linux-kernel - Re: [PATCH linux-next] serial: dz: use atomic_inc and atomic_dec instead of atomic

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Date:   Thu, 13 Oct 2022 08:24:00 +0200
From:   Jiri Slaby <jirislaby@...nel.org>
To:     xu.panda668@...il.com, macro@...am.me.uk
Cc:     linux-kernel@...r.kernel.org, Xu Panda <xu.panda@....com.cn>,
        Zeal Robot <zealci@....com.cn>
Subject: Re: [PATCH linux-next] serial: dz: use atomic_inc and atomic_dec
 instead of atomic_add

On 12. 10. 22, 12:09, xu.panda668@...il.com wrote:
> From: Xu Panda <xu.panda@....com.cn>
> 
> There is a better way for atomic_dec_return and atomic_inc.

While the patch below looks fine, I don't understand this sentence ^^^. 
Care to reformulate? And please append () when writing about function names.

> Reported-by: Zeal Robot <zealci@....com.cn>
> Signed-off-by: Xu Panda <xu.panda@....com.cn>
> ---
>   drivers/tty/serial/dz.c | 14 +++++++-------
>   1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/tty/serial/dz.c b/drivers/tty/serial/dz.c
> index 829b452daee9..84476cef3278 100644
> --- a/drivers/tty/serial/dz.c
> +++ b/drivers/tty/serial/dz.c
> @@ -404,14 +404,14 @@ static int dz_startup(struct uart_port *uport)
>   	int ret;
>   	u16 tmp;
>   
> -	irq_guard = atomic_add_return(1, &mux->irq_guard);
> +	irq_guard = atomic_inc_return(&mux->irq_guard);
>   	if (irq_guard != 1)
>   		return 0;
>   
>   	ret = request_irq(dport->port.irq, dz_interrupt,
>   			  IRQF_SHARED, "dz", mux);
>   	if (ret) {
> -		atomic_add(-1, &mux->irq_guard);
> +		atomic_dec(&mux->irq_guard);
>   		printk(KERN_ERR "dz: Cannot get IRQ %d!\n", dport->port.irq);
>   		return ret;
>   	}
> @@ -448,7 +448,7 @@ static void dz_shutdown(struct uart_port *uport)
>   	dz_stop_tx(&dport->port);
>   	spin_unlock_irqrestore(&dport->port.lock, flags);
>   
> -	irq_guard = atomic_add_return(-1, &mux->irq_guard);
> +	irq_guard = atomic_dec_return(&mux->irq_guard);
>   	if (!irq_guard) {
>   		/* Disable interrupts.  */
>   		tmp = dz_in(dport, DZ_CSR);
> @@ -668,7 +668,7 @@ static void dz_release_port(struct uart_port *uport)
>   	iounmap(uport->membase);
>   	uport->membase = NULL;
>   
> -	map_guard = atomic_add_return(-1, &mux->map_guard);
> +	map_guard = atomic_dec_return(&mux->map_guard);
>   	if (!map_guard)
>   		release_mem_region(uport->mapbase, dec_kn_slot_size);
>   }
> @@ -691,11 +691,11 @@ static int dz_request_port(struct uart_port *uport)
>   	int map_guard;
>   	int ret;
>   
> -	map_guard = atomic_add_return(1, &mux->map_guard);
> +	map_guard = atomic_inc_return(&mux->map_guard);
>   	if (map_guard == 1) {
>   		if (!request_mem_region(uport->mapbase, dec_kn_slot_size,
>   					"dz")) {
> -			atomic_add(-1, &mux->map_guard);
> +			atomic_dec(&mux->map_guard);
>   			printk(KERN_ERR
>   			       "dz: Unable to reserve MMIO resource\n");
>   			return -EBUSY;
> @@ -703,7 +703,7 @@ static int dz_request_port(struct uart_port *uport)
>   	}
>   	ret = dz_map_port(uport);
>   	if (ret) {
> -		map_guard = atomic_add_return(-1, &mux->map_guard);
> +		map_guard = atomic_dec_return(&mux->map_guard);
>   		if (!map_guard)
>   			release_mem_region(uport->mapbase, dec_kn_slot_size);
>   		return ret;

-- 
js
suse labs