linux-kernel - Re: [PATCH v1 1/1] serial: 8250_port: Drop duplicate NULL check

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Message-ID: <c2f50f9e-fc4c-dc6f-8bc7-8cc758c741dc@linux.intel.com>
Date: Wed, 28 Jan 2026 17:09:31 +0200 (EET)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
    "Jiri Slaby (SUSE)" <jirislaby@...nel.org>, 
    LKML <linux-kernel@...r.kernel.org>, 
    linux-serial <linux-serial@...r.kernel.org>
Subject: Re: [PATCH v1 1/1] serial: 8250_port: Drop duplicate NULL check

On Wed, 28 Jan 2026, Andy Shevchenko wrote:

> serial8250_release_dma() is NULL-aware, no need to check this in the caller.
> While at it, make sure DMA won't be used again, by NULLifying the pointer.
> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  drivers/tty/serial/8250/8250_port.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index 21fdf84f118f..c40d750d5a4b 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -2366,8 +2366,8 @@ void serial8250_do_shutdown(struct uart_port *port)
>  
>  	synchronize_irq(port->irq);
>  
> -	if (up->dma)
> -		serial8250_release_dma(up);
> +	serial8250_release_dma(up);
> +	up->dma = NULL;
>  
>  	scoped_guard(uart_port_lock_irqsave, port) {
>  		if (port->flags & UPF_FOURPORT) {
> 

Seems reasonable safeguard,

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>


-- 
 i.