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Subject: Re: [PATCH v2] ipv6: acquire write lock for addr_list in
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To:     Niels Dossche <dossche.niels@gmail.com>,
        Paolo Abeni <pabeni@redhat.com>, netdev@vger.kernel.org
Cc:     "David S. Miller" <davem@davemloft.net>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        Jakub Kicinski <kuba@kernel.org>
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On 3/19/22 7:17 AM, Niels Dossche wrote:
> I have an additional question about the locks on the addr_list actually.
> In addrconf_ifdown, there's a loop on addr_list within a write lock in idev->lock
>> list_for_each_entry_safe(ifa, tmp, &idev->addr_list, if_list)
> The loop body unlocks the idev->lock and reacquires it later. I assume because of the lock dependency on ifa->lock and the calls that acquire the mc_lock? Shouldn't that list iteration also be protected during the whole iteration?
> 


That loop needs to be improved as well. Locking in ipv6 code is a bit
hairy.