Commit 57a05918 authored Dec 10, 2014 by Oleg Nesterov Committed by Linus Torvalds Dec 10, 2014

exit: reparent: cleanup the changing of ->parent



1. Cosmetic, but "if (t->parent == father)" looks a bit confusing.
   We need to change t->parent if and only if t is not traced.

2. If we actually want this BUG_ON() to ensure that parent/ptrace
   match each other, then we should also take ptrace_reparented()
   case into account too.

3. Change this code to use for_each_thread() instead of deprecated
   while_each_thread().

[dan.carpenter@oracle.com: silence a bogus static checker warning]
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Aaron Tomlin <atomlin@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
Cc: Sterling Alexander <stalexan@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Roland McGrath <roland@hack.frob.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent dc2fd4b0

kernel/exit.c

+5 −8

Original line number	Diff line number	Diff line
		@@ -557,7 +557,7 @@ static void reparent_leader(struct task_struct father, struct task_struct p,

		static void forget_original_parent(struct task_struct *father)
		{
		struct task_struct p, n, *reaper;
		struct task_struct p, t, n, reaper;
		LIST_HEAD(dead_children);

		write_lock_irq(&tasklist_lock);
		@@ -569,18 +569,15 @@ static void forget_original_parent(struct task_struct *father)
		reaper = find_new_reaper(father);

		list_for_each_entry_safe(p, n, &father->children, sibling) {
		struct task_struct *t = p;

		do {
		for_each_thread(p, t) {
		t->real_parent = reaper;
		if (t->parent == father) {
		BUG_ON(t->ptrace);
		BUG_ON((!t->ptrace) != (t->parent == father));
		if (likely(!t->ptrace))
		t->parent = t->real_parent;
		}
		if (t->pdeath_signal)
		group_send_sig_info(t->pdeath_signal,
		SEND_SIG_NOINFO, t);
		} while_each_thread(p, t);
		}
		reparent_leader(father, p, &dead_children);
		}
		write_unlock_irq(&tasklist_lock);