netdev - Re: [PATCH] ixp4xx_eth: Fix an error handling path in ixp4xx_eth

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Date:   Wed, 21 Dec 2022 17:38:45 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     Michal Swiatkowski <michal.swiatkowski@...ux.intel.com>
Cc:     Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        Krzysztof Halasa <khalasa@...p.pl>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Krzysztof Hałasa <khc@...waw.pl>,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH] ixp4xx_eth: Fix an error handling path in
 ixp4xx_eth_probe()

On Wed, 21 Dec 2022 19:50:23 +0100 Michal Swiatkowski wrote:
> On Wed, Dec 21, 2022 at 08:17:52AM +0100, Christophe JAILLET wrote:
> > If an error occurs after a successful ixp4xx_mdio_register() call, it
> > should be undone by a corresponding ixp4xx_mdio_remove().  
> 
> What about error when mdio_bus is 0? It means that mdio_register can
> return no error, but sth happen and there is no need to call mdio_remove
> in this case?
> 
> I mean:
>  /* If the instance with the MDIO bus has not yet appeared,
>   * defer probing until it gets probed.
>   */
>   if (!mdio_bus)
> 	return -EPROBE_DEFER;

Indeed, I think a closer look is warranted, this code operates on
global variables, it's also not clear to me whether it's safe to always
call remove, even if has_mdio is false?

> > Add the missing call in the error handling path, as already done in the
> > remove function.
> > 
> > Fixes: 2098c18d6cf6 ("IXP4xx: Add PHYLIB support to Ethernet driver.")
> > Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> > ---
> >  drivers/net/ethernet/xscale/ixp4xx_eth.c | 8 ++++++--
> >  1 file changed, 6 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/net/ethernet/xscale/ixp4xx_eth.c b/drivers/net/ethernet/xscale/ixp4xx_eth.c
> > index 3b0c5f177447..007d68b385a5 100644
> > --- a/drivers/net/ethernet/xscale/ixp4xx_eth.c
> > +++ b/drivers/net/ethernet/xscale/ixp4xx_eth.c
> > @@ -1490,8 +1490,10 @@ static int ixp4xx_eth_probe(struct platform_device *pdev)
> >  
> >  	netif_napi_add_weight(ndev, &port->napi, eth_poll, NAPI_WEIGHT);  
> netif_napi_add_weight() doesn't need to be unrolled in case of error
> (call netif_napi_del() or something)?

free_netdev() cleans it up automatically