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Subject: Re: [PATCH 2/4] staging: r8188eu: reformat long computation lines
From:   Joe Perches <joe@perches.com>
To:     Deepak R Varma <drv@mailo.com>
Cc:     David Laight <David.Laight@aculab.com>,
        'Greg KH' <gregkh@linuxfoundation.org>,
        "outreachy@lists.linux.dev" <outreachy@lists.linux.dev>,
        "Larry.Finger@lwfinger.net" <Larry.Finger@lwfinger.net>,
        "phil@philpotter.co.uk" <phil@philpotter.co.uk>,
        "paskripkin@gmail.com" <paskripkin@gmail.com>,
        "linux-staging@lists.linux.dev" <linux-staging@lists.linux.dev>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "kumarpraveen@linux.microsoft.com" <kumarpraveen@linux.microsoft.com>,
        "saurabh.truth@gmail.com" <saurabh.truth@gmail.com>
Date:   Tue, 18 Oct 2022 23:38:22 -0700
In-Reply-To: <Y0+WYIVTugrs6khA@debian-BULLSEYE-live-builder-AMD64>
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On Wed, 2022-10-19 at 11:47 +0530, Deepak R Varma wrote:
> On Tue, Oct 18, 2022 at 10:43:07PM -0700, Joe Perches wrote:
> > On Tue, 2022-10-18 at 18:12 +0530, Deepak R Varma wrote:
> > > On Tue, Oct 18, 2022 at 11:21:26AM +0000, David Laight wrote:
> > > > From: Greg KH
> > > > > Sent: 17 October 2022 15:10
> > > > > 
> > > > > On Mon, Oct 17, 2022 at 06:52:50PM +0530, Deepak R Varma wrote:
> > > > > > Reformat long running computation instructions to improve code readability.
> > > > > > Address following checkpatch script complaints:
> > > > > > 	CHECK: line length of 171 exceeds 100 columns
> > > > > > 	CHECK: line length of 113 exceeds 100 columns
> > []
> > > > > > diff --git a/drivers/staging/r8188eu/core/rtw_br_ext.c b/drivers/staging/r8188eu/core/rtw_br_ext.c
> > []
> > > > > > @@ -211,8 +211,10 @@ static int __nat25_network_hash(unsigned char *network_addr)
> > > > > >  	} else if (network_addr[0] == NAT25_IPX) {
> > > > > >  		unsigned long x;
> > > > > > 
> > > > > > -		x = network_addr[1] ^ network_addr[2] ^ network_addr[3] ^ network_addr[4] ^
> > > > > network_addr[5] ^
> > > > > > -			network_addr[6] ^ network_addr[7] ^ network_addr[8] ^ network_addr[9] ^
> > > > > network_addr[10];
> > > > > > +		x = network_addr[1] ^ network_addr[2] ^ network_addr[3] ^
> > > > > 
> > > > > Why not go out to [4] here and then you are one line shorter?
> > > > 
> > > > and/or use a shorter variable name....
> > > Hi David,
> > > I have already re-submitted the patch set with 4 in line arrangement. Do you
> > > still suggest using shorter variable names?
> > 
> > Assuming this code is not performance sensitive, I suggest not just
> > molifying checkpatch but perhaps improving the code by adding a helper
> > function something like:
> > 
> > u8 xor_array_u8(u8 *x, size_t len)
> > {
> > 	size_t i;
> > 	u8 xor = x[0];
> > 
> > 	for (i = 1; i < len; i++)
> > 		xor ^= x[i];
> > 
> > 	return xor;
> > }
> > 
> > so for instance this could be:
> > 
> > 		x = xor_array_u8(&network_addr[1], 10);
> > 
> 
> Hi Joe,
> Great suggestion. Thank you.
> Is there a way to confirm that this improvement won't impact performance? Will I
> need any specific hardware / device to run tests?

I suggest reading the code to see if the uses are in some fast path.