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

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Date:   Mon, 7 May 2018 14:51:46 +0200
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     Daniel Wagner <wagi@...om.org>
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

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.

> +	} else
>  #endif
>  	if (oops_in_progress)
> -		locked = spin_trylock(&port->lock);
> +		locked = spin_trylock_irqsave(&port->lock, flags);
>  	else
> -		spin_lock(&port->lock);
> +		spin_lock_irqsave(&port->lock, flags);
>  
>  	/* first save SCSCR then disable interrupts, keep clock source */
>  	ctrl = serial_port_in(port, SCSCR);

Sebastian