tty: push the BKL down into the handlers a bit

Start trying to untangle the remaining BKL mess

Updated to fix missing unlock_kernel noted by Dan Carpenter
Signed-off-by: Alan "I must be out of my tree" Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/char/pty.c

@@ -659,7 +659,7 @@ static int __ptmx_open(struct inode *inode, struct file *filp)
 	if (!retval)
 		return 0;
 out1:
-	tty_release_dev(filp);
+	tty_release(inode, filp);
 	return retval;
 out:
 	devpts_kill_index(inode, index);

drivers/char/tty_ldisc.c

@@ -34,6 +34,8 @@
 #include <linux/vt_kern.h>
 #include <linux/selection.h>
 
+#include <linux/smp_lock.h>	/* For the moment */
+
 #include <linux/kmod.h>
 #include <linux/nsproxy.h>
 
@@ -545,6 +547,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 	if (IS_ERR(new_ldisc))
 		return PTR_ERR(new_ldisc);
 
+	lock_kernel();
 	/*
 	 *	We need to look at the tty locking here for pty/tty pairs
 	 *	when both sides try to change in parallel.
@@ -558,6 +561,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 	 */
 
 	if (tty->ldisc->ops->num == ldisc) {
+		unlock_kernel();
 		tty_ldisc_put(new_ldisc);
 		return 0;
 	}
@@ -569,6 +573,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 
 	tty_wait_until_sent(tty, 0);
 
+	unlock_kernel();
 	mutex_lock(&tty->ldisc_mutex);
 
 	/*
@@ -582,6 +587,9 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 			test_bit(TTY_LDISC_CHANGING, &tty->flags) == 0);
 		mutex_lock(&tty->ldisc_mutex);
 	}
+
+	lock_kernel();
+
 	set_bit(TTY_LDISC_CHANGING, &tty->flags);
 
 	/*
@@ -592,6 +600,8 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 	tty->receive_room = 0;
 
 	o_ldisc = tty->ldisc;
+
+	unlock_kernel();
 	/*
 	 *	Make sure we don't change while someone holds a
 	 *	reference to the line discipline. The TTY_LDISC bit
@@ -617,12 +627,14 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 	flush_scheduled_work();
 
 	mutex_lock(&tty->ldisc_mutex);
+	lock_kernel();
 	if (test_bit(TTY_HUPPED, &tty->flags)) {
 		/* We were raced by the hangup method. It will have stomped
 		   the ldisc data and closed the ldisc down */
 		clear_bit(TTY_LDISC_CHANGING, &tty->flags);
 		mutex_unlock(&tty->ldisc_mutex);
 		tty_ldisc_put(new_ldisc);
+		unlock_kernel();
 		return -EIO;
 	}
 
@@ -664,6 +676,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 	if (o_work)
 		schedule_delayed_work(&o_tty->buf.work, 1);
 	mutex_unlock(&tty->ldisc_mutex);
+	unlock_kernel();
 	return retval;
 }
 

include/linux/tty.h

@@ -449,7 +449,7 @@ extern void initialize_tty_struct(struct tty_struct *tty,
 		struct tty_driver *driver, int idx);
 extern struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
 								int first_ok);
-extern void tty_release_dev(struct file *filp);
+extern int tty_release(struct inode *inode, struct file *filp);
 extern int tty_init_termios(struct tty_struct *tty);
 
 extern struct tty_struct *tty_pair_get_tty(struct tty_struct *tty);