diff mbox series

[1/1] tty: serial: samsung: add spin_lock for interrupt and console_write

Message ID 20220406082216.11206-2-jaewon02.kim@samsung.com
State Superseded
Headers show
Series tty: serial: samsung: add spin_lock in console_write | expand

Commit Message

Jaewon Kim April 6, 2022, 8:22 a.m. UTC
The console_write and IRQ handler can run concurrently.
Problems may occurs console_write is continuously executed while
the IRQ handler is running.

Signed-off-by: Jaewon Kim <jaewon02.kim@samsung.com>
---
 drivers/tty/serial/samsung_tty.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

Comments

Greg Kroah-Hartman April 6, 2022, 8:21 a.m. UTC | #1
On Wed, Apr 06, 2022 at 05:22:16PM +0900, Jaewon Kim wrote:
> The console_write and IRQ handler can run concurrently.
> Problems may occurs console_write is continuously executed while
> the IRQ handler is running.
> 
> Signed-off-by: Jaewon Kim <jaewon02.kim@samsung.com>
> ---
>  drivers/tty/serial/samsung_tty.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c
> index e1585fbae909..9db479d728b5 100644
> --- a/drivers/tty/serial/samsung_tty.c
> +++ b/drivers/tty/serial/samsung_tty.c
> @@ -2480,12 +2480,24 @@ s3c24xx_serial_console_write(struct console *co, const char *s,
>  			     unsigned int count)
>  {
>  	unsigned int ucon = rd_regl(cons_uart, S3C2410_UCON);
> +	unsigned long flags;
> +	bool locked = 1;

"1" is not a boolean :)
Jaewon Kim April 6, 2022, 8:39 a.m. UTC | #2
Hello 

On 22. 4. 6. 17:21, Greg Kroah-Hartman wrote: 
> On Wed, Apr 06, 2022 at 05:22:16PM +0900, Jaewon Kim wrote:
> > The console_write and IRQ handler can run concurrently.
> > Problems may occurs console_write is continuously executed while the
> > IRQ handler is running.
> >
> > Signed-off-by: Jaewon Kim <jaewon02.kim@samsung.com>
> > ---
> >  drivers/tty/serial/samsung_tty.c | 12 ++++++++++++
> >  1 file changed, 12 insertions(+)
> >
> > diff --git a/drivers/tty/serial/samsung_tty.c
> > b/drivers/tty/serial/samsung_tty.c
> > index e1585fbae909..9db479d728b5 100644
> > --- a/drivers/tty/serial/samsung_tty.c
> > +++ b/drivers/tty/serial/samsung_tty.c
> > @@ -2480,12 +2480,24 @@ s3c24xx_serial_console_write(struct console *co, const char *s,
> >  			     unsigned int count)
> >  {
> >  	unsigned int ucon = rd_regl(cons_uart, S3C2410_UCON);
> > +	unsigned long flags;
> > +	bool locked = 1;
> 
> "1" is not a boolean :)

return value of spin_trylock() is 1 or 0.
It seems better to keep it as an int than to change it to bool.
I will return it to int.


Thanks
Jaewon Kim
Jaewon Kim April 6, 2022, 11:19 a.m. UTC | #3
On 22. 4. 6. 18:48, Jiri Slaby wrote:> On 06. 04. 22, 10:39, Jaewon Kim wrote:
> > On 22. 4. 6. 17:21, Greg Kroah-Hartman wrote:
> >> On Wed, Apr 06, 2022 at 05:22:16PM +0900, Jaewon Kim wrote:
> >>> The console_write and IRQ handler can run concurrently.
> >>> Problems may occurs console_write is continuously executed while the
> >>> IRQ handler is running.
> >>>
> >>> Signed-off-by: Jaewon Kim <jaewon02.kim@samsung.com>
> >>> ---
> >>>   drivers/tty/serial/samsung_tty.c | 12 ++++++++++++
> >>>   1 file changed, 12 insertions(+)
> >>>
> >>> diff --git a/drivers/tty/serial/samsung_tty.c
> >>> b/drivers/tty/serial/samsung_tty.c
> >>> index e1585fbae909..9db479d728b5 100644
> >>> --- a/drivers/tty/serial/samsung_tty.c
> >>> +++ b/drivers/tty/serial/samsung_tty.c
> >>> @@ -2480,12 +2480,24 @@ s3c24xx_serial_console_write(struct console *co, const char *s,
> >>>   			     unsigned int count)
> >>>   {
> >>>   	unsigned int ucon = rd_regl(cons_uart, S3C2410_UCON);
> >>> +	unsigned long flags;
> >>> +	bool locked = 1;
> >>
> >> "1" is not a boolean :)
> >
> > return value of spin_trylock() is 1 or 0.
> > It seems better to keep it as an int than to change it to bool.
> > I will return it to int.
> 
> Hi, no, do not that. Simply use bool/true/false.
> 

Okay, Thanks to review.
I will fix 1 to bool in next v3 patch.

> thanks,
> --
> js
> suse labs

Thanks
Jaewon Kim
diff mbox series

Patch

diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c
index e1585fbae909..9db479d728b5 100644
--- a/drivers/tty/serial/samsung_tty.c
+++ b/drivers/tty/serial/samsung_tty.c
@@ -2480,12 +2480,24 @@  s3c24xx_serial_console_write(struct console *co, const char *s,
 			     unsigned int count)
 {
 	unsigned int ucon = rd_regl(cons_uart, S3C2410_UCON);
+	unsigned long flags;
+	bool locked = 1;
 
 	/* not possible to xmit on unconfigured port */
 	if (!s3c24xx_port_configured(ucon))
 		return;
 
+	if (cons_uart->sysrq)
+		locked = 0;
+	else if (oops_in_progress)
+		locked = spin_trylock_irqsave(&cons_uart->lock, flags);
+	else
+		spin_lock_irqsave(&cons_uart->lock, flags);
+
 	uart_console_write(cons_uart, s, count, s3c24xx_serial_console_putchar);
+
+	if (locked)
+		spin_unlock_irqrestore(&cons_uart->lock, flags);
 }
 
 /* Shouldn't be __init, as it can be instantiated from other module */