From cea37afd28f1bb7ca09a0c27e75f89cf2df9147d Mon Sep 17 00:00:00 2001 From: Johan Hovold <johan@kernel.org> Date: Fri, 16 Apr 2021 16:05:57 +0200 Subject: [PATCH] serial: stm32: defer sysrq processing Use the uart_unlock_and_check_sysrq() helper to defer sysrq processing until receive processing is done and the port lock has been released. This allows cleaning up the console_write() implementation by not having to work around the recursive sysrq case (by dropping locking completely) and also makes the console code work with PREEMPT_RT by no longer relying on local_irq_save(). Reviewed-by: Valentin Caron<valentin.caron@foss.st.com> Signed-off-by: Johan Hovold <johan@kernel.org> Link: https://lore.kernel.org/r/20210416140557.25177-4-johan@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- drivers/tty/serial/stm32-usart.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-) diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index 3524ed2c0c730d..24a1dfe7058b81 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -270,12 +270,12 @@ static void stm32_usart_receive_chars(struct uart_port *port, bool threaded) } } - if (uart_handle_sysrq_char(port, c)) + if (uart_prepare_sysrq_char(port, c)) continue; uart_insert_char(port, sr, USART_SR_ORE, c, flag); } - spin_unlock(&port->lock); + uart_unlock_and_check_sysrq(port); tty_flip_buffer_push(tport); } @@ -1430,13 +1430,10 @@ static void stm32_usart_console_write(struct console *co, const char *s, u32 old_cr1, new_cr1; int locked = 1; - local_irq_save(flags); - if (port->sysrq) - locked = 0; - else if (oops_in_progress) - locked = spin_trylock(&port->lock); + if (oops_in_progress) + locked = spin_trylock_irqsave(&port->lock, flags); else - spin_lock(&port->lock); + spin_lock_irqsave(&port->lock, flags); /* Save and disable interrupts, enable the transmitter */ old_cr1 = readl_relaxed(port->membase + ofs->cr1); @@ -1450,8 +1447,7 @@ static void stm32_usart_console_write(struct console *co, const char *s, writel_relaxed(old_cr1, port->membase + ofs->cr1); if (locked) - spin_unlock(&port->lock); - local_irq_restore(flags); + spin_unlock_irqrestore(&port->lock, flags); } static int stm32_usart_console_setup(struct console *co, char *options) -- GitLab