From: Thomas Gleixner <tglx@xxxxxxxxxxxxx> When a serial port is used for kernel console output, then all modifications to the UART registers which are done from other contexts, e.g. getty, termios, are interference points for the kernel console. So far this has been ignored and the printk output is based on the principle of hope. The rework of the console infrastructure which aims to support threaded and atomic consoles, requires to mark sections which modify the UART registers as unsafe. This allows the atomic write function to make informed decisions and eventually to restore operational state. It also allows to prevent the regular UART code from modifying UART registers while printk output is in progress. All modifications of UART registers are guarded by the UART port lock, which provides an obvious synchronization point with the console infrastructure. To avoid adding this functionality to all UART drivers, wrap the spin_[un]lock*() invocations for uart_port::lock into helper functions which just contain the spin_[un]lock*() invocations for now. In a subsequent step these helpers will gain the console synchronization mechanisms. Converted with coccinelle. No functional change. Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> --- drivers/tty/serial/altera_uart.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/drivers/tty/serial/altera_uart.c b/drivers/tty/serial/altera_uart.c index a9c41942190c..77835ac68df2 100644 --- a/drivers/tty/serial/altera_uart.c +++ b/drivers/tty/serial/altera_uart.c @@ -164,13 +164,13 @@ static void altera_uart_break_ctl(struct uart_port *port, int break_state) struct altera_uart *pp = container_of(port, struct altera_uart, port); unsigned long flags; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); if (break_state == -1) pp->imr |= ALTERA_UART_CONTROL_TRBK_MSK; else pp->imr &= ~ALTERA_UART_CONTROL_TRBK_MSK; altera_uart_update_ctrl_reg(pp); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); } static void altera_uart_set_termios(struct uart_port *port, @@ -187,10 +187,10 @@ static void altera_uart_set_termios(struct uart_port *port, tty_termios_copy_hw(termios, old); tty_termios_encode_baud_rate(termios, baud, baud); - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); uart_update_timeout(port, termios->c_cflag, baud); altera_uart_writel(port, baudclk, ALTERA_UART_DIVISOR_REG); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); /* * FIXME: port->read_status_mask and port->ignore_status_mask @@ -264,12 +264,12 @@ static irqreturn_t altera_uart_interrupt(int irq, void *data) isr = altera_uart_readl(port, ALTERA_UART_STATUS_REG) & pp->imr; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); if (isr & ALTERA_UART_STATUS_RRDY_MSK) altera_uart_rx_chars(port); if (isr & ALTERA_UART_STATUS_TRDY_MSK) altera_uart_tx_chars(port); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); return IRQ_RETVAL(isr); } @@ -313,13 +313,13 @@ static int altera_uart_startup(struct uart_port *port) } } - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); /* Enable RX interrupts now */ pp->imr = ALTERA_UART_CONTROL_RRDY_MSK; altera_uart_update_ctrl_reg(pp); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); return 0; } @@ -329,13 +329,13 @@ static void altera_uart_shutdown(struct uart_port *port) struct altera_uart *pp = container_of(port, struct altera_uart, port); unsigned long flags; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); /* Disable all interrupts now */ pp->imr = 0; altera_uart_update_ctrl_reg(pp); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); if (port->irq) free_irq(port->irq, port); -- 2.39.2
