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/sb1250-duart.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/tty/serial/sb1250-duart.c b/drivers/tty/serial/sb1250-duart.c index f3cd69346482..dbec29d9a6c3 100644 --- a/drivers/tty/serial/sb1250-duart.c +++ b/drivers/tty/serial/sb1250-duart.c @@ -610,7 +610,7 @@ static void sbd_set_termios(struct uart_port *uport, struct ktermios *termios, else aux &= ~M_DUART_CTS_CHNG_ENA; - spin_lock(&uport->lock); + uart_port_lock(uport); if (sport->tx_stopped) command |= M_DUART_TX_DIS; @@ -632,7 +632,7 @@ static void sbd_set_termios(struct uart_port *uport, struct ktermios *termios, write_sbdchn(sport, R_DUART_CMD, command); - spin_unlock(&uport->lock); + uart_port_unlock(uport); } @@ -839,22 +839,22 @@ static void sbd_console_write(struct console *co, const char *s, unsigned int mask; /* Disable transmit interrupts and enable the transmitter. */ - spin_lock_irqsave(&uport->lock, flags); + uart_port_lock_irqsave(uport, &flags); mask = read_sbdshr(sport, R_DUART_IMRREG((uport->line) % 2)); write_sbdshr(sport, R_DUART_IMRREG((uport->line) % 2), mask & ~M_DUART_IMR_TX); write_sbdchn(sport, R_DUART_CMD, M_DUART_TX_EN); - spin_unlock_irqrestore(&uport->lock, flags); + uart_port_unlock_irqrestore(uport, flags); uart_console_write(&sport->port, s, count, sbd_console_putchar); /* Restore transmit interrupts and the transmitter enable. */ - spin_lock_irqsave(&uport->lock, flags); + uart_port_lock_irqsave(uport, &flags); sbd_line_drain(sport); if (sport->tx_stopped) write_sbdchn(sport, R_DUART_CMD, M_DUART_TX_DIS); write_sbdshr(sport, R_DUART_IMRREG((uport->line) % 2), mask); - spin_unlock_irqrestore(&uport->lock, flags); + uart_port_unlock_irqrestore(uport, flags); } static int __init sbd_console_setup(struct console *co, char *options) -- 2.39.2
