diff options
| author | Xinyu Chen <xinyu.chen@freescale.com> | 2012-08-27 09:36:51 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-09-05 12:44:44 -0700 |
| commit | 9ec1882df244c4ee1baa692676fef5e8b0f5487d (patch) | |
| tree | c324ffa8ce389ed628f05ba3c5e9fde1eeb90537 /drivers/tty | |
| parent | fea7a08acb13524b47711625eebea40a0ede69a0 (diff) | |
tty: serial: imx: console write routing is unsafe on SMP
The console feature's write routing is unsafe on SMP with
the startup/shutdown call.
There could be several consumers of the console
* the kernel printk
* the init process using /dev/kmsg to call printk to show log
* shell, which open /dev/console and write with sys_write()
The shell goes into the normal uart open/write routing,
but the other two go into the console operations.
The open routing calls imx serial startup, which will write USR1/2
register without any lock and critical with imx_console_write call.
Add a spin_lock for startup/shutdown/console_write routing.
This patch is a port from Freescale's Android kernel.
Signed-off-by: Xinyu Chen <xinyu.chen@freescale.com>
Tested-by: Dirk Behme <dirk.behme@de.bosch.com>
CC: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/serial/imx.c | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index d5c689d6217..908178fc5a3 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -754,6 +754,7 @@ static int imx_startup(struct uart_port *port) } } + spin_lock_irqsave(&sport->port.lock, flags); /* * Finally, clear and enable interrupts */ @@ -807,7 +808,6 @@ static int imx_startup(struct uart_port *port) /* * Enable modem status interrupts */ - spin_lock_irqsave(&sport->port.lock,flags); imx_enable_ms(&sport->port); spin_unlock_irqrestore(&sport->port.lock,flags); @@ -837,10 +837,13 @@ static void imx_shutdown(struct uart_port *port) { struct imx_port *sport = (struct imx_port *)port; unsigned long temp; + unsigned long flags; + spin_lock_irqsave(&sport->port.lock, flags); temp = readl(sport->port.membase + UCR2); temp &= ~(UCR2_TXEN); writel(temp, sport->port.membase + UCR2); + spin_unlock_irqrestore(&sport->port.lock, flags); if (USE_IRDA(sport)) { struct imxuart_platform_data *pdata; @@ -869,12 +872,14 @@ static void imx_shutdown(struct uart_port *port) * Disable all interrupts, port and break condition. */ + spin_lock_irqsave(&sport->port.lock, flags); temp = readl(sport->port.membase + UCR1); temp &= ~(UCR1_TXMPTYEN | UCR1_RRDYEN | UCR1_RTSDEN | UCR1_UARTEN); if (USE_IRDA(sport)) temp &= ~(UCR1_IREN); writel(temp, sport->port.membase + UCR1); + spin_unlock_irqrestore(&sport->port.lock, flags); } static void @@ -1217,6 +1222,9 @@ imx_console_write(struct console *co, const char *s, unsigned int count) struct imx_port *sport = imx_ports[co->index]; struct imx_port_ucrs old_ucr; unsigned int ucr1; + unsigned long flags; + + spin_lock_irqsave(&sport->port.lock, flags); /* * First, save UCR1/2/3 and then disable interrupts @@ -1242,6 +1250,8 @@ imx_console_write(struct console *co, const char *s, unsigned int count) while (!(readl(sport->port.membase + USR2) & USR2_TXDC)); imx_port_ucrs_restore(&sport->port, &old_ucr); + + spin_unlock_irqrestore(&sport->port.lock, flags); } /* |