diff options
Diffstat (limited to 'kernel/exit.c')
| -rw-r--r-- | kernel/exit.c | 1527 |
1 files changed, 1527 insertions, 0 deletions
diff --git a/kernel/exit.c b/kernel/exit.c new file mode 100644 index 0000000..6dd4ebe --- /dev/null +++ b/kernel/exit.c @@ -0,0 +1,1527 @@ +/* + * linux/kernel/exit.c + * + * Copyright (C) 1991, 1992 Linus Torvalds + */ + +#include <linux/config.h> +#include <linux/mm.h> +#include <linux/slab.h> +#include <linux/interrupt.h> +#include <linux/smp_lock.h> +#include <linux/module.h> +#include <linux/completion.h> +#include <linux/personality.h> +#include <linux/tty.h> +#include <linux/namespace.h> +#include <linux/key.h> +#include <linux/security.h> +#include <linux/cpu.h> +#include <linux/acct.h> +#include <linux/file.h> +#include <linux/binfmts.h> +#include <linux/ptrace.h> +#include <linux/profile.h> +#include <linux/mount.h> +#include <linux/proc_fs.h> +#include <linux/mempolicy.h> +#include <linux/cpuset.h> +#include <linux/syscalls.h> + +#include <asm/uaccess.h> +#include <asm/unistd.h> +#include <asm/pgtable.h> +#include <asm/mmu_context.h> + +extern void sem_exit (void); +extern struct task_struct *child_reaper; + +int getrusage(struct task_struct *, int, struct rusage __user *); + +static void __unhash_process(struct task_struct *p) +{ + nr_threads--; + detach_pid(p, PIDTYPE_PID); + detach_pid(p, PIDTYPE_TGID); + if (thread_group_leader(p)) { + detach_pid(p, PIDTYPE_PGID); + detach_pid(p, PIDTYPE_SID); + if (p->pid) + __get_cpu_var(process_counts)--; + } + + REMOVE_LINKS(p); +} + +void release_task(struct task_struct * p) +{ + int zap_leader; + task_t *leader; + struct dentry *proc_dentry; + +repeat: + atomic_dec(&p->user->processes); + spin_lock(&p->proc_lock); + proc_dentry = proc_pid_unhash(p); + write_lock_irq(&tasklist_lock); + if (unlikely(p->ptrace)) + __ptrace_unlink(p); + BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children)); + __exit_signal(p); + __exit_sighand(p); + __unhash_process(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(leader->exit_signal == -1); + 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 = (leader->exit_signal == -1); + } + + sched_exit(p); + write_unlock_irq(&tasklist_lock); + spin_unlock(&p->proc_lock); + proc_pid_flush(proc_dentry); + release_thread(p); + put_task_struct(p); + + p = leader; + if (unlikely(zap_leader)) + goto repeat; +} + +/* we are using it only for SMP init */ + +void unhash_process(struct task_struct *p) +{ + struct dentry *proc_dentry; + + spin_lock(&p->proc_lock); + proc_dentry = proc_pid_unhash(p); + write_lock_irq(&tasklist_lock); + __unhash_process(p); + write_unlock_irq(&tasklist_lock); + spin_unlock(&p->proc_lock); + proc_pid_flush(proc_dentry); +} + +/* + * 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... + */ +int session_of_pgrp(int pgrp) +{ + struct task_struct *p; + int sid = -1; + + read_lock(&tasklist_lock); + do_each_task_pid(pgrp, PIDTYPE_PGID, p) { + if (p->signal->session > 0) { + sid = p->signal->session; + goto out; + } + } while_each_task_pid(pgrp, PIDTYPE_PGID, p); + p = find_task_by_pid(pgrp); + if (p) + sid = p->signal->session; +out: + read_unlock(&tasklist_lock); + + 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(int pgrp, task_t *ignored_task) +{ + struct task_struct *p; + int ret = 1; + + do_each_task_pid(pgrp, PIDTYPE_PGID, p) { + if (p == ignored_task + || p->exit_state + || p->real_parent->pid == 1) + continue; + if (process_group(p->real_parent) != pgrp + && p->real_parent->signal->session == p->signal->session) { + ret = 0; + break; + } + } while_each_task_pid(pgrp, PIDTYPE_PGID, p); + return