linux-kernel - Re: [PATCH v2] serial: sh-sci: Use spin_{try}lock

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Date:   Tue, 8 May 2018 09:18:44 +0200
From:   Daniel Wagner <wagi@...om.org>
To:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:     linux-kernel@...r.kernel.org,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        linux-rt-users@...r.kernel.org, linux-serial@...r.kernel.org,
        linux-sh@...r.kernel.org, gregkh@...uxfoundation.org,
        Daniel Wagner <daniel.wagner@...mens.com>
Subject: Re: [PATCH v2] serial: sh-sci: Use spin_{try}lock_irqsave instead of
 open coding version

Hi Sebastian,

On 05/07/2018 02:51 PM, Sebastian Andrzej Siewior wrote:
> On 2018-05-04 18:30:41 [+0200], Daniel Wagner wrote:
>> --- a/drivers/tty/serial/sh-sci.c
>> +++ b/drivers/tty/serial/sh-sci.c
>> @@ -2890,16 +2890,16 @@ static void serial_console_write(struct console *co, const char *s,
>>   	unsigned long flags;
>>   	int locked = 1;
>>   
>> -	local_irq_save(flags);
>>   #if defined(SUPPORT_SYSRQ)
>> -	if (port->sysrq)
>> +	if (port->sysrq) {
>>   		locked = 0;
>> -	else
>> +		local_irq_save(flags);
> 
> how is this helping? You should see a splat after a sysrq request.

You are right, I didn't really think this through.

Should 'echo t > /proc/sysrq' trigger the splat? At least I was so naive 
that think it would be enough.

Thanks,
Daniel