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reparent_thread: don't call kill_orphaned_pgrp() if task_detached()

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If task_detached(p) == T, then either

  a) p is not the main thread, we will find the group leader on the
     ->children list.

or

  b) p is the group leader but its ->exit_state = EXIT_DEAD.  This
     can only happen when the last sub-thread has died, but in that case
     that thread has already called kill_orphaned_pgrp() from
     exit_notify().

In both cases kill_orphaned_pgrp() looks bogus.

Move the task_detached() check up and simplify the code, this is also
right from the "common sense" pov: we should do nothing with the detached
childs, except move them to the new parent's ->children list.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.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 2009-04-02 16:58:15 -07:00 committed by Linus Torvalds
parent 4576145c1e
commit 0a967a044a
1 changed files with 4 additions and 4 deletions
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6
kernel/exit.c
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@ -818,6 +818,8 @@ static void reparent_thread(struct task_struct *p, struct task_struct *father)
list_move_tail(&p->sibling, &p->real_parent->children); list_move_tail(&p->sibling, &p->real_parent->children);
if (task_detached(p))
return;
/* If this is a threaded reparent there is no need to /* If this is a threaded reparent there is no need to
* notify anyone anything has happened. * notify anyone anything has happened.
*/ */
@ -825,15 +827,13 @@ static void reparent_thread(struct task_struct *p, struct task_struct *father)
return; return;
/* We don't want people slaying init. */ /* We don't want people slaying init. */
if (!task_detached(p))
p->exit_signal = SIGCHLD; p->exit_signal = SIGCHLD;
/* If we'd notified the old parent about this child's death, /* If we'd notified the old parent about this child's death,
* also notify the new parent. * also notify the new parent.
*/ */
if (!ptrace_reparented(p) && if (!ptrace_reparented(p) &&
p->exit_state == EXIT_ZOMBIE && p->exit_state == EXIT_ZOMBIE && thread_group_empty(p))
!task_detached(p) && thread_group_empty(p))
do_notify_parent(p, p->exit_signal); do_notify_parent(p, p->exit_signal);
kill_orphaned_pgrp(p, father); kill_orphaned_pgrp(p, father);