From 2c66151cbc2cc68465489fdf64d16bd1c6ca4d0e Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Thu, 12 Sep 2002 21:36:11 -0700 Subject: [PATCH] sys_exit() threading improvements, BK-curr This implements the 'keep the initial thread around until every thread in the group exits' concept in a different, less intrusive way, along your suggestions. There is no exit_done completion handling anymore, freeing of the task is still done by wait4(). This has the following side-effect: detached threads/processes can only be started within a thread group, not in a standalone way. (This also fixes the bugs introduced by the ->exit_done code, which made it possible for a zombie task to be reactivated.) I've introduced the p->group_leader pointer, which can/will be used for other purposes in the future as well - since from now on the thread group leader is always existent. Right now it's used to notify the parent of the thread group leader from the last non-leader thread that exits [if the thread group leader is a zombie already]. --- include/linux/init_task.h | 1 + include/linux/sched.h | 6 ++++-- 2 files changed, 5 insertions(+), 2 deletions(-) (limited to 'include/linux') diff --git a/include/linux/init_task.h b/include/linux/init_task.h index bdf03241a009..c66cbf8d9f5c 100644 --- a/include/linux/init_task.h +++ b/include/linux/init_task.h @@ -61,6 +61,7 @@ .parent = &tsk, \ .children = LIST_HEAD_INIT(tsk.children), \ .sibling = LIST_HEAD_INIT(tsk.sibling), \ + .group_leader = &tsk, \ .thread_group = LIST_HEAD_INIT(tsk.thread_group), \ .wait_chldexit = __WAIT_QUEUE_HEAD_INITIALIZER(tsk.wait_chldexit),\ .real_timer = { \ diff --git a/include/linux/sched.h b/include/linux/sched.h index bdce46f40af2..513c065e281c 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -219,8 +219,6 @@ struct signal_struct { /* thread group exit support */ int group_exit; int group_exit_code; - - struct completion group_exit_done; }; /* @@ -316,6 +314,7 @@ struct task_struct { struct task_struct *parent; /* parent process */ struct list_head children; /* list of my children */ struct list_head sibling; /* linkage in my parent's children list */ + struct task_struct *group_leader; struct list_head thread_group; /* PID hash table linkage. */ @@ -827,6 +826,9 @@ static inline task_t *prev_thread(task_t *p) #define thread_group_leader(p) (p->pid == p->tgid) +#define delay_group_leader(p) \ + (p->tgid == p->pid && !list_empty(&p->thread_group)) + extern void unhash_process(struct task_struct *p); /* Protects ->fs, ->files, ->mm, and synchronises with wait4(). Nests inside tasklist_lock */ -- cgit v1.2.3