diff options
| -rw-r--r-- | include/linux/sched.h | 1 | ||||
| -rw-r--r-- | kernel/exit.c | 50 |
2 files changed, 22 insertions, 29 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index f8497059f88c..7781de5e5e7b 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -212,6 +212,7 @@ print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq); /* in tsk->exit_state */ #define EXIT_ZOMBIE 16 #define EXIT_DEAD 32 +#define EXIT_TRACE (EXIT_ZOMBIE | EXIT_DEAD) /* in tsk->state again */ #define TASK_DEAD 64 #define TASK_WAKEKILL 128 diff --git a/kernel/exit.c b/kernel/exit.c index e354cbb13a9b..022a0ff17318 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -560,6 +560,9 @@ static void reparent_leader(struct task_struct *father, struct task_struct *p, struct list_head *dead) { list_move_tail(&p->sibling, &p->real_parent->children); + + if (p->exit_state == EXIT_DEAD) + return; /* * If this is a threaded reparent there is no need to * notify anyone anything has happened. @@ -567,19 +570,9 @@ 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. - * - * Note: we do this even if it is EXIT_DEAD, wait_task_zombie() - * can change ->exit_state to EXIT_ZOMBIE. If this is the final - * state, do_notify_parent() was already called and ->exit_signal - * doesn't matter. - */ + /* We don't want people slaying init. */ p->exit_signal = SIGCHLD; - if (p->exit_state == EXIT_DEAD) - return; - /* If it has exited notify the new parent about this child's death. */ if (!p->ptrace && p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) { @@ -1043,17 +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 ? 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. @@ -1114,7 +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); @@ -1159,14 +1148,14 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) * If this is not a sub-thread, notify the parent. * If parent wants a zombie, don't release it now. */ + state = EXIT_DEAD; if (thread_group_leader(p) && - !do_notify_parent(p, p->exit_signal)) { - p->exit_state = EXIT_ZOMBIE; - p = NULL; - } + !do_notify_parent(p, p->exit_signal)) + state = EXIT_ZOMBIE; + p->exit_state = state; write_unlock_irq(&tasklist_lock); } - if (p != NULL) + if (state == EXIT_DEAD) release_task(p); return retval; @@ -1362,12 +1351,15 @@ static int wait_consider_task(struct wait_opts *wo, int ptrace, } /* dead body doesn't have much to contribute */ - if (unlikely(p->exit_state == EXIT_DEAD)) { + if (unlikely(p->exit_state == EXIT_DEAD)) + return 0; + + 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; } |