[v1] ath5k: fix WARNING opportunity for swap.

[PATCH] ath5k: fix WARNING opportunity for swap.

Posted by Mahmoud Maatuq 2 years, 6 months ago

coccinielle reported the following:
./drivers/net/wireless/ath/ath5k/phy.c:1573:25-26: WARNING opportunity for swap()

Signed-off-by: Mahmoud Maatuq <mahmoudmatook.mm@gmail.com>
---
 drivers/net/wireless/ath/ath5k/phy.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

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]);
 			}
 		}
 	}
-- 
2.34.1

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

Posted by Jiri Slaby 2 years, 6 months ago

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/

> Signed-off-by: Mahmoud Maatuq <mahmoudmatook.mm@gmail.com>
> ---
>   drivers/net/wireless/ath/ath5k/phy.c | 5 +----
>   1 file changed, 1 insertion(+), 4 deletions(-)
> 
> 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

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

Posted by Mahmoud Matook 2 years, 6 months ago

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 and avoid the cost of context
switching.


> > Signed-off-by: Mahmoud Maatuq <mahmoudmatook.mm@gmail.com>
> > ---
> >   drivers/net/wireless/ath/ath5k/phy.c | 5 +----
> >   1 file changed, 1 insertion(+), 4 deletions(-)
> > 
> > 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

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

Posted by Mahmoud Matook 2 years, 5 months ago

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.

if it's the case so make sense to use sort().
but should I send the modifications on the same thread?
as the subject needs to be changed.
ex: repalce double loop with sort function
    replace bubble sort with heap sort. 

>> and avoid the cost of context switching.

> What context switching?

I used the wrong expression, I meant function call overhead 
e.g store/load registers.

>>>> 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

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

Posted by Jiri Slaby 2 years, 6 months ago

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