pidns: Use task_active_pid_ns where appropriate

The expressions tsk->nsproxy->pid_ns and task_active_pid_ns
aka ns_of_pid(task_pid(tsk)) should have the same number of
cache line misses with the practical difference that
ns_of_pid(task_pid(tsk)) is released later in a processes life.

Furthermore by using task_active_pid_ns it becomes trivial
to write an unshare implementation for the the pid namespace.

So I have used task_active_pid_ns everywhere I can.

In fork since the pid has not yet been attached to the
process I use ns_of_pid, to achieve the same effect.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index 8b20ab7d3aa2..7798c247f4b9 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1442,7 +1442,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 
                 if (thread_group_leader(p)) {
                         if (is_child_reaper(pid))
-                                p->nsproxy->pid_ns->child_reaper = p;
+                                ns_of_pid(pid)->child_reaper = p;
 
                         p->signal->leader_pid = pid;
                         p->signal->tty = tty_kref_get(current->signal->tty);