ret; /* (sighing) "Often!" */ +} + +int is_orphaned_pgrp(int pgrp) +{ + int retval; + + read_lock(&tasklist_lock); + retval = will_become_orphaned_pgrp(pgrp, NULL); + read_unlock(&tasklist_lock); + + return retval; +} + +static inline int has_stopped_jobs(int pgrp) +{ + int retval = 0; + struct task_struct *p; + + do_each_task_pid(pgrp, PIDTYPE_PGID, p) { + if (p->state != TASK_STOPPED) + continue; + + /* If p is stopped by a debugger on a signal that won't + stop it, then don't count p as stopped. This isn't + perfect but it's a good approximation. */ + if (unlikely (p->ptrace) + && p->exit_code != SIGSTOP + && p->exit_code != SIGTSTP + && p->exit_code != SIGTTOU + && p->exit_code != SIGTTIN) + continue; + + retval = 1; + break; + } while_each_task_pid(pgrp, PIDTYPE_PGID, p); + return retval; +} + +/** + * reparent_to_init() - Reparent the calling kernel thread to the init task. + * + * If a kernel thread is launched as a result of a system call, or if + * it ever exits, it should generally reparent itself to init so that + * it 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_init() gives the caller full capabilities. + */ +void reparent_to_init(void) +{ + write_lock_irq(&tasklist_lock); + + ptrace_unlink(current); + /* Reparent to init */ + REMOVE_LINKS(current); + current->parent = child_reaper; + current->real_parent = child_reaper; + SET_LINKS(current); + + /* Set the exit signal to SIGCHLD so we signal init on exit */ + current->exit_signal = SIGCHLD; + + if ((current->policy == SCHED_NORMAL) && (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(pid_t session, pid_t pgrp) +{ + struct task_struct *curr = current; + + if (curr->signal->session != session) { + detach_pid(curr, PIDTYPE_SID); + curr->signal->session = session; + attach_pid(curr, PIDTYPE_SID, session); + } + if (process_group(curr) != pgrp) { + detach_pid(curr, PIDTYPE_PGID); + curr->signal->pgrp = pgrp; + attach_pid(curr, PIDTYPE_PGID, pgrp); + } +} + +void set_special_pids(pid_t session, pid_t pgrp) +{ + write_lock_irq(&tasklist_lock); + __set_special_pids(session, pgrp); + 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 (sig < 1 || sig > _NSIG) + 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 (sig < 1 || sig > _NSIG) + return -EINVAL; + + spin_lock_irq(¤t->sighand->siglock); + sigaddset(¤t->blocked, sig); + 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); + + set_special_pids(1, 1); + down(&tty_sem); + current->signal->tty = NULL; + up(&tty_sem); + + /* 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_init(); +} + +EXPORT_SYMBOL(daemonize); + +static inline void close_files(struct files_struct * files) +{ + int i, j; + + j = 0; + for (;;) { + unsigned long set; + i = j * __NFDBITS; + if (i >= files->max_fdset || i >= files->max_fds) + break; + set = files->open_fds->fds_bits[j++]; + while (set) { + if (set & 1) { + struct file * file = xchg(&files->fd[i], NULL); + if (file) + filp_close(file, files); + } + 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 fastcall put_files_struct(struct files_struct *files) +{ + if (atomic_dec_and_test(&files->count)) { + close_files(files); + /* + * Free the fd and fdset arrays if we expanded them. + */ + if (files->fd != &files->fd_array[0]) + free_fd_array(files->fd, files->max_fds); + if (files->max_fdset > __FD_SETSIZE) { + free_fdset(files->open_fds, files->max_fdset); + free_fdset(files->close_on_exec, files->max_fdset); + } + kmem_cache_free(files_cachep, files); + } +} + +EXPORT_SYMBOL(put_files_struct); + +static inline 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 exit_files(struct