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

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Message-ID: <50527d62-3c4e-3b61-5f17-225379c1d6c3@gmail.com>
Date:   Sat, 9 Oct 2021 23:47:00 +0530
From:   Saurav Girepunje <saurav.girepunje@...il.com>
To:     "Fabio M. De Francesco" <fmdefrancesco@...il.com>,
        gregkh@...uxfoundation.org, linux-staging@...ts.linux.dev
Cc:     saurav.girepunje@...mail.com, fabioaiuto83@...il.com,
        ross.schm.dev@...il.com, marcocesati@...il.com,
        insafonov@...il.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: rtl8723bs: os_dep: simplify the return
 statement.



On 09/10/21 10:29 pm, Fabio M. De Francesco wrote:
> On Saturday, October 9, 2021 5:39:12 PM 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>
>> ---
>>   .../staging/rtl8723bs/os_dep/ioctl_cfg80211.c | 29 ++++++++++---------
>>   1 file changed, 15 insertions(+), 14 deletions(-)
>>
>> diff --git a/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c b/drivers/
> staging/rtl8723bs/os_dep/ioctl_cfg80211.c
>> index 0868f56e2979..574fdb6adce7 100644
>> --- a/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c
>> +++ b/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c
>> @@ -2282,18 +2282,18 @@ static int rtw_cfg80211_add_monitor_if(struct
> adapter *padapter, char *name, str
>>
>>   	if (!name) {
>>   		ret = -EINVAL;
>> -		goto out;
>> +		goto err_out;
>>   	}
>>
>>   	if (pwdev_priv->pmon_ndev) {
>>   		ret = -EBUSY;
>> -		goto out;
>> +		goto err_out;
>>   	}
>>
>>   	mon_ndev = alloc_etherdev(sizeof(struct
> rtw_netdev_priv_indicator));
>>   	if (!mon_ndev) {
>>   		ret = -ENOMEM;
>> -		goto out;
>> +		goto err_out;
>>   	}
>>
>>   	mon_ndev->type = ARPHRD_IEEE80211_RADIOTAP;
>> @@ -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;
>> @@ -2322,22 +2322,23 @@ 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);
>>
>> -out:
>> -	if (ret && mon_wdev) {
>> -		kfree(mon_wdev);
>> -		mon_wdev = NULL;
>> -	}
>> +err_register:
>>
>> -	if (ret && mon_ndev) {
>> -		free_netdev(mon_ndev);
>> -		*ndev = mon_ndev = NULL;
>> -	}
>> +	kfree(mon_wdev);
>> +	mon_wdev = NULL;
>> +
>> +err_zmalloc:
>> +
>> +	free_netdev(mon_ndev);
>> +	*ndev = mon_ndev = NULL;
>> +
>> +err_out:
>>
>>   	return ret;
>>   }
>> --
>> 2.32.0
>>
> At a quick look it seems that now you unconditionally free memory and free a
> network device immediately after the last memcpy().
> 
> Why are you doing this even if no errors are returned from device and memory
> allocations (i.e., while "ret" is still equal to zero)?
> 
> Thanks,
> 
> Fabio
>   
> 
> 
> 

Thanks Fabio for review. Yes, That is missed.
I can do that in either one of the way.
Either I should check for ret before free or I should use goto out(may 
be I will rename err_out goto label to "out" only) just after the memcpy 
statement so that function will not free for no error case and return 
ret value only.

Please let me know you input on above.

Regards,
Saurav Girepunje