[ovs-dev] [PATCH v2] netdev-dpdk: Fix flow control not configuring.

[Tomasz Konieczny]

Currently OVS is unable to change flow control configuration in DPDK
because new settings are being overwritten by current settings with
rte_eth_dev_flow_ctrl_get(). The fix restores correct order of
operations and at the same time does not trigger error on devices
without flow control support when flow control not requested.

Fixes: 7e1de65e8dfb ("netdev-dpdk: Fix failure to configure flow control at netdev-init.")
Signed-off-by: Tomasz Konieczny <tomaszx.konieczny at intel.com>
Co-authored-by: Ilya Maximets <i.maximets at samsung.com>
Signed-off-by: Ilya Maximets <i.maximets at samsung.com>
---
Version history: [PATCH v1] netdev-dpdk: Fix flow control configuration.
---
 lib/netdev-dpdk.c | 34 +++++++++++++++++++++++++++-------
 1 file changed, 27 insertions(+), 7 deletions(-)

diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
index bc20d68..942bb86 100644
--- a/lib/netdev-dpdk.c
+++ b/lib/netdev-dpdk.c
@@ -1770,7 +1770,7 @@ netdev_dpdk_set_config(struct netdev *netdev, const struct smap *args,
                        char **errp)
 {
     struct netdev_dpdk *dev = netdev_dpdk_cast(netdev);
-    bool rx_fc_en, tx_fc_en, autoneg, lsc_interrupt_mode;
+    bool rx_fc_en, tx_fc_en, autoneg, lsc_interrupt_mode, flow_control_requested;
     enum rte_eth_fc_mode fc_mode;
     static const enum rte_eth_fc_mode fc_mode_set[2][2] = {
         {RTE_FC_NONE,     RTE_FC_TX_PAUSE},
@@ -1858,15 +1858,35 @@ netdev_dpdk_set_config(struct netdev *netdev, const struct smap *args,
     autoneg = smap_get_bool(args, "flow-ctrl-autoneg", false);
 
     fc_mode = fc_mode_set[tx_fc_en][rx_fc_en];
+
+    flow_control_requested = true;
+    if (!smap_get(args, "rx-flow-ctrl") && !smap_get(args, "tx-flow-ctrl")
+        && !smap_get(args, "flow-ctrl-autoneg")) {
+        /* FIXME: User didn't ask for flow control configuration.
+         *        For now we'll not print a warning if flow control is not
+         *        supported by the DPDK port. */
+        flow_control_requested = false;
+    }
+
+    /* Get the Flow control configuration. */
+    err = rte_eth_dev_flow_ctrl_get(dev->port_id, &dev->fc_conf);
+    if (err) {
+        if (err == -ENOTSUP) {
+            if (flow_control_requested) {
+                VLOG_WARN("%s: Flow control is not supported.",
+                    netdev_get_name(netdev));
+            }
+            err = 0; /* Not fatal. */
+        } else {
+            VLOG_WARN("%s: Cannot get flow control parameters: %s",
+                      netdev_get_name(netdev), rte_strerror(-err));
+        }
+        goto out;
+    }
+
     if (dev->fc_conf.mode != fc_mode || autoneg != dev->fc_conf.autoneg) {
         dev->fc_conf.mode = fc_mode;
         dev->fc_conf.autoneg = autoneg;
-        /* Get the Flow control configuration for DPDK-ETH */
-        err = rte_eth_dev_flow_ctrl_get(dev->port_id, &dev->fc_conf);
-        if (err) {
-            VLOG_WARN("Cannot get flow control parameters on port "
-                DPDK_PORT_ID_FMT", err=%d", dev->port_id, err);
-        }
         dpdk_eth_flow_ctrl_setup(dev);
     }
 
-- 
2.7.4