From: Thomas Gleixner Date: Thu, 14 Sep 2023 20:43:36 +0206 Subject: [PATCH 019/134] serial: ar933x: 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/20230914183831.587273-20-john.ogness@linutronix.de Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sebastian Andrzej Siewior --- drivers/tty/serial/ar933x_uart.c | 26 +++++++++++++------------- 1 file changed, 13 insertions(+), 13 deletions(-) --- a/drivers/tty/serial/ar933x_uart.c +++ b/drivers/tty/serial/ar933x_uart.c @@ -133,9 +133,9 @@ static unsigned int ar933x_uart_tx_empty unsigned long flags; unsigned int rdata; - spin_lock_irqsave(&up->port.lock, flags); + uart_port_lock_irqsave(&up->port, &flags); rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG); - spin_unlock_irqrestore(&up->port.lock, flags); + uart_port_unlock_irqrestore(&up->port, flags); return (rdata & AR933X_UART_DATA_TX_CSR) ? 0 : TIOCSER_TEMT; } @@ -220,14 +220,14 @@ static void ar933x_uart_break_ctl(struct container_of(port, struct ar933x_uart_port, port); unsigned long flags; - spin_lock_irqsave(&up->port.lock, flags); + uart_port_lock_irqsave(&up->port, &flags); if (break_state == -1) ar933x_uart_rmw_set(up, AR933X_UART_CS_REG, AR933X_UART_CS_TX_BREAK); else ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG, AR933X_UART_CS_TX_BREAK); - spin_unlock_irqrestore(&up->port.lock, flags); + uart_port_unlock_irqrestore(&up->port, flags); } /* @@ -318,7 +318,7 @@ static void ar933x_uart_set_termios(stru * 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); /* disable the UART */ ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG, @@ -352,7 +352,7 @@ static void ar933x_uart_set_termios(stru AR933X_UART_CS_IF_MODE_M << AR933X_UART_CS_IF_MODE_S, AR933X_UART_CS_IF_MODE_DCE << AR933X_UART_CS_IF_MODE_S); - spin_unlock_irqrestore(&up->port.lock, flags); + uart_port_unlock_irqrestore(&up->port, flags); if (tty_termios_baud_rate(new)) tty_termios_encode_baud_rate(new, baud, baud); @@ -450,7 +450,7 @@ static irqreturn_t ar933x_uart_interrupt if ((status & AR933X_UART_CS_HOST_INT) == 0) return IRQ_NONE; - spin_lock(&up->port.lock); + uart_port_lock(&up->port); status = ar933x_uart_read(up, AR933X_UART_INT_REG); status &= ar933x_uart_read(up, AR933X_UART_INT_EN_REG); @@ -468,7 +468,7 @@ static irqreturn_t ar933x_uart_interrupt ar933x_uart_tx_chars(up); } - spin_unlock(&up->port.lock); + uart_port_unlock(&up->port); return IRQ_HANDLED; } @@ -485,7 +485,7 @@ static int ar933x_uart_startup(struct ua if (ret) return ret; - spin_lock_irqsave(&up->port.lock, flags); + uart_port_lock_irqsave(&up->port, &flags); /* Enable HOST interrupts */ ar933x_uart_rmw_set(up, AR933X_UART_CS_REG, @@ -498,7 +498,7 @@ static int ar933x_uart_startup(struct ua /* Enable RX interrupts */ ar933x_uart_start_rx_interrupt(up); - spin_unlock_irqrestore(&up->port.lock, flags); + uart_port_unlock_irqrestore(&up->port, flags); return 0; } @@ -632,9 +632,9 @@ static void ar933x_uart_console_write(st if (up->port.sysrq) locked = 0; else if (oops_in_progress) - locked = spin_trylock(&up->port.lock); + locked = uart_port_trylock(&up->port); else - spin_lock(&up->port.lock); + uart_port_lock(&up->port); /* * First save the IER then disable the interrupts @@ -654,7 +654,7 @@ static void ar933x_uart_console_write(st ar933x_uart_write(up, AR933X_UART_INT_REG, AR933X_UART_INT_ALLINTS); if (locked) - spin_unlock(&up->port.lock); + uart_port_unlock(&up->port); local_irq_restore(flags); }