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([2001:67c:2fbc:1:3779:22d5:a322:7c13]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-aa20df51632sm47447466b.49.2024.11.14.02.32.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 14 Nov 2024 02:32:10 -0800 (PST) Message-ID: <5ae6f624-5196-42f7-a0b8-85e2847b3fdf@openvpn.net> Date: Thu, 14 Nov 2024 11:32:36 +0100 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next v11 18/23] ovpn: implement peer add/get/dump/delete via netlink To: Sabrina Dubroca Cc: Eric Dumazet , Jakub Kicinski , Paolo Abeni , Donald Hunter , Shuah Khan , ryazanov.s.a@gmail.com, Andrew Lunn , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org References: <20241029-b4-ovpn-v11-0-de4698c73a25@openvpn.net> <20241029-b4-ovpn-v11-18-de4698c73a25@openvpn.net> <136282ad-77d9-4799-bd2d-f3c3c9df99c0@openvpn.net> Content-Language: en-US From: Antonio Quartulli Autocrypt: addr=antonio@openvpn.net; keydata= xsFNBFN3k+ABEADEvXdJZVUfqxGOKByfkExNpKzFzAwHYjhOb3MTlzSLlVKLRIHxe/Etj13I X6tcViNYiIiJxmeHAH7FUj/yAISW56lynAEt7OdkGpZf3HGXRQz1Xi0PWuUINa4QW+ipaKmv voR4b1wZQ9cZ787KLmu10VF1duHW/IewDx9GUQIzChqQVI3lSHRCo90Z/NQ75ZL/rbR3UHB+ EWLIh8Lz1cdE47VaVyX6f0yr3Itx0ZuyIWPrctlHwV5bUdA4JnyY3QvJh4yJPYh9I69HZWsj qplU2WxEfM6+OlaM9iKOUhVxjpkFXheD57EGdVkuG0YhizVF4p9MKGB42D70pfS3EiYdTaKf WzbiFUunOHLJ4hyAi75d4ugxU02DsUjw/0t0kfHtj2V0x1169Hp/NTW1jkqgPWtIsjn+dkde dG9mXk5QrvbpihgpcmNbtloSdkRZ02lsxkUzpG8U64X8WK6LuRz7BZ7p5t/WzaR/hCdOiQCG RNup2UTNDrZpWxpwadXMnJsyJcVX4BAKaWGsm5IQyXXBUdguHVa7To/JIBlhjlKackKWoBnI Ojl8VQhVLcD551iJ61w4aQH6bHxdTjz65MT2OrW/mFZbtIwWSeif6axrYpVCyERIDEKrX5AV rOmGEaUGsCd16FueoaM2Hf96BH3SI3/q2w+g058RedLOZVZtyQARAQABzSdBbnRvbmlvIFF1 YXJ0dWxsaSA8YW50b25pb0BvcGVudnBuLm5ldD7Cwa0EEwEIAFcCGwMFCwkIBwMFFQoJCAsF FgIDAQACHgECF4AFCRWQ2TIWIQTKvaEoIBfCZyGYhcdI8My2j1nRTAUCYRUquBgYaGtwczov L2tleXMub3BlbnBncC5vcmcACgkQSPDMto9Z0UzmcxAAjzLeD47We0R4A/14oDKlZxXO0mKL fCzaWFsdhQCDhZkgxoHkYRektK2cEOh4Vd+CnfDcPs/iZ1i2+Zl+va79s4fcUhRReuwi7VCg 7nHiYSNC7qZo84Wzjz3RoGYyJ6MKLRn3zqAxUtFECoS074/JX1sLG0Z3hi19MBmJ/teM84GY IbSvRwZu+VkJgIvZonFZjbwF7XyoSIiEJWQC+AKvwtEBNoVOMuH0tZsgqcgMqGs6lLn66RK4 tMV1aNeX6R+dGSiu11i+9pm7sw8tAmsfu3kQpyk4SB3AJ0jtXrQRESFa1+iemJtt+RaSE5LK 5sGLAO+oN+DlE0mRNDQowS6q/GBhPCjjbTMcMfRoWPCpHZZfKpv5iefXnZ/xVj7ugYdV2T7z r6VL2BRPNvvkgbLZgIlkWyfxRnGh683h4vTqRqTb1wka5pmyBNAv7vCgqrwfvaV1m7J9O4B5 PuRjYRelmCygQBTXFeJAVJvuh2efFknMh41R01PP2ulXAQuVYEztq3t3Ycw6+HeqjbeqTF8C DboqYeIM18HgkOqRrn3VuwnKFNdzyBmgYh/zZx/dJ3yWQi/kfhR6TawAwz6GdbQGiu5fsx5t u14WBxmzNf9tXK7hnXcI24Z1z6e5jG6U2Swtmi8sGSh6fqV4dBKmhobEoS7Xl496JN2NKuaX jeWsF2rOwE0EZmhJFwEIAOAWiIj1EYkbikxXSSP3AazkI+Y/ICzdFDmiXXrYnf/mYEzORB0K vqNRQOdLyjbLKPQwSjYEt1uqwKaD1LRLbA7FpktAShDK4yIljkxhvDI8semfQ5WE/1Jj/I/Q U+4VXhkd6UvvpyQt/LiWvyAfvExPEvhiMnsg2zkQbBQ/M4Ns7ck0zQ4BTAVzW/GqoT2z03mg p1FhxkfzHMKPQ6ImEpuY5cZTQwrBUgWif6HzCtQJL7Ipa2fFnDaIHQeiJG0RXl/g9x3YlwWG sxOFrpWWsh6GI0Mo2W2nkinEIts48+wNDBCMcMlOaMYpyAI7fT5ziDuG2CBA060ZT7qqdl6b