From: Antonio Quartulli <antonio@openvpn.net>
To: Sabrina Dubroca <sd@queasysnail.net>
Cc: netdev@vger.kernel.org, Jakub Kicinski <kuba@kernel.org>,
Sergey Ryazanov <ryazanov.s.a@gmail.com>,
Paolo Abeni <pabeni@redhat.com>,
Eric Dumazet <edumazet@google.com>, Andrew Lunn <andrew@lunn.ch>,
Esben Haabendal <esben@geanix.com>
Subject: Re: [PATCH net-next v3 09/24] ovpn: implement basic TX path (UDP)
Date: Mon, 13 May 2024 09:37:06 +0200 [thread overview]
Message-ID: <2d707980-72d1-49d1-a9e8-f794fcc590cb@openvpn.net> (raw)
In-Reply-To: <ZkE2JmBCj-yJ3xYK@hog>
On 12/05/2024 23:35, Sabrina Dubroca wrote:
> 2024-05-06, 03:16:22 +0200, Antonio Quartulli wrote:
>> +/* send skb to connected peer, if any */
>> +static void ovpn_queue_skb(struct ovpn_struct *ovpn, struct sk_buff *skb,
>> + struct ovpn_peer *peer)
>> +{
>> + int ret;
>> +
>> + if (likely(!peer))
>> + /* retrieve peer serving the destination IP of this packet */
>> + peer = ovpn_peer_get_by_dst(ovpn, skb);
>> + if (unlikely(!peer)) {
>> + net_dbg_ratelimited("%s: no peer to send data to\n",
>> + ovpn->dev->name);
>> + goto drop;
>> + }
>> +
>> + ret = ptr_ring_produce_bh(&peer->tx_ring, skb);
>> + if (unlikely(ret < 0)) {
>> + net_err_ratelimited("%s: cannot queue packet to TX ring\n",
>> + peer->ovpn->dev->name);
>> + goto drop;
>> + }
>> +
>> + if (!queue_work(ovpn->crypto_wq, &peer->encrypt_work))
>> + ovpn_peer_put(peer);
>
> I wanted to come back to this after going through the crypto patch,
> because this felt like a strange construct when I first looked at this
> patch.
>
> Why are you using a workqueue here? Based on the kdoc for crypto_wq
> ("used to schedule crypto work that may sleep during TX/RX"), it's to
> deal with async crypto.
>
> If so, why not use the more standard way of dealing with async crypto
> in contexts that cannot sleep, ie letting the crypto core call the
> "done" callback asynchronously? You need to do all the proper refcount
> handling, but IMO it's cleaner and simpler than this workqueue and
> ptr_ring. You can see an example of that in macsec (macsec_encrypt_*
> in drivers/net/macsec.c).
Aha! You don't know how happy I was when I found the doc describing how
to convert the async code into sync-looking :-) With the detail that I
had to move to a different context, as the code may want to sleep (hence
the introduction of the workqueue).
It looks like I am little fan of WQs, while you are telling me to avoid
them if possible.
I presume that using WQs comes with a non-negligible cost, therefore if
we can just get things done without having to use them, then I should
just don't.
I think I could go back to no-workqueue encrypt/decrypt.
Do you think this may have any impact on any future multi-core
optimization? Back then I also thought that going through workers may
make improvements in this area easier. But I could just be wrong.
Regards,
--
Antonio Quartulli
OpenVPN Inc.