task_struct *tsk) +{ + __exit_files(tsk); +} + +static inline 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)) { + dput(fs->root); + mntput(fs->rootmnt); + dput(fs->pwd); + mntput(fs->pwdmnt); + if (fs->altroot) { + dput(fs->altroot); + mntput(fs->altrootmnt); + } + kmem_cache_free(fs_cachep, fs); + } +} + +void put_fs_struct(struct fs_struct *fs) +{ + __put_fs_struct(fs); +} + +static inline 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); + } +} + +void exit_fs(struct task_struct *tsk) +{ + __exit_fs(tsk); +} + +EXPORT_SYMBOL_GPL(exit_fs); + +/* + * Turn us into a lazy TLB process if we + * aren't already.. + */ +void exit_mm(struct task_struct * tsk) +{ + struct mm_struct *mm = tsk->mm; + + mm_release(tsk, mm); + if (!mm) + return; + /* + * Serialize with any possible pending coredump. + * We must hold mmap_sem around checking core_waiters + * and clearing tsk->mm. The core-inducing thread + * will increment core_waiters for each thread in the + * group with ->mm != NULL. + */ + down_read(&mm->mmap_sem); + if (mm->core_waiters) { + up_read(&mm->mmap_sem); + down_write(&mm->mmap_sem); + if (!--mm->core_waiters) + complete(mm->core_startup_done); + up_write(&mm->mmap_sem); + + wait_for_completion(&mm->core_done); + down_read(&mm->mmap_sem); + } + atomic_inc(&mm->mm_count); + if (mm != tsk->active_mm) BUG(); + /* more a memory barrier than a real lock */ + task_lock(tsk); + tsk->mm = NULL; + up_read(&mm->mmap_sem); + enter_lazy_tlb(mm, current); + task_unlock(tsk); + mmput(mm); +} + +static inline void choose_new_parent(task_t *p, task_t *reaper, task_t *child_reaper) +{ + /* + * Make sure we're not reparenting to ourselves and that + * the parent is not a zombie. + */ + BUG_ON(p == reaper || reaper->exit_state >= EXIT_ZOMBIE); + p->real_parent = reaper; + if (p->parent == p->real_parent) + BUG(); +} + +static inline void reparent_thread(task_t *p, task_t *father, int traced) +{ + /* We don't want people slaying init. */ + if (p->exit_signal != -1) + p->exit_signal = SIGCHLD; + + if (p->pdeath_signal) + /* We already hold the tasklist_lock here. */ + group_send_sig_info(p->pdeath_signal, (void *) 0, p); + + /* Move the child from its dying parent to the new one. */ + if (unlikely(traced)) { + /* Preserve ptrace links if someone else is tracing this child. */ + list_del_init(&p->ptrace_list); + if (p->parent != p->real_parent) + list_add(&p->ptrace_list, &p->real_parent->ptrace_children); + } else { + /* If this child is being traced, then we're the one tracing it + * anyway, so let go of it. + */ + p->ptrace = 0; + list_del_init(&p->sibling); + p->parent = p->real_parent; + list_add_tail(&p->sibling, &p->parent->children); + + /* If we'd notified the old parent about this child's death, + * also notify the new parent. + */ + if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 && + thread_group_empty(p)) + do_notify_parent(p, p->exit_signal); + else if (p->state == TASK_TRACED) { + /* + * If it was at a trace stop, turn it into + * a normal stop since it's no longer being + * traced. + */ + ptrace_untrace(p); + } + } + + /* + * process group orphan check + * Case ii: Our child is in a different pgrp + * than we are, and it was the only connection + * outside, so the child pgrp is now orphaned. + */ + if ((process_group(p) != process_group(father)) && + (p->signal->session == father->signal->session)) { + int pgrp = process_group(p); + + if (will_become_orphaned_pgrp(pgrp, NULL) && has_stopped_jobs(pgrp)) { + __kill_pg_info(SIGHUP, (void *)1, pgrp); + __kill_pg_info(SIGCONT, (void *)1, pgrp); + } + } +} + +/* + * 