sys_getsid: don't use ->nsproxy directly

With the new semantics of find_vpid() we don't need to play with ->nsproxy
explicitely, _vxx() do the right things.

Also s/tasklist/rcu/.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 7 deletions

diff --git a/kernel/sys.c b/kernel/sys.c
index ee2e78dbea6c..5a61f8071b8e 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1025,19 +1025,16 @@ asmlinkage long sys_getsid(pid_t pid)
         else {
                 int retval;
                 struct task_struct *p;
-                struct pid_namespace *ns;
-
-                ns = current->nsproxy->pid_ns;
 
-                read_lock(&tasklist_lock);
-                p = find_task_by_pid_ns(pid, ns);
+                rcu_read_lock();
+                p = find_task_by_vpid(pid);
                 retval = -ESRCH;
                 if (p) {
                         retval = security_task_getsid(p);
                         if (!retval)
-                                retval = task_session_nr_ns(p, ns);
+                                retval = task_session_vnr(p);
                 }
-                read_unlock(&tasklist_lock);
+                rcu_read_unlock();
                 return retval;
         }
 }