From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thomas Graf <tgraf@suug.ch>
Subject: Re: [PATCH net-next 5/6] netns: use a spin_lock to protect nsid
 management
Date: Wed, 6 May 2015 14:23:14 +0200
Message-ID: <20150506122314.GJ25248@pox.localdomain>
References: <1430906288-5108-1-git-send-email-nicolas.dichtel@6wind.com>
 <1430906288-5108-6-git-send-email-nicolas.dichtel@6wind.com>
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To: Nicolas Dichtel <nicolas.dichtel@6wind.com>
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On 05/06/15 at 11:58am, Nicolas Dichtel wrote:
> +/* Should be called with nsid_lock held. If a new id is assigned, the bool alloc
> + * is set to true, thus the caller knows that the new id must be notified via
> + * rtnl.
> + */
>  static int __peernet2id(struct net *net, struct net *peer, bool *alloc)
>  {
>  	int id = idr_for_each(&net->netns_ids, net_eq_idr, peer);
>  	bool alloc_it = *alloc;
>  
> -	ASSERT_RTNL();
> -
>  	*alloc = false;
>  
>  	/* Magic value for id 0. */

If split into __peernet2id() and __peernet2id_alloc() then this could
live with RCU protection I guess so we only take the lock when we
actually allocate.