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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 29 Dec 2015 01:38:02 +0700
From:	Ivan Safonov <insafonov@...il.com>
To:	Joe Perches <joe@...ches.com>,
	QCA ath9k Development <ath9k-devel@....qualcomm.com>
Cc:	Kalle Valo <kvalo@...eaurora.org>, linux-wireless@...r.kernel.org,
	ath9k-devel@...ts.ath9k.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] /drivers/net/wireless/ath/ath9k remove unnecessary ?:
 operator

On 12/29/2015 12:56 AM, Joe Perches wrote:
> 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

X is fixed constant. In this case X is {0, 1, 2}.

>> @@ -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.

therm_on = (thermometer < 0) ? 0 : (thermometer == 0) =>
therm_on = (true) ? 0 : (thermometer == 0) =>

therm_on is 0


therm_on = thermometer == 0 =>

therm_on = false


false is equal to 0


Value of the thermometer variable isanerror code, or athermometercode. 
The thermometercode is never equal to the error code (thermometercode >= 
0, error code <0).
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/