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In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 02/03/2025 19:59, Sabrina Dubroca wrote: > 2025-02-27, 02:21:37 +0100, Antonio Quartulli wrote: >> Moreover export tcp_release_cb by means of EXPORT_SYMBOL instead of >> EXPORT_IPV6_MOD, so that other modules can use it, even if IPV6 is >> not compiled in. > > Is that really needed? You're saving tcp.sk_cb.prot, so you could just > call peer->tcp.sk_cb.prot->release_cb? (with a bit of care since it's > called after peer_put) > > [I don't know what the maintainers' preference is wrt "re-exporting" > symbols that got moved to EXPORT_IPV6_MOD] Mh yeah, I like your suggestion as I don't have to change the EXPORT and also I don't have to make assumptions on the original value of ->release_cb as I can just call it. Will follow your suggestion. Thanks! > > > [...] >> +static void ovpn_tcp_send_sock(struct ovpn_peer *peer, struct sock *sk) >> +{ >> + struct sk_buff *skb = peer->tcp.out_msg.skb; >> + >> + if (!skb) >> + return; >> + >> + if (peer->tcp.tx_in_progress) >> + return; >> + >> + peer->tcp.tx_in_progress = true; >> + >> + do { >> + int ret = skb_send_sock_locked(sk, skb, >> + peer->tcp.out_msg.offset, >> + peer->tcp.out_msg.len); >> + if (unlikely(ret < 0)) { >> + if (ret == -EAGAIN) >> + goto out; >> + >> + net_warn_ratelimited("%s: TCP error to peer %u: %d\n", >> + netdev_name(peer->ovpn->dev), >> + peer->id, ret); >> + >> + /* in case of TCP error we can't recover the VPN >> + * stream therefore we abort the connection >> + */ >> + ovpn_peer_del(peer, >> + OVPN_DEL_PEER_REASON_TRANSPORT_ERROR); > > I don't think this works: > > ovpn_peer_del -> unlock_ovpn -> ovpn_socket_release -> might_sleep > > but we can get to ovpn_tcp_send_sock in a few contexts that are not > allowed to sleep: > > ovpn_tcp_send_skb -> ovpn_tcp_send_sock_skb -> ovpn_tcp_send_sock > __sk_flush_backlog -> release_cb = ovpn_tcp_release -> ovpn_tcp_send_sock_skb > release_sock -> release_cb = ovpn_tcp_release -> ovpn_tcp_send_sock_skb > > > (I checked all other paths leading to unlock_ovpn/ovpn_socket_release, > this is the only one I could find that is not allowed to sleep. So it > would likely be easier to push this peer_del (or even just the > handling of release_list) into some other sleepable context than > trying to reshuffle all the other paths) ACK (and thanks for double checking all other paths!) I will do some magic on this peer_del() in order to make it sleep without issues. Thanks! Regards, > -- Antonio Quartulli OpenVPN Inc.