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 global child reaper process (ie "init") + */ +static inline void forget_original_parent(struct task_struct * father, + struct list_head *to_release) +{ + struct task_struct *p, *reaper = father; + struct list_head *_p, *_n; + + do { + reaper = next_thread(reaper); + if (reaper == father) { + reaper = child_reaper; + break; + } + } while (reaper->exit_state); + + /* + * There are only two places where our children can be: + * + * - in our child list + * - in our ptraced child list + * + * Search them and reparent children. + */ + list_for_each_safe(_p, _n, &father->children) { + int ptrace; + p = list_entry(_p,struct task_struct,sibling); + + ptrace = p->ptrace; + + /* if father isn't the real parent, then ptrace must be enabled */ + BUG_ON(father != p->real_parent && !ptrace); + + if (father == p->real_parent) { + /* reparent with a reaper, real father it's us */ + choose_new_parent(p, reaper, child_reaper); + reparent_thread(p, father, 0); + } else { + /* reparent ptraced task to its real parent */ + __ptrace_unlink (p); + if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 && + thread_group_empty(p)) + do_notify_parent(p, p->exit_signal); + } + + /* + * if the ptraced child is a zombie with exit_signal == -1 + * we must collect it before we exit, or it will remain + * zombie forever since we prevented it from self-reap itself + * while it was being traced by us, to be able to see it in wait4. + */ + if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && p->exit_signal == -1)) + list_add(&p->ptrace_list, to_release); + } + list_for_each_safe(_p, _n, &father->ptrace_children) { + p = list_entry(_p,struct task_struct,ptrace_list); + choose_new_parent(p, reaper, child_reaper); + reparent_thread(p, father, 1); + } +} + +/* + * Send signals to all our closest relatives so that they know + * to properly mourn us.. + */ +static void exit_notify(struct task_struct *tsk) +{ + int state; + struct task_struct *t; + struct list_head ptrace_dead, *_p, *_n; + + if (signal_pending(tsk) && !(tsk->signal->flags & SIGNAL_GROUP_EXIT) + && !thread_group_empty(tsk)) { + /* + * This occurs when there was a race between our exit + * syscall and a group signal choosing us as the one to + * wake up. It could be that we are the only thread + * alerted to check for pending signals, but another thread + * should be woken now to take the signal since we will not. + * Now we'll wake all the threads in the group just to make + * sure someone gets all the pending signals. + */ + read_lock(&tasklist_lock); + spin_lock_irq(&tsk->sighand->siglock); + for (t = next_thread(tsk); t != tsk; t = next_thread(t)) + if (!signal_pending(t) && !(t->flags & PF_EXITING)) { + recalc_sigpending_tsk(t); + if (signal_pending(t)) + signal_wake_up(t, 0); + } + spin_unlock_irq(&tsk->sighand->siglock); + read_unlock(&tasklist_lock); + } + + write_lock_irq(&tasklist_lock); + + /* + * 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) + */ + + INIT_LIST_HEAD(&ptrace_dead); + forget_original_parent(tsk, &ptrace_dead); + BUG_ON(!list_empty(&tsk->children)); + BUG_ON(!list_empty(&tsk->ptrace_children)); + + /* + * 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) + * + * Case i: Our father is in a different pgrp than we are + * and we were the only connection outside, so our pgrp + * is about to become orphaned. + */ + + t = tsk->real_parent; + + if ((process_group(t) != process_group(tsk)) && + (t->signal->session == tsk->signal->session) && + will_become_orphaned_pgrp(process_group(tsk), tsk) && + has_stopped_jobs(process_group(tsk))) { + __kill_pg_info(SIGHUP, (void *)1, process_group(tsk)); + __kill_pg_info(SIGCONT, (void *)1, process_group(tsk)); + } + + /* 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 && tsk->exit_signal != -1 && + ( tsk->parent_exec_id != t->self_exec_id || + tsk->self_exec_id != tsk->parent_exec_id) + && !capable(CAP_KILL)) + tsk->exit_signal = SIGCHLD; + + + /* If something other than our normal parent is ptracing us, then + * send it a SIGCHLD instead of honoring exit_signal. exit_signal + * only has special meaning to our real parent. + */ + if (tsk->exit_signal != -1 && thread_group_empty(tsk)) { + int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD; + do_notify_parent(tsk, signal); + } else if (tsk->ptrace) { + do_notify_parent(tsk, SIGCHLD); + } + + state = EXIT_ZOMBIE; + if (tsk->exit_signal == -1 && + (likely(tsk->ptrace == 0) || + unlikely(tsk->parent->signal->flags & SIGNAL_GROUP_EXIT))) + state = EXIT_DEAD; + tsk->exit_state = state; + + write_unlock_irq(&tasklist_lock); + + list_for_each_safe(_p, _n, &ptrace_dead) { + list_del_init(_p); + t = list_entry(_p,struct task_struct,ptrace_list); + release_task(t); + } + + /* If the process is dead, release it - nobody will wait for it */ + if (state == EXIT_DEAD) + release_task(tsk); + + /* PF_DEAD causes final put_task_struct after we schedule. */ + preempt_disable(); + tsk->flags |= PF_DEAD; +} + +fastcall NORET_TYPE void do_exit(long code) +{ + struct task_struct *tsk = current; + int group_dead; + + profile_task_exit(tsk); + + if (unlikely(in_interrupt())) + panic("Aiee, killing interrupt handler!"); + if (unlikely(!tsk->pid)) + panic("Attempted to kill the idle task!"); + if (unlikely(tsk->pid == 1)) + panic("Attempted to kill init!"); + if (tsk->io_context) + exit_io_context(); + + if (unlikely(current->ptrace & PT_TRACE_EXIT)) { + current->ptrace_message = code; + ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP); + } + + tsk->flags |= PF_EXITING; + + /* + * Make sure we don't try to process any timer firings + * while we are already exiting. + */ + tsk->it_virt_expires = cputime_zero; + tsk->it_prof_expires = cputime_zero; + tsk->it_sched_expires = 0; + + if (unlikely(in_atomic())) + printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n", + current->comm, current->pid, + preempt_count()); + + acct_update_integrals(tsk); + update_mem_hiwater(tsk); + group_dead = atomic_dec_and_test(&tsk->signal->live); + if (group_dead) { + del_timer_sync(&tsk->signal->real_timer); + acct_process(code); + } + exit_mm(tsk); + + exit_sem(tsk); + __exit_files(tsk); + __exit_fs(tsk); + exit_namespace(tsk); + exit_thread(); + cpuset_exit(tsk); + exit_keys(tsk); + + if (group_dead && tsk->signal->leader) + disassociate_ctty(1); + + module_put(tsk->thread_info->exec_domain->module); + if (tsk->binfmt) + module_put(tsk->binfmt->module); + + tsk->exit_code = code; + exit_notify(tsk); +#ifdef CONFIG_NUMA + mpol_free(tsk->mempolicy); + tsk->mempolicy = NULL; +#endif + + BUG_ON(!(current->flags & PF_DEAD)); + schedule(); + BUG(); + /* Avoid "noreturn function does return". */ + for (;;) ; +} + +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); +} + +task_t fastcall *next_thread(const task_t *p) +{ + return pid_task(p->pids[PIDTYPE_TGID].pid_list.next, PIDTYPE_TGID); +} + +EXPORT_SYMBOL(next_thread); + +/* + * 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) +{ + BUG_ON(exit_code & 0x80); /* core dumps don't get here */ + + if (current->signal->flags & SIGNAL_GROUP_EXIT) + exit_code = current->signal->group_exit_code; + else if (!thread_group_empty(current)) { + struct signal_struct *const