[PATCH] do_notify_parent_cldstop() cleanup

This patch simplifies the usage of do_notify_parent_cldstop(), it lessens
the source and .text size slightly, and makes the code (in my opinion) a
bit more readable.

I am sending this patch now because I'm afraid Paul will touch
do_notify_parent_cldstop() really soon, It's better to cleanup first.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

kernel/signal.c

@@ -678,7 +678,7 @@ static int check_kill_permission(int sig, struct siginfo *info,
 
 /* forward decl */
 static void do_notify_parent_cldstop(struct task_struct *tsk,
-				     struct task_struct *parent,
+				     int to_self,
 				     int why);
 
 /*
@@ -729,14 +729,7 @@ static void handle_stop_signal(int sig, struct task_struct *p)
 			p->signal->group_stop_count = 0;
 			p->signal->flags = SIGNAL_STOP_CONTINUED;
 			spin_unlock(&p->sighand->siglock);
-			if (p->ptrace & PT_PTRACED)
-				do_notify_parent_cldstop(p, p->parent,
-							 CLD_STOPPED);
-			else
-				do_notify_parent_cldstop(
-					p->group_leader,
-					p->group_leader->real_parent,
-							 CLD_STOPPED);
+			do_notify_parent_cldstop(p, (p->ptrace & PT_PTRACED), CLD_STOPPED);
 			spin_lock(&p->sighand->siglock);
 		}
 		rm_from_queue(SIG_KERNEL_STOP_MASK, &p->signal->shared_pending);
@@ -777,14 +770,7 @@ static void handle_stop_signal(int sig, struct task_struct *p)
 			p->signal->flags = SIGNAL_STOP_CONTINUED;
 			p->signal->group_exit_code = 0;
 			spin_unlock(&p->sighand->siglock);
-			if (p->ptrace & PT_PTRACED)
-				do_notify_parent_cldstop(p, p->parent,
-							 CLD_CONTINUED);
-			else
-				do_notify_parent_cldstop(
-					p->group_leader,
-					p->group_leader->real_parent,
-							 CLD_CONTINUED);
+			do_notify_parent_cldstop(p, (p->ptrace & PT_PTRACED), CLD_CONTINUED);
 			spin_lock(&p->sighand->siglock);
 		} else {
 			/*
@@ -1542,14 +1528,20 @@ void do_notify_parent(struct task_struct *tsk, int sig)
 	spin_unlock_irqrestore(&psig->siglock, flags);
 }
 
-static void
-do_notify_parent_cldstop(struct task_struct *tsk, struct task_struct *parent,
-			 int why)
+static void do_notify_parent_cldstop(struct task_struct *tsk, int to_self, int why)
 {
 	struct siginfo info;
 	unsigned long flags;
+	struct task_struct *parent;
 	struct sighand_struct *sighand;
 
+	if (to_self)
+		parent = tsk->parent;
+	else {
+		tsk = tsk->group_leader;
+		parent = tsk->real_parent;
+	}
+
 	info.si_signo = SIGCHLD;
 	info.si_errno = 0;
 	info.si_pid = tsk->pid;
@@ -1618,8 +1610,7 @@ static void ptrace_stop(int exit_code, int nostop_code, siginfo_t *info)
 		   !(current->ptrace & PT_ATTACHED)) &&
 	    (likely(current->parent->signal != current->signal) ||
 	     !unlikely(current->signal->flags & SIGNAL_GROUP_EXIT))) {
-		do_notify_parent_cldstop(current, current->parent,
-					 CLD_TRAPPED);
+		do_notify_parent_cldstop(current, 1, CLD_TRAPPED);
 		read_unlock(&tasklist_lock);
 		schedule();
 	} else {
@@ -1668,25 +1659,25 @@ void ptrace_notify(int exit_code)
 static void
 finish_stop(int stop_count)
 {
+	int to_self;
+
 	/*
 	 * If there are no other threads in the group, or if there is
 	 * a group stop in progress and we are the last to stop,
 	 * report to the parent.  When ptraced, every thread reports itself.
 	 */
-	if (stop_count < 0 || (current->ptrace & PT_PTRACED)) {
-		read_lock(&tasklist_lock);
-		do_notify_parent_cldstop(current, current->parent,
-					 CLD_STOPPED);
-		read_unlock(&tasklist_lock);
-	}
-	else if (stop_count == 0) {
+	if (stop_count < 0 || (current->ptrace & PT_PTRACED))
+		to_self = 1;
+	else if (stop_count == 0)
+		to_self = 0;
+	else
+		goto out;
+
 	read_lock(&tasklist_lock);
-		do_notify_parent_cldstop(current->group_leader,
-					 current->group_leader->real_parent,
-					 CLD_STOPPED);
+	do_notify_parent_cldstop(current, to_self, CLD_STOPPED);
 	read_unlock(&tasklist_lock);
-	}
 
+out:
 	schedule();
 	/*
 	 * Now we don't run again until continued.