From 8117e347406278fd399b077add4e638cd017ae2d Mon Sep 17 00:00:00 2001 From: Johannes Thumshirn Date: Thu, 6 Aug 2015 09:16:37 +0200 Subject: tty: serial: men_z135_uart.c: Fix race between IRQ and set_termios() 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 Cc: stable@vger.kernel.org # v4.0+ Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/men_z135_uart.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) (limited to 'drivers') diff --git a/drivers/tty/serial/men_z135_uart.c b/drivers/tty/serial/men_z135_uart.c index 35c55505b3eb..5a41b8fbb10a 100644 --- 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, void *data) 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, void *data) 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, void *data) 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 uart_port *port, 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 uart_port *port, 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) -- cgit v1.2.3