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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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30
kernel/exit.c
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@ -459,6 +459,17 @@ static void exit_mm(struct task_struct *tsk)
clear_thread_flag(TIF_MEMDIE); 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) static struct task_struct *find_child_reaper(struct task_struct *father)
__releases(&tasklist_lock) __releases(&tasklist_lock)
__acquires(&tasklist_lock) __acquires(&tasklist_lock)
@ -469,9 +480,8 @@ static struct task_struct *find_child_reaper(struct task_struct *father)
if (likely(reaper != father)) if (likely(reaper != father))
return reaper; return reaper;
for_each_thread(father, reaper) { reaper = find_alive_thread(father);
if (reaper->flags & PF_EXITING) if (reaper) {
continue;
pid_ns->child_reaper = reaper; pid_ns->child_reaper = reaper;
return 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, static struct task_struct *find_new_reaper(struct task_struct *father,
struct task_struct *child_reaper) struct task_struct *child_reaper)
{ {
struct task_struct *thread; struct task_struct *thread, *reaper;
for_each_thread(father, thread) { thread = find_alive_thread(father);
if (thread->flags & PF_EXITING) if (thread)
continue;
return thread; return thread;
}
if (father->signal->has_child_subreaper) { if (father->signal->has_child_subreaper) {
struct task_struct *reaper;
/* /*
* Find the first ->is_child_subreaper ancestor in our pid_ns. * Find the first ->is_child_subreaper ancestor in our pid_ns.
* We start from father to ensure we can not look into another * We start from father to ensure we can not look into another
@ -520,12 +527,11 @@ static struct task_struct *find_new_reaper(struct task_struct *father,
break; break;
if (!reaper->signal->is_child_subreaper) if (!reaper->signal->is_child_subreaper)
continue; continue;
for_each_thread(reaper, thread) { thread = find_alive_thread(reaper);
if (!(thread->flags & PF_EXITING)) if (thread)
return thread; return thread;
} }
} }
}
return child_reaper; return child_reaper;
} }