize() will |
| * have disabled all of them by default). |
| */ |
| int allow_signal(int sig) |
| { |
| if (!valid_signal(sig) || sig < 1) |
| return -EINVAL; |
| |
| spin_lock_irq(¤t->sighand->siglock); |
| sigdelset(¤t->blocked, sig); |
| if (!current->mm) { |
| /* Kernel threads handle their own signals. |
| Let the signal code know it'll be handled, so |
| that they don't get converted to SIGKILL or |
| just silently dropped */ |
| current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2; |
| } |
| recalc_sigpending(); |
| spin_unlock_irq(¤t->sighand->siglock); |
| return 0; |
| } |
| |
| EXPORT_SYMBOL(allow_signal); |
| |
| int disallow_signal(int sig) |
| { |
| if (!valid_signal(sig) || sig < 1) |
| return -EINVAL; |
| |
| spin_lock_irq(¤t->sighand->siglock); |
| current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN; |
| recalc_sigpending(); |
| spin_unlock_irq(¤t->sighand->siglock); |
| return 0; |
| } |
| |
| EXPORT_SYMBOL(disallow_signal); |
| |
| /* |
| * Put all the gunge required to become a kernel thread without |
| * attached user resources in one place where it belongs. |
| */ |
| |
| void daemonize(const char *name, ...) |
| { |
| va_list args; |
| struct fs_struct *fs; |
| sigset_t blocked; |
| |
| va_start(args, name); |
| vsnprintf(current->comm, sizeof(current->comm), name, args); |
| va_end(args); |
| |
| /* |
| * If we were started as result of loading a module, close all of the |
| * user space pages. We don't need them, and if we didn't close them |
| * they would be locked into memory. |
| */ |
| exit_mm(current); |
| /* |
| * We don't want to have TIF_FREEZE set if the system-wide hibernation |
| * or suspend transition begins right now. |
| */ |
| current->flags |= (PF_NOFREEZE | PF_KTHREAD); |
| |
| if (current->nsproxy != &init_nsproxy) { |
| get_nsproxy(&init_nsproxy); |
| switch_task_namespaces(current, &init_nsproxy); |
| } |
| set_special_pids(&init_struct_pid); |
| proc_clear_tty(current); |
| |
| /* Block and flush all signals */ |
| sigfillset(&blocked); |
| sigprocmask(SIG_BLOCK, &blocked, NULL); |
| flush_signals(current); |
| |
| /* Become as one with the init task */ |
| |
| exit_fs(current); /* current->fs->count--; */ |
| fs = init_task.fs; |
| current->fs = fs; |
| atomic_inc(&fs->count); |
| |
| exit_files(current); |
| current->files = init_task.files; |
| atomic_inc(¤t->files->count); |
| |
| reparent_to_kthreadd(); |
| } |
| |
| EXPORT_SYMBOL(daemonize); |
| |
| static void close_files(struct files_struct * files) |
| { |
| int i, j; |
| struct fdtable *fdt; |
| |
| j = 0; |
| |
| /* |
| * It is safe to dereference the fd table without RCU or |
| * ->file_lock because this is the last reference to the |
| * files structure. |
| */ |
| fdt = files_fdtable(files); |
| for (;;) { |
| unsigned long set; |
| i = j * __NFDBITS; |
| if (i >= fdt->max_fds) |
| break; |
| set = fdt->open_fds->fds_bits[j++]; |
| while (set) { |
| if (set & 1) { |
| struct file * file = xchg(&fdt->fd[i], NULL); |
| if (file) { |
| filp_close(file, files); |
| cond_resched(); |
| } |
| } |
| i++; |
| set >>= 1; |
| } |
| } |
| } |
| |
| struct files_struct *get_files_struct(struct task_struct *task) |
| { |
| struct files_struct *files; |
| |
| task_lock(task); |
| files = task->files; |
| if (files) |
| atomic_inc(&files->count); |
| task_unlock(task); |
| |
| return files; |
| } |
| |
| void put_files_struct(struct files_struct *files) |
| { |
| struct fdtable *fdt; |
| |
| if (atomic_dec_and_test(&files->count)) { |
| close_files(files); |
| /* |
| * Free the fd and fdset arrays if we expanded them. |
| * If the fdtable was embedded, pass files for freeing |
| * at the end of the RCU grace period. Otherwise, |
| * you can free files immediately. |
| */ |
| 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); |
| } |
| } |
| |
| void put_fs_struct(struct fs_struct *fs) |
| { |
