Re: [PATCH] /drivers/net/wireless/ath/ath9k remove unnecessary ?: operator

Joe Perches
2015-12-28T17:56:57Z

On Mon, 2015-12-28 at 20:48 +0700, Ivan Safonov wrote:
> ((thermometer < 0) ? 0 : (thermometer == X)) and (thermometer == X) are equal for X >= 0.

X is not guaranteed to be >= 0 here

> Signed-off-by: Ivan Safonov <insafonov@gmail.com>
> ---
>  drivers/net/wireless/ath/ath9k/ar9003_eeprom.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/wireless/ath/ath9k/ar9003_eeprom.c b/drivers/net/wireless/ath/ath9k/ar9003_eeprom.c
[]
> @@ -4097,16 +4097,16 @@ static void ar9003_hw_thermometer_apply(struct ath_hw *ah)
>   REG_RMW_FIELD(ah, AR_PHY_65NM_CH2_RXTX4,
>         AR_PHY_65NM_CH0_RXTX4_THERM_ON_OVR, therm_on);
>
> - therm_on = (thermometer < 0) ? 0 : (thermometer == 0);
> + therm_on = thermometer == 0;

This code is not equivalent.

Check what happens when thermometer is -1.

>   REG_RMW_FIELD(ah, AR_PHY_65NM_CH0_RXTX4,
>         AR_PHY_65NM_CH0_RXTX4_THERM_ON, therm_on);
>   if (pCap->chip_chainmask & BIT(1)) {
> - therm_on = (thermometer < 0) ? 0 : (thermometer == 1);
> + therm_on = thermometer == 1;
>   REG_RMW_FIELD(ah, AR_PHY_65NM_CH1_RXTX4,
>         AR_PHY_65NM_CH0_RXTX4_THERM_ON, therm_on);
>   }
>   if (pCap->chip_chainmask & BIT(2)) {
> - therm_on = (thermometer < 0) ? 0 : (thermometer == 2);
> + therm_on = thermometer == 2;
>   REG_RMW_FIELD(ah, AR_PHY_65NM_CH2_RXTX4,
>         AR_PHY_65NM_CH0_RXTX4_THERM_ON, therm_on);
>   }