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In-Reply-To: <04558c43-6b7d-4076-a6eb-d60222a292fc@openvpn.net> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 09/05/2024 16:36, Antonio Quartulli wrote: > On 09/05/2024 16:17, Sabrina Dubroca wrote: >> 2024-05-09, 15:44:26 +0200, Antonio Quartulli wrote: >>> On 09/05/2024 15:04, Sabrina Dubroca wrote: >>>>>>> +void ovpn_peer_release(struct ovpn_peer *peer) >>>>>>> +{ >>>>>>> +    call_rcu(&peer->rcu, ovpn_peer_release_rcu); >>>>>>> +} >>>>>>> + >>>>>>> +/** >>>>>>> + * ovpn_peer_delete_work - work scheduled to release peer in >>>>>>> process context >>>>>>> + * @work: the work object >>>>>>> + */ >>>>>>> +static void ovpn_peer_delete_work(struct work_struct *work) >>>>>>> +{ >>>>>>> +    struct ovpn_peer *peer = container_of(work, struct ovpn_peer, >>>>>>> +                          delete_work); >>>>>>> +    ovpn_peer_release(peer); >>>>>> >>>>>> Does call_rcu really need to run in process context? >>>>> >>>>> Reason for switching to process context is that we have to invoke >>>>> ovpn_nl_notify_del_peer (that sends a netlink event to userspace) >>>>> and the >>>>> latter requires a reference to the peer. >>>> >>>> I'm confused. When you say "requires a reference to the peer", do you >>>> mean accessing fields of the peer object? I don't see why this >>>> requires ovpn_nl_notify_del_peer to to run from process context. >>> >>> ovpn_nl_notify_del_peer sends a netlink message to userspace and I >>> was under >>> the impression that it may block/sleep, no? >>> For this reason I assumed it must be executed in process context. >> >> With s/GFP_KERNEL/GFP_ATOMIC/, it should be ok to run from whatever >> context. Firing up a workqueue just to send a 100B netlink message >> seems a bit overkill. > > Oh ok, I thought the send could be a problem too. > > Will test with GFP_ATOMIC then. Thanks for the hint. I am back and unfortunately we also have (added by a later patch): 294 napi_disable(&peer->napi); 295 netif_napi_del(&peer->napi); that need to be executed in process context. So it seems I must fire up the worker anyway.. -- Antonio Quartulli OpenVPN Inc.