linux-kernel - Re: [PATCH v2] staging: rtl8723bs: os_dep: simplify the return statement.

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Message-ID: <b9ba5a6f-ac0c-de0f-d105-90c50235ea5c@gmail.com>
Date:   Mon, 11 Oct 2021 23:40:17 +0530
From:   Saurav Girepunje <saurav.girepunje@...il.com>
To:     "Fabio M. De Francesco" <fmdefrancesco@...il.com>,
        gregkh@...uxfoundation.org
Cc:     fabioaiuto83@...il.com, ross.schm.dev@...il.com,
        marcocesati@...il.com, insafonov@...il.com,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org,
        saurav.girepunje@...mail.com
Subject: Re: [PATCH v2] staging: rtl8723bs: os_dep: simplify the return
 statement.



On 10/10/21 12:54 pm, Fabio M. De Francesco wrote:
> On Sunday, October 10, 2021 7:06:05 AM CEST Saurav Girepunje wrote:
>> Remove the unneeded and redundant check of variable on goto out.
>> Simplify the return using multiple goto label to avoid
>> unneeded check.
>>
>> Signed-off-by: Saurav Girepunje <saurav.girepunje@...il.com>
>> ---
>>
>> ChangeLog V2:
>> 	-Add goto out after the memcpy for no error case return with
>> 	 ret only. Free is not required on no error case.
>>
>> ChangeLog V1:
>> 	-Remove the unneeded and redundant check of variable on
>> 	 goto out.
>> 	-Simplify the return using multiple goto label to avoid
>> 	 unneeded check.
>>
>>  .../staging/rtl8723bs/os_dep/ioctl_cfg80211.c | 22 +++++++++----------
>>  1 file changed, 10 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c b/drivers/
> staging/rtl8723bs/os_dep/ioctl_cfg80211.c
>> index 0868f56e2979..ae9579dc0848 100644
>> --- a/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c
>> +++ b/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c
>> @@ -2312,7 +2312,7 @@ static int rtw_cfg80211_add_monitor_if(struct adapter 
> *padapter, char *name, str
>>  	mon_wdev = rtw_zmalloc(sizeof(struct wireless_dev));
>>  	if (!mon_wdev) {
>>  		ret = -ENOMEM;
>> -		goto out;
>> +		goto err_zmalloc;
>>  	}
>>
>>  	mon_wdev->wiphy = padapter->rtw_wdev->wiphy;
>> @@ -2322,23 +2322,21 @@ static int rtw_cfg80211_add_monitor_if(struct 
> adapter *padapter, char *name, str
>>
>>  	ret = cfg80211_register_netdevice(mon_ndev);
>>  	if (ret) {
>> -		goto out;
>> +		goto err_register;
>>  	}
>>
>>  	*ndev = pwdev_priv->pmon_ndev = mon_ndev;
>>  	memcpy(pwdev_priv->ifname_mon, name, IFNAMSIZ+1);
>> +	goto out;
> 
> I think this is the right thing to do in order to remove the bug you 
> introduced in v1. Well done.
> 
Most of the people suggesting to use return 0 from here instead of goto.
I will send another patch.
>>
>> -out:
>> -	if (ret && mon_wdev) {
>> -		kfree(mon_wdev);
>> -		mon_wdev = NULL;
>> -	}
>> -
>> -	if (ret && mon_ndev) {
>> -		free_netdev(mon_ndev);
>> -		*ndev = mon_ndev = NULL;
>> -	}
>> +err_register:
>> +	kfree(mon_wdev);
>> +	mon_wdev = NULL;
>>
>> +err_zmalloc:
>> +	free_netdev(mon_ndev);
>> +	*ndev = mon_ndev = NULL;
> 
> Not sure about what the Linux coding guidelines say, but I think that 
> assigning NULL to local (on stack) pointers (mon_wdev, mon_ndev) at this 
> point is unnecessary. There is no risk of reusing them after the "out" 
> labelled block, because at function exit they are destroyed when the stack is 
> unwound.
> 
> If you decide to remove these assignments, take care to leave "*ndev = NULL;" 
> as-is (why?).
> 
Yes, This is also improvement needed on this function.
> Aside from this minor objection...
> 
> Acked-by: Fabio M. De Francesco <fmdefrancesco@...il.com>
> 
> Thanks,
> 
> Fabio
> 
>> +out:
>>  	return ret;
>>  }
>>
>> --
>> 2.32.0
>>
>>
>>
> 
> 
> 
> 
Regards,
Saurav