tty: Untangle termios and mm mutex dependencies

Although this doesn't cause any problems it could potentially do so for
future mmap using devices. No real work is needed to sort it out so untangle
it before it causes problems

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/char/tty_ioctl.c

@@ -626,9 +626,25 @@ static int set_termios(struct tty_struct *tty, void __user *arg, int opt)
 	return 0;
 }
 
+static void copy_termios(struct tty_struct *tty, struct ktermios *kterm)
+{
+	mutex_lock(&tty->termios_mutex);
+	memcpy(kterm, tty->termios, sizeof(struct ktermios));
+	mutex_unlock(&tty->termios_mutex);
+}
+
+static void copy_termios_locked(struct tty_struct *tty, struct ktermios *kterm)
+{
+	mutex_lock(&tty->termios_mutex);
+	memcpy(kterm, tty->termios_locked, sizeof(struct ktermios));
+	mutex_unlock(&tty->termios_mutex);
+}
+
 static int get_termio(struct tty_struct *tty, struct termio __user *termio)
 {
-	if (kernel_termios_to_user_termio(termio, tty->termios))
+	struct ktermios kterm;
+	copy_termios(tty, &kterm);
+	if (kernel_termios_to_user_termio(termio, &kterm))
 		return -EFAULT;
 	return 0;
 }
@@ -930,6 +946,8 @@ int tty_mode_ioctl(struct tty_struct *tty, struct file *file,
 	struct tty_struct *real_tty;
 	void __user *p = (void __user *)arg;
 	int ret = 0;
+	struct ktermios kterm;
+	struct termiox ktermx;
 
 	if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
 	    tty->driver->subtype == PTY_TYPE_MASTER)
@@ -965,23 +983,20 @@ int tty_mode_ioctl(struct tty_struct *tty, struct file *file,
 		return set_termios(real_tty, p, TERMIOS_OLD);
 #ifndef TCGETS2
 	case TCGETS:
-		mutex_lock(&real_tty->termios_mutex);
-		if (kernel_termios_to_user_termios((struct termios __user *)arg, real_tty->termios))
+		copy_termios(real_tty, &kterm);
+		if (kernel_termios_to_user_termios((struct termios __user *)arg, &kterm))
 			ret = -EFAULT;
-		mutex_unlock(&real_tty->termios_mutex);
 		return ret;
 #else
 	case TCGETS:
-		mutex_lock(&real_tty->termios_mutex);
-		if (kernel_termios_to_user_termios_1((struct termios __user *)arg, real_tty->termios))
+		copy_termios(real_tty, &kterm);
+		if (kernel_termios_to_user_termios_1((struct termios __user *)arg, &kterm))
 			ret = -EFAULT;
-		mutex_unlock(&real_tty->termios_mutex);
 		return ret;
 	case TCGETS2:
-		mutex_lock(&real_tty->termios_mutex);
-		if (kernel_termios_to_user_termios((struct termios2 __user *)arg, real_tty->termios))
+		copy_termios(real_tty, &kterm);
+		if (kernel_termios_to_user_termios((struct termios2 __user *)arg, &kterm))
 			ret = -EFAULT;
-		mutex_unlock(&real_tty->termios_mutex);
 		return ret;
 	case TCSETSF2:
 		return set_termios(real_tty, p,  TERMIOS_FLUSH | TERMIOS_WAIT);
@@ -1000,34 +1015,36 @@ int tty_mode_ioctl(struct tty_struct *tty, struct file *file,
 		return set_termios(real_tty, p, TERMIOS_TERMIO);
 #ifndef TCGETS2
 	case TIOCGLCKTRMIOS:
-		mutex_lock(&real_tty->termios_mutex);
-		if (kernel_termios_to_user_termios((struct termios __user *)arg, real_tty->termios_locked))
+		copy_termios_locked(real_tty, &kterm);
+		if (kernel_termios_to_user_termios((struct termios __user *)arg, &kterm))
 			ret = -EFAULT;
-		mutex_unlock(&real_tty->termios_mutex);
 		return ret;
 	case TIOCSLCKTRMIOS:
 		if (!capable(CAP_SYS_ADMIN))
 			return -EPERM;
-		mutex_lock(&real_tty->termios_mutex);
-		if (user_termios_to_kernel_termios(real_tty->termios_locked,
+		copy_termios_locked(real_tty, &kterm);
+		if (user_termios_to_kernel_termios(&kterm,
 					       (struct termios __user *) arg))
-			ret = -EFAULT;
+			return -EFAULT;
+		mutex_lock(&real_tty->termios_mutex);
+		memcpy(real_tty->termios_locked, &kterm, sizeof(struct ktermios));
 		mutex_unlock(&real_tty->termios_mutex);
-		return ret;
+		return 0;
 #else
 	case TIOCGLCKTRMIOS:
-		mutex_lock(&real_tty->termios_mutex);
-		if (kernel_termios_to_user_termios_1((struct termios __user *)arg, real_tty->termios_locked))
+		copy_termios_locked(real_tty, &kterm);
+		if (kernel_termios_to_user_termios_1((struct termios __user *)arg, &kterm))
 			ret = -EFAULT;
-		mutex_unlock(&real_tty->termios_mutex);
 		return ret;
 	case TIOCSLCKTRMIOS:
 		if (!capable(CAP_SYS_ADMIN))
-			ret = -EPERM;
-		mutex_lock(&real_tty->termios_mutex);
-		if (user_termios_to_kernel_termios_1(real_tty->termios_locked,
+			return -EPERM;
+		copy_termios_locked(real_tty, &kterm);
+		if (user_termios_to_kernel_termios_1(&kterm,
 					       (struct termios __user *) arg))
-			ret = -EFAULT;
+			return -EFAULT;
+		mutex_lock(&real_tty->termios_mutex);
+		memcpy(real_tty->termios_locked, &kterm, sizeof(struct ktermios));
 		mutex_unlock(&real_tty->termios_mutex);
 		return ret;
 #endif
@@ -1036,9 +1053,10 @@ int tty_mode_ioctl(struct tty_struct *tty, struct file *file,
 		if (real_tty->termiox == NULL)
 			return -EINVAL;
 		mutex_lock(&real_tty->termios_mutex);
-		if (copy_to_user(p, real_tty->termiox, sizeof(struct termiox)))
-			ret = -EFAULT;
+		memcpy(&ktermx, real_tty->termiox, sizeof(struct termiox));
 		mutex_unlock(&real_tty->termios_mutex);
+		if (copy_to_user(p, &ktermx, sizeof(struct termiox)))
+			ret = -EFAULT;
 		return ret;
 	case TCSETX:
 		return set_termiox(real_tty, p, 0);
@@ -1048,10 +1066,9 @@ int tty_mode_ioctl(struct tty_struct *tty, struct file *file,
 		return set_termiox(real_tty, p, TERMIOS_FLUSH);
 #endif		
 	case TIOCGSOFTCAR:
-		mutex_lock(&real_tty->termios_mutex);
-		ret = put_user(C_CLOCAL(real_tty) ? 1 : 0,
+		copy_termios(real_tty, &kterm);
+		ret = put_user((kterm.c_cflag & CLOCAL) ? 1 : 0,
 						(int __user *)arg);
-		mutex_unlock(&real_tty->termios_mutex);
 		return ret;
 	case TIOCSSOFTCAR:
 		if (get_user(arg, (unsigned int __user *) arg))