linux-kernel - Re: [Outreachy kernel] [PATCH 3/5] staging: rtl8712: Remove unnecessary else after return

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Date:   Mon, 27 Feb 2017 22:19:51 +0100 (CET)
From:   Julia Lawall <julia.lawall@...6.fr>
To:     simran singhal <singhalsimran0@...il.com>
cc:     gregkh@...uxfoundation.org, lustre-devel@...ts.lustre.org,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        linux-fbdev@...r.kernel.org, outreachy-kernel@...glegroups.com
Subject: Re: [Outreachy kernel] [PATCH 3/5] staging: rtl8712: Remove unnecessary
 else after return



On Mon, 27 Feb 2017, simran singhal wrote:

> This patch fixes the checkpatch warning that else is not generally
> useful after a break or return.
>
> This was done using Coccinelle:
> @@
> expression e2;
> statement s1;
> @@
> if(e2) { ... return ...; }
> -else
>          s1

One might be surprised that the following code was detected using the
above semantic patch, because in the code below there is no return in the
if branches.  Actually, as a special feature, when one has an if branch
that ends in return, Coccinelle will skip through any gotos and see if the
return is matched afterward.  Indeed it is a common pattern to have

if (...) {
   foo(x);
   bar(y);
   return -ENOMEM;
}

But the code can also be cut up as eg

if (...) {
   ret = -ENOMEM;
   goto out;
}
...
out:
   foo(x);
   bar(y);
   return ret;

To avoid having to write multiple patterns for these cases, Coccinelle
will just jump through the return in the second case, allowing the same
pattern to match both of them.

julia

>
> Signed-off-by: simran singhal <singhalsimran0@...il.com>
> ---
>  drivers/staging/rtl8712/os_intfs.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/staging/rtl8712/os_intfs.c b/drivers/staging/rtl8712/os_intfs.c
> index 8836b31..3062167 100644
> --- a/drivers/staging/rtl8712/os_intfs.c
> +++ b/drivers/staging/rtl8712/os_intfs.c
> @@ -411,8 +411,7 @@ static int netdev_open(struct net_device *pnetdev)
>  			goto netdev_open_error;
>  		if (!padapter->dvobjpriv.inirp_init)
>  			goto netdev_open_error;
> -		else
> -			padapter->dvobjpriv.inirp_init(padapter);
> +		padapter->dvobjpriv.inirp_init(padapter);
>  		r8712_set_ps_mode(padapter, padapter->registrypriv.power_mgnt,
>  				  padapter->registrypriv.smart_ps);
>  	}
> --
> 2.7.4
>
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