linux-kernel - Re: [PATCH v2 3/3] tty: serial: samsung_tty: Use abs() to simplify some code

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Message-ID: <524b5587-4099-0f5f-40c6-cfc6e4c20274@kernel.org>
Date:   Mon, 12 Jun 2023 07:31:18 +0200
From:   Jiri Slaby <jirislaby@...nel.org>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Alim Akhtar <alim.akhtar@...sung.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        Walter Harms <wharms@....de>,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-serial@...r.kernel.org
Subject: Re: [PATCH v2 3/3] tty: serial: samsung_tty: Use abs() to simplify
 some code

On 12. 06. 23, 7:13, Jiri Slaby wrote:
> On 10. 06. 23, 17:59, Christophe JAILLET wrote:
>> Use abs() instead of hand-writing it.
>>
>> Suggested-by: Walter Harms <wharms@....de>
>> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
>> ---
>> v2: new patch
>> ---
>>   drivers/tty/serial/samsung_tty.c | 5 ++---
>>   1 file changed, 2 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/tty/serial/samsung_tty.c 
>> b/drivers/tty/serial/samsung_tty.c
>> index 0b37019820b4..b29e9dfd81a6 100644
>> --- a/drivers/tty/serial/samsung_tty.c
>> +++ b/drivers/tty/serial/samsung_tty.c
>> @@ -24,6 +24,7 @@
>>   #include <linux/dmaengine.h>
>>   #include <linux/dma-mapping.h>
>>   #include <linux/slab.h>
>> +#include <linux/math.h>
>>   #include <linux/module.h>
>>   #include <linux/ioport.h>
>>   #include <linux/io.h>
>> @@ -1485,9 +1486,7 @@ static unsigned int s3c24xx_serial_getclk(struct 
>> s3c24xx_uart_port *ourport,
>>           }
>>           quot--;
>> -        calc_deviation = req_baud - baud;
>> -        if (calc_deviation < 0)
>> -            calc_deviation = -calc_deviation;
>> +        calc_deviation = abs(req_baud - baud);
> 
> Does this work provided req_baud and baud are unsigned?

Oh, yes, it does, _hopefully_. A bit unexpectedly for me, but:
  * abs - return absolute value of an argument
  * @x: the value.  If it is unsigned type, it is converted to signed 
type first.

So:

Reviewed-by: Jiri Slaby <jirislaby@...nel.org>

It would help noting this in the commit log.

> thanks,-- 
js
suse labs