next prev parent reply other threads:[~2024-05-13 7:35 UTC|newest]
Thread overview: 111+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-06 1:16 [PATCH net-next v3 00/24] Introducing OpenVPN Data Channel Offload Antonio Quartulli
2024-05-06 1:16 ` [PATCH net-next v3 01/24] netlink: add NLA_POLICY_MAX_LEN macro Antonio Quartulli
2024-05-06 1:16 ` [PATCH net-next v3 02/24] net: introduce OpenVPN Data Channel Offload (ovpn) Antonio Quartulli
2024-05-06 1:16 ` [PATCH net-next v3 03/24] ovpn: add basic netlink support Antonio Quartulli
2024-05-08 0:10 ` Jakub Kicinski
2024-05-08 7:42 ` Antonio Quartulli
2024-05-08 14:42 ` Sabrina Dubroca
2024-05-08 14:51 ` Antonio Quartulli
2024-05-06 1:16 ` [PATCH net-next v3 04/24] ovpn: add basic interface creation/destruction/management routines Antonio Quartulli
2024-05-08 0:18 ` Jakub Kicinski
2024-05-08 7:53 ` Antonio Quartulli
2024-05-08 14:52 ` Sabrina Dubroca
2024-05-09 1:06 ` Jakub Kicinski
2024-05-09 8:25 ` Antonio Quartulli
2024-05-09 10:09 ` Sabrina Dubroca
2024-05-09 10:35 ` Antonio Quartulli
2024-05-09 12:16 ` Sabrina Dubroca
2024-05-09 13:25 ` Antonio Quartulli
2024-05-09 13:52 ` Sabrina Dubroca
2024-05-06 1:16 ` [PATCH net-next v3 05/24] ovpn: implement interface creation/destruction via netlink Antonio Quartulli
2024-05-08 0:21 ` Jakub Kicinski
2024-05-08 9:49 ` Antonio Quartulli
2024-05-09 1:09 ` Jakub Kicinski
2024-05-09 8:30 ` Antonio Quartulli
2024-05-06 1:16 ` [PATCH net-next v3 06/24] ovpn: keep carrier always on Antonio Quartulli
2024-05-06 1:16 ` [PATCH net-next v3 07/24] ovpn: introduce the ovpn_peer object Antonio Quartulli
2024-05-08 16:06 ` Sabrina Dubroca
2024-05-08 20:31 ` Antonio Quartulli
2024-05-09 13:04 ` Sabrina Dubroca
2024-05-09 13:24 ` Andrew Lunn
2024-05-10 18:57 ` Antonio Quartulli
2024-05-11 0:28 ` Jakub Kicinski
2024-05-09 13:44 ` Antonio Quartulli
2024-05-09 13:55 ` Andrew Lunn
2024-05-09 14:17 ` Sabrina Dubroca
2024-05-09 14:36 ` Antonio Quartulli
2024-05-09 14:53 ` Antonio Quartulli
2024-05-10 10:30 ` Sabrina Dubroca
2024-05-10 12:34 ` Antonio Quartulli
2024-05-10 14:11 ` Sabrina Dubroca
2024-05-13 10:09 ` Simon Horman
2024-05-13 10:53 ` Antonio Quartulli
2024-05-13 15:04 ` Simon Horman
2024-05-06 1:16 ` [PATCH net-next v3 08/24] ovpn: introduce the ovpn_socket object Antonio Quartulli
2024-05-08 17:10 ` Sabrina Dubroca
2024-05-08 20:38 ` Antonio Quartulli
2024-05-09 13:32 ` Sabrina Dubroca
2024-05-09 13:46 ` Antonio Quartulli
2024-05-06 1:16 ` [PATCH net-next v3 09/24] ovpn: implement basic TX path (UDP) Antonio Quartulli
2024-05-10 13:01 ` Sabrina Dubroca
2024-05-10 13:39 ` Antonio Quartulli
2024-05-12 21:35 ` Sabrina Dubroca
2024-05-13 7:37 ` Antonio Quartulli [this message]
2024-05-13 9:36 ` Sabrina Dubroca
2024-05-13 9:47 ` Antonio Quartulli
2024-05-06 1:16 ` [PATCH net-next v3 10/24] ovpn: implement basic RX " Antonio Quartulli
2024-05-10 13:45 ` Sabrina Dubroca
2024-05-10 14:41 ` Antonio Quartulli