| /* No need to hold fs->lock if we are killing it */ |
| if (atomic_dec_and_test(&fs->count)) { |
| path_put(&fs->root); |
| path_put(&fs->pwd); |
| kmem_cache_free(fs_cachep, fs); |
| } |
| } |
| |
| void exit_fs(struct task_struct *tsk) |
| { |
| struct fs_struct * fs = tsk->fs; |
| |
| if (fs) { |
| task_lock(tsk); |
| tsk->fs = NULL; |
| task_unlock(tsk); |
| put_fs_struct(fs); |
| } |
| } |
| |
| EXPORT_SYMBOL_GPL(exit_fs); |
| |
| #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->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, |
| * so that subsystems can understand the callback and take action. |
| */ |
| down_write(&mm->mmap_sem); |
| cgroup_mm_owner_callbacks(mm->owner, NULL); |
| mm->owner = NULL; |
| up_write(&mm->mmap_sem); |
| return; |
| |
| assign_new_owner: |
| BUG_ON(c == p); |
| get_task_struct(c); |
| read_unlock(&tasklist_lock); |
| down_write(&mm->mmap_sem); |
| /* |
| * The task_lock protects c->mm from changing. |
| * We always want mm->owner->mm == mm |
| */ |
| task_lock(c); |
| if (c->mm != mm) { |
| task_unlock(c); |
| up_write(&mm->mmap_sem); |
| put_task_struct(c); |
| goto retry; |
| } |
| cgroup_mm_owner_callbacks(mm->owner, c); |
| mm->owner = c; |
| task_unlock(c); |
| up_write(&mm->mmap_sem); |
| 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); |
| } |
| |
| /* |
| * Return nonzero if @parent's children should reap themselves. |
| * |
| * Called with write_lock_irq(&tasklist_lock) held. |
| */ |
| static int ignoring_children(struct task_struct *parent) |
| { |
| int ret; |
| struct sighand_struct *psig = parent->sighand; |
| unsigned long flags; |
| spin_lock_irqsave(&psig->siglock, flags); |
| ret = (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN || |
| (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT)); |
| spin_unlock_irqrestore(&psig->siglock, flags); |
| return ret; |
| } |
| |
| /* |
| * Detach all tasks we were using ptrace on. |
| * Any that need to be release_task'd are put on the @dead list. |
| * |
| * Called with write_lock(&tasklist_lock) held. |
| */ |
| static void ptrace_exit(struct task_struct *parent, struct list_head *dead) |
| { |
| struct task_struct *p, *n; |
| int ign = -1; |
| |
| list_for_each_entry_safe(p, n, &parent->ptraced, ptrace_entry) { |
| __ptrace_unlink(p); |
| |
| if (p->exit_state != EXIT_ZOMBIE) |
| continue; |
| |
| /* |
| * If it's a zombie, our attachedness prevented normal |
| * parent notification or self-reaping. Do notification |
| * now if it would have happened earlier. If it should |
| * reap itself, add it to the @dead list. We can't call |
| * release_task() here because we already hold tasklist_lock. |
| * |
| * If it's our own child, there is no notification to do. |
| * But if our normal children self-reap, then this child |
| * was prevented by ptrace and we must reap it now. |
| */ |
| if (!task_detached(p) && thread_group_empty(p)) { |
| if (!same_thread_group(p->real_parent, parent)) |
| do_notify_parent(p, p->exit_signal); |
| else { |
| if (ign < 0) |
| ign = ignoring_children(parent); |
| if (ign) |
| p->exit_signal = -1; |
| } |
| } |
| |
| if (task_detached(p)) { |
| /* |
| * Mark it as in the process of being reaped. |
| */ |
| p->exit_state = EXIT_DEAD; |
| list_add(&p->ptrace_entry, dead); |
| } |
| } |
| } |
| |
| /* |
| * Finish up exit-time ptrace cleanup. |
| * |
| * Called without locks. |
| */ |
| static void ptrace_exit_finish(struct task_struct *parent, |
| struct list_head *dead) |
| { |
| struct task_struct *p, *n; |
| |
| BUG_ON(!list_empty(&parent->ptraced)); |
| |
| list_for_each_entry_safe(p, n, dead, ptrace_entry) { |
| list_del_init(&p->ptrace_entry); |
| release_task(p); |
| } |
| } |
| |
| static void reparent_thread(struct task_struct *p, struct task_struct *father) |
| { |
| if (p->pdeath_signal) |
| /* We already hold the tasklist_lock here. */ |
| group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p); |
