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H A D | virtio-net.c | diff df8d07081718c29d04d106583d9c300128686cda Thu Oct 20 04:58:45 CDT 2022 Laurent Vivier <lvivier@redhat.com> virtio-net: fix bottom-half packet TX on asynchronous completion
When virtio-net is used with the socket netdev backend, the backend can be busy and not able to collect new packets.
In this case, net_socket_receive() returns 0 and registers a poll function to detect when the socket is ready again.
In virtio_net_tx_bh(), virtio_net_flush_tx() forwards the 0, the virtio notifications are disabled and the function is not re-scheduled, waiting for the backend to be ready.
When the socket netdev backend is again able to send packets, the poll function re-starts to flush remaining packets. This is done by calling virtio_net_tx_complete(). It re-enables notifications and calls again virtio_net_flush_tx().
But it seems if virtio_net_flush_tx() reaches the tx_burst value all the queue is not flushed and no new notification is sent to re-schedule virtio_net_tx_bh(). Nothing re-start to flush the queue and remaining packets are stuck in the queue.
To fix that, detect in virtio_net_tx_complete() if virtio_net_flush_tx() has been stopped by tx_burst and if yes re-schedule the bottom half function virtio_net_tx_bh() to flush the remaining packets.
This is what is done in virtio_net_tx_bh() when the virtio_net_flush_tx() is synchronous, and completly by-passed when the operation needs to be asynchronous.
Fixes: a697a334b3c4 ("virtio-net: Introduce a new bottom half packet TX") Cc: alex.williamson@redhat.com Signed-off-by: Laurent Vivier <lvivier@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
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