ptrace: do not use task->ptrace directly in core kernel

No functional changes.

- Nobody except ptrace.c & co should use ptrace flags directly, we have
  task_ptrace() for that.

- No need to specially check PT_PTRACED, we must not have other PT_ bits
  set without PT_PTRACED. And no need to know this flag exists.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/signal.c b/kernel/signal.c
index d81f495..09ccc1c 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1410,7 +1410,7 @@
  	/* do_notify_parent_cldstop should have been called instead.  */
  	BUG_ON(task_is_stopped_or_traced(tsk));
 
-	BUG_ON(!tsk->ptrace &&
+	BUG_ON(!task_ptrace(tsk) &&
 	       (tsk->group_leader != tsk || !thread_group_empty(tsk)));
 
 	info.si_signo = sig;
@@ -1449,7 +1449,7 @@
 
 	psig = tsk->parent->sighand;
 	spin_lock_irqsave(&psig->siglock, flags);
-	if (!tsk->ptrace && sig == SIGCHLD &&
+	if (!task_ptrace(tsk) && sig == SIGCHLD &&
 	    (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
 	     (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
 		/*
@@ -1486,7 +1486,7 @@
 	struct task_struct *parent;
 	struct sighand_struct *sighand;
 
-	if (tsk->ptrace & PT_PTRACED)
+	if (task_ptrace(tsk))
 		parent = tsk->parent;
 	else {
 		tsk = tsk->group_leader;
@@ -1535,7 +1535,7 @@
 
 static inline int may_ptrace_stop(void)
 {
-	if (!likely(current->ptrace & PT_PTRACED))
+	if (!likely(task_ptrace(current)))
 		return 0;
 	/*
 	 * Are we in the middle of do_coredump?
@@ -1753,7 +1753,7 @@
 static int ptrace_signal(int signr, siginfo_t *info,
 			 struct pt_regs *regs, void *cookie)
 {
-	if (!(current->ptrace & PT_PTRACED))
+	if (!task_ptrace(current))
 		return signr;
 
 	ptrace_signal_deliver(regs, cookie);