From mboxrd@z Thu Jan  1 00:00:00 1970
From: ebiederm@xmission.com (Eric W. Biederman)
Subject: Re: [PATCH 7/8] net: Allow setting the network namespace by fd
Date: Thu, 23 Sep 2010 09:16:04 -0700
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	<m1hbhgq1v1.fsf@fess.ebiederm.org> <4C9B62A1.7020606@hp.com>
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In-Reply-To: <4C9B62A1.7020606@hp.com> (Brian Haley's message of "Thu, 23 Sep
	2010 10:22:25 -0400")
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To: Brian Haley <brian.haley@hp.com>
Cc: linux-kernel@vger.kernel.org, Linux Containers <containers@lists.osdl.org>, netdev@vger.kernel.org, netfilter-devel@vger.kernel.org, linux-fsdevel@vger.kernel.org, jamal <hadi@cyberus.ca>, Daniel Lezcano <daniel.lezcano@free.fr>, Linus Torvalds <torvalds@linux-foundation.org>, Michael Kerrisk <mtk.manpages@gmail.com>, Ulrich Drepper <drepper@gmail.com>, Al Viro <viro@ZenIV.linux.org.uk>, David Miller <davem@davemloft.net>, "Serge E. Hallyn" <serge@hallyn.com>, Pavel Emelyanov <xemul@openvz.org>, Pavel Emelyanov <xemul@parallels.com>, Ben Greear <greearb@candelatech.com>, Matt Helsley <matthltc@us.ibm.com>, Jonathan Corbet <corbet@lwn.net>, Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>, Jan Engelhardt <jengelh@medozas.de>, Patrick McHardy <kaber@trash.net>
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Brian Haley <brian.haley@hp.com> writes:

> On 09/23/2010 04:51 AM, Eric W. Biederman wrote:
>> 
>> Take advantage of the new abstraction and allow network devices
>> to be placed in any network namespace that we have a fd to talk
>> about.
>> 
> ...
>> +struct net *get_net_ns_by_fd(int fd)
>> +{
>> +	struct proc_inode *ei;
>> +	struct file *file;
>> +	struct net *net;
>> +
>> +	file = NULL;
>
> No need to initialize this.
>
>> +	net = ERR_PTR(-EINVAL);
>
> or this?
>
>> +	file = proc_ns_fget(fd);
>> +	if (!fd)
>> +		goto out;
>> +		return ERR_PTR(-EINVAL);
>
> Shouldn't this be:
>
> 	if (!file)
>
> And the "goto" seems wrong, especially without a {} here.  Unless you
> meant to keep the "goto" and branch below?

I think I changed my mind half way through writing the code and never
did anything about it.  Oops.

Thanks fixed.  It is now:

struct net *get_net_ns_by_fd(int fd)
{
	struct proc_inode *ei;
	struct file *file;
	struct net *net;

	net = ERR_PTR(-EINVAL);
	file = proc_ns_fget(fd);
	if (!file)
		goto out;

	ei = PROC_I(file->f_dentry->d_inode);
	if (ei->ns_ops != &netns_operations)
		goto out;

	net = get_net(ei->ns);
out:
	if (file)
		fput(file);
	return net;
}

Which at least makes sense.  Now to test it to double check it does what
it should do.

Eric