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exit: reparent: introduce find_alive_thread()

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Add the new simple helper to factor out the for_each_thread() code in
find_child_reaper() and find_new_reaper().  It can also simplify the
potential PF_EXITING -> exit_state change, plus perhaps we can change this
code to take SIGNAL_GROUP_EXIT into account.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Aaron Tomlin <atomlin@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Kay Sievers <kay@vrfy.org>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Sterling Alexander <stalexan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2014-12-10 15:55:14 -08:00 • committed by Linus Torvalds
commit c9dc05bfdb
1 changed files with 19 additions and 13 deletions
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32
kernel/exit.c
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@ -459,6 +459,17 @@ static void exit_mm(struct task_struct *tsk)
clear_thread_flag(TIF_MEMDIE);
}
static struct task_struct *find_alive_thread(struct task_struct *p)
{
struct task_struct *t;
for_each_thread(p, t) {
if (!(t->flags & PF_EXITING))
return t;
}
return NULL;
}
static struct task_struct *find_child_reaper(struct task_struct *father)
__releases(&tasklist_lock)
__acquires(&tasklist_lock)
@ -469,9 +480,8 @@ static struct task_struct *find_child_reaper(struct task_struct *father)
if (likely(reaper != father))
return reaper;
for_each_thread(father, reaper) {
if (reaper->flags & PF_EXITING)
continue;
reaper = find_alive_thread(father);
if (reaper) {
pid_ns->child_reaper = reaper;
return reaper;
}
@ -497,16 +507,13 @@ static struct task_struct *find_child_reaper(struct task_struct *father)
static struct task_struct *find_new_reaper(struct task_struct *father,
struct task_struct *child_reaper)
{
struct task_struct *thread;
struct task_struct *thread, *reaper;
for_each_thread(father, thread) {
if (thread->flags & PF_EXITING)
continue;
thread = find_alive_thread(father);
if (thread)
return thread;
}
if (father->signal->has_child_subreaper) {
struct task_struct *reaper;
/*
* Find the first ->is_child_subreaper ancestor in our pid_ns.
* We start from father to ensure we can not look into another
@ -520,10 +527,9 @@ static struct task_struct *find_new_reaper(struct task_struct *father,
break;
if (!reaper->signal->is_child_subreaper)
continue;
for_each_thread(reaper, thread) {
if (!(thread->flags & PF_EXITING))
return thread;
}
thread = find_alive_thread(reaper);
if (thread)
return thread;
}
}