2022-09-27 11:36:02

by Jiri Slaby

Subject: [PATCH 4/4] tty: serial: do unlock on a common path in altera_jtaguart_console_putc()

port->lock is unlocked in each branch in altera_jtaguart_console_putc(),
so do it before the "if". "status" needs not be under the lock, as the
register was already read.

Cc: Tobias Klauser <[email protected]>
Signed-off-by: Jiri Slaby <[email protected]>
---
drivers/tty/serial/altera_jtaguart.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/altera_jtaguart.c b/drivers/tty/serial/altera_jtaguart.c
index ac8ce418de36..c2d154d78e54 100644
--- a/drivers/tty/serial/altera_jtaguart.c
+++ b/drivers/tty/serial/altera_jtaguart.c
@@ -310,11 +310,12 @@ static void altera_jtaguart_console_putc(struct uart_port *port, unsigned char c

spin_lock_irqsave(&port->lock, flags);
while (!altera_jtaguart_tx_space(port, &status)) {
+ spin_unlock_irqrestore(&port->lock, flags);
+
if ((status & ALTERA_JTAGUART_CONTROL_AC_MSK) == 0) {
- spin_unlock_irqrestore(&port->lock, flags);
return; /* no connection activity */
}
- spin_unlock_irqrestore(&port->lock, flags);
+
cpu_relax();
spin_lock_irqsave(&port->lock, flags);
}
--
2.37.3

2022-09-27 15:56:30

by Tobias Klauser

Subject: Re: [PATCH 4/4] tty: serial: do unlock on a common path in altera_jtaguart_console_putc()

On 2022-09-27 at 13:18:19 +0200, Jiri Slaby <[email protected]> wrote:
> port->lock is unlocked in each branch in altera_jtaguart_console_putc(),
> so do it before the "if". "status" needs not be under the lock, as the
> register was already read.
>
> Cc: Tobias Klauser <[email protected]>
> Signed-off-by: Jiri Slaby <[email protected]>

Acked-by: Tobias Klauser <[email protected]>

Thanks

2022-09-28 10:37:49

by Ilpo Järvinen

Subject: Re: [PATCH 4/4] tty: serial: do unlock on a common path in altera_jtaguart_console_putc()

On Tue, 27 Sep 2022, Jiri Slaby wrote:

> port->lock is unlocked in each branch in altera_jtaguart_console_putc(),
> so do it before the "if". "status" needs not be under the lock, as the
> register was already read.
>
> Cc: Tobias Klauser <[email protected]>
> Signed-off-by: Jiri Slaby <[email protected]>
> ---
> drivers/tty/serial/altera_jtaguart.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/tty/serial/altera_jtaguart.c b/drivers/tty/serial/altera_jtaguart.c
> index ac8ce418de36..c2d154d78e54 100644
> --- a/drivers/tty/serial/altera_jtaguart.c
> +++ b/drivers/tty/serial/altera_jtaguart.c
> @@ -310,11 +310,12 @@ static void altera_jtaguart_console_putc(struct uart_port *port, unsigned char c
>
> spin_lock_irqsave(&port->lock, flags);
> while (!altera_jtaguart_tx_space(port, &status)) {
> + spin_unlock_irqrestore(&port->lock, flags);
> +
> if ((status & ALTERA_JTAGUART_CONTROL_AC_MSK) == 0) {
> - spin_unlock_irqrestore(&port->lock, flags);
> return; /* no connection activity */
> }

There braces are now unnecessary.

Reviewed-by: Ilpo J?rvinen <[email protected]>

--
i.


> - spin_unlock_irqrestore(&port->lock, flags);
> +
> cpu_relax();
> spin_lock_irqsave(&port->lock, flags);
> }
>