| |
| list_move_tail(&p->sibling, &p->real_parent->children); |
| |
| /* 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. */ |
| if (!task_detached(p)) |
| p->exit_signal = SIGCHLD; |
| |
| /* If we'd notified the old parent about this child's death, |
| * also notify the new parent. |
| */ |
| if (!ptrace_reparented(p) && |
| p->exit_state == EXIT_ZOMBIE && |
| !task_detached(p) && thread_group_empty(p)) |
| do_notify_parent(p, p->exit_signal); |
| |
| kill_orphaned_pgrp(p, father); |
| } |
| |
| /* |
| * 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; |
| } |
| |
| static void forget_original_parent(struct task_struct *father) |
| { |
| struct task_struct *p, *n, *reaper; |
| LIST_HEAD(ptrace_dead); |
| |
| write_lock_irq(&tasklist_lock); |
| reaper = find_new_reaper(father); |
| /* |
| * First clean up ptrace if we were using it. |
| */ |
| ptrace_exit(father, &ptrace_dead); |
| |
| list_for_each_entry_safe(p, n, &father->children, sibling) { |
| p->real_parent = reaper; |
| if (p->parent == father) { |
| BUG_ON(p->ptrace); |
| p->parent = p->real_parent; |
| } |
| reparent_thread(p, father); |
| } |
| |
| write_unlock_irq(&tasklist_lock); |
| BUG_ON(!list_empty(&father->children)); |
| |
| ptrace_exit_finish(father, &ptrace_dead); |
| } |
| |
| /* |
| * 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) && |
| !capable(CAP_KILL)) |
| 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 *n = end_of_stack(current); |
| unsigned long free; |
| |
| while (*n == 0) |
| n++; |
| free = (unsigned long)n - (unsigned long)end_of_stack(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; |
| if (tsk->io_context) |
| exit_io_context(); |
| 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(); |
| 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); |
| if (tsk->mm) { |
| update_hiwater_rss(tsk->mm); |
| update_hiwater_vm(tsk->mm); |
| } |
| 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); |
| exit_keys(tsk); |
| |
| 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); |
| exit_notify(tsk, group_dead); |
| #ifdef CONFIG_NUMA |
| mpol_put(tsk->mempolicy); |
| tsk->mempolicy = NULL; |
| #endif |
| #ifdef CONFIG_FUTEX |
| /* |
| * This must happen late, after the PID is not |
| * hashed anymore: |
| */ |
| 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); |
| |
| asmlinkage long sys_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. |
| */ |
| asmlinkage void sys_exit_group(int error_code) |
| { |
| do_group_exit((error_code & 0xff) << 8); |
| } |
| |
| 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(enum pid_type type, struct pid *pid, int options, |
| struct task_struct *p) |
| { |
| int err; |
| |
| if (type < PIDTYPE_MAX) { |
| if (task_pid_type(p, type) != 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) ^ ((options & __WCLONE) != 0)) |
| && !(options & __WALL)) |
| return 0; |
| |
| err = security_task_wait(p); |
| if (err) |
| return err; |
| |
| return 1; |
| } |
| |
| static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid, |
| int why, int status, |
| struct siginfo __user *infop, |
| struct rusage __user *rusagep) |
| { |
| int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0; |
| |
| put_task_struct(p); |
| 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 task_struct *p, int options, |
| struct siginfo __user *infop, |
| int __user *stat_addr, struct rusage __user *ru) |
| { |
| unsigned long state; |
| int retval, status, traced; |
| pid_t pid = task_pid_vnr(p); |
| |
| if (!likely(options & WEXITED)) |
| return 0; |
| |
| if (unlikely(options & WNOWAIT)) { |
| uid_t uid = p->uid; |
| 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(p, pid, uid, why, |
| status, infop, ru); |
| } |
| |
| /* |
| * 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); |
| |
| if (likely(!traced)) { |
| struct signal_struct *psig; |
| struct signal_struct *sig; |
