[dpdk-stable] [PATCH 20.11] net/virtio: fix interrupt unregistering for listening socket

[Ilya Maximets]

[ upstream commit 23abee9dea8b7469559389bea67af1b68e5a9b81 ]

virtio_user_dev_server_reconnect() is typically called from the
interrupt context while checking the link state:

  vhost_user_update_link_state()
  --> virtio_user_server_reconnect()

Under this conditions callback unregistering always fails.  This means
that listenfd is never unregistered and continue to trigger interrupts.
For example, if second client will try to connect to the same socket,
the server will receive interrupts infinitely because it will not
accept them while listen fd is readable and generates epoll events.

Fix that by moving reconfiguration of interrupts out of the
interrupt context to alarm handler.

'virtio_user_delayed_handler' renamed to
'virtio_user_delayed_disconnect_handler' to better reflect its
purpose.

Additionally improved error logging around interrupt management.

Fixes: bd8f50a45d0f ("net/virtio-user: support server mode")
Cc: stable at dpdk.org

Signed-off-by: Ilya Maximets <i.maximets at ovn.org>
Reviewed-by: Maxime Coquelin <maxime.coquelin at redhat.com>
---
 drivers/net/virtio/virtio_user_ethdev.c | 72 ++++++++++++++++++-------
 1 file changed, 54 insertions(+), 18 deletions(-)

diff --git a/drivers/net/virtio/virtio_user_ethdev.c b/drivers/net/virtio/virtio_user_ethdev.c
index 78998427cc..45edd2ae60 100644
--- a/drivers/net/virtio/virtio_user_ethdev.c
+++ b/drivers/net/virtio/virtio_user_ethdev.c
@@ -63,6 +63,32 @@ virtio_user_reset_queues_packed(struct rte_eth_dev *dev)
 	rte_spinlock_unlock(&hw->state_lock);
 }
 
+static void
+virtio_user_delayed_intr_reconfig_handler(void *param)
+{
+	struct virtio_hw *hw = (struct virtio_hw *)param;
+	struct rte_eth_dev *eth_dev = &rte_eth_devices[hw->port_id];
+	struct virtio_user_dev *dev = virtio_user_get_dev(hw);
+
+	PMD_DRV_LOG(DEBUG, "Unregistering intr fd: %d",
+		    eth_dev->intr_handle->fd);
+
+	if (rte_intr_callback_unregister(eth_dev->intr_handle,
+					 virtio_interrupt_handler,
+					 eth_dev) != 1)
+		PMD_DRV_LOG(ERR, "interrupt unregister failed");
+
+	eth_dev->intr_handle->fd = dev->vhostfd;
+
+	PMD_DRV_LOG(DEBUG, "Registering intr fd: %d", eth_dev->intr_handle->fd);
+
+	if (rte_intr_callback_register(eth_dev->intr_handle,
+				       virtio_interrupt_handler, eth_dev))
+		PMD_DRV_LOG(ERR, "interrupt register failed");
+
+	if (rte_intr_enable(eth_dev->intr_handle) < 0)
+		PMD_DRV_LOG(ERR, "interrupt enable failed");
+}
 
 static int
 virtio_user_server_reconnect(struct virtio_user_dev *dev)
@@ -148,24 +174,21 @@ virtio_user_server_reconnect(struct virtio_user_dev *dev)
 			PMD_DRV_LOG(ERR, "interrupt disable failed");
 			return -1;
 		}
-		rte_intr_callback_unregister(eth_dev->intr_handle,
-					     virtio_interrupt_handler,
-					     eth_dev);
-		eth_dev->intr_handle->fd = connectfd;
-		rte_intr_callback_register(eth_dev->intr_handle,
-					   virtio_interrupt_handler, eth_dev);
-
-		if (rte_intr_enable(eth_dev->intr_handle) < 0) {
-			PMD_DRV_LOG(ERR, "interrupt enable failed");
-			return -1;
-		}
+		/*
+		 * This function can be called from the interrupt handler, so
+		 * we can't unregister interrupt handler here.  Setting
+		 * alarm to do that later.
+		 */
+		rte_eal_alarm_set(1,
+			virtio_user_delayed_intr_reconfig_handler,
+			(void *)hw);
 	}
 	PMD_INIT_LOG(NOTICE, "server mode virtio-user reconnection succeeds!");
 	return 0;
 }
 
 static void
-virtio_user_delayed_handler(void *param)
+virtio_user_delayed_disconnect_handler(void *param)
 {
 	struct virtio_hw *hw = (struct virtio_hw *)param;
 	struct rte_eth_dev *eth_dev = &rte_eth_devices[hw->port_id];
@@ -175,8 +198,14 @@ virtio_user_delayed_handler(void *param)
 		PMD_DRV_LOG(ERR, "interrupt disable failed");
 		return;
 	}
-	rte_intr_callback_unregister(eth_dev->intr_handle,
-				     virtio_interrupt_handler, eth_dev);
+
+	PMD_DRV_LOG(DEBUG, "Unregistering intr fd: %d",
+		    eth_dev->intr_handle->fd);
+	if (rte_intr_callback_unregister(eth_dev->intr_handle,
+					 virtio_interrupt_handler,
+					 eth_dev) != 1)
+		PMD_DRV_LOG(ERR, "interrupt unregister failed");
+
 	if (dev->is_server) {
 		if (dev->vhostfd >= 0) {
 			close(dev->vhostfd);
@@ -188,8 +217,15 @@ virtio_user_delayed_handler(void *param)
 				~(1ULL << VHOST_USER_PROTOCOL_F_STATUS);
 		}
 		eth_dev->intr_handle->fd = dev->listenfd;
-		rte_intr_callback_register(eth_dev->intr_handle,
-					   virtio_interrupt_handler, eth_dev);
+
+		PMD_DRV_LOG(DEBUG, "Registering intr fd: %d",
+			    eth_dev->intr_handle->fd);
+
+		if (rte_intr_callback_register(eth_dev->intr_handle,
+					       virtio_interrupt_handler,
+					       eth_dev))
+			PMD_DRV_LOG(ERR, "interrupt register failed");
+
 		if (rte_intr_enable(eth_dev->intr_handle) < 0) {
 			PMD_DRV_LOG(ERR, "interrupt enable failed");
 			return;
@@ -235,8 +271,8 @@ virtio_user_read_dev_config(struct virtio_hw *hw, size_t offset,
 				 * unregistered here, set an alarm to do it.
 				 */
 				rte_eal_alarm_set(1,
-						  virtio_user_delayed_handler,
-						  (void *)hw);
+					virtio_user_delayed_disconnect_handler,
+					(void *)hw);
 			} else {
 				dev->net_status |= VIRTIO_NET_S_LINK_UP;
 			}
-- 
2.26.3