From: Thomas Gleixner Date: Thu, 14 Sep 2023 20:43:51 +0206 Subject: [PATCH 034/134] serial: ma35d1: Use port lock wrappers Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.6/older/patches-6.6.7-rt18.tar.xz 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 Signed-off-by: John Ogness Link: https://lore.kernel.org/r/20230914183831.587273-35-john.ogness@linutronix.de Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sebastian Andrzej Siewior --- drivers/tty/serial/ma35d1_serial.c | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-) --- a/drivers/tty/serial/ma35d1_serial.c +++ b/drivers/tty/serial/ma35d1_serial.c @@ -269,16 +269,16 @@ static void receive_chars(struct uart_ma 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(struc 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(str * 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(str 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(s 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(s 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)