linux-kernel - Re: [PATCH v4] staging: rtl8723bs: Use % 4096u instead of & 0xfff

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Message-ID: <CADYq+fa0nJdq2+kMkwwb-s0ePH_8qN_R5Lu6SfNpH1pUsdRksg@mail.gmail.com>
Date: Mon, 7 Apr 2025 08:51:18 +0100
From: Samuel Abraham <abrahamadekunle50@...il.com>
To: Greg KH <gregkh@...uxfoundation.org>
Cc: julia.lawall@...ia.fr, outreachy@...ts.linux.dev, 
	linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org, 
	dan.carpenter@...aro.org, andy@...nel.org, david.laight.linux@...il.com
Subject: Re: [PATCH v4] staging: rtl8723bs: Use % 4096u instead of & 0xfff

On Mon, Apr 7, 2025 at 7:55 AM Greg KH <gregkh@...uxfoundation.org> wrote:
>
> On Mon, Apr 07, 2025 at 08:36:35AM +0200, Greg KH wrote:
> > On Mon, Apr 07, 2025 at 06:30:50AM +0000, Abraham Samuel Adekunle wrote:
> > > The sequence number is constrained to a range of [0, 4095], which
> > > is a total of 4096 values. The bitmask operation using `0xfff` is
> > > used to perform this wrap-around. While this is functionally correct,
> > > it obscures the intended semantic of a 4096-based wrap.
> > >
> > > Using a modulo operation with `4096u` makes the wrap-around logic
> >
> > <snip>
> >
> > > -                           psta->sta_xmitpriv.txseq_tid[pattrib->priority] &= 0xFFF;
> > > +                           psta->sta_xmitpriv.txseq_tid[pattrib->priority] &= 4096u;
> >
> > I do not see a modulo operation here, only another & operation.

I'm sorry ...
> >
> > >                             pattrib->seqnum = psta->sta_xmitpriv.txseq_tid[pattrib->priority];
> > >
> > >                             SetSeqNum(hdr, pattrib->seqnum);
> > > @@ -963,11 +963,11 @@ s32 rtw_make_wlanhdr(struct adapter *padapter, u8 *hdr, struct pkt_attrib *pattr
> > >                                     if (SN_LESS(pattrib->seqnum, tx_seq)) {
> > >                                             pattrib->ampdu_en = false;/* AGG BK */
> > >                                     } else if (SN_EQUAL(pattrib->seqnum, tx_seq)) {
> > > -                                           psta->BA_starting_seqctrl[pattrib->priority & 0x0f] = (tx_seq+1)&0xfff;
> > > +                                           psta->BA_starting_seqctrl[pattrib->priority & 0x0f] = (tx_seq+1)&4096u;
> >
> > This also looks odd, nothing is being "AND" here, it's an address value
> > being set (and an odd one at that, but that's another issue...)
>
> Sorry, no, I was wrong, it is being & here, but not %.  My fault,
> the lack of spaces here threw me.

I want to add spaces for readability. But since the changes occurs on
the same line,
I am a bit confused about the best approach to take
Do I create a patchset, a patch for adding spaces, and a second for
changing from & to %?

Also, should be second patch be based on the file after the first
change I made, or it should be based on the original staging
tree file.

Thanks
Adekunle.