From: Johan Hovold <johan@kernel.org>
To: Tian Tao <tiantao6@hisilicon.com>
Cc: gregkh@linuxfoundation.org, jirislaby@kernel.org,
afaerber@suse.de, manivannan.sadhasivam@linaro.org,
linux-serial@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] tty: serial: replace spin_lock_irqsave by spin_lock in hard IRQ
Date: Fri, 20 Nov 2020 09:23:00 +0100 [thread overview]
Message-ID: <X7d85DKvisjA3nYv@localhost> (raw)
In-Reply-To: <1605776489-16283-1-git-send-email-tiantao6@hisilicon.com>
On Thu, Nov 19, 2020 at 05:01:29PM +0800, Tian Tao wrote:
> The code has been in a irq-disabled context since it is hard IRQ. There
> is no necessity to do it again.
>
> Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
> ---
> drivers/tty/serial/owl-uart.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/tty/serial/owl-uart.c b/drivers/tty/serial/owl-uart.c
> index c149f8c3..472fdaf 100644
> --- a/drivers/tty/serial/owl-uart.c
> +++ b/drivers/tty/serial/owl-uart.c
> @@ -251,10 +251,9 @@ static void owl_uart_receive_chars(struct uart_port *port)
> static irqreturn_t owl_uart_irq(int irq, void *dev_id)
> {
> struct uart_port *port = dev_id;
> - unsigned long flags;
> u32 stat;
>
> - spin_lock_irqsave(&port->lock, flags);
> + spin_lock(&port->lock);
Same thing here; this will break with forced irq threading (i.e.
"threadirqs") since the console code can still end up being called from
interrupt context.
> stat = owl_uart_read(port, OWL_UART_STAT);
>
> @@ -268,7 +267,7 @@ static irqreturn_t owl_uart_irq(int irq, void *dev_id)
> stat |= OWL_UART_STAT_RIP | OWL_UART_STAT_TIP;
> owl_uart_write(port, stat, OWL_UART_STAT);
>
> - spin_unlock_irqrestore(&port->lock, flags);
> + spin_unlock(&port->lock);
>
> return IRQ_HANDLED;
> }
Johan
next prev parent reply other threads:[~2020-11-20 8:23 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-19 9:01 [PATCH] tty: serial: replace spin_lock_irqsave by spin_lock in hard IRQ Tian Tao
2020-11-19 9:03 ` Jiri Slaby
2020-11-20 8:23 ` Johan Hovold [this message]
2020-11-20 11:25 ` tiantao (H)
2020-11-20 12:49 ` Johan Hovold
2020-11-20 20:00 ` David Laight
2020-11-21 15:17 ` Johan Hovold
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