Commit cea37afd authored by Johan Hovold's avatar Johan Hovold Committed by Greg Kroah-Hartman
Browse files

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: default avatarValentin <Caron&lt;valentin.caron@foss.st.com>
Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210416140557.25177-4-johan@kernel.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent e359b441

drivers/tty/serial/stm32-usart.c

+6 −10
Original line number Diff line number Diff line
@@ -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)