linux-kernel - Re: [PATCH 2/2] staging: r8188eu: convert rtw_set_802_11_add

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Message-ID: <20220801070059.GA3460@kadam>
Date:   Mon, 1 Aug 2022 10:00:59 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Phillip Potter <phil@...lpotter.co.uk>
Cc:     gregkh@...uxfoundation.org, Larry.Finger@...inger.net,
        paskripkin@...il.com, martin@...ser.cx, straube.linux@...il.com,
        fmdefrancesco@...il.com, abdun.nihaal@...il.com,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] staging: r8188eu: convert rtw_set_802_11_add_wep
 error code semantics

On Sat, Jul 30, 2022 at 07:36:57PM +0100, Phillip Potter wrote:
> On Fri, Jul 29, 2022 at 09:48:03AM +0300, Dan Carpenter wrote:
> > On Fri, Jul 29, 2022 at 12:11:50AM +0100, Phillip Potter wrote:
> > > -u8 rtw_set_802_11_add_wep(struct adapter *padapter, struct ndis_802_11_wep *wep)
> > > +int rtw_set_802_11_add_wep(struct adapter *padapter, struct ndis_802_11_wep *wep)
> > >  {
> > >  	int		keyid, res;
> > >  	struct security_priv *psecuritypriv = &padapter->securitypriv;
> > > -	u8		ret = _SUCCESS;
> > > +	int		ret = 0;
> > >  
> > >  	keyid = wep->KeyIndex & 0x3fffffff;
> > >  
> > >  	if (keyid >= 4) {
> > > -		ret = false;
> > > +		ret = -EOPNOTSUPP;
> > >  		goto exit;
> > >  	}
> > >  
> > > @@ -424,7 +424,7 @@ u8 rtw_set_802_11_add_wep(struct adapter *padapter, struct ndis_802_11_wep *wep)
> > >  	res = rtw_set_key(padapter, psecuritypriv, keyid, 1);
> > >  
> > >  	if (res == _FAIL)
> > > -		ret = false;
> > > +		ret = -ENOMEM;
> > >  exit:
> > >  
> > >  	return ret;
> > 
> > No, this isn't right.  This now returns 1 on success and negative
> > error codes on error.
> > 
> > There are a couple anti-patterns here:
> > 
> > 1) Do nothing gotos
> > 2) Mixing error paths and success paths.
> > 
> > If you avoid mixing error paths and success paths then you get a pattern
> > called: "Solid return zero."  This is where the end of the function has
> > a very chunky "return 0;" to mark that it is successful.  You want that.
> > Some people do a "if (ret == 0) return ret;".  Nope.  "return ret;" is
> > not chunky.
> > 
> > regards,
> > dan carpenter
> > 
> 
> Hi Dan,
> 
> Thank you for the review firstly, much appreciated.
> 
> I'm happy of course to rewrite this to address any concerns, but
> I was hoping I could clarify what you've said though? Apologies if I've
> missed it, but how is this function now returning 1 on success? It sets
> ret to 0 (success) at the start and then sets it to one of two negative
> error codes depending on what happens. Am I missing something here?
> (Perfectly possible that I am).

You're right.  I misread "res" as "ret".  It's another anti-pattern to
have two "ret" variables.  The code is fine but so ugly for no reason.

regards,
dan carpenter