From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:59152 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755861AbbISRis (ORCPT ); Sat, 19 Sep 2015 13:38:48 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Johannes Thumshirn , Peter Hurley , Andreas Werner Subject: [PATCH 4.1 061/102] tty: serial: men_z135_uart.c: Fix race between IRQ and set_termios() Date: Sat, 19 Sep 2015 10:28:13 -0700 Message-Id: <20150919171748.189475800@linuxfoundation.org> In-Reply-To: <20150919171745.474069671@linuxfoundation.org> References: <20150919171745.474069671@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: stable-owner@vger.kernel.org List-ID: 4.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Johannes Thumshirn commit 8117e347406278fd399b077add4e638cd017ae2d upstream. Fix panic caused by a race between men_z135_intr() and men_z135_set_termios(). men_z135_intr() and men_z135_set_termios() both hold the struct uart_port::lock spinlock, but men_z135_intr() does a spin_lock_irqsave() and men_z135_set_termios() does a normal spin_lock(), which can lead to a deadlock when an interrupt is called while the lock is being helt by men_z135_set_termios(). This was discovered using a insmod, hardware looppback send/receive, rmmod stress test. Signed-off-by: Johannes Thumshirn Reviewed-by: Peter Hurley Cc: Andreas Werner Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/men_z135_uart.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) --- a/drivers/tty/serial/men_z135_uart.c +++ b/drivers/tty/serial/men_z135_uart.c @@ -392,7 +392,6 @@ static irqreturn_t men_z135_intr(int irq struct men_z135_port *uart = (struct men_z135_port *)data; struct uart_port *port = &uart->port; bool handled = false; - unsigned long flags; int irq_id; uart->stat_reg = ioread32(port->membase + MEN_Z135_STAT_REG); @@ -401,7 +400,7 @@ static irqreturn_t men_z135_intr(int irq if (!irq_id) goto out; - spin_lock_irqsave(&port->lock, flags); + spin_lock(&port->lock); /* It's save to write to IIR[7:6] RXC[9:8] */ iowrite8(irq_id, port->membase + MEN_Z135_STAT_REG); @@ -427,7 +426,7 @@ static irqreturn_t men_z135_intr(int irq handled = true; } - spin_unlock_irqrestore(&port->lock, flags); + spin_unlock(&port->lock); out: return IRQ_RETVAL(handled); } @@ -717,7 +716,7 @@ static void men_z135_set_termios(struct baud = uart_get_baud_rate(port, termios, old, 0, uart_freq / 16); - spin_lock(&port->lock); + spin_lock_irq(&port->lock); if (tty_termios_baud_rate(termios)) tty_termios_encode_baud_rate(termios, baud, baud); @@ -725,7 +724,7 @@ static void men_z135_set_termios(struct iowrite32(bd_reg, port->membase + MEN_Z135_BAUD_REG); uart_update_timeout(port, termios->c_cflag, baud); - spin_unlock(&port->lock); + spin_unlock_irq(&port->lock); } static const char *men_z135_type(struct uart_port *port)