tty: Push the lock down further into the ldisc code

[pandora-kernel.git] / drivers / char / tty_ldisc.c

diff --git a/drivers/char/tty_ldisc.c b/drivers/char/tty_ldisc.c
index feb5507..3f653f7 100644 (file)
--- 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>
 
@@ -443,8 +445,14 @@ static void tty_set_termios_ldisc(struct tty_struct *tty, int num)
 static int tty_ldisc_open(struct tty_struct *tty, struct tty_ldisc *ld)
 {
        WARN_ON(test_and_set_bit(TTY_LDISC_OPEN, &tty->flags));
-       if (ld->ops->open)
-               return ld->ops->open(tty);
+       if (ld->ops->open) {
+               int ret;
+                /* BKL here locks verus a hangup event */
+               lock_kernel();
+               ret = ld->ops->open(tty);
+               unlock_kernel();
+               return ret;
+       }
        return 0;
 }
 
@@ -545,6 +553,7 @@ 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.
@@ -558,10 +567,12 @@ 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;
        }
 
+       unlock_kernel();
        /*
         *      Problem: What do we do if this blocks ?
         *      We could deadlock here
@@ -582,6 +593,9 @@ 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 +606,8 @@ 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 +633,14 @@ 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 +682,7 @@ 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;
 }