TTY: call tty_driver_lookup_tty unconditionally

Commit 4a2b5fddd5 (Move tty lookup/reopen to caller) made the call to
tty_driver_lookup_tty conditional in tty_open. It doesn't look like it
was an intention. Or if it was, it was not documented in the changelog
and the code now looks weird. For example there would be no need to
remember the tty driver and tty index. Further the condition depends
on a tty which we drop a reference of already.

If I'm looking correctly, this should not matter thanks to the locking
currently done there. Thus, tty_driver->ttys[idx] cannot change under
our hands. But anyway, it makes sense to change that to the old
behaviour.

Introduced-in: v2.6.28-rc2
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: stable <stable@vger.kernel.org>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Alan Cox <alan@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 767ecbb4761a9b24eb1af90d58b72c83e8d14b05..0425170d9ed62954416cba3ca1c356b4a8498d8d 100644 (file)
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -1821,7 +1821,7 @@ int tty_release(struct inode *inode, struct file *filp)
 
 static int tty_open(struct inode *inode, struct file *filp)
 {
-       struct tty_struct *tty = NULL;
+       struct tty_struct *tty;
        int noctty, retval;
        struct tty_driver *driver;
        int index;
@@ -1892,17 +1892,14 @@ retry_open:
                return -ENODEV;
        }
 got_driver:
-       if (!tty) {
-               /* check whether we're reopening an existing tty */
-               tty = tty_driver_lookup_tty(driver, inode, index);
-
-               if (IS_ERR(tty)) {
-                       tty_unlock();
-                       mutex_unlock(&tty_mutex);
-                       tty_driver_kref_put(driver);
-                       tty_free_file(filp);
-                       return PTR_ERR(tty);
-               }
+       /* check whether we're reopening an existing tty */
+       tty = tty_driver_lookup_tty(driver, inode, index);
+       if (IS_ERR(tty)) {
+               tty_unlock();
+               mutex_unlock(&tty_mutex);
+               tty_driver_kref_put(driver);
+               tty_free_file(filp);
+               return PTR_ERR(tty);
        }
 
        if (tty) {