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>

1 files changed, 13 insertions, 0 deletions

diff --git a/drivers/char/tty_ldisc.c b/drivers/char/tty_ldisc.c
index feb55075819b..d914e77f7f01 100644
--- a/drivers/char/tty_ldisc.c
+++ b/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;
 }