The port lock is a spinlock_t which is becomes a sleeping lock on PREEMPT_RT. The driver splits the locking function into two parts: local_irq_save() and uart_port_lock() and this breaks PREEMPT_RT. Handle sysrq requests sysrq once the port lock is dropped. Remove the special case in the console write routine an always use the complete locking function. Cc: Vladimir Zapolskiy <vz@xxxxxxxxx> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> --- drivers/tty/serial/lpc32xx_hs.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-) diff --git a/drivers/tty/serial/lpc32xx_hs.c b/drivers/tty/serial/lpc32xx_hs.c index ec20329f06036..e70fa59dbcc3b 100644 --- a/drivers/tty/serial/lpc32xx_hs.c +++ b/drivers/tty/serial/lpc32xx_hs.c @@ -136,20 +136,16 @@ static void lpc32xx_hsuart_console_write(struct console *co, const char *s, int locked = 1; touch_nmi_watchdog(); - local_irq_save(flags); - if (up->port.sysrq) - locked = 0; - else if (oops_in_progress) - locked = uart_port_trylock(&up->port); + if (oops_in_progress) + locked = uart_port_trylock_irqsave(&up->port, &flags); else - uart_port_lock(&up->port); + uart_port_lock_irqsave(&up->port, &flags); uart_console_write(&up->port, s, count, lpc32xx_hsuart_console_putchar); wait_for_xmit_empty(&up->port); if (locked) - uart_port_unlock(&up->port); - local_irq_restore(flags); + uart_port_unlock_irqrestore(&up->port, flags); } static int __init lpc32xx_hsuart_console_setup(struct console *co, @@ -268,7 +264,8 @@ static void __serial_lpc32xx_rx(struct uart_port *port) tty_insert_flip_char(tport, 0, TTY_FRAME); } - tty_insert_flip_char(tport, (tmp & 0xFF), flag); + if (!uart_prepare_sysrq_char(port, tmp & 0xff)) + tty_insert_flip_char(tport, (tmp & 0xFF), flag); tmp = readl(LPC32XX_HSUART_FIFO(port->membase)); } @@ -333,7 +330,7 @@ static irqreturn_t serial_lpc32xx_interrupt(int irq, void *dev_id) __serial_lpc32xx_tx(port); } - uart_port_unlock(port); + uart_unlock_and_check_sysrq(port); return IRQ_HANDLED; } -- 2.43.0
