From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932462AbcAHUd6 (ORCPT ); Fri, 8 Jan 2016 15:33:58 -0500 Received: from 216-12-86-13.cv.mvl.ntelos.net ([216.12.86.13]:50808 "EHLO brightrain.aerifal.cx" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932417AbcAHUd4 (ORCPT ); Fri, 8 Jan 2016 15:33:56 -0500 Date: Fri, 8 Jan 2016 15:33:50 -0500 From: Rich Felker To: Peter Korsgaard Cc: linux-serial@vger.kernel.org, Greg Kroah-Hartman , Jiri Slaby , linux-kernel@vger.kernel.org Subject: [PATCH] serial-uartlite: fix missing locking in isr Message-ID: <20160108203350.GA23919@brightrain.aerifal.cx> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Rich Felker The uartlite driver suffers from missing/duplicate/corrupted character data when the interrupt handler runs concurrently with access to the device from another cpu. Take the port spinlock to exclude concurrent access. Signed-off-by: Rich Felker --- diff --git a/drivers/tty/serial/uartlite.c b/drivers/tty/serial/uartlite.c index 189f52e..3b818ec 100644 --- a/drivers/tty/serial/uartlite.c +++ b/drivers/tty/serial/uartlite.c @@ -194,7 +194,9 @@ static irqreturn_t ulite_isr(int irq, void *dev_id) { struct uart_port *port = dev_id; int busy, n = 0; + unsigned long flags; + spin_lock_irqsave(&port->lock, flags); do { int stat = uart_in32(ULITE_STATUS, port); busy = ulite_receive(port, stat); @@ -202,6 +204,8 @@ static irqreturn_t ulite_isr(int irq, void *dev_id) n++; } while (busy); + spin_unlock_irqrestore(&port->lock, flags); + /* work done? */ if (n > 1) { tty_flip_buffer_push(&port->state->port);