kernel: rename is_single_threaded(task) to current_is_single_threaded(void)

- is_single_threaded(task) is not safe unless task == current,
  we can't use task->signal or task->mm.

- it doesn't make sense unless task == current, the task can
  fork right after the check.

Rename it to current_is_single_threaded() and kill the argument.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>

2 files changed, 2 insertions, 2 deletions

diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index 276d27882ce8..ed929af466d3 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -702,7 +702,7 @@ long join_session_keyring(const char *name)
         /* only permit this if there's a single thread in the thread group -
          * this avoids us having to adjust the creds on all threads and risking
          * ENOMEM */
-        if (!is_single_threaded(current))
+        if (!current_is_single_threaded())
                 return -EMLINK;
 
         new = prepare_creds();
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 2081055f6783..e65677da36bd 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -5187,7 +5187,7 @@ static int selinux_setprocattr(struct task_struct *p,
 
                 /* Only allow single threaded processes to change context */
                 error = -EPERM;
-                if (!is_single_threaded(p)) {
+                if (!current_is_single_threaded()) {
                         error = security_bounded_transition(tsec->sid, sid);
                         if (error)
                                 goto abort_change;