From a8555458720b1f187d628e12679e35c30882c339 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner <tglx@linutronix.de> Date: Thu, 14 Sep 2023 20:44:07 +0206 Subject: [PATCH 076/204] serial: rda: Use port lock wrappers 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@linutronix.de> Signed-off-by: John Ogness <john.ogness@linutronix.de> Link: https://lore.kernel.org/r/20230914183831.587273-51-john.ogness@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- drivers/tty/serial/rda-uart.c | 34 +++++++++++++++++----------------- 1 file changed, 17 insertions(+), 17 deletions(-) Index: linux-6.6.58-rt45/drivers/tty/serial/rda-uart.c =================================================================== @ linux-6.6.58-rt45/drivers/tty/serial/rda-uart.c:142 @ static unsigned int rda_uart_tx_empty(st unsigned int ret; u32 val; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); val = rda_uart_read(port, RDA_UART_STATUS); ret = (val & RDA_UART_TX_FIFO_MASK) ? TIOCSER_TEMT : 0; - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); return ret; } @ linux-6.6.58-rt45/drivers/tty/serial/rda-uart.c:249 @ static void rda_uart_set_termios(struct unsigned int baud; u32 irq_mask; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); baud = uart_get_baud_rate(port, termios, old, 9600, port->uartclk / 4); rda_uart_change_baudrate(rda_port, baud); @ linux-6.6.58-rt45/drivers/tty/serial/rda-uart.c:328 @ static void rda_uart_set_termios(struct /* update the per-port timeout */ uart_update_timeout(port, termios->c_cflag, baud); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); } static void rda_uart_send_chars(struct uart_port *port) @ linux-6.6.58-rt45/drivers/tty/serial/rda-uart.c:411 @ static irqreturn_t rda_interrupt(int irq unsigned long flags; u32 val, irq_mask; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); /* Clear IRQ cause */ val = rda_uart_read(port, RDA_UART_IRQ_CAUSE); @ linux-6.6.58-rt45/drivers/tty/serial/rda-uart.c:428 @ static irqreturn_t rda_interrupt(int irq rda_uart_send_chars(port); } - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); return IRQ_HANDLED; } @ linux-6.6.58-rt45/drivers/tty/serial/rda-uart.c:439 @ static int rda_uart_startup(struct uart_ int ret; u32 val; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); rda_uart_write(port, 0, RDA_UART_IRQ_MASK); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); ret = request_irq(port->irq, rda_interrupt, IRQF_NO_SUSPEND, "rda-uart", port); if (ret) return ret; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); val = rda_uart_read(port, RDA_UART_CTRL); val |= RDA_UART_ENABLE; @ linux-6.6.58-rt45/drivers/tty/serial/rda-uart.c:459 @ static int rda_uart_startup(struct uart_ val |= (RDA_UART_RX_DATA_AVAILABLE | RDA_UART_RX_TIMEOUT); rda_uart_write(port, val, RDA_UART_IRQ_MASK); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); return 0; } @ linux-6.6.58-rt45/drivers/tty/serial/rda-uart.c:469 @ static void rda_uart_shutdown(struct uar unsigned long flags; u32 val; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); rda_uart_stop_tx(port); rda_uart_stop_rx(port); @ linux-6.6.58-rt45/drivers/tty/serial/rda-uart.c:478 @ static void rda_uart_shutdown(struct uar val &= ~RDA_UART_ENABLE; rda_uart_write(port, val, RDA_UART_CTRL); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); } static const char *rda_uart_type(struct uart_port *port) @ linux-6.6.58-rt45/drivers/tty/serial/rda-uart.c:518 @ static void rda_uart_config_port(struct rda_uart_request_port(port); } - spin_lock_irqsave(&port->lock, irq_flags); + uart_port_lock_irqsave(port, &irq_flags); /* Clear mask, so no surprise interrupts. */ rda_uart_write(port, 0, RDA_UART_IRQ_MASK); @ linux-6.6.58-rt45/drivers/tty/serial/rda-uart.c:526 @ static void rda_uart_config_port(struct /* Clear status register */ rda_uart_write(port, 0, RDA_UART_STATUS); - spin_unlock_irqrestore(&port->lock, irq_flags); + uart_port_unlock_irqrestore(port, irq_flags); } static void rda_uart_release_port(struct uart_port *port) @ linux-6.6.58-rt45/drivers/tty/serial/rda-uart.c:600 @ static void rda_uart_port_write(struct u if (port->sysrq) { locked = 0; } else if (oops_in_progress) { - locked = spin_trylock(&port->lock); + locked = uart_port_trylock(port); } else { - spin_lock(&port->lock); + uart_port_lock(port); locked = 1; } @ linux-6.6.58-rt45/drivers/tty/serial/rda-uart.c:618 @ static void rda_uart_port_write(struct u rda_uart_write(port, old_irq_mask, RDA_UART_IRQ_MASK); if (locked) - spin_unlock(&port->lock); + uart_port_unlock(port); local_irq_restore(flags); }