On Fri, Feb 4, 2022 at 9:43 PM Gaetan Rivet <[email protected]> wrote:
> Port flush and offload uninit should be moved after the datapath
> has been reconfigured. That way, no other thread such as PMDs will
> find this port to poll and enqueue further offload requests.
>
> After a flush, almost no further offload request for this port should
> be found in the queue.
>
> There will still be some issued by revalidators, but they
> will be catched when the offload thread fails to take a netdev ref.
>
catched --> caught
>
> This change fixes the issue of datapath reference being improperly
> accessed by offload threads while it is being destroyed.
>
> Fixes: 5b0aa55776cb ("dpif-netdev: Execute flush from offload thread.")
> Fixes: 62d1c28e9ce0 ("dpif-netdev: Flush offload rules upon port
> deletion.")
> Signed-off-by: Ilya Maximets <[email protected]>
> Signed-off-by: Gaetan Rivet <[email protected]>
> ---
> lib/dpif-netdev.c | 13 +++++++++++--
> 1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
> index e28e0b554..b5702e6a1 100644
> --- a/lib/dpif-netdev.c
> +++ b/lib/dpif-netdev.c
> @@ -2313,13 +2313,22 @@ static void
> do_del_port(struct dp_netdev *dp, struct dp_netdev_port *port)
> OVS_REQ_WRLOCK(dp->port_rwlock)
> {
> - dp_netdev_offload_flush(dp, port);
> - netdev_uninit_flow_api(port->netdev);
> hmap_remove(&dp->ports, &port->node);
> seq_change(dp->port_seq);
>
> reconfigure_datapath(dp);
>
> + /* Flush and disable offloads only after 'port' has been made
> + * inaccessible through datapath reconfiguration.
> + * This prevents having PMDs enqueuing offload requests after
> + * the flush.
> + * When only this port is deleted instead of the whole datapath,
> + * revalidator threads are still active and can still enqueue
> + * offload modification or deletion. Managing those stray requests
> + * is done in the offload threads. */
> + dp_netdev_offload_flush(dp, port);
> + netdev_uninit_flow_api(port->netdev);
> +
> port_destroy(port);
> }
>
> --
> 2.31.1
>
Acked-by: Sriharsha Basavapatna <[email protected]>
Thanks,
-Harsha
>
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>
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