From e9cef8625e997a5ade9cddd2d501257dfee7cb62 Mon Sep 17 00:00:00 2001
From: Peter Hurley <peter@hurleysoftware.com>
Date: Thu, 22 Jan 2015 12:24:31 -0500
Subject: [PATCH] serial: 8250: Prevent concurrent updates to shadow registers
The port shadow registers, ->fcr and ->mcr, must be protected from
concurrent updates. Relocate the shadow register updates in
serial8250_do_set_termios() to the port lock critical section.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/tty/serial/8250/8250_core.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 1449c56506b773..57d13b058a484a 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -2549,6 +2549,15 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
port->uartclk / 16);
quot = serial8250_get_divisor(up, baud, &frac);
+ /*
+ * Ok, we're now changing the port state. Do it with
+ * interrupts disabled.
+ */
+ serial8250_rpm_get(up);
+ spin_lock_irqsave(&port->lock, flags);
+
+ up->lcr = cval; /* Save computed LCR */
+
if (up->capabilities & UART_CAP_FIFO && port->fifosize > 1) {
/* NOTE: If fifo_bug is not set, a user can set RX_trigger. */
if ((baud < 2400 && !up->dma) || up->fifo_bug) {
@@ -2571,15 +2580,6 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
up->mcr |= UART_MCR_AFE;
}
- /*
- * Ok, we're now changing the port state. Do it with
- * interrupts disabled.
- */
- serial8250_rpm_get(up);
- spin_lock_irqsave(&port->lock, flags);
-
- up->lcr = cval; /* Save computed LCR */
-
/*
* Update the per-port timeout.
*/
--
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