aXUAEQEAAcLBfAQYAQgAJhYhBMq9oSggF8JnIZiFx0jwzLaPWdFMBQJmaEkXAhsMBQkB4TOA AAoJEEjwzLaPWdFMbRUP/0t5FrjF8KY6uCU4Tx029NYKDN9zJr0CVwSGsNfC8WWonKs66QE1 pd6xBVoBzu5InFRWa2ed6d6vBw2BaJHC0aMg3iwwBbEgPn4Jx89QfczFMJvFm+MNc2DLDrqN zaQSqBzQ5SvUjxh8lQ+iqAhi0MPv4e2YbXD0ROyO+ITRgQVZBVXoPm4IJGYWgmVmxP34oUQh BM7ipfCVbcOFU5OPhd9/jn1BCHzir+/i0fY2Z/aexMYHwXUMha/itvsBHGcIEYKk7PL9FEfs wlbq+vWoCtUTUc0AjDgB76AcUVxxJtxxpyvES9aFxWD7Qc+dnGJnfxVJI0zbN2b37fX138Bf 27NuKpokv0sBnNEtsD7TY4gBz4QhvRNSBli0E5bGUbkM31rh4Iz21Qk0cCwR9D/vwQVsgPvG ioRqhvFWtLsEt/xKolOmUWA/jP0p8wnQ+3jY6a/DJ+o5LnVFzFqbK3fSojKbfr3bY33iZTSj DX9A4BcohRyqhnpNYyHL36gaOnNnOc+uXFCdoQkI531hXjzIsVs2OlfRufuDrWwAv+em2uOT BnRX9nFx9kPSO42TkFK55Dr5EDeBO3v33recscuB8VVN5xvh0GV57Qre+9sJrEq7Es9W609a +M0yRJWJEjFnMa/jsGZ+QyLD5QTL6SGuZ9gKI3W1SfFZOzV7hHsxPTZ6 Organization: OpenVPN Inc. In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 13/11/2024 12:05, Sabrina Dubroca wrote: > 2024-11-12, 15:26:59 +0100, Antonio Quartulli wrote: >> On 11/11/2024 16:41, Sabrina Dubroca wrote: >>> 2024-10-29, 11:47:31 +0100, Antonio Quartulli wrote: >>>> +void ovpn_peer_hash_vpn_ip(struct ovpn_peer *peer) >>>> + __must_hold(&peer->ovpn->peers->lock) >>> >>> Changes to peer->vpn_addrs are not protected by peers->lock, so those >>> could be getting updated while we're rehashing (and taking peer->lock >>> in ovpn_nl_peer_modify as I'm suggesting above also wouldn't prevent >>> that). >>> >> >> /me screams :-D > > Sorry :) > >> Indeed peers->lock is only about protecting the lists, not the content of >> the listed objects. >> >> How about acquiring the peers->lock before calling ovpn_nl_peer_modify()? > > It seems like it would work. Maybe a bit weird to have conditional > locking (MP mode only), but ok. You already have this lock ordering > (hold peers->lock before taking peer->lock) in > ovpn_peer_keepalive_work_mp, so there should be no deadlock from doing > the same thing in the netlink code. Yeah. > > Then I would also do that in ovpn_peer_float to protect that rehash. I am not extremely comfortable with this, because it means acquiring peers->lock on every packet (right now we do so only on peer->lock) and it may defeat the advantage of the RCU locking on the hashtables. Wouldn't you agree? An alternative would be to hold peer->lock for the entire function, but this will lead to dead locks...no go either. > > It feels like peers->lock is turning into a duplicate of > ovpn->lock. ovpn->lock used for P2P mode, peers->lock used > equivalently for MP mode. You might consider merging them (but I > wouldn't see it as necessary for merging the series unless there's a > locking issue with the current proposal). I agree: ovpn->lock was introduced to protect ovpn's fields, but actually the only one e protect is peer. They are truly the same and I could therefore get rid of ovpn->peers->lock and always use ovpn->lock. Will see how invasive this is and decide whether to commit it to v12 or not. Thanks! Regards, -- Antonio Quartulli OpenVPN Inc.