linux-kernel - Re: [PATCH v2 3/3] staging: rtl8723bs: Prevent duplicate NULL tests on a value

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Message-ID: <Z-6PlWGmn09hYYKU@smile.fi.intel.com>
Date: Thu, 3 Apr 2025 16:39:33 +0300
From: Andy Shevchenko <andy@...nel.org>
To: Abraham Samuel Adekunle <abrahamadekunle50@...il.com>
Cc: outreachy@...ts.linux.dev, julia.lawall@...ia.fr,
	gregkh@...uxfoundation.org, linux-staging@...ts.linux.dev,
	linux-kernel@...r.kernel.org, hdegoede@...hat.com,
	mchehab@...nel.org, sakari.ailus@...ux.intel.com
Subject: Re: [PATCH v2 3/3] staging: rtl8723bs: Prevent duplicate NULL tests
 on a value

On Thu, Apr 03, 2025 at 02:26:43PM +0100, Abraham Samuel Adekunle wrote:
> When a value has been tested for NULL in an expression, a
> second NULL test on the same value in another expression
> is unnecessary when the value has not been assigned NULL.
> 
> Remove unnecessary duplicate NULL tests on the same value that
> has previously been NULL tested.
> 
> Found by Coccinelle

Missing period.

...

> +			psta->sta_xmitpriv.txseq_tid[pattrib->priority]++;
> +			psta->sta_xmitpriv.txseq_tid[pattrib->priority] &= 0xFFF;
> +			pattrib->seqnum = psta->sta_xmitpriv.txseq_tid[pattrib->priority];
> +
> +			SetSeqNum(hdr, pattrib->seqnum);
> +
> +			/* check if enable ampdu */
> +			if (pattrib->ht_en && psta->htpriv.ampdu_enable)
> +				if (psta->htpriv.agg_enable_bitmap & BIT(pattrib->priority))
> +					pattrib->ampdu_en = true;
> +
> +			/* re-check if enable ampdu by BA_starting_seqctrl */
> +			if (pattrib->ampdu_en == true) {
> +				u16 tx_seq;
> +
> +				tx_seq = psta->BA_starting_seqctrl[pattrib->priority & 0x0f];
> +
> +				/* check BA_starting_seqctrl */
> +				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;

While at it, make this more readable:

					psta->BA_starting_seqctrl[pattrib->priority & 0x0f] =
						(tx_seq + 1) & 0xfff;


> +					pattrib->ampdu_en = true;/* AGG EN */
> +				} else {

> +					psta->BA_starting_seqctrl[pattrib->priority & 0x0f] = (pattrib->seqnum+1)&0xfff;

Ditto.

Also consider to use module operator as it shows the exact amount of the
records we support in the circular buffer.

					psta->BA_starting_seqctrl[pattrib->priority & 0x0f] =
						(pattrib->seqnum + 1) % 4096;

Since it's power-of-two denominator, it will be optimised by the compiler to
the same code as it's now.

> +					pattrib->ampdu_en = true;/* AGG EN */
>  				}

-- 
With Best Regards,
Andy Shevchenko