| struct task_cputime cputime; |
| |
| /* |
| * 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 p->parent->signal fields, |
| * as other threads in the parent group can be right |
| * here reaping other children at the same time. |
| * |
| * We use thread_group_cputime() to get times for the thread |
| * group, which consolidates times for all threads in the |
| * group including the group leader. |
| */ |
| spin_lock_irq(&p->parent->sighand->siglock); |
| psig = p->parent->signal; |
| sig = p->signal; |
| thread_group_cputime(p, &cputime); |
| psig->cutime = |
| cputime_add(psig->cutime, |
| cputime_add(cputime.utime, |
| sig->cutime)); |
| psig->cstime = |
| cputime_add(psig->cstime, |
| cputime_add(cputime.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->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 = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0; |
| status = (p->signal->flags & SIGNAL_GROUP_EXIT) |
| ? p->signal->group_exit_code : p->exit_code; |
| if (!retval && stat_addr) |
| retval = put_user(status, stat_addr); |
| 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(p->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; |
| } |
| |
| /* |
| * 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(int ptrace, struct task_struct *p, |
| int options, struct siginfo __user *infop, |
| int __user *stat_addr, struct rusage __user *ru) |
| { |
| int retval, exit_code, why; |
| uid_t uid = 0; /* unneeded, required by compiler */ |
| pid_t pid; |
| |
| if (!(options & WUNTRACED)) |
| return 0; |
| |
| exit_code = 0; |
| spin_lock_irq(&p->sighand->siglock); |
| |
| if (unlikely(!task_is_stopped_or_traced(p))) |
| goto unlock_sig; |
| |
| if (!ptrace && p->signal->group_stop_count > 0) |
| /* |
| * A group stop is in progress and this is the group leader. |
| * We won't report until all threads have stopped. |
| */ |
| goto unlock_sig; |
| |
| exit_code = p->exit_code; |
| if (!exit_code) |
| goto unlock_sig; |
| |
| if (!unlikely(options & WNOWAIT)) |
| p->exit_code = 0; |
| |
| uid = 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(options & WNOWAIT)) |
| return wait_noreap_copyout(p, pid, uid, |
| why, exit_code, |
| infop, ru); |
| |
| retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0; |
| if (!retval && stat_addr) |
| retval = put_user((exit_code << 8) | 0x7f, stat_addr); |
| 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 task_struct *p, int options, |
| struct siginfo __user *infop, |
| int __user *stat_addr, struct rusage __user *ru) |
| { |
| int retval; |
| pid_t pid; |
| uid_t uid; |
| |
| if (!unlikely(options & 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(options & WNOWAIT)) |
| p->signal->flags &= ~SIGNAL_STOP_CONTINUED; |
| spin_unlock_irq(&p->sighand->siglock); |
| |
| pid = task_pid_vnr(p); |
| uid = p->uid; |
| get_task_struct(p); |
| read_unlock(&tasklist_lock); |
| |
| if (!infop) { |
| retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0; |
| put_task_struct(p); |
| if (!retval && stat_addr) |
| retval = put_user(0xffff, stat_addr); |
| if (!retval) |
| retval = pid; |
| } else { |
| retval = wait_noreap_copyout(p, pid, uid, |
| CLD_CONTINUED, SIGCONT, |
| infop, ru); |
| 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 task_struct *parent, int ptrace, |
| struct task_struct *p, int *notask_error, |
| enum pid_type type, struct pid *pid, int options, |
| struct siginfo __user *infop, |
| int __user *stat_addr, struct rusage __user *ru) |
| { |
| int ret = eligible_child(type, pid, options, 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 (*notask_error) |
| *notask_error = ret; |
| } |
| |
| if (likely(!ptrace) && unlikely(p->ptrace)) { |
| /* |
| * This child is hidden by ptrace. |
| * We aren't allowed to see it now, but eventually we will. |
| */ |
| *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(p, options, infop, stat_addr, ru); |
| |
| /* |
