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

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Date:   Sun, 10 Oct 2021 09:24:58 +0200
From:   "Fabio M. De Francesco" <fmdefrancesco@...il.com>
To:     gregkh@...uxfoundation.org, saurav.girepunje@...il.com,
        Saurav Girepunje <saurav.girepunje@...il.com>
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 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.

> 
> -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?).

Aside from this minor objection...

Acked-by: Fabio M. De Francesco <fmdefrancesco@...il.com>

Thanks,

Fabio

> +out:
>  	return ret;
>  }
> 
> --
> 2.32.0
> 
> 
>