tty, serial: Fix race and NULL check in uart_close()

Commit 46d57a449aa1 ("serial: use tty_port pointers in the core code")
contained two bugs that causes (rare) crashes:

 - the rename typoed one site

 - a NULL check was missed

Reported-and-tested-by: Ingo Molnar <mingo@elte.hu>
Cc: Greg KH <gregkh@suse.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 1689bda..dcc7244 100644 (file)
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -1270,6 +1270,9 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
 
        BUG_ON(!kernel_locked());
 
+       if (!state)
+               return;
+
        uport = state->uart_port;
        port = &state->port;
 
@@ -1316,9 +1319,9 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
         */
        if (port->flags & ASYNC_INITIALIZED) {
                unsigned long flags;
-               spin_lock_irqsave(&port->lock, flags);
+               spin_lock_irqsave(&uport->lock, flags);
                uport->ops->stop_rx(uport);
-               spin_unlock_irqrestore(&port->lock, flags);
+               spin_unlock_irqrestore(&uport->lock, flags);
                /*
                 * Before we drop DTR, make sure the UART transmitter
                 * has completely drained; this is especially