[PATCH v2 3/7] net/netvsc: retry full probe when IB device not ready during hotplug

[Long Li <longli@microsoft.com>]

When rte_eal_hotplug_add returns -ENODEV during VF hot-add, it means the
MANA IB/verbs device is not yet registered by the mana_ib kernel module.
This happens because the mana_ib auxiliary driver probes asynchronously
after the MANA net driver creates the network interface.

On Azure VMs, the gap between netdev registration and IB device
registration can be several seconds. Previously, netvsc would log the
error and give up after finding the matching MAC address.

Now, on -ENODEV, restart the full retry loop from the PCI device
existence check. This re-scans the net directory to pick up any
interface renames (e.g. eth1 -> ens1) and retries until the IB device
is ready.

The -EEXIST return (device already probed by another netvsc port on the
same PCI device) is handled silently, as hn_vf_add will find the
already-probed VF port.

Fixes: a2a23a794b3a ("net/netvsc: support VF device hot add/remove")
Cc: stable@dpdk.org
Signed-off-by: Long Li <longli@microsoft.com>
---
v2:
- Restored ERR log level for non-ENODEV/non-EEXIST failures
  from rte_eal_hotplug_add (was incorrectly lowered to NOTICE)
- Added comment explaining why ENODEV retry is safe
  (bounded by PCI sysfs disappearance)

 drivers/net/netvsc/hn_ethdev.c | 29 ++++++++++++++++++++++++-----
 1 file changed, 24 insertions(+), 5 deletions(-)

diff --git a/drivers/net/netvsc/hn_ethdev.c b/drivers/net/netvsc/hn_ethdev.c
index 1fa64cab18..130fea38ab 100644
--- a/drivers/net/netvsc/hn_ethdev.c
+++ b/drivers/net/netvsc/hn_ethdev.c
@@ -716,17 +716,36 @@ static void netvsc_hotplug_retry(void *args)
 			 * parent device, restore its args.
 			 */
 			ret = rte_eal_hotplug_add(d->bus->name, d->name, drv_str ? drv_str : "");
-			if (ret) {
-				PMD_DRV_LOG(ERR,
-					    "Failed to add PCI device %s",
+			free(drv_str);
+
+			if (ret == -ENODEV) {
+				/* IB device not ready yet (mana_ib not probed).
+				 * Restart the full retry from the PCI device
+				 * check so we re-verify the device exists and
+				 * get fresh interface names after any renames.
+				 * This retries indefinitely — the PCI sysfs
+				 * check at the top of this function ensures
+				 * we stop if the device disappears.
+				 */
+				PMD_DRV_LOG(NOTICE,
+					    "IB device not ready for %s, "
+					    "restarting probe in 1 second",
 					    d->name);
+				closedir(di);
+				rte_eal_alarm_set(NETVSC_HOTADD_RETRY_INTERVAL,
+						  netvsc_hotplug_retry,
+						  hot_ctx);
+				return;
 			}
 
-			free(drv_str);
+			if (ret && ret != -EEXIST)
+				PMD_DRV_LOG(ERR,
+					    "Failed to add PCI device %s (ret=%d)",
+					    d->name, ret);
 
 			ret = hn_vf_add(dev, hv);
 			if (ret)
-				PMD_DRV_LOG(ERR, "Failed to add VF in hotplug retry: %d", ret);
+				PMD_DRV_LOG(ERR, "Failed to add VF: %d", ret);
 			break;
 		}
 	}
-- 
2.43.0