sig = current->signal; + struct sighand_struct *const sighand = current->sighand; + read_lock(&tasklist_lock); + spin_lock_irq(&sighand->siglock); + if (sig->flags & SIGNAL_GROUP_EXIT) + /* Another thread got here before we took the lock. */ + exit_code = sig->group_exit_code; + else { + sig->flags = SIGNAL_GROUP_EXIT; + sig->group_exit_code = exit_code; + zap_other_threads(current); + } + spin_unlock_irq(&sighand->siglock); + read_unlock(&tasklist_lock); + } + + 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 int eligible_child(pid_t pid, int options, task_t *p) +{ + if (pid > 0) { + if (p->pid != pid) + return 0; + } else if (!pid) { + if (process_group(p) != process_group(current)) + return 0; + } else if (pid != -1) { + if (process_group(p) != -pid) + return 0; + } + + /* + * Do not consider detached threads that are + * not ptraced: + */ + if (p->exit_signal == -1 && !p->ptrace) + 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; + /* + * Do not consider thread group leaders that are + * in a non-empty thread group: + */ + if (current->tgid != p->tgid && delay_group_leader(p)) + return 2; + + if (security_task_wait(p)) + return 0; + + return 1; +} + +static int wait_noreap_copyout(task_t *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(task_t *p, int noreap, + struct siginfo __user *infop, + int __user *stat_addr, struct rusage __user *ru) +{ + unsigned long state; + int retval; + int status; + + if (unlikely(noreap)) { + pid_t pid = p->pid; + uid_t uid = p->uid; + int exit_code = p->exit_code; + int why, status; + + if (unlikely(p->exit_state != EXIT_ZOMBIE)) + return 0; + if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) + return 0; + 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; + } + if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) { + /* + * This can only happen in a race with a ptraced thread + * dying on another processor. + */ + return 0; + } + + if (likely(p->real_parent == p->parent) && likely(p->signal)) { + /* + * 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. + */ + spin_lock_irq(&p->parent->sighand->siglock); + p->parent->signal->cutime = + cputime_add(p->parent->signal->cutime, + cputime_add(p->utime, + cputime_add(p->signal->utime, + p->signal->cutime))); + p->parent->signal->cstime = + cputime_add(p->parent->signal->cstime, + cputime_add(p->stime, + cputime_add(p->signal->stime, + p->signal->cstime))); + p->parent->signal->cmin_flt += + p->min_flt + p->signal->min_flt + p->signal->cmin_flt; + p->parent->signal->cmaj_flt += + p->maj_flt + p->signal->maj_flt + p->signal->cmaj_flt; + p->parent->signal->cnvcsw += + p->nvcsw + p->signal->nvcsw + p->signal->cnvcsw; + p->parent->signal->cnivcsw += + p->nivcsw + p->signal->nivcsw + p->signal->cnivcsw; + 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(p->pid, &infop->si_pid); + if (!retval && infop) + retval = put_user(p->uid, &infop->si_uid); + if (retval) { + // TODO: is this safe? + p->exit_state = EXIT_ZOMBIE; + return retval; + } + retval = p->pid; + if (p->real_parent != p->parent) { + write_lock_irq(&tasklist_lock); + /* Double-check with lock held. */ + if (p->real_parent != p->parent) { + __ptrace_unlink(p); + // TODO: is this safe? + p->exit_state = EXIT_ZOMBIE; + /* + * If this is not a detached task, notify the parent. + * If it's still not detached after that, don't release + * it now. + */ + if (p->exit_signal != -1) { + do_notify_parent(p, p->exit_signal); + if (p->exit_signal != -1) + p = NULL; + } + } + write_unlock_irq(&tasklist_lock); + } + if (p != NULL) + release_task(p); + BUG_ON(!retval); + 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(task_t *p, int delayed_group_leader, int noreap, + struct siginfo __user *infop, + int __user *stat_addr, struct rusage __user *ru) +{ + int retval, exit_code; + + if (!p->exit_code) + return 0; + if (delayed_group_leader && !