Merge branch 'linux-linaro-lsk-v4.4' into linux-linaro-lsk-v4.4-android

[firefly-linux-kernel-4.4.55.git] / drivers / tty / tty_io.c

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 0c41dbcb90b8bc7d8ab430d562206e7c2469411f..7cef54334b122d22d9f610cacf0a126b615872a8 100644 (file)
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -1282,18 +1282,22 @@ int tty_send_xchar(struct tty_struct *tty, char ch)
        int     was_stopped = tty->stopped;
 
        if (tty->ops->send_xchar) {
+               down_read(&tty->termios_rwsem);
                tty->ops->send_xchar(tty, ch);
+               up_read(&tty->termios_rwsem);
                return 0;
        }
 
        if (tty_write_lock(tty, 0) < 0)
                return -ERESTARTSYS;
 
+       down_read(&tty->termios_rwsem);
        if (was_stopped)
                start_tty(tty);
        tty->ops->write(tty, &ch, 1);
        if (was_stopped)
                stop_tty(tty);
+       up_read(&tty->termios_rwsem);
        tty_write_unlock(tty);
        return 0;
 }
@@ -1458,13 +1462,13 @@ static int tty_reopen(struct tty_struct *tty)
 {
        struct tty_driver *driver = tty->driver;
 
-       if (!tty->count)
-               return -EIO;
-
        if (driver->type == TTY_DRIVER_TYPE_PTY &&
            driver->subtype == PTY_TYPE_MASTER)
                return -EIO;
 
+       if (!tty->count)
+               return -EAGAIN;
+
        if (test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
                return -EBUSY;
 
@@ -2065,7 +2069,12 @@ retry_open:
 
                if (tty) {
                        mutex_unlock(&tty_mutex);
-                       tty_lock(tty);
+                       retval = tty_lock_interruptible(tty);
+                       if (retval) {
+                               if (retval == -EINTR)
+                                       retval = -ERESTARTSYS;
+                               goto err_unref;
+                       }
                        /* safe to drop the kref from tty_driver_lookup_tty() */
                        tty_kref_put(tty);
                        retval = tty_reopen(tty);
@@ -2083,7 +2092,11 @@ retry_open:
 
        if (IS_ERR(tty)) {
                retval = PTR_ERR(tty);
-               goto err_file;
+               if (retval != -EAGAIN || signal_pending(current))
+                       goto err_file;
+               tty_free_file(filp);
+               schedule();
+               goto retry_open;
        }
 
        tty_add_file(tty, filp);
@@ -2152,6 +2165,7 @@ retry_open:
        return 0;
 err_unlock:
        mutex_unlock(&tty_mutex);
+err_unref:
        /* after locks to avoid deadlock */
        if (!IS_ERR_OR_NULL(driver))
                tty_driver_kref_put(driver);
@@ -2648,6 +2662,28 @@ static int tiocsetd(struct tty_struct *tty, int __user *p)
        return ret;
 }
 
+/**
+ *     tiocgetd        -       get line discipline
+ *     @tty: tty device
+ *     @p: pointer to user data
+ *
+ *     Retrieves the line discipline id directly from the ldisc.
+ *
+ *     Locking: waits for ldisc reference (in case the line discipline
+ *             is changing or the tty is being hungup)
+ */
+
+static int tiocgetd(struct tty_struct *tty, int __user *p)
+{
+       struct tty_ldisc *ld;
+       int ret;
+
+       ld = tty_ldisc_ref_wait(tty);
+       ret = put_user(ld->ops->num, p);
+       tty_ldisc_deref(ld);
+       return ret;
+}
+
 /**
  *     send_break      -       performed time break
  *     @tty: device to break on
@@ -2874,7 +2910,7 @@ long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
        case TIOCGSID:
                return tiocgsid(tty, real_tty, p);
        case TIOCGETD:
-               return put_user(tty->ldisc->ops->num, (int __user *)p);
+               return tiocgetd(tty, p);
        case TIOCSETD:
                return tiocsetd(tty, p);
        case TIOCVHANGUP: