linux-kernel - Re: [PATCH] net: ag71xx: remove dead code path

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Message-ID: <ZuFMe-WoIIwr8E1o@pengutronix.de>
Date: Wed, 11 Sep 2024 09:53:31 +0200
From: Oleksij Rempel <o.rempel@...gutronix.de>
To: Andrew Lunn <andrew@...n.ch>
Cc: Qianqiang Liu <qianqiang.liu@....com>, chris.snook@...il.com,
	davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
	pabeni@...hat.com, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: ag71xx: remove dead code path

On Tue, Sep 10, 2024 at 05:58:22PM +0200, Andrew Lunn wrote:
> On Tue, Sep 10, 2024 at 11:22:54PM +0800, Qianqiang Liu wrote:
> > The 'err' is always zero, so the following branch can never be executed:
> > if (err) {
> > 	ndev->stats.rx_dropped++;
> > 	kfree_skb(skb);
> > }
> > Therefore, the 'if' statement can be removed.
> 
> This code was added by Oleksij Rempel <o.rempel@...gutronix.de>. It is
> good to Cc: him, he might have useful comments.

Yes, please.

> Your changed does look correct, but maybe ret was actually supposed to
> be set somewhere? Is there an actual bug hiding here somewhere?

Hm, let's see... this issue existed in the openwrt code and I didn't
spotted it by upstreaming.

The only place which may fail in this part is napi_build_skb(), we will
need to count it probably with rx_errors++.

I'm ok with this patch, it can be reworked to use rx_errors++ on
napi_build_skb() instead or this can be done in a separate patch.

If you like to keep this patch as is, here is my:
Reviewed-by: Oleksij Rempel <o.rempel@...gutronix.de>

Thank you!

Regards,
Oleksij
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