userns: Use cred->user_ns instead of cred->user->user_ns

Optimize performance and prepare for the removal of the user_ns reference
from user_struct.  Remove the slow long walk through cred->user->user_ns and
instead go straight to cred->user_ns.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index ee8d49b9c309..24e0a5a94824 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -198,7 +198,7 @@ int __ptrace_may_access(struct task_struct *task, unsigned int mode)
                 return 0;
         rcu_read_lock();
         tcred = __task_cred(task);
-        if (cred->user->user_ns == tcred->user->user_ns &&
+        if (cred->user_ns == tcred->user_ns &&
             (cred->uid == tcred->euid &&
              cred->uid == tcred->suid &&
              cred->uid == tcred->uid  &&
@@ -206,7 +206,7 @@ int __ptrace_may_access(struct task_struct *task, unsigned int mode)
              cred->gid == tcred->sgid &&
              cred->gid == tcred->gid))
                 goto ok;
-        if (ptrace_has_cap(tcred->user->user_ns, mode))
+        if (ptrace_has_cap(tcred->user_ns, mode))
                 goto ok;
         rcu_read_unlock();
         return -EPERM;