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/ma35d1_serial.c | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-) diff --git a/drivers/tty/serial/ma35d1_serial.c b/drivers/tty/serial/ma35d1_serial.c index 465b1def9e11..6fac924f7c12 100644 --- a/drivers/tty/serial/ma35d1_serial.c +++ b/drivers/tty/serial/ma35d1_serial.c @@ -269,16 +269,16 @@ static void receive_chars(struct uart_ma35d1_port *up) if (uart_handle_sysrq_char(&up->port, ch)) continue; - spin_lock(&up->port.lock); + uart_port_lock(&up->port); uart_insert_char(&up->port, fsr, MA35_FSR_RX_OVER_IF, ch, flag); - spin_unlock(&up->port.lock); + uart_port_unlock(&up->port); fsr = serial_in(up, MA35_FSR_REG); } while (!(fsr & MA35_FSR_RX_EMPTY) && (max_count-- > 0)); - spin_lock(&up->port.lock); + uart_port_lock(&up->port); tty_flip_buffer_push(&up->port.state->port); - spin_unlock(&up->port.lock); + uart_port_unlock(&up->port); } static irqreturn_t ma35d1serial_interrupt(int irq, void *dev_id) @@ -364,14 +364,14 @@ static void ma35d1serial_break_ctl(struct uart_port *port, int break_state) unsigned long flags; u32 lcr; - spin_lock_irqsave(&up->port.lock, flags); + uart_port_lock_irqsave(&up->port, &flags); lcr = serial_in(up, MA35_LCR_REG); if (break_state != 0) lcr |= MA35_LCR_BREAK; else lcr &= ~MA35_LCR_BREAK; serial_out(up, MA35_LCR_REG, lcr); - spin_unlock_irqrestore(&up->port.lock, flags); + uart_port_unlock_irqrestore(&up->port, flags); } static int ma35d1serial_startup(struct uart_port *port) @@ -441,7 +441,7 @@ static void ma35d1serial_set_termios(struct uart_port *port, * Ok, we're now changing the port state. Do it with * interrupts disabled. */ - spin_lock_irqsave(&up->port.lock, flags); + uart_port_lock_irqsave(&up->port, &flags); up->port.read_status_mask = MA35_FSR_RX_OVER_IF; if (termios->c_iflag & INPCK) @@ -475,7 +475,7 @@ static void ma35d1serial_set_termios(struct uart_port *port, serial_out(up, MA35_LCR_REG, lcr); - spin_unlock_irqrestore(&up->port.lock, flags); + uart_port_unlock_irqrestore(&up->port, flags); } static const char *ma35d1serial_type(struct uart_port *port) @@ -560,9 +560,9 @@ static void ma35d1serial_console_write(struct console *co, const char *s, u32 co if (up->port.sysrq) locked = 0; else if (oops_in_progress) - locked = spin_trylock_irqsave(&up->port.lock, flags); + locked = uart_port_trylock_irqsave(&up->port, &flags); else - spin_lock_irqsave(&up->port.lock, flags); + uart_port_lock_irqsave(&up->port, &flags); /* * First save the IER then disable the interrupts @@ -576,7 +576,7 @@ static void ma35d1serial_console_write(struct console *co, const char *s, u32 co serial_out(up, MA35_IER_REG, ier); if (locked) - spin_unlock_irqrestore(&up->port.lock, flags); + uart_port_unlock_irqrestore(&up->port, flags); } static int __init ma35d1serial_console_setup(struct console *co, char *options) -- 2.39.2
