tty: the vhangup syscall is racy

We now have the infrastructure to sort this out but rather than teaching
the syscall tty lock rules we move the hard work into a tty helper

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 19 insertions, 0 deletions

diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 913b50258f90..b5f57d0b30ee 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -730,6 +730,25 @@ void tty_vhangup(struct tty_struct *tty)
 EXPORT_SYMBOL(tty_vhangup);
 
 /**
+ *      tty_vhangup_self        -       process vhangup for own ctty
+ *
+ *      Perform a vhangup on the current controlling tty
+ */
+
+void tty_vhangup_self(void)
+{
+        struct tty_struct *tty;
+
+        mutex_lock(&tty_mutex);
+        tty = get_current_tty();
+        if (tty) {
+                tty_vhangup(tty);
+                tty_kref_put(tty);
+        }
+        mutex_unlock(&tty_mutex);
+}
+
+/**
  *      tty_hung_up_p           -       was tty hung up
  *      @filp: file pointer of tty
  *