Add more debugging for spurious xennet disconnect

Author: marmarek

0001-DEBUG.patch

@@ -0,0 +1,54 @@
+From db8c3370d9813a664b096a66e86601b1ffb9236e Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Marek=20Marczykowski-G=C3=B3recki?=
+ <[email protected]>
+Date: Mon, 27 Oct 2025 19:42:00 +0100
+Subject: [PATCH 2/2] DEBUG
+
+---
+ drivers/net/xen-netfront.c         | 2 ++
+ drivers/xen/xenbus/xenbus_client.c | 9 +++++++++
+ 2 files changed, 11 insertions(+)
+
+diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
+index a11a0e9494005..e6a2d72764fce 100644
+--- a/drivers/net/xen-netfront.c
++++ b/drivers/net/xen-netfront.c
+@@ -1817,6 +1817,7 @@ static void xennet_disconnect_backend(struct netfront_info *info)
+ 	unsigned int i = 0;
+ 	unsigned int num_queues = info->netdev->real_num_tx_queues;
+ 
++	printk(KERN_CRIT "xennet_disconnect_backend info %p\n", info);
+ 	netif_carrier_off(info->netdev);
+ 
+ 	for (i = 0; i < num_queues && info->queues; ++i) {
+@@ -2659,6 +2660,7 @@ static void xennet_remove(struct xenbus_device *dev)
+ {
+ 	struct netfront_info *info = dev_get_drvdata(&dev->dev);
+ 
++	printk(KERN_CRIT "xennet_remove %p\n", dev);
+ 	xennet_bus_close(dev);
+ 	xennet_disconnect_backend(info);
+ 
+diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c
+index ce2f49d9aa4ad..ac7fe6b1433fd 100644
+--- a/drivers/xen/xenbus/xenbus_client.c
++++ b/drivers/xen/xenbus/xenbus_client.c
+@@ -275,6 +275,15 @@ __xenbus_switch_state(struct xenbus_device *dev,
+  */
+ int xenbus_switch_state(struct xenbus_device *dev, enum xenbus_state state)
+ {
++	if (WARN(state == XenbusStateClosed || state == XenbusStateClosing,
++	     "switching %s (%p) to state %d, otherend: %s, vanished: %d\n",
++	  	   dev->nodename, dev, state, dev->otherend, dev->vanished)) {
++		char *otherend = NULL;
++		int err = xenbus_gather(XBT_NIL, dev->nodename, "backend", "%s", &otherend, NULL);
++		printk(KERN_CRIT "xs (%d): backend: %s\n", err, otherend);
++		if (otherend)
++			kfree(otherend);
++	}
+ 	if (dev->vanished)
+ 		return 0;
+ 	return __xenbus_switch_state(dev, state, 0);
+-- 
+2.51.0
+

kernel.spec.in

@@ -146,6 +146,7 @@ Patch30: 0004-pvops-respect-removable-xenstore-flag-for-block-devi.patch
 Patch31: 0001-PCI-add-a-reset-quirk-for-Intel-I219LM-ethernet-adap.patch
 Patch32: 0001-Revert-e1000e-change-k1-configuration-on-MTP-and-lat.patch
 Patch33: 0001-xen-xenbus-better-handle-backend-crash.patch
+Patch34: 0001-DEBUG.patch
 
 # S0ix support:
 Patch61: xen-events-Add-wakeup-support-to-xen-pirq.patch