From mboxrd@z Thu Jan  1 00:00:00 1970
From: Daniel Lezcano <dlezcano-NmTC/0ZBporQT0dZR+AlfA@public.gmane.org>
Subject: Re: [PATCH 7/8] net: Allow setting the network namespace by fd
Date: Fri, 24 Sep 2010 15:46:28 +0200
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Cc: Pavel Emelyanov <xemul-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>, Ulrich Drepper <drepper-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
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        linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Jan Engelhardt <jengelh-nopoi9nDyk+ELgA04lAiVw@public.gmane.org>,
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        Michael Kerrisk <mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
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To: "Eric W. Biederman" <ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
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On 09/23/2010 10:51 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.
>
> Signed-off-by: Eric W. Biederman<ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
> ---

[ ... ]

> +struct net *get_net_ns_by_fd(int fd)
> +{
> +	struct proc_inode *ei;
> +	struct file *file;
> +	struct net *net;
> +
> +	file = NULL;
> +	net = ERR_PTR(-EINVAL);
> +	file = proc_ns_fget(fd);
> +	if (!fd)
> +		goto out;
> +		return ERR_PTR(-EINVAL);
> +
> +	ei = PROC_I(file->f_dentry->d_inode);
> +	if (ei->ns_ops !=&netns_operations)
> +		goto out;

Is this check necessary here ? proc_ns_fget checks "file->f_op != 
&ns_file_operations", no ?