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Date: Mon, 3 Mar 2008 08:11:38 +0300
From: Oleg Nesterov <oleg@...sign.ru>
To: Christoph Hellwig <hch@...radead.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Roland McGrath <roland@...hat.com>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] introduce task_detached() helper
On 03/02, Christoph Hellwig wrote:
>
> On Mon, Mar 03, 2008 at 07:17:49AM +0300, Oleg Nesterov wrote:
> > +#define task_detached(p) ((p)->exit_signal == -1)
>
> Why is this a macro, no inline?
Well, it is so trivial... OK, let it be inline. exit.o is not the same,
but hopefully it is still correct ;)
[PATCH 1/2] introduce task_detached() helper
exit.c has numerous "->exit_signal == -1" comparisons, this check is subtle and
deserves a helper. Imho makes the code more parseable for humans. At least it's
surely more greppable.
Also, a couple of whitespace cleanups. No functional changes.
Signed-off-by: Oleg Nesterov <oleg@...sign.ru>
--- 25/kernel/exit.c~4_TD_INLINE 2008-03-03 07:54:23.000000000 +0300
+++ 25/kernel/exit.c 2008-03-03 08:02:50.000000000 +0300
@@ -52,6 +52,11 @@
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 +165,7 @@ 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 +175,7 @@ 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);
@@ -655,14 +660,14 @@ reparent_thread(struct task_struct *p, s
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);
@@ -715,18 +720,18 @@ static void forget_original_parent(struc
} 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);
}
@@ -783,26 +788,26 @@ static void exit_notify(struct task_stru
* 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 = (tsk->parent == tsk->real_parent)
+ ? tsk->exit_signal : SIGCHLD;
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;
@@ -1106,7 +1111,7 @@ static int eligible_child(enum pid_type
* 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;
@@ -1298,9 +1303,9 @@ static int wait_task_zombie(struct task_
* 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;
}
--
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