3.10-stable review patch. If anyone has any objections, please let me know.
------------------ From: Peter Hurley <[email protected]> commit 7fd6f640f2dd17dac6ddd6702c378cb0bb9cfa11 upstream. Trying to write console output from within the serial console driver while the port->lock is held causes recursive deadlock: CPU 0 spin_lock_irqsave(&port->lock) printk() console_unlock() call_console_drivers() serial8250_console_write() spin_lock_irqsave(&port->lock) ** DEADLOCK ** The 8250_dw i/o accessors try to write a console error message if the LCR workaround was unsuccessful. When the port->lock is already held (eg., when called from serial8250_set_termios()), this deadlocks. Make the error message a FIXME until a general solution is devised. Cc: Tim Kryger <[email protected]> Reported-by: Zhang Zhen <[email protected]> Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- drivers/tty/serial/8250/8250_dw.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) --- a/drivers/tty/serial/8250/8250_dw.c +++ b/drivers/tty/serial/8250/8250_dw.c @@ -98,7 +98,10 @@ static void dw8250_serial_out(struct uar dw8250_force_idle(p); writeb(value, p->membase + (UART_LCR << p->regshift)); } - dev_err(p->dev, "Couldn't set LCR to %d\n", value); + /* + * FIXME: this deadlocks if port->lock is already held + * dev_err(p->dev, "Couldn't set LCR to %d\n", value); + */ } } @@ -128,7 +131,10 @@ static void dw8250_serial_out32(struct u dw8250_force_idle(p); writel(value, p->membase + (UART_LCR << p->regshift)); } - dev_err(p->dev, "Couldn't set LCR to %d\n", value); + /* + * FIXME: this deadlocks if port->lock is already held + * dev_err(p->dev, "Couldn't set LCR to %d\n", value); + */ } } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
