linux-kernel - Re: [PATCH] staging: r8188eu: refactor rtw_is_cckrates{only}

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Date:   Tue, 17 Aug 2021 11:36:09 -0700
From:   Joe Perches <joe@...ches.com>
To:     Greg KH <gregkh@...uxfoundation.org>,
        Michael Straube <straube.linux@...il.com>
Cc:     Larry.Finger@...inger.net, phil@...lpotter.co.uk, martin@...ser.cx,
        fmdefrancesco@...il.com, linux-staging@...ts.linux.dev,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: r8188eu: refactor
 rtw_is_cckrates{only}_included()

On Tue, 2021-08-17 at 19:57 +0200, Greg KH wrote:
> On Mon, Aug 16, 2021 at 09:31:25PM +0200, Michael Straube wrote:
> > Refactor functions rtw_is_cckrates_included() and
> > rtw_is_cckratesonly_included(). Add new helper function rtw_is_cckrate()
> > that allows to make the code more compact. Improves readability and
> > slightly reduces object file size. Change the return type to bool to
> > reflect that the functions return boolean values.
[]
> > diff --git a/drivers/staging/r8188eu/core/rtw_ieee80211.c b/drivers/staging/r8188eu/core/rtw_ieee80211.c
[]
> > +bool rtw_is_cckratesonly_included(u8 *rate)
> >  {
> > -	u32 i = 0;
> > +	u8 r;
> >  
> > 
> > -	while (rate[i] != 0) {
> > -		if  ((((rate[i]) & 0x7f) != 2) && (((rate[i]) & 0x7f) != 4) &&
> > -		     (((rate[i]) & 0x7f) != 11)  && (((rate[i]) & 0x7f) != 22))
> > +	while ((r = *rate++)) {
> 
> Ick, no.
> 
> While it might be fun to play with pointers like this, trying to
> determine the precidence issues involved with reading from, and then
> incrementing the pointer like this is crazy.
> 
> The original was obvious as to how it was walking through the array.

It's sad to believe *ptr++ is not obvious to you as it's very commonly
used in the kernel sources (over 10,000 instances).