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().
Signed-off-by: Johan Hovold <[email protected]>
---
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 3524ed2c0c73..24a1dfe7058b 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)
--
2.26.3
Hi,
On 4/16/21 4:05 PM, Johan Hovold wrote:
> 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().
>
> Signed-off-by: Johan Hovold <[email protected]>
Reviewed-by: Valentin Caron<[email protected]>
> ---
> 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 3524ed2c0c73..24a1dfe7058b 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)