diff options
Diffstat (limited to 'kernel/exit.c')
| -rw-r--r-- | kernel/exit.c | 150 |
1 files changed, 119 insertions, 31 deletions
diff --git a/kernel/exit.c b/kernel/exit.c index 2a9d98c641ac..1510f78a0ffa 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -19,6 +19,7 @@ #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> @@ -52,6 +53,11 @@ 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--; @@ -160,7 +166,7 @@ repeat: 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); + BUG_ON(task_detached(leader)); do_notify_parent(leader, leader->exit_signal); /* * If we were the last child thread and the leader has @@ -170,7 +176,7 @@ repeat: * do_notify_parent() will have marked it self-reaping in * that case. */ - zap_leader = (leader->exit_signal == -1); + zap_leader = task_detached(leader); } write_unlock_irq(&tasklist_lock); @@ -329,13 +335,11 @@ void __set_special_pids(struct pid *pid) pid_t nr = pid_nr(pid); if (task_session(curr) != pid) { - detach_pid(curr, PIDTYPE_SID); - attach_pid(curr, PIDTYPE_SID, pid); + change_pid(curr, PIDTYPE_SID, pid); set_task_session(curr, nr); } if (task_pgrp(curr) != pid) { - detach_pid(curr, PIDTYPE_PGID); - attach_pid(curr, PIDTYPE_PGID, pid); + change_pid(curr, PIDTYPE_PGID, pid); set_task_pgrp(curr, nr); } } @@ -557,6 +561,88 @@ void exit_fs(struct task_struct *tsk) 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 (!mm) + return 0; + 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); + return; + +assign_new_owner: + BUG_ON(c == p); + get_task_struct(c); + /* + * The task_lock protects c->mm from changing. + * We always want mm->owner->mm == mm + */ + task_lock(c); + /* + * Delay read_unlock() till we have the task_lock() + * to ensure that c does not slip away underneath us + */ + read_unlock(&tasklist_lock); + if (c->mm != mm) { + task_unlock(c); + put_task_struct(c); + goto retry; + } + cgroup_mm_owner_callbacks(mm->owner, c); + mm->owner = c; + task_unlock(c); + put_task_struct(c); +} +#endif /* CONFIG_MM_OWNER */ + /* * Turn us into a lazy TLB process if we * aren't already.. @@ -596,6 +682,7 @@ static void exit_mm(struct task_struct * tsk) /* We don't want this task to be frozen prematurely */ clear_freeze_flag(tsk); task_unlock(tsk); + mm_update_next_owner(mm); mmput(mm); } @@ -610,7 +697,7 @@ reparent_thread(struct task_struct *p, struct task_struct *father, int traced) 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) + if (ptrace_reparented(p)) list_add(&p->ptrace_list, &p->real_parent->ptrace_children); } else { /* If this child is being traced, then we're the one tracing it @@ -634,18 +721,18 @@ reparent_thread(struct task_struct *p, struct task_struct *father, int traced) /* If this is a threaded reparent there is no need to * notify anyone anything has happened. */ - if (p->real_parent->group_leader == father->group_leader) + if (same_thread_group(p->real_parent, father)) return; /* We don't want people slaying init. */ - if (p->exit_signal != -1) + 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 (!traced && p->exit_state == EXIT_ZOMBIE && - p->exit_signal != -1 && thread_group_empty(p)) + !task_detached(p) && thread_group_empty(p)) do_notify_parent(p, p->exit_signal); kill_orphaned_pgrp(p, father); @@ -698,18 +785,18 @@ static void forget_original_parent(struct task_struct *father) } else { /* reparent ptraced task to its real parent */ __ptrace_unlink (p); - if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 && + if (p->exit_state == EXIT_ZOMBIE && !task_detached(p) && 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 the ptraced child is a detached zombie 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)) + if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && task_detached(p))) list_add(&p->ptrace_list, &ptrace_dead); } @@ -766,29 +853,30 @@ static void exit_notify(struct task_struct *tsk, int group_dead) * we have changed execution domain as these two values started * the same after a fork. */ - if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 && + 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->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; + if (!task_detached(tsk) && thread_group_empty(tsk)) { + int signal = ptrace_reparented(tsk) ? + SIGCHLD : tsk->exit_signal; 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)) + if (task_detached(tsk) && likely(!tsk->ptrace)) state = EXIT_DEAD; tsk->exit_state = state; + /* mt-exec, de_thread() is waiting for us */ if (thread_group_leader(tsk) && tsk->signal->notify_count < 0 && tsk->signal->group_exit_task) @@ -1032,12 +1120,13 @@ asmlinkage long sys_exit(int error_code) 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 (current->signal->flags & SIGNAL_GROUP_EXIT) - exit_code = current->signal->group_exit_code; + if (signal_group_exit(sig)) + exit_code = sig->group_exit_code; else if (!thread_group_empty(current)) { - struct signal_struct *const sig = current->signal; struct sighand_struct *const sighand = current->sighand; spin_lock_irq(&sighand->siglock); if (signal_group_exit(sig)) @@ -1089,7 +1178,7 @@ static int eligible_child(enum pid_type type, struct pid *pid, int options, * Do not consider detached threads that are * not ptraced: */ - if (p->exit_signal == -1 && !p->ptrace) + if (task_detached(p) && !p->ptrace) return 0; /* Wait for all children (clone and not) if __WALL is set; @@ -1179,8 +1268,7 @@ static int wait_task_zombie(struct task_struct *p, int noreap, return 0; } - /* traced means p->ptrace, but not vice versa */ - traced = (p->real_parent != p->parent); + traced = ptrace_reparented(p); if (likely(!traced)) { struct signal_struct *psig; @@ -1281,9 +1369,9 @@ static int wait_task_zombie(struct task_struct *p, int noreap, * If it's still not detached after that, don't release * it now. */ - if (p->exit_signal != -1) { + if (!task_detached(p)) { do_notify_parent(p, p->exit_signal); - if (p->exit_signal != -1) { + if (!task_detached(p)) { p->exit_state = EXIT_ZOMBIE; p = NULL; } |