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

From Joe Perches <joe@perches.com>
Newsgroups linux.kernel
Subject Re: [PATCH] net: dsa: loop: Check for memory allocation failure
Date 2017-05-08 21:50 +0200
Message-ID <tEWPo-8b6-5@gated-at.bofh.it> (permalink)
References <tE0BH-3Xk-5@gated-at.bofh.it> <tEPEe-3LB-9@gated-at.bofh.it> <tEQ7g-3UW-27@gated-at.bofh.it>
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On Mon, 2017-05-08 at 20:32 +0800, Julia Lawall wrote:
> 
> On Mon, 8 May 2017, David Laight wrote:
> 
> > From: Christophe JAILLET
> > > Sent: 06 May 2017 06:30
> > > If 'devm_kzalloc' fails, a NULL pointer will be dereferenced.
> > > Return -ENOMEM instead, as done for some other memory allocation just a
> > > few lines above.
> > 
> > ...
> > > --- a/drivers/net/dsa/dsa_loop.c
> > > +++ b/drivers/net/dsa/dsa_loop.c
> > > @@ -256,6 +256,9 @@ static int dsa_loop_drv_probe(struct mdio_device *mdiodev)
> > >  		return -ENOMEM;
> > > 
> > >  	ps = devm_kzalloc(&mdiodev->dev, sizeof(*ps), GFP_KERNEL);
> > > +	if (!ps)
> > > +		return -ENOMEM;
> > > +
> > >  	ps->netdev = dev_get_by_name(&init_net, pdata->netdev);
> > >  	if (!ps->netdev)
> > >  		return -EPROBE_DEFER;
> > 
> > On the face if it this code leaks like a sieve.
> 
> I don't think so.  The allocations (dsa_switch_alloc and devm_kzalloc) use
> devm functions.

It's at least wasteful.

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;
	}

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Thread

[PATCH] net: dsa: loop: Check for memory allocation failure Christophe JAILLET <christophe.jaillet@wanadoo.fr> - 2017-05-06 07:40 +0200
  Re: [PATCH] net: dsa: loop: Check for memory allocation failure Andrew Lunn <andrew@lunn.ch> - 2017-05-06 16:50 +0200
  Re: [PATCH] net: dsa: loop: Check for memory allocation failure Florian Fainelli <f.fainelli@gmail.com> - 2017-05-08 01:30 +0200
  RE: [PATCH] net: dsa: loop: Check for memory allocation failure David Laight <David.Laight@ACULAB.COM> - 2017-05-08 14:10 +0200
    RE: [PATCH] net: dsa: loop: Check for memory allocation failure Julia Lawall <julia.lawall@lip6.fr> - 2017-05-08 14:40 +0200
      Re: [PATCH] net: dsa: loop: Check for memory allocation failure Joe Perches <joe@perches.com> - 2017-05-08 21:50 +0200
        Re: [PATCH] net: dsa: loop: Check for memory allocation failure Julia Lawall <julia.lawall@lip6.fr> - 2017-05-09 01:50 +0200
          Re: [PATCH] net: dsa: loop: Check for memory allocation failure Florian Fainelli <f.fainelli@gmail.com> - 2017-05-09 02:40 +0200
            Re: [PATCH] net: dsa: loop: Check for memory allocation failure Julia Lawall <julia.lawall@lip6.fr> - 2017-05-09 02:50 +0200
            Re: [PATCH] net: dsa: loop: Check for memory allocation failure Joe Perches <joe@perches.com> - 2017-05-09 17:20 +0200
              Re: [PATCH] net: dsa: loop: Check for memory allocation failure Christophe JAILLET <christophe.jaillet@wanadoo.fr> - 2017-05-10 06:40 +0200
                Re: [PATCH] net: dsa: loop: Check for memory allocation failure Julia Lawall <julia.lawall@lip6.fr> - 2017-05-10 06:50 +0200
                Re: [PATCH] net: dsa: loop: Check for memory allocation failure Marion & Christophe JAILLET <christophe.jaillet@wanadoo.fr> - 2017-05-10 07:00 +0200
  Re: [PATCH] net: dsa: loop: Check for memory allocation failure David Miller <davem@davemloft.net> - 2017-05-08 21:10 +0200

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