netdev - Re: [PATCH] ipv6: release idev lock before calling ipv6_ifa

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Date:	Fri, 29 Jan 2016 17:43:03 -0800 (PST)
From:	David Miller <davem@...emloft.net>
To:	gregory.herrero@...el.com
Cc:	netdev@...r.kernel.org, kuznet@....inr.ac.ru, jmorris@...ei.org,
	yoshfuji@...ux-ipv6.org, kaber@...sh.net,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ipv6: release idev lock before calling
 ipv6_ifa_notify()

From: Gregory Herrero <gregory.herrero@...el.com>
Date: Thu, 28 Jan 2016 09:34:52 +0100

> @@ -2302,8 +2302,11 @@ static void manage_tempaddrs(struct inet6_dev *idev,
>  			ift->flags &= ~IFA_F_DEPRECATED;
>  
>  		spin_unlock(&ift->lock);
> -		if (!(flags&IFA_F_TENTATIVE))
> +		if (!(flags & IFA_F_TENTATIVE)) {
> +			read_unlock_bh(&idev->lock);
>  			ipv6_ifa_notify(0, ift);
> +			read_lock_bh(&idev->lock);
> +		}
>  	}
>  
>  	if ((create || list_empty(&idev->tempaddr_list)) &&

You can't do this, the idev->lock has to be held to keep the list we
are iterating over from changing.