ptrace: s/tracehook_tracer_task()/ptrace_parent()/

tracehook.h is on the way out.  Rename tracehook_tracer_task() to
ptrace_parent() and move it from tracehook.h to ptrace.h.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: John Johansen <john.johansen@canonical.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>

fs/proc/array.c

@@ -172,7 +172,7 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
 		task_tgid_nr_ns(rcu_dereference(p->real_parent), ns) : 0;
 	tpid = 0;
 	if (pid_alive(p)) {
-		struct task_struct *tracer = tracehook_tracer_task(p);
+		struct task_struct *tracer = ptrace_parent(p);
 		if (tracer)
 			tpid = task_pid_nr_ns(tracer, ns);
 	}

fs/proc/base.c

@@ -216,7 +216,7 @@ static struct mm_struct *__check_mem_permission(struct task_struct *task)
 	if (task_is_stopped_or_traced(task)) {
 		int match;
 		rcu_read_lock();
-		match = (tracehook_tracer_task(task) == current);
+		match = (ptrace_parent(task) == current);
 		rcu_read_unlock();
 		if (match && ptrace_may_access(task, PTRACE_MODE_ATTACH))
 			return mm;

include/linux/ptrace.h

@@ -150,6 +150,24 @@ int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
 			    unsigned long data);
 
+/**
+ * ptrace_parent - return the task that is tracing the given task
+ * @task: task to consider
+ *
+ * Returns %NULL if no one is tracing @task, or the &struct task_struct
+ * pointer to its tracer.
+ *
+ * Must called under rcu_read_lock().  The pointer returned might be kept
+ * live only by RCU.  During exec, this may be called with task_lock() held
+ * on @task, still held from when check_unsafe_exec() was called.
+ */
+static inline struct task_struct *ptrace_parent(struct task_struct *task)
+{
+	if (unlikely(task->ptrace))
+		return rcu_dereference(task->parent);
+	return NULL;
+}
+
 /**
  * ptrace_event_enabled - test whether a ptrace event is enabled
  * @task: ptracee of interest

include/linux/tracehook.h

@@ -129,24 +129,6 @@ static inline void tracehook_report_syscall_exit(struct pt_regs *regs, int step)
 	ptrace_report_syscall(regs);
 }
 
-/**
- * tracehook_tracer_task - return the task that is tracing the given task
- * @tsk:		task to consider
- *
- * Returns NULL if no one is tracing @task, or the &struct task_struct
- * pointer to its tracer.
- *
- * Must called under rcu_read_lock().  The pointer returned might be kept
- * live only by RCU.  During exec, this may be called with task_lock()
- * held on @task, still held from when tracehook_unsafe_exec() was called.
- */
-static inline struct task_struct *tracehook_tracer_task(struct task_struct *tsk)
-{
-	if (tsk->ptrace & PT_PTRACED)
-		return rcu_dereference(tsk->parent);
-	return NULL;
-}
-
 /**
  * tracehook_signal_handler - signal handler setup is complete
  * @sig:		number of signal being delivered

security/apparmor/domain.c

@@ -67,7 +67,7 @@ static int may_change_ptraced_domain(struct task_struct *task,
 	int error = 0;
 
 	rcu_read_lock();
-	tracer = tracehook_tracer_task(task);
+	tracer = ptrace_parent(task);
 	if (tracer) {
 		/* released below */
 		cred = get_task_cred(tracer);

security/selinux/hooks.c

@@ -2048,7 +2048,7 @@ static int selinux_bprm_set_creds(struct linux_binprm *bprm)
 			u32 ptsid = 0;
 
 			rcu_read_lock();
-			tracer = tracehook_tracer_task(current);
+			tracer = ptrace_parent(current);
 			if (likely(tracer != NULL)) {
 				sec = __task_cred(tracer)->security;
 				ptsid = sec->sid;
@@ -5314,7 +5314,7 @@ static int selinux_setprocattr(struct task_struct *p,
 		   Otherwise, leave SID unchanged and fail. */
 		ptsid = 0;
 		task_lock(p);
-		tracer = tracehook_tracer_task(p);
+		tracer = ptrace_parent(p);
 		if (tracer)
 			ptsid = task_sid(tracer);
 		task_unlock(p);