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/pxa.c | 30 +++++++++++++++--------------- 1 file changed, 15 insertions(+), 15 deletions(-) diff --git a/drivers/tty/serial/pxa.c b/drivers/tty/serial/pxa.c index 73c60f5ea027..46e70e155aab 100644 --- a/drivers/tty/serial/pxa.c +++ b/drivers/tty/serial/pxa.c @@ -225,14 +225,14 @@ static inline irqreturn_t serial_pxa_irq(int irq, void *dev_id) iir = serial_in(up, UART_IIR); if (iir & UART_IIR_NO_INT) return IRQ_NONE; - spin_lock(&up->port.lock); + uart_port_lock(&up->port); lsr = serial_in(up, UART_LSR); if (lsr & UART_LSR_DR) receive_chars(up, &lsr); check_modem_status(up); if (lsr & UART_LSR_THRE) transmit_chars(up); - spin_unlock(&up->port.lock); + uart_port_unlock(&up->port); return IRQ_HANDLED; } @@ -242,9 +242,9 @@ static unsigned int serial_pxa_tx_empty(struct uart_port *port) unsigned long flags; unsigned int ret; - spin_lock_irqsave(&up->port.lock, flags); + uart_port_lock_irqsave(&up->port, &flags); ret = serial_in(up, UART_LSR) & UART_LSR_TEMT ? TIOCSER_TEMT : 0; - spin_unlock_irqrestore(&up->port.lock, flags); + uart_port_unlock_irqrestore(&up->port, flags); return ret; } @@ -295,13 +295,13 @@ static void serial_pxa_break_ctl(struct uart_port *port, int break_state) struct uart_pxa_port *up = (struct uart_pxa_port *)port; unsigned long flags; - spin_lock_irqsave(&up->port.lock, flags); + uart_port_lock_irqsave(&up->port, &flags); if (break_state == -1) up->lcr |= UART_LCR_SBC; else up->lcr &= ~UART_LCR_SBC; serial_out(up, UART_LCR, up->lcr); - spin_unlock_irqrestore(&up->port.lock, flags); + uart_port_unlock_irqrestore(&up->port, flags); } static int serial_pxa_startup(struct uart_port *port) @@ -346,10 +346,10 @@ static int serial_pxa_startup(struct uart_port *port) */ serial_out(up, UART_LCR, UART_LCR_WLEN8); - spin_lock_irqsave(&up->port.lock, flags); + uart_port_lock_irqsave(&up->port, &flags); up->port.mctrl |= TIOCM_OUT2; serial_pxa_set_mctrl(&up->port, up->port.mctrl); - spin_unlock_irqrestore(&up->port.lock, flags); + uart_port_unlock_irqrestore(&up->port, flags); /* * Finally, enable interrupts. Note: Modem status interrupts @@ -383,10 +383,10 @@ static void serial_pxa_shutdown(struct uart_port *port) up->ier = 0; serial_out(up, UART_IER, 0); - spin_lock_irqsave(&up->port.lock, flags); + uart_port_lock_irqsave(&up->port, &flags); up->port.mctrl &= ~TIOCM_OUT2; serial_pxa_set_mctrl(&up->port, up->port.mctrl); - spin_unlock_irqrestore(&up->port.lock, flags); + uart_port_unlock_irqrestore(&up->port, flags); /* * Disable break condition and FIFOs @@ -434,7 +434,7 @@ serial_pxa_set_termios(struct uart_port *port, struct ktermios *termios, * 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); /* * Ensure the port will be enabled. @@ -504,7 +504,7 @@ serial_pxa_set_termios(struct uart_port *port, struct ktermios *termios, up->lcr = cval; /* Save LCR */ serial_pxa_set_mctrl(&up->port, up->port.mctrl); serial_out(up, UART_FCR, fcr); - spin_unlock_irqrestore(&up->port.lock, flags); + uart_port_unlock_irqrestore(&up->port, flags); } static void @@ -608,9 +608,9 @@ serial_pxa_console_write(struct console *co, const char *s, unsigned int count) 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 @@ -628,7 +628,7 @@ serial_pxa_console_write(struct console *co, const char *s, unsigned int count) serial_out(up, UART_IER, ier); if (locked) - spin_unlock(&up->port.lock); + uart_port_unlock(&up->port); local_irq_restore(flags); clk_disable(up->clk); -- 2.39.2
