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>

diff --git a/kernel/sys.c b/kernel/sys.c
index ee2e78d..5a61f80 100644 (file)
--- 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;
        }
 }