(p->ptrace & PT_PTRACED) && + p->signal && 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. + */ + 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); + read_unlock(&tasklist_lock); + + if (unlikely(noreap)) { + pid_t pid = p->pid; + uid_t uid = p->uid; + int why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED; + + exit_code = p->exit_code; + if (unlikely(!exit_code) || + unlikely(p->state > TASK_STOPPED)) + goto bail_ref; + return wait_noreap_copyout(p, pid, uid, + why, (exit_code << 8) | 0x7f, + infop, ru); + } + + write_lock_irq(&tasklist_lock); + + /* + * This uses xchg to be atomic with the thread resuming and setting + * it. It must also be done with the write lock held to prevent a + * race with the EXIT_ZOMBIE case. + */ + exit_code = xchg(&p->exit_code, 0); + if (unlikely(p->exit_state)) { + /* + * The task resumed and then died. Let the next iteration + * catch it in EXIT_ZOMBIE. Note that exit_code might + * already be zero here if it resumed and did _exit(0). + * The task itself is dead and won't touch exit_code again; + * other processors in this function are locked out. + */ + p->exit_code = exit_code; + exit_code = 0; + } + if (unlikely(exit_code == 0)) { + /* + * Another thread in this function got to it first, or it + * resumed, or it resumed and then died. + */ + write_unlock_irq(&tasklist_lock); +bail_ref: + put_task_struct(p); + /* + * We are returning to the wait loop without having successfully + * removed the process and having released the lock. We cannot + * continue, since the "p" task pointer is potentially stale. + * + * Return -EAGAIN, and do_wait() will restart the loop from the + * beginning. Do _not_ re-acquire the lock. + */ + return -EAGAIN; + } + + /* move to end of parent's list to avoid starvation */ + remove_parent(p); + add_parent(p, p->parent); + + write_unlock_irq(&tasklist_lock); + + 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)((p->ptrace & PT_PTRACED) + ? CLD_TRAPPED : CLD_STOPPED), + &infop->si_code); + if (!retval && infop) + retval = put_user(exit_code, &infop->si_status); + if (!retval && infop) + retval = put_user(p->pid, &infop->si_pid); + if (!retval && infop) + retval = put_user(p->uid, &infop->si_uid); + if (!retval) + retval = p->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(task_t *p, int noreap, + struct siginfo __user *infop, + int __user *stat_addr, struct rusage __user *ru) +{ + int retval; + pid_t pid; + uid_t uid; + + if (unlikely(!p->signal)) + 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 (!noreap) + p->signal->flags &= ~SIGNAL_STOP_CONTINUED; + spin_unlock_irq(&p->sighand->siglock); + + pid = p->pid; + 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 = p->pid; + } else { + retval = wait_noreap_copyout(p, pid, uid, + CLD_CONTINUED, SIGCONT, + infop, ru); + BUG_ON(retval == 0); + } + + return retval; +} + + +static inline int my_ptrace_child(struct task_struct *p) +{ + if (!(p->ptrace & PT_PTRACED)) + return 0; + if (!