xen-netfront: recreate queues correctly when reconnecting
When reconnecting to the backend (after a resume/migration, for example), a different number of queues may be required (since the guest may have moved to a different host with different capabilities). During the reconnection the old queues are torn down and new ones created. Introduce xennet_create_queues() and xennet_destroy_queues() that fixes three bugs during the reconnection. - The old info->queues was leaked. - The old queue's napi instances were not deleted. - The new queue's napi instances were left disabled (which meant no packets could be received). The xennet_destroy_queues() calls is deferred until the reconnection instead of the disconnection (in xennet_disconnect_backend()) because napi_disable() might sleep. Signed-off-by: David Vrabel <david.vrabel@citrix.com> Reviewed-by: Wei Liu <wei.liu2@citrix.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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765418694b
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ce58725fec
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@ -1699,8 +1699,6 @@ static int xennet_init_queue(struct netfront_queue *queue)
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goto exit_free_tx;
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}
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netif_napi_add(queue->info->netdev, &queue->napi, xennet_poll, 64);
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return 0;
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exit_free_tx:
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@ -1791,6 +1789,70 @@ error:
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return err;
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}
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static void xennet_destroy_queues(struct netfront_info *info)
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{
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unsigned int i;
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rtnl_lock();
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for (i = 0; i < info->netdev->real_num_tx_queues; i++) {
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struct netfront_queue *queue = &info->queues[i];
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if (netif_running(info->netdev))
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napi_disable(&queue->napi);
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netif_napi_del(&queue->napi);
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}
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rtnl_unlock();
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kfree(info->queues);
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info->queues = NULL;
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}
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static int xennet_create_queues(struct netfront_info *info,
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unsigned int num_queues)
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{
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unsigned int i;
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int ret;
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info->queues = kcalloc(num_queues, sizeof(struct netfront_queue),
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GFP_KERNEL);
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if (!info->queues)
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return -ENOMEM;
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rtnl_lock();
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for (i = 0; i < num_queues; i++) {
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struct netfront_queue *queue = &info->queues[i];
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queue->id = i;
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queue->info = info;
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ret = xennet_init_queue(queue);
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if (ret < 0) {
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dev_warn(&info->netdev->dev, "only created %d queues\n",
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num_queues);
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num_queues = i;
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break;
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}
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netif_napi_add(queue->info->netdev, &queue->napi,
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xennet_poll, 64);
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if (netif_running(info->netdev))
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napi_enable(&queue->napi);
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}
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netif_set_real_num_tx_queues(info->netdev, num_queues);
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rtnl_unlock();
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if (num_queues == 0) {
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dev_err(&info->netdev->dev, "no queues\n");
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return -EINVAL;
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}
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return 0;
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}
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/* Common code used when first setting up, and when resuming. */
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static int talk_to_netback(struct xenbus_device *dev,
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struct netfront_info *info)
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@ -1827,42 +1889,20 @@ static int talk_to_netback(struct xenbus_device *dev,
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goto out;
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}
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/* Allocate array of queues */
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info->queues = kcalloc(num_queues, sizeof(struct netfront_queue), GFP_KERNEL);
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if (!info->queues) {
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err = -ENOMEM;
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goto out;
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}
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rtnl_lock();
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netif_set_real_num_tx_queues(info->netdev, num_queues);
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rtnl_unlock();
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if (info->queues)
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xennet_destroy_queues(info);
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err = xennet_create_queues(info, num_queues);
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if (err < 0)
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goto destroy_ring;
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/* Create shared ring, alloc event channel -- for each queue */
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for (i = 0; i < num_queues; ++i) {
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queue = &info->queues[i];
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queue->id = i;
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queue->info = info;
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err = xennet_init_queue(queue);
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if (err) {
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/* xennet_init_queue() cleans up after itself on failure,
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* but we still have to clean up any previously initialised
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* queues. If i > 0, set num_queues to i, then goto
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* destroy_ring, which calls xennet_disconnect_backend()
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* to tidy up.
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*/
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if (i > 0) {
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rtnl_lock();
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netif_set_real_num_tx_queues(info->netdev, i);
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rtnl_unlock();
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goto destroy_ring;
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} else {
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goto out;
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}
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}
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err = setup_netfront(dev, queue, feature_split_evtchn);
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if (err) {
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/* As for xennet_init_queue(), setup_netfront() will tidy
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* up the current queue on error, but we need to clean up
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/* setup_netfront() will tidy up the current
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* queue on error, but we need to clean up
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* those already allocated.
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*/
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if (i > 0) {
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