An upcoming feature of IBM VNIC protocol is the ability to configure
redundant backing devices for a VNIC client. In case of a failure
on the current backing device, the driver will receive a signal
from the hypervisor indicating that a failover will occur. The driver
will then wait for a message from the backing device before starting
the establishing a new connection.

Signed-off-by: Thomas Falcon <tlfal...@linux.vnet.ibm.com>
---
RFC because this patch doesn't apply to the net-next tree yet.
It relies on some patches that were recently included in the net tree.
---
 drivers/net/ethernet/ibm/ibmvnic.c | 35 ++++++++++++++++++++++++++++++++---
 drivers/net/ethernet/ibm/ibmvnic.h |  2 ++
 2 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c 
b/drivers/net/ethernet/ibm/ibmvnic.c
index 88f3c85..0922298 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -203,7 +203,8 @@ static void free_long_term_buff(struct ibmvnic_adapter 
*adapter,
        struct device *dev = &adapter->vdev->dev;
 
        dma_free_coherent(dev, ltb->size, ltb->buff, ltb->addr);
-       send_request_unmap(adapter, ltb->map_id);
+       if (!adapter->failover)
+               send_request_unmap(adapter, ltb->map_id);
 }
 
 static int alloc_rx_pool(struct ibmvnic_adapter *adapter,
@@ -471,7 +472,10 @@ static int ibmvnic_open(struct net_device *netdev)
        crq.logical_link_state.link_state = IBMVNIC_LOGICAL_LNK_UP;
        ibmvnic_send_crq(adapter, &crq);
 
-       netif_tx_start_all_queues(netdev);
+       if (!adapter->failover)
+               netif_tx_start_all_queues(netdev);
+       else
+               netif_tx_wake_all_queues(netdev);
 
        return 0;
 
@@ -522,7 +526,10 @@ static int ibmvnic_close(struct net_device *netdev)
        for (i = 0; i < adapter->req_rx_queues; i++)
                napi_disable(&adapter->napi[i]);
 
-       netif_tx_stop_all_queues(netdev);
+       if (!adapter->failover)
+               netif_tx_stop_all_queues(netdev);
+       else
+               netif_tx_disable(netdev);
 
        if (adapter->bounce_buffer) {
                if (!dma_mapping_error(dev, adapter->bounce_buffer_dma)) {
@@ -3280,6 +3287,10 @@ static void ibmvnic_handle_crq(union ibmvnic_crq *crq,
                        rc = ibmvnic_send_crq_init(adapter);
                        if (rc)
                                dev_err(dev, "Error sending init rc=%ld\n", rc);
+               } else if (gen_crq->cmd == IBMVNIC_DEVICE_FAILOVER) {
+                       dev_info(dev, "Backing device failover detected\n");
+                       netif_carrier_off(netdev);
+                       adapter->failover = true;
                } else {
                        /* The adapter lost the connection */
                        dev_err(dev, "Virtual Adapter failed (rc=%d)\n",
@@ -3615,8 +3626,17 @@ static void handle_crq_init_rsp(struct work_struct *work)
        struct device *dev = &adapter->vdev->dev;
        struct net_device *netdev = adapter->netdev;
        unsigned long timeout = msecs_to_jiffies(30000);
+       bool restart = false;
        int rc;
 
+       if (adapter->failover) {
+               release_sub_crqs(adapter);
+               if (netif_running(netdev)) {
+                       ibmvnic_close(netdev);
+                       restart = true;
+               }
+       }
+
        send_version_xchg(adapter);
        reinit_completion(&adapter->init_done);
        if (!wait_for_completion_timeout(&adapter->init_done, timeout)) {
@@ -3645,6 +3665,14 @@ static void handle_crq_init_rsp(struct work_struct *work)
 
        netdev->real_num_tx_queues = adapter->req_tx_queues;
 
+       if (adapter->failover) {
+               if (restart)
+                       ibmvnic_open(netdev);
+               netif_carrier_on(netdev);
+               adapter->failover = false;
+               return;
+       }
+
        rc = register_netdev(netdev);
        if (rc) {
                dev_err(dev,
@@ -3692,6 +3720,7 @@ static int ibmvnic_probe(struct vio_dev *dev, const 
struct vio_device_id *id)
        dev_set_drvdata(&dev->dev, netdev);
        adapter->vdev = dev;
        adapter->netdev = netdev;
+       adapter->failover = false;
 
        ether_addr_copy(adapter->mac_addr, mac_addr_p);
        ether_addr_copy(netdev->dev_addr, adapter->mac_addr);
diff --git a/drivers/net/ethernet/ibm/ibmvnic.h 
b/drivers/net/ethernet/ibm/ibmvnic.h
index e82898f..bfc84c7 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.h
+++ b/drivers/net/ethernet/ibm/ibmvnic.h
@@ -830,6 +830,7 @@ enum ibmvfc_crq_format {
        IBMVNIC_CRQ_INIT                 = 0x01,
        IBMVNIC_CRQ_INIT_COMPLETE        = 0x02,
        IBMVNIC_PARTITION_MIGRATED       = 0x06,
+       IBMVNIC_DEVICE_FAILOVER          = 0x08,
 };
 
 struct ibmvnic_crq_queue {
@@ -1047,4 +1048,5 @@ struct ibmvnic_adapter {
        u8 map_id;
 
        struct work_struct vnic_crq_init;
+       bool failover;
 };
-- 
1.8.3.1

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