Merge tag 'firewire-updates' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee139...

[cascardo/linux.git] / drivers / tty / pty.c

diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index eeae7fa..59af394 100644 (file)
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -26,11 +26,13 @@
 #include <linux/bitops.h>
 #include <linux/devpts_fs.h>
 #include <linux/slab.h>
+#include <linux/mutex.h>
 
 
 #ifdef CONFIG_UNIX98_PTYS
 static struct tty_driver *ptm_driver;
 static struct tty_driver *pts_driver;
+static DEFINE_MUTEX(devpts_mutex);
 #endif
 
 static void pty_close(struct tty_struct *tty, struct file *filp)
@@ -45,6 +47,7 @@ static void pty_close(struct tty_struct *tty, struct file *filp)
        wake_up_interruptible(&tty->read_wait);
        wake_up_interruptible(&tty->write_wait);
        tty->packet = 0;
+       /* Review - krefs on tty_link ?? */
        if (!tty->link)
                return;
        tty->link->packet = 0;
@@ -54,12 +57,15 @@ static void pty_close(struct tty_struct *tty, struct file *filp)
        if (tty->driver->subtype == PTY_TYPE_MASTER) {
                set_bit(TTY_OTHER_CLOSED, &tty->flags);
 #ifdef CONFIG_UNIX98_PTYS
-               if (tty->driver == ptm_driver)
+               if (tty->driver == ptm_driver) {
+                       mutex_lock(&devpts_mutex);
                        devpts_pty_kill(tty->link);
+                       mutex_unlock(&devpts_mutex);
+               }
 #endif
-               tty_unlock();
+               tty_unlock(tty);
                tty_vhangup(tty->link);
-               tty_lock();
+               tty_lock(tty);
        }
 }
 
@@ -475,13 +481,17 @@ static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
  *     @idx: tty index
  *
  *     Look up a pty master device. Called under the tty_mutex for now.
- *     This provides our locking.
+ *     This provides our locking for the tty pointer.
  */
 
 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
                struct inode *pts_inode, int idx)
 {
-       struct tty_struct *tty = devpts_get_tty(pts_inode, idx);
+       struct tty_struct *tty;
+
+       mutex_lock(&devpts_mutex);
+       tty = devpts_get_tty(pts_inode, idx);
+       mutex_unlock(&devpts_mutex);
        /* Master must be open before slave */
        if (!tty)
                return ERR_PTR(-EIO);
@@ -613,24 +623,29 @@ static int ptmx_open(struct inode *inode, struct file *filp)
                return retval;
 
        /* find a device that is not in use. */
-       tty_lock();
+       mutex_lock(&devpts_mutex);
        index = devpts_new_index(inode);
-       tty_unlock();
        if (index < 0) {
                retval = index;
                goto err_file;
        }
 
+       mutex_unlock(&devpts_mutex);
+
        mutex_lock(&tty_mutex);
-       tty_lock();
+       mutex_lock(&devpts_mutex);
        tty = tty_init_dev(ptm_driver, index);
-       mutex_unlock(&tty_mutex);
 
        if (IS_ERR(tty)) {
                retval = PTR_ERR(tty);
                goto out;
        }
 
+       /* The tty returned here is locked so we can safely
+          drop the mutex */
+       mutex_unlock(&devpts_mutex);
+       mutex_unlock(&tty_mutex);
+
        set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
 
        tty_add_file(tty, filp);
@@ -643,16 +658,17 @@ static int ptmx_open(struct inode *inode, struct file *filp)
        if (retval)
                goto err_release;
 
-       tty_unlock();
+       tty_unlock(tty);
        return 0;
 err_release:
-       tty_unlock();
+       tty_unlock(tty);
        tty_release(inode, filp);
        return retval;
 out:
+       mutex_unlock(&tty_mutex);
        devpts_kill_index(inode, index);
-       tty_unlock();
 err_file:
+        mutex_unlock(&devpts_mutex);
        tty_free_file(filp);
        return retval;
 }