netdev - Re: [PATCH 4/5] net: ch9200: add missing error handling in ch9200

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Message-ID: <aAD9GsY02U4dGBJ1@gmail.com>
Date: Thu, 17 Apr 2025 14:07:38 +0100
From: Qasim Ijaz <qasdev00@...il.com>
To: Jakub Kicinski <kuba@...nel.org>
Cc: andrew+netdev@...n.ch, davem@...emloft.net, edumazet@...gle.com,
	pabeni@...hat.com, horms@...nel.org, linux-usb@...r.kernel.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	syzbot+3361c2d6f78a3e0892f9@...kaller.appspotmail.com,
	stable@...r.kernel.org
Subject: Re: [PATCH 4/5] net: ch9200: add missing error handling in
 ch9200_bind()

On Tue, Apr 15, 2025 at 08:47:08PM -0700, Jakub Kicinski wrote:
> On Sat, 12 Apr 2025 19:38:28 +0100 Qasim Ijaz wrote:
> >  	retval = usbnet_get_endpoints(dev, intf);
> > -	if (retval)
> > +	if (retval < 0)
> >  		return retval;
> 
> This change is unnecessary ? Commit message speaks of control_write(),
> this is usbnet_get_endpoints().

So this change was done mainly for consistency with the other error checks in the function. 
Essentially in my one of my previous patches (<https://lore.kernel.org/all/20250317175117.GI688833@kernel.org/>) 
I was using "if (retval)" for error handling, however after Simon's recommendation to use "if (retval < 0)" I 
changed this. In this particular function I took Simons advice but then noticed that the 
usbnet_get_endpoints() check was still using "if (retval)" so I decided to make it the same as the others. 

The behaviour is still the same regardless of it we do "if (retval < 0)" or "if (retval)" for 
checking usbnet_get_endpoints() since it returns 0 on success or negative on failure. 

So in ch9200_bind:

In the first case of "if (retval)", if the usbnet_get_endpoints() function fails 
and returns negative then we execute this branch and it returns negative, if it 
succeeds with 0 then the ch9200_bind function continues.

In the second case of "if (retval < 0)", if the usbnet_get_endpoints() function 
fails and returns negative then we execute this branch and it returns negative, 
if it succeeds with 0 then ch9200_bind function continues.

If you like I can include this in the patch description for clarity or remove it entirely.