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From: "Toke Høiland-Jørgensen" <toke@redhat.com>
To: Maciej Fijalkowski <maciej.fijalkowski@intel.com>,
	bpf@vger.kernel.org, netdev@vger.kernel.org,
	daniel@iogearbox.net, ast@kernel.org, andrii@kernel.org
Cc: bjorn.topel@intel.com, magnus.karlsson@intel.com,
	ciara.loftus@intel.com, john.fastabend@gmail.com,
	Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Subject: Re: [PATCH v5 bpf-next 06/17] libbpf: xsk: use bpf_link
Date: Wed, 31 Mar 2021 15:10:14 +0200	[thread overview]
Message-ID: <87o8ezpiyx.fsf@toke.dk> (raw)
In-Reply-To: <20210329224316.17793-7-maciej.fijalkowski@intel.com>

Maciej Fijalkowski <maciej.fijalkowski@intel.com> writes:

> Currently, if there are multiple xdpsock instances running on a single
> interface and in case one of the instances is terminated, the rest of
> them are left in an inoperable state due to the fact of unloaded XDP
> prog from interface.
>
> Consider the scenario below:
>
> // load xdp prog and xskmap and add entry to xskmap at idx 10
> $ sudo ./xdpsock -i ens801f0 -t -q 10
>
> // add entry to xskmap at idx 11
> $ sudo ./xdpsock -i ens801f0 -t -q 11
>
> terminate one of the processes and another one is unable to work due to
> the fact that the XDP prog was unloaded from interface.
>
> To address that, step away from setting bpf prog in favour of bpf_link.
> This means that refcounting of BPF resources will be done automatically
> by bpf_link itself.
>
> Provide backward compatibility by checking if underlying system is
> bpf_link capable. Do this by looking up/creating bpf_link on loopback
> device. If it failed in any way, stick with netlink-based XDP prog.
> therwise, use bpf_link-based logic.
>
> When setting up BPF resources during xsk socket creation, check whether
> bpf_link for a given ifindex already exists via set of calls to
> bpf_link_get_next_id -> bpf_link_get_fd_by_id -> bpf_obj_get_info_by_fd
> and comparing the ifindexes from bpf_link and xsk socket.
>
> For case where resources exist but they are not AF_XDP related, bail out
> and ask user to remove existing prog and then retry.
>
> Lastly, do a bit of refactoring within __xsk_setup_xdp_prog and pull out
> existing code branches based on prog_id value onto separate functions
> that are responsible for resource initialization if prog_id was 0 and
> for lookup existing resources for non-zero prog_id as that implies that
> XDP program is present on the underlying net device. This in turn makes
> it easier to follow, especially the teardown part of both branches.
>
> Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>

Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>


  reply	other threads:[~2021-03-31 13:11 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-29 22:42 [PATCH v5 bpf-next 00/17] AF_XDP selftests improvements & bpf_link Maciej Fijalkowski
2021-03-29 22:43 ` [PATCH v5 bpf-next 01/17] selftests: xsk: don't call worker_pkt_dump() for stats test Maciej Fijalkowski
2021-03-29 22:43 ` [PATCH v5 bpf-next 02/17] selftests: xsk: remove struct ifaceconfigobj Maciej Fijalkowski
2021-03-29 22:43 ` [PATCH v5 bpf-next 03/17] selftests: xsk: remove unused function Maciej Fijalkowski
2021-03-29 22:43 ` [PATCH v5 bpf-next 04/17] selftests: xsk: remove inline keyword from source file Maciej Fijalkowski
2021-03-29 22:43 ` [PATCH v5 bpf-next 05/17] selftests: xsk: simplify frame traversal in dumping thread Maciej Fijalkowski
2021-03-29 22:43 ` [PATCH v5 bpf-next 06/17] libbpf: xsk: use bpf_link Maciej Fijalkowski
2021-03-31 13:10   ` Toke Høiland-Jørgensen [this message]
2021-03-29 22:43 ` [PATCH v5 bpf-next 07/17] samples: bpf: do not unload prog within xdpsock Maciej Fijalkowski
2021-03-29 22:43 ` [PATCH v5 bpf-next 08/17] selftests: xsk: remove thread for netns switch Maciej Fijalkowski
2021-03-29 22:43 ` [PATCH v5 bpf-next 09/17] selftests: xsk: split worker thread Maciej Fijalkowski
2021-03-29 22:43 ` [PATCH v5 bpf-next 10/17] selftests: xsk: remove Tx synchronization resources Maciej Fijalkowski
2021-03-29 22:43 ` [PATCH v5 bpf-next 11/17] selftests: xsk: refactor teardown/bidi test cases and testapp_validate Maciej Fijalkowski
2021-03-29 22:43 ` [PATCH v5 bpf-next 12/17] selftests: xsk: remove sync_mutex_tx and atomic var Maciej Fijalkowski
2021-03-29 22:43 ` [PATCH v5 bpf-next 13/17] veth: implement ethtool's get_channels() callback Maciej Fijalkowski
2021-03-29 22:43 ` [PATCH v5 bpf-next 14/17] selftests: xsk: implement bpf_link test Maciej Fijalkowski
2021-03-29 22:43 ` [PATCH v5 bpf-next 15/17] selftests: xsk: remove thread attribute Maciej Fijalkowski
2021-03-29 22:43 ` [PATCH v5 bpf-next 16/17] selftests: xsk: Remove mutex and condition variable Maciej Fijalkowski
2021-03-29 22:43 ` [PATCH v5 bpf-next 17/17] selftests: xsk: Remove unused defines Maciej Fijalkowski
2021-03-30 16:34 ` [PATCH v5 bpf-next 00/17] AF_XDP selftests improvements & bpf_link Alexei Starovoitov

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