linux-kernel - Re: [PATCH net-next 07/15] net: dsa: mt7530: do not run mt7530_setup

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Message-ID: <48b664fb-edf9-4170-abde-2eb99e04f0e5@suswa.mountain>
Date: Tue, 2 Jan 2024 14:16:45 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Arınç ÜNAL <arinc.unal@...nc9.com>
Cc: Vladimir Oltean <olteanv@...il.com>, Simon Horman <horms@...nel.org>,
	Daniel Golle <daniel@...rotopia.org>,
	Landen Chao <Landen.Chao@...iatek.com>,
	DENG Qingfang <dqfext@...il.com>,
	Sean Wang <sean.wang@...iatek.com>, Andrew Lunn <andrew@...n.ch>,
	Florian Fainelli <f.fainelli@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Matthias Brugger <matthias.bgg@...il.com>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	Russell King <linux@...linux.org.uk>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-mediatek@...ts.infradead.org,
	Frank Wunderlich <frank-w@...lic-files.de>,
	Bartel Eerdekens <bartel.eerdekens@...stell8.be>,
	mithat.guner@...ont.com, erkin.bozoglu@...ont.com
Subject: Re: [PATCH net-next 07/15] net: dsa: mt7530: do not run
 mt7530_setup_port5() if port 5 is disabled

On Sun, Dec 17, 2023 at 03:22:27PM +0300, Arınç ÜNAL wrote:
> On 8.12.2023 21:46, Vladimir Oltean wrote:
> > Hmm, maybe the problem, all along, was that we let the -ENODEV return
> > code from of_get_phy_mode() pass through? "interface" will really be
> > uninitialized in that case. It's not a false positive.
> > 
> > Instead of:
> > 
> > 	ret = of_get_phy_mode(mac_np, &interface);
> > 	if (ret && ret != -ENODEV) {
> > 		...
> > 		return ret;
> > 	}
> > 
> > it should have been like this, to not complain:
> > 
> > 	ret = of_get_phy_mode(mac_np, &interface);
> > 	if (ret) {
> > 		...
> > 		return ret;
> > 	}
> > 
> 
> I just tried this, smatch still reports "interface" as uninitialised.
> 
> $ export ARCH=mips CROSS_COMPILE=mips-linux-gnu-
> $ ../smatch/smatch_scripts/kchecker --spammy drivers/net/dsa/mt7530.c
> 
>   UPD     include/config/kernel.release
>   UPD     include/generated/utsrelease.h
>   CHECK   scripts/mod/empty.c
>   CALL    scripts/checksyscalls.sh
>   CC      drivers/net/dsa/mt7530.o
>   CHECK   drivers/net/dsa/mt7530.c
> drivers/net/dsa/mt7530.c:217 mt7530_mii_read() warn: call of 'warn_slowpath_fmt' with non-constant format argument
> drivers/net/dsa/mt7530.c:454 mt7530_setup_port6() error: uninitialized symbol 'ncpo1'.
> drivers/net/dsa/mt7530.c:868 mt7530_set_ageing_time() error: uninitialized symbol 'age_count'.
> drivers/net/dsa/mt7530.c:868 mt7530_set_ageing_time() error: uninitialized symbol 'age_unit'.
> drivers/net/dsa/mt7530.c:2324 mt7530_setup() error: uninitialized symbol 'interface'.

That's so strange.

Vladimir was right that I was misreading what he said and also hadn't
noticed the break.

For me, his approach silences the warning with or without the cross
function DB.  Also of_get_phy_mode() initializes interface on all paths
so checking for -EINVAL doesn't matter as far as this warning is
concerned.

regards,
dan carpenter