virtio_net: Fix recursive call to cpus_read_lock()
[ Upstream commit5.4-rM2-2.2.x-imx-squashedde33212f76
] virtnet_set_channels can recursively call cpus_read_lock if CONFIG_XPS and CONFIG_HOTPLUG are enabled. The path is: virtnet_set_channels - calls get_online_cpus(), which is a trivial wrapper around cpus_read_lock() netif_set_real_num_tx_queues netif_reset_xps_queues_gt netif_reset_xps_queues - calls cpus_read_lock() This call chain and potential deadlock happens when the number of TX queues is reduced. This commit the removes netif_set_real_num_[tr]x_queues calls from inside the get/put_online_cpus section, as they don't require that it be held. Fixes:47be24796c
("virtio-net: fix the set affinity bug when CPU IDs are not consecutive") Signed-off-by: Jeff Dike <jdike@akamai.com> Acked-by: Jason Wang <jasowang@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Link: https://lore.kernel.org/r/20201223025421.671-1-jdike@akamai.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
parent
5404192a87
commit
dffef999e4
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@ -2072,14 +2072,16 @@ static int virtnet_set_channels(struct net_device *dev,
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get_online_cpus();
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get_online_cpus();
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err = _virtnet_set_queues(vi, queue_pairs);
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err = _virtnet_set_queues(vi, queue_pairs);
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if (!err) {
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if (err) {
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netif_set_real_num_tx_queues(dev, queue_pairs);
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put_online_cpus();
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netif_set_real_num_rx_queues(dev, queue_pairs);
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goto err;
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virtnet_set_affinity(vi);
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}
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}
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virtnet_set_affinity(vi);
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put_online_cpus();
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put_online_cpus();
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netif_set_real_num_tx_queues(dev, queue_pairs);
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netif_set_real_num_rx_queues(dev, queue_pairs);
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err:
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return err;
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return err;
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}
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}
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