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SubjectRe: [PATCH] tty: serial: replace spin_lock_irqsave by spin_lock in hard IRQ
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在 2020/11/20 16:23, Johan Hovold 写道:
> 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.
As the following code shows, owl_uart_irq does not run in the irq
threading context.
ret = request_irq(port->irq, owl_uart_irq, IRQF_TRIGGER_HIGH,
"owl-uart", port);
if (ret)
return ret;

>
>> 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
>
> .
>

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