linux-kernel - Re: [PATCH] net: dsa: loop: Check for memory allocation failure

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Date:   Tue, 09 May 2017 08:18:27 -0700
From:   Joe Perches <joe@...ches.com>
To:     Florian Fainelli <f.fainelli@...il.com>,
        Julia Lawall <julia.lawall@...6.fr>
Cc:     David Laight <David.Laight@...LAB.COM>,
        'Christophe JAILLET' <christophe.jaillet@...adoo.fr>,
        "andrew@...n.ch" <andrew@...n.ch>,
        "vivien.didelot@...oirfairelinux.com" 
        <vivien.didelot@...oirfairelinux.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kernel-janitors@...r.kernel.org" <kernel-janitors@...r.kernel.org>
Subject: Re: [PATCH] net: dsa: loop: Check for memory allocation failure

On Mon, 2017-05-08 at 17:35 -0700, Florian Fainelli wrote:
> On 05/08/2017 04:46 PM, Julia Lawall wrote:
> > On Mon, 8 May 2017, Joe Perches wrote:
> > > Each time -EPROBE_DEFER occurs, another set of calls to
> > > dsa_switch_alloc and dev_kzalloc also occurs.
> > > 
> > > Perhaps it'd be better to do:
> > > 
> > > 	if (ps->netdev) {
> > > 		devm_kfree(&devmdev->dev, ps);
> > > 		devm_kfree(&mdiodev->dev, ds);
> > > 		return -EPROBE_DEFER;
> > > 	}
> > 
> > Is EPROBE_DEFER handled differently than other kinds of errors?
> 
> In the core device driver model, yes, EPROBE_DEFER is treated
> differently than other errors because it puts the driver on a retry queue.
> 
> EPROBE_DEFER is already a slow and exceptional path, and this is a
> mock-up driver, so I am not sure what value there is in trying to
> balance devm_kzalloc() with corresponding devm_kfree()...

Example code should be as correct as possible.