From 58a8c208a9960285e65eecd15a185d03b81a5c18 Mon Sep 17 00:00:00 2001
From: Jiri Olsa <Jiri Olsa jolsa@redhat.com>
Date: Tue, 20 Apr 2010 14:22:13 +0200
Subject: [PATCH 2/4] notifier tty_list/tty_is_active functions

---
 drivers/char/tty_io.c |   48 ++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/tty.h   |    5 +++++
 2 files changed, 53 insertions(+), 0 deletions(-)

diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index f0463d0..b4d4f60 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -159,6 +159,54 @@ static LIST_HEAD(tty_structs); /* linked list of tty structs */
 static ATOMIC_NOTIFIER_HEAD(tty_notifier_list);
 
 /**
+ *     tty_list - list all the active ttys
+ *     @cb: callback function called for each active tty
+ *
+ *     Returns true, if there's active tty for given type and line.
+ */
+void tty_list(cb_tty_list_t cb, void *data)
+{
+	struct tty_struct *tty;
+
+	mutex_lock(&tty_mutex);
+
+	list_for_each_entry(tty, &tty_structs, list)
+		cb(data, tty);
+
+	mutex_unlock(&tty_mutex);
+}
+EXPORT_SYMBOL_GPL(tty_list);
+
+/**
+ *     tty_is_active - checks wether the tty is active
+ *     @type: tty driver type
+ *     @line: tty line
+ *
+ *     Returns true, if there's active tty for given type and line.
+ */
+bool tty_is_active(int type, int line)
+{
+	struct tty_struct *tty;
+	bool found = false;
+
+	mutex_lock(&tty_mutex);
+	list_for_each_entry(tty, &tty_structs, list) {
+		struct tty_driver *driver = tty->driver;
+
+		if (driver->type != type)
+			continue;
+
+		if (line == tty->index) {
+			found = true;
+			break;
+		}
+	}
+	mutex_unlock(&tty_mutex);
+	return found;
+}
+EXPORT_SYMBOL_GPL(tty_is_active);
+
+/**
  *	register_tty_notifier - register tty notifier
  *
  *	Locking: none
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 7d57719..3945347 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -343,8 +343,13 @@ struct tty_notifier_param {
 	size_t size;
 };
 
+typedef void(*cb_tty_list_t)(void *data, struct tty_struct *tty);
+
 extern int register_tty_notifier(struct notifier_block *nb);
 extern int unregister_tty_notifier(struct notifier_block *nb);
+extern void tty_list(cb_tty_list_t cb, void *data);
+extern bool tty_is_active(int type, int line);
+
 
 #endif /* CONFIG_TTY_NOTIFIER */
 
-- 
1.6.6.1