| * It's stopped or running now, so it might |
| * later continue, exit, or stop again. |
| */ |
| *notask_error = 0; |
| |
| if (task_is_stopped_or_traced(p)) |
| return wait_task_stopped(ptrace, p, options, |
| infop, stat_addr, ru); |
| |
| return wait_task_continued(p, options, infop, stat_addr, ru); |
| } |
| |
| /* |
| * 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 task_struct *tsk, int *notask_error, |
| enum pid_type type, struct pid *pid, int options, |
| struct siginfo __user *infop, int __user *stat_addr, |
| struct rusage __user *ru) |
| { |
| 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(tsk, 0, p, notask_error, |
| type, pid, options, |
| infop, stat_addr, ru); |
| if (ret) |
| return ret; |
| } |
| } |
| |
| return 0; |
| } |
| |
| static int ptrace_do_wait(struct task_struct *tsk, int *notask_error, |
| enum pid_type type, struct pid *pid, int options, |
| struct siginfo __user *infop, int __user *stat_addr, |
| struct rusage __user *ru) |
| { |
| struct task_struct *p; |
| |
| /* |
| * Traditionally we see ptrace'd stopped tasks regardless of options. |
| */ |
| options |= WUNTRACED; |
| |
| list_for_each_entry(p, &tsk->ptraced, ptrace_entry) { |
| int ret = wait_consider_task(tsk, 1, p, notask_error, |
| type, pid, options, |
| infop, stat_addr, ru); |
| if (ret) |
| return ret; |
| } |
| |
| return 0; |
| } |
| |
| static long do_wait(enum pid_type type, struct pid *pid, int options, |
| struct siginfo __user *infop, int __user *stat_addr, |
| struct rusage __user *ru) |
| { |
| DECLARE_WAITQUEUE(wait, current); |
| struct task_struct *tsk; |
| int retval; |
| |
| trace_sched_process_wait(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 @retval to zero if we see any child that might later |
| * match our criteria, even if we are not able to reap it yet. |
| */ |
| retval = -ECHILD; |
| if ((type < PIDTYPE_MAX) && (!pid || hlist_empty(&pid->tasks[type]))) |
| goto end; |
| |
| current->state = TASK_INTERRUPTIBLE; |
| read_lock(&tasklist_lock); |
| tsk = current; |
| do { |
| int tsk_result = do_wait_thread(tsk, &retval, |
| type, pid, options, |
| infop, stat_addr, ru); |
| if (!tsk_result) |
| tsk_result = ptrace_do_wait(tsk, &retval, |
| type, pid, options, |
| infop, stat_addr, ru); |
| if (tsk_result) { |
| /* |
| * tasklist_lock is unlocked and we have a final result. |
| */ |
| retval = tsk_result; |
| goto end; |
| } |
| |
| if (options & __WNOTHREAD) |
| break; |
| tsk = next_thread(tsk); |
| BUG_ON(tsk->signal != current->signal); |
| } while (tsk != current); |
| read_unlock(&tasklist_lock); |
| |
| if (!retval && !(options & WNOHANG)) { |
| retval = -ERESTARTSYS; |
| if (!signal_pending(current)) { |
| schedule(); |
| goto repeat; |
| } |
| } |
| |
| end: |
| current->state = TASK_RUNNING; |
| remove_wait_queue(¤t->signal->wait_chldexit,&wait); |
| if (infop) { |
| 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; |
| } |
| |
| asmlinkage long sys_waitid(int which, pid_t upid, |
| struct siginfo __user *infop, int options, |
| struct rusage __user *ru) |
| { |
| 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); |
| ret = do_wait(type, pid, options, infop, NULL, ru); |
| put_pid(pid); |
| |
| /* avoid REGPARM breakage on x86: */ |
| asmlinkage_protect(5, ret, which, upid, infop, options, ru); |
| return ret; |
| } |
| |
| asmlinkage long sys_wait4(pid_t upid, int __user *stat_addr, |
| int options, struct rusage __user *ru) |
| { |
| 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_pid(task_pgrp(current)); |
| } else /* upid > 0 */ { |
| type = PIDTYPE_PID; |
| pid = find_get_pid(upid); |
| } |
| |
| ret = do_wait(type, pid, options | WEXITED, NULL, stat_addr, ru); |
| 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. |
| */ |
| asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options) |
| { |
| return sys_wait4(pid, stat_addr, options, NULL); |
| } |
| |
| #endif |