diff options
Diffstat (limited to 'kernel/exit.c')
| -rw-r--r-- | kernel/exit.c | 110 |
1 files changed, 52 insertions, 58 deletions
diff --git a/kernel/exit.c b/kernel/exit.c index 6480d1c85d7a..6ed6a1d552b5 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -570,7 +570,7 @@ static void reparent_leader(struct task_struct *father, struct task_struct *p, if (same_thread_group(p->real_parent, father)) return; - /* We don't want people slaying init. */ + /* We don't want people slaying init. */ p->exit_signal = SIGCHLD; /* If it has exited notify the new parent about this child's death. */ @@ -784,9 +784,10 @@ void do_exit(long code) exit_shm(tsk); exit_files(tsk); exit_fs(tsk); + if (group_dead) + disassociate_ctty(1); exit_task_namespaces(tsk); exit_task_work(tsk); - check_stack_usage(); exit_thread(); /* @@ -799,19 +800,15 @@ void do_exit(long code) cgroup_exit(tsk); - if (group_dead) - disassociate_ctty(1); - module_put(task_thread_info(tsk)->exec_domain->module); - proc_exit_connector(tsk); - /* * FIXME: do that only when needed, using sched_exit tracepoint */ flush_ptrace_hw_breakpoint(tsk); exit_notify(tsk, group_dead); + proc_exit_connector(tsk); #ifdef CONFIG_NUMA task_lock(tsk); mpol_put(tsk->mempolicy); @@ -844,6 +841,7 @@ void do_exit(long code) validate_creds_for_do_exit(tsk); + check_stack_usage(); preempt_disable(); if (tsk->nr_dirtied) __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied); @@ -1038,17 +1036,13 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) return wait_noreap_copyout(wo, p, pid, uid, why, status); } + traced = ptrace_reparented(p); /* - * Try to move the task's state to DEAD - * only one thread is allowed to do this: + * Move the task's state to DEAD/TRACE, only one thread can do this. */ - state = xchg(&p->exit_state, EXIT_DEAD); - if (state != EXIT_ZOMBIE) { - BUG_ON(state != EXIT_DEAD); + state = traced && thread_group_leader(p) ? EXIT_TRACE : EXIT_DEAD; + if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE) return 0; - } - - traced = ptrace_reparented(p); /* * It can be ptraced but not reparented, check * thread_group_leader() to filter out sub-threads. @@ -1109,7 +1103,7 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) /* * Now we are sure this task is interesting, and no other - * thread can reap it because we set its state to EXIT_DEAD. + * thread can reap it because we its state == DEAD/TRACE. */ read_unlock(&tasklist_lock); @@ -1146,22 +1140,19 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) if (!retval) retval = pid; - if (traced) { + if (state == EXIT_TRACE) { write_lock_irq(&tasklist_lock); /* We dropped tasklist, ptracer could die and untrace */ ptrace_unlink(p); - /* - * If this is not a sub-thread, notify the parent. - * If parent wants a zombie, don't release it now. - */ - if (thread_group_leader(p) && - !do_notify_parent(p, p->exit_signal)) { - p->exit_state = EXIT_ZOMBIE; - p = NULL; - } + + /* If parent wants a zombie, don't release it now */ + state = EXIT_ZOMBIE; + if (do_notify_parent(p, p->exit_signal)) + state = EXIT_DEAD; + p->exit_state = state; write_unlock_irq(&tasklist_lock); } - if (p != NULL) + if (state == EXIT_DEAD) release_task(p); return retval; @@ -1338,7 +1329,12 @@ static int wait_task_continued(struct wait_opts *wo, struct task_struct *p) static int wait_consider_task(struct wait_opts *wo, int ptrace, struct task_struct *p) { - int ret = eligible_child(wo, p); + int ret; + + if (unlikely(p->exit_state == EXIT_DEAD)) + return 0; + + ret = eligible_child(wo, p); if (!ret) return ret; @@ -1356,33 +1352,44 @@ static int wait_consider_task(struct wait_opts *wo, int ptrace, return 0; } - /* dead body doesn't have much to contribute */ - if (unlikely(p->exit_state == EXIT_DEAD)) { + if (unlikely(p->exit_state == EXIT_TRACE)) { /* - * But do not ignore this task until the tracer does - * wait_task_zombie()->do_notify_parent(). + * ptrace == 0 means we are the natural parent. In this case + * we should clear notask_error, debugger will notify us. */ - if (likely(!ptrace) && unlikely(ptrace_reparented(p))) + if (likely(!ptrace)) wo->notask_error = 0; return 0; } - /* slay zombie? */ - if (p->exit_state == EXIT_ZOMBIE) { + if (likely(!ptrace) && unlikely(p->ptrace)) { /* - * A zombie ptracee is only visible to its ptracer. - * Notification and reaping will be cascaded to the real - * parent when the ptracer detaches. + * If it is traced by its real parent's group, just pretend + * the caller is ptrace_do_wait() and reap this child if it + * is zombie. + * + * This also hides group stop state from real parent; otherwise + * a single stop can be reported twice as group and ptrace stop. + * If a ptracer wants to distinguish these two events for its + * own children it should create a separate process which takes + * the role of real parent. */ - if (likely(!ptrace) && unlikely(p->ptrace)) { - /* it will become visible, clear notask_error */ - wo->notask_error = 0; - return 0; - } + if (!ptrace_reparented(p)) + ptrace = 1; + } + /* slay zombie? */ + if (p->exit_state == EXIT_ZOMBIE) { /* we don't reap group leaders with subthreads */ - if (!delay_group_leader(p)) - return wait_task_zombie(wo, p); + if (!delay_group_leader(p)) { + /* + * A zombie ptracee is only visible to its ptracer. + * Notification and reaping will be cascaded to the + * real parent when the ptracer detaches. + */ + if (unlikely(ptrace) || likely(!p->ptrace)) + return wait_task_zombie(wo, p); + } /* * Allow access to stopped/continued state via zombie by @@ -1408,19 +1415,6 @@ static int wait_consider_task(struct wait_opts *wo, int ptrace, wo->notask_error = 0; } else { /* - * If @p is ptraced by a task in its real parent's group, - * hide group stop/continued state when looking at @p as - * the real parent; otherwise, a single stop can be - * reported twice as group and ptrace stops. - * - * If a ptracer wants to distinguish the two events for its - * own children, it should create a separate process which - * takes the role of real parent. - */ - if (likely(!ptrace) && p->ptrace && !ptrace_reparented(p)) - return 0; - - /* * @p is alive and it's gonna stop, continue or exit, so * there always is something to wait for. */ |