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authorEric W. Biederman <ebiederm@xmission.com>2012-05-31 16:26:39 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-05-31 17:49:31 -0700
commit3208450488ae724196f1efffc457e4265957c04e (patch)
treebfad76a020bf5635e6529b3105f6ea4b521d7973 /kernel/signal.c
parent9eaa3d9bb2c4da99b1161cfcc63f3e77d9d3d156 (diff)
downloadvexpress-lsk-3208450488ae724196f1efffc457e4265957c04e.tar.gz
pidns: use task_active_pid_ns in do_notify_parent
Using task_active_pid_ns is more robust because it works even after we have called exit_namespaces. This change allows us to have parent processes that are zombies. Normally a zombie parent processes is crazy and the last thing you would want to have but in the case of not letting the init process of a pid namespace be reaped until all of it's children are dead and reaped a zombie parent process is exactly what we want. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pavel Emelyanov <xemul@parallels.com> Cc: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Louis Rilling <louis.rilling@kerlabs.com> Cc: Mike Galbraith <efault@gmx.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/signal.c')
-rw-r--r--kernel/signal.c11
1 files changed, 5 insertions, 6 deletions
diff --git a/kernel/signal.c b/kernel/signal.c
index f7b41821763..08dfbd748cd 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1656,19 +1656,18 @@ bool do_notify_parent(struct task_struct *tsk, int sig)
info.si_signo = sig;
info.si_errno = 0;
/*
- * we are under tasklist_lock here so our parent is tied to
- * us and cannot exit and release its namespace.
+ * We are under tasklist_lock here so our parent is tied to
+ * us and cannot change.
*
- * the only it can is to switch its nsproxy with sys_unshare,
- * bu uncharing pid namespaces is not allowed, so we'll always
- * see relevant namespace
+ * task_active_pid_ns will always return the same pid namespace
+ * until a task passes through release_task.
*
* write_lock() currently calls preempt_disable() which is the
* same as rcu_read_lock(), but according to Oleg, this is not
* correct to rely on this
*/
rcu_read_lock();
- info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
+ info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
task_uid(tsk));
rcu_read_unlock();