tty: Add a kref count
Introduce a kref to the tty structure and use it to protect the tty->signal
tty references. For now we don't introduce it for anything else.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/tty.h b/include/linux/tty.h
index e3612c3..b6e6c26 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -209,6 +209,7 @@
struct tty_struct {
int magic;
+ struct kref kref;
struct tty_driver *driver;
const struct tty_operations *ops;
int index;
@@ -311,6 +312,23 @@
extern void console_init(void);
extern int vcs_init(void);
+/**
+ * tty_kref_get - get a tty reference
+ * @tty: tty device
+ *
+ * Return a new reference to a tty object. The caller must hold
+ * sufficient locks/counts to ensure that their existing reference cannot
+ * go away
+ */
+
+extern inline struct tty_struct *tty_kref_get(struct tty_struct *tty)
+{
+ if (tty)
+ kref_get(&tty->kref);
+ return tty;
+}
+extern void tty_kref_put(struct tty_struct *tty);
+
extern int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
const char *routine);
extern char *tty_name(struct tty_struct *tty, char *buf);