2024-05-06 1:16 ` [PATCH net-next v3 11/24] ovpn: implement packet processing Antonio Quartulli
2024-05-12 8:46 ` Sabrina Dubroca
2024-05-13 7:14 ` Antonio Quartulli
2024-05-13 9:24 ` Sabrina Dubroca
2024-05-13 9:31 ` Antonio Quartulli
2024-05-22 14:08 ` Antonio Quartulli
2024-05-22 14:28 ` Andrew Lunn
2024-05-06 1:16 ` [PATCH net-next v3 12/24] ovpn: store tunnel and transport statistics Antonio Quartulli
2024-05-12 8:47 ` Sabrina Dubroca
2024-05-13 7:25 ` Antonio Quartulli
2024-05-13 9:19 ` Sabrina Dubroca
2024-05-13 9:33 ` Antonio Quartulli
2024-05-06 1:16 ` [PATCH net-next v3 13/24] ovpn: implement TCP transport Antonio Quartulli
2024-05-13 13:37 ` Antonio Quartulli
2024-05-13 15:34 ` Jakub Kicinski
2024-05-13 14:50 ` Sabrina Dubroca
2024-05-13 22:20 ` Antonio Quartulli
2024-05-14 8:58 ` Sabrina Dubroca
2024-05-14 22:11 ` Antonio Quartulli
2024-05-15 10:19 ` Sabrina Dubroca
2024-05-15 12:54 ` Antonio Quartulli
2024-05-15 14:55 ` Sabrina Dubroca
2024-05-15 19:44 ` Antonio Quartulli
2024-05-15 20:35 ` Sabrina Dubroca
2024-05-15 20:39 ` Antonio Quartulli
2024-05-06 1:16 ` [PATCH net-next v3 14/24] ovpn: implement multi-peer support Antonio Quartulli
2024-05-28 14:44 ` Sabrina Dubroca
2024-05-28 19:41 ` Antonio Quartulli
2024-05-29 15:16 ` Sabrina Dubroca
2024-05-29 20:15 ` Antonio Quartulli
2024-05-29 20:45 ` Sabrina Dubroca
2024-05-06 1:16 ` [PATCH net-next v3 15/24] ovpn: implement peer lookup logic Antonio Quartulli
2024-05-28 16:42 ` Sabrina Dubroca
2024-05-28 20:09 ` Antonio Quartulli
2024-05-29 16:42 ` Sabrina Dubroca
2024-05-29 20:19 ` Antonio Quartulli
2024-05-06 1:16 ` [PATCH net-next v3 16/24] ovpn: implement keepalive mechanism Antonio Quartulli
2024-05-06 1:16 ` [PATCH net-next v3 17/24] ovpn: add support for updating local UDP endpoint Antonio Quartulli
2024-05-06 1:16 ` [PATCH net-next v3 18/24] ovpn: add support for peer floating Antonio Quartulli
2024-05-06 1:16 ` [PATCH net-next v3 19/24] ovpn: implement peer add/dump/delete via netlink Antonio Quartulli
2024-05-06 1:16 ` [PATCH net-next v3 20/24] ovpn: implement key add/del/swap " Antonio Quartulli
2024-05-06 1:16 ` [PATCH net-next v3 21/24] ovpn: kill key and notify userspace in case of IV exhaustion Antonio Quartulli
2024-05-06 1:16 ` [PATCH net-next v3 22/24] ovpn: notify userspace when a peer is deleted Antonio Quartulli
2024-05-06 1:16 ` [PATCH net-next v3 23/24] ovpn: add basic ethtool support Antonio Quartulli
2024-05-06 1:16 ` [PATCH net-next v3 24/24] testing/selftest: add test tool and scripts for ovpn module Antonio Quartulli
2024-05-07 23:55 ` Jakub Kicinski
2024-05-08 9:51 ` Antonio Quartulli
2024-05-09 0:50 ` Jakub Kicinski
2024-05-09 8:40 ` Antonio Quartulli
2024-05-07 23:48 ` [PATCH net-next v3 00/24] Introducing OpenVPN Data Channel Offload Jakub Kicinski
2024-05-08 9:56 ` Antonio Quartulli
2024-05-09 0:53 ` Jakub Kicinski
2024-05-09 8:41 ` Antonio Quartulli
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