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

Jaewon Kim
2022-04-05T03:35:20Z

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 | 14 ++++++++++++++
1 file changed, 14 insertions(+)

diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c
index e1585fbae909..d362e8e114f1 100644
--- a/drivers/tty/serial/samsung_tty.c
+++ b/drivers/tty/serial/samsung_tty.c
@@ -2480,12 +2480,26 @@ 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;
+ int locked = 1;

/* not possible to xmit on unconfigured port */
if (!s3c24xx_port_configured(ucon))
return;

+ local_irq_save(flags);
+ if (cons_uart->sysrq)
+ locked = 0;
+ else if (oops_in_progress)
+ locked = spin_trylock(&cons_uart->lock);
+ else
+ spin_lock(&cons_uart->lock);
+
uart_console_write(cons_uart, s, count, s3c24xx_serial_console_putchar);
+
+ if (locked)
+ spin_unlock(&cons_uart->lock);
+ local_irq_restore(flags);
}

/* Shouldn't be __init, as it can be instantiated from other module */
--
2.35.1