linux-kernel - Re: [PATCH] ath5k: fix WARNING opportunity for swap.

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Date:   Wed, 9 Aug 2023 12:40:44 +0200
From:   Jiri Slaby <jirislaby@...nel.org>
To:     mickflemm@...il.com, mcgrof@...nel.org, kvalo@...nel.org,
        linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-kernel-mentees@...ts.linuxfoundation.org
Subject: Re: [PATCH] ath5k: fix WARNING opportunity for swap.

On 08. 08. 23, 21:42, Mahmoud Matook wrote:
> On 08/08, Jiri Slaby wrote:
> 
>> On 07. 08. 23, 22:10, Mahmoud Maatuq wrote:
>>> coccinielle reported the following:
>>> ./drivers/net/wireless/ath/ath5k/phy.c:1573:25-26: WARNING opportunity for swap()
>>
>>
>> OK, once again:
>> https://lore.kernel.org/all/0c3acbd4-6ab2-5cc5-6293-54e30093cce2@kernel.org/
> 
> 
> I had a look at the commit history, to see why the original developer
> didn't use sort() function, and name the array variable sort but found
> nothing.
> I have some doubts that he might did that intentionally, so not to call
> sort() function for such small array

It happens once in 10 s and in a work. No worries about that.

> and avoid the cost of context switching.

What context switching?

>>> diff --git a/drivers/net/wireless/ath/ath5k/phy.c b/drivers/net/wireless/ath/ath5k/phy.c
>>> index 5797ef9c73d7..f87eb684f223 100644
>>> --- a/drivers/net/wireless/ath/ath5k/phy.c
>>> +++ b/drivers/net/wireless/ath/ath5k/phy.c
>>> @@ -1562,16 +1562,13 @@ static s16
>>>    ath5k_hw_get_median_noise_floor(struct ath5k_hw *ah)
>>>    {
>>>    	s16 sort[ATH5K_NF_CAL_HIST_MAX];
>>> -	s16 tmp;
>>>    	int i, j;
>>>    	memcpy(sort, ah->ah_nfcal_hist.nfval, sizeof(sort));
>>>    	for (i = 0; i < ATH5K_NF_CAL_HIST_MAX - 1; i++) {
>>>    		for (j = 1; j < ATH5K_NF_CAL_HIST_MAX - i; j++) {
>>>    			if (sort[j] > sort[j - 1]) {
>>> -				tmp = sort[j];
>>> -				sort[j] = sort[j - 1];
>>> -				sort[j - 1] = tmp;
>>> +				swap(sort[j], sort[j - 1]);
>>>    			}
>>>    		}
>>>    	}
>>
>> -- 
>> js
>> suse labs

-- 
js
suse labs