diff options
| author | Xinyu Chen <xinyu.chen@freescale.com> | 2011-12-02 14:38:21 +0800 |
|---|---|---|
| committer | Jason Liu <r64343@freescale.com> | 2012-01-09 21:08:53 +0800 |
| commit | 80e525d66d1818722db18e21dc7f1dc41f314156 (patch) | |
| tree | 4ad3d487125d83358d7621e1bb225462d48ad97b /drivers/tty | |
| parent | af78a5d2475570cc0af529b81425bfcf0fe28669 (diff) | |
ENGR00163703 uart: console write routing is unsafe on SMP
The console feature's write routing is unsafe on SMP with
the startup/shutdown call. It happend to cause Android bootup
without shell runnable.
Actually on Android boot, there's 3 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.
Here add spin_lock for startup/shutdown/console_write routing.
Remove the imx_setup_ufcr() call on startup when CONSOLE enabled,
as this will cause clock reinit, and output garbage.
Signed-off-by: Xinyu Chen <xinyu.chen@freescale.com>
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/serial/imx.c | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 0a8c6d0f963a..e484c82b6de9 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -902,7 +902,9 @@ static int imx_startup(struct uart_port *port) unsigned long flags, temp; struct tty_struct *tty; +#ifndef CONFIG_SERIAL_CORE_CONSOLE imx_setup_ufcr(sport, 0); +#endif /* disable the DREN bit (Data Ready interrupt enable) before * requesting IRQs @@ -976,6 +978,7 @@ static int imx_startup(struct uart_port *port) INIT_WORK(&sport->tsk_dma_rx, dma_rx_work); } + spin_lock_irqsave(&sport->port.lock, flags); /* * Finally, clear and enable interrupts */ @@ -1040,7 +1043,6 @@ 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); @@ -1074,10 +1076,13 @@ 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; @@ -1106,12 +1111,15 @@ 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); + if (sport->enable_dma) imx_uart_dma_exit(sport); } @@ -1272,6 +1280,7 @@ imx_set_termios(struct uart_port *port, struct ktermios *termios, if (UART_ENABLE_MS(&sport->port, termios->c_cflag)) imx_enable_ms(&sport->port); + } static const char *imx_type(struct uart_port *port) @@ -1392,7 +1401,9 @@ imx_console_write(struct console *co, const char *s, unsigned int count) { struct imx_port *sport = imx_ports[co->index]; unsigned int old_ucr1, old_ucr2, ucr1; + unsigned long flags; + spin_lock_irqsave(&sport->port.lock, flags); /* * First, save UCR1/2 and then disable interrupts */ @@ -1418,6 +1429,7 @@ imx_console_write(struct console *co, const char *s, unsigned int count) writel(old_ucr1, sport->port.membase + UCR1); writel(old_ucr2, sport->port.membase + UCR2); + spin_unlock_irqrestore(&sport->port.lock, flags); } /* |