(p->ptrace & PT_ATTACHED)) + return 1; + /* + * This child was PTRACE_ATTACH'd. We should be seeing it only if + * we are the attacher. If we are the real parent, this is a race + * inside ptrace_attach. It is waiting for the tasklist_lock, + * which we have to switch the parent links, but has already set + * the flags in p->ptrace. + */ + return (p->parent != p->real_parent); +} + +static long do_wait(pid_t pid, int options, struct siginfo __user *infop, + int __user *stat_addr, struct rusage __user *ru) +{ + DECLARE_WAITQUEUE(wait, current); + struct task_struct *tsk; + int flag, retval; + + add_wait_queue(¤t->signal->wait_chldexit,&wait); +repeat: + /* + * We will set this flag if we see any child that might later + * match our criteria, even if we are not able to reap it yet. + */ + flag = 0; + current->state = TASK_INTERRUPTIBLE; + read_lock(&tasklist_lock); + tsk = current; + do { + struct task_struct *p; + struct list_head *_p; + int ret; + + list_for_each(_p,&tsk->children) { + p = list_entry(_p,struct task_struct,sibling); + + ret = eligible_child(pid, options, p); + if (!ret) + continue; + + switch (p->state) { + case TASK_TRACED: + if (!my_ptrace_child(p)) + continue; + /*FALLTHROUGH*/ + case TASK_STOPPED: + /* + * It's stopped now, so it might later + * continue, exit, or stop again. + */ + flag = 1; + if (!(options & WUNTRACED) && + !my_ptrace_child(p)) + continue; + retval = wait_task_stopped(p, ret == 2, + (options & WNOWAIT), + infop, + stat_addr, ru); + if (retval == -EAGAIN) + goto repeat; + if (retval != 0) /* He released the lock. */ + goto end; + break; + default: + // case EXIT_DEAD: + if (p->exit_state == EXIT_DEAD) + continue; + // case EXIT_ZOMBIE: + if (p->exit_state == EXIT_ZOMBIE) { + /* + * Eligible but we cannot release + * it yet: + */ + if (ret == 2) + goto check_continued; + if (!likely(options & WEXITED)) + continue; + retval = wait_task_zombie( + p, (options & WNOWAIT), + infop, stat_addr, ru); + /* He released the lock. */ + if (retval != 0) + goto end; + break; + } +check_continued: + /* + * It's running now, so it might later + * exit, stop, or stop and then continue. + */ + flag = 1; + if (!unlikely(options & WCONTINUED)) + continue; + retval = wait_task_continued( + p, (options & WNOWAIT), + infop, stat_addr, ru); + if (retval != 0) /* He released the lock. */ + goto end; + break; + } + } + if (!flag) { + list_for_each(_p, &tsk->ptrace_children) { + p = list_entry(_p, struct task_struct, + ptrace_list); + if (!eligible_child(pid, options, p)) + continue; + flag = 1; + break; + } + } + if (options & __WNOTHREAD) + break; + tsk = next_thread(tsk); + if (tsk->signal != current->signal) + BUG(); + } while (tsk != current); + + read_unlock(&tasklist_lock); + if (flag) { + retval = 0; + if (options & WNOHANG) + goto end; + retval = -ERESTARTSYS; + if (signal_pending(current)) + goto end; + schedule(); + goto repeat; + } + retval = -ECHILD; +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 pid, + struct siginfo __user *infop, int options, + struct rusage __user *ru) +{ + long ret; + + if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED)) + return -EINVAL; + if (!(options & (WEXITED|WSTOPPED|WCONTINUED))) + return -EINVAL; + + switch (which) { + case P_ALL: + pid = -1; + break; + case P_PID: + if (pid <= 0) + return -EINVAL; + break; + case P_PGID: + if (pid <= 0) + return -EINVAL; + pid = -pid; + break; + default: + return -EINVAL; + } + + ret = do_wait(pid, options, infop, NULL, ru); + + /* avoid REGPARM breakage on x86: */ + prevent_tail_call(ret); + return ret; +} + +asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr, + int options, struct rusage __user *ru) +{ + long ret; + + if (options & ~(WNOHANG|WUNTRACED|WCONTINUED| + __WNOTHREAD|__WCLONE|__WALL)) + return -EINVAL; + ret = do_wait(pid, options | WEXITED, NULL, stat_addr, ru); + + /* avoid REGPARM breakage on x86: */ + prevent_tail_call(ret); + 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 |
