From 2831096e21503897ee474c23131c3feb8db0ffb1 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 10 Dec 2014 15:45:30 -0800 Subject: [PATCH] exit: reparent: cleanup the usage of reparent_leader() 1. Now that reparent_leader() doesn't abuse ->sibling we can shift list_move_tail() from reparent_leader() to forget_original_parent() and turn it into a single list_splice_tail_init(). This also makes BUG_ON(!list_empty()) and list_for_each_entry_safe() unnecessary. 2. This also allows to shift the same_thread_group() check, it looks a bit more clear in the caller. Signed-off-by: Oleg Nesterov Cc: Aaron Tomlin Cc: Alexey Dobriyan Cc: "Eric W. Biederman" , Cc: Sterling Alexander Cc: Peter Zijlstra Cc: Roland McGrath Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/exit.c | 22 +++++++++------------- 1 file changed, 9 insertions(+), 13 deletions(-) diff --git a/kernel/exit.c b/kernel/exit.c index 464971e6923e..772e9175735c 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -529,15 +529,7 @@ static struct task_struct *find_new_reaper(struct task_struct *father) 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. - */ - if (same_thread_group(p->real_parent, father)) + if (unlikely(p->exit_state == EXIT_DEAD)) return; /* We don't want people slaying init. */ @@ -568,7 +560,7 @@ static void forget_original_parent(struct task_struct *father) exit_ptrace(father); reaper = find_new_reaper(father); - list_for_each_entry_safe(p, n, &father->children, sibling) { + list_for_each_entry(p, &father->children, sibling) { for_each_thread(p, t) { t->real_parent = reaper; BUG_ON((!t->ptrace) != (t->parent == father)); @@ -578,12 +570,16 @@ static void forget_original_parent(struct task_struct *father) group_send_sig_info(t->pdeath_signal, SEND_SIG_NOINFO, t); } - reparent_leader(father, p, &dead_children); + /* + * If this is a threaded reparent there is no need to + * notify anyone anything has happened. + */ + if (!same_thread_group(reaper, father)) + reparent_leader(father, p, &dead_children); } + list_splice_tail_init(&father->children, &reaper->children); write_unlock_irq(&tasklist_lock); - BUG_ON(!list_empty(&father->children)); - list_for_each_entry_safe(p, n, &dead_children, ptrace_entry) { list_del_init(&p->ptrace_entry); release_task(p); -- 2.20.1