Re: Re: [Bug 1612] Can't start VM when vif set and udev version is greater than 151

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

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On Wed, Jul 07, 2010 at 08:30:19AM +0100, Jan Beulich wrote:
> >>> On 06.07.10 at 18:46, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> wrote:
> >> For reference, below is the diff for what we're now using.
> > 
> > Ah nice.. 
> > 
> > I get this:
> > patch -p1 --dry-run < ~/p.patch 
> > patching file drivers/xen/netback/xenbus.c
> > Hunk #1 succeeded at 19 with fuzz 1.
> > Hunk #2 FAILED at 29.
> > Hunk #3 FAILED at 40.
> > patch: **** malformed patch at line 120: nv *env)
> > 
> > If it would not be too much trouble, can you attach it as an attachment?
> 
> Sure, here you go.

And attached is it redone against the pv-ops kernel. Let me poke the
folks on the BZ to see if they would be willing to test this.


diff --git a/drivers/xen/netback/xenbus.c b/drivers/xen/netback/xenbus.c
index ba7b1de..805ce48 100644
--- a/drivers/xen/netback/xenbus.c
+++ b/drivers/xen/netback/xenbus.c
@@ -19,6 +19,7 @@
 
 #include <stdarg.h>
 #include <linux/module.h>
+#include <linux/rwsem.h>
 #include <xen/xenbus.h>
 #include "common.h"
 
@@ -28,6 +29,7 @@
     printk("netback/xenbus (%s:%d) " fmt ".\n", __FUNCTION__, __LINE__, ##args)
 #endif
 
+static DECLARE_RWSEM(teardown_sem);
 
 static int connect_rings(struct backend_info *);
 static void connect(struct backend_info *);
@@ -41,14 +43,19 @@ static int netback_remove(struct xenbus_device *dev)
 	//netback_remove_accelerators(be, dev);
 
 	unregister_hotplug_status_watch(be);
-	if (be->netif) {
+	if (be->netif)
 		kobject_uevent(&dev->dev.kobj, KOBJ_OFFLINE);
+
+	down_write(&teardown_sem);
+	if (be->netif) {
 		xenbus_rm(XBT_NIL, dev->nodename, "hotplug-status");
 		netif_disconnect(be->netif);
 		be->netif = NULL;
 	}
-	kfree(be);
 	dev_set_drvdata(&dev->dev, NULL);
+	up_write(&teardown_sem);
+	kfree(be);
+
 	return 0;
 }
 
@@ -168,7 +175,7 @@ static int netback_uevent(struct xenbus_device *xdev, struct kobj_uevent_env *en
 
 	DPRINTK("netback_uevent");
 
-	be = dev_get_drvdata(&xdev->dev);
+	be = dev_get_drvdata(&xdev->dev);/
 	if (!be)
 		return 0;
 	netif = be->netif;
@@ -187,9 +194,14 @@ static int netback_uevent(struct xenbus_device *xdev, struct kobj_uevent_env *en
 		kfree(val);
 	}
 
-	if (add_uevent_var(env, "vif=%s", netif->dev->name))
-		return -ENOMEM;
-
+	down_read(&teardown_sem);
+	be = dev_get_drvdata(&xdev->dev);
+	if (be && be->netif)
+		if (add_uevent_var(env, "vif=%s", netif->dev->name)) {
+			up_read(&teardown_sem);
+			return -ENOMEM;
+		}
+	up_read(&teardown_sem);
 	return 0;
 }
 
@@ -199,6 +211,7 @@ static void backend_create_netif(struct backend_info *be)
 	int err;
 	long handle;
 	struct xenbus_device *dev = be->dev;
+	netif_t *netif;
 
 	if (be->netif != NULL)
 		return;
@@ -209,13 +222,13 @@ static void backend_create_netif(struct backend_info *be)
 		return;
 	}
 
-	be->netif = netif_alloc(&dev->dev, dev->otherend_id, handle);
-	if (IS_ERR(be->netif)) {
-		err = PTR_ERR(be->netif);
-		be->netif = NULL;
+	netif = netif_alloc(&dev->dev, dev->otherend_id, handle);
+	if (IS_ERR(netif)) {
+		err = PTR_ERR(netif);
 		xenbus_dev_fatal(dev, err, "creating interface");
 		return;
 	}
+	be->netif = netif;
 
 	kobject_uevent(&dev->dev.kobj, KOBJ_ONLINE);
 }

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diff --git a/drivers/xen/netback/xenbus.c b/drivers/xen/netback/xenbus.c
index ba7b1de..805ce48 100644
--- a/drivers/xen/netback/xenbus.c
+++ b/drivers/xen/netback/xenbus.c
@@ -19,6 +19,7 @@
 
 #include <stdarg.h>
 #include <linux/module.h>
+#include <linux/rwsem.h>
 #include <xen/xenbus.h>
 #include "common.h"
 
@@ -28,6 +29,7 @@
     printk("netback/xenbus (%s:%d) " fmt ".\n", __FUNCTION__, __LINE__, ##args)
 #endif
 
+static DECLARE_RWSEM(teardown_sem);
 
 static int connect_rings(struct backend_info *);
 static void connect(struct backend_info *);
@@ -41,14 +43,19 @@ static int netback_remove(struct xenbus_device *dev)
 	//netback_remove_accelerators(be, dev);
 
 	unregister_hotplug_status_watch(be);
-	if (be->netif) {
+	if (be->netif)
 		kobject_uevent(&dev->dev.kobj, KOBJ_OFFLINE);
+
+	down_write(&teardown_sem);
+	if (be->netif) {
 		xenbus_rm(XBT_NIL, dev->nodename, "hotplug-status");
 		netif_disconnect(be->netif);
 		be->netif = NULL;
 	}
-	kfree(be);
 	dev_set_drvdata(&dev->dev, NULL);
+	up_write(&teardown_sem);
+	kfree(be);
+
 	return 0;
 }
 
@@ -168,7 +175,7 @@ static int netback_uevent(struct xenbus_device *xdev, struct kobj_uevent_env *en
 
 	DPRINTK("netback_uevent");
 
-	be = dev_get_drvdata(&xdev->dev);
+	be = dev_get_drvdata(&xdev->dev);/
 	if (!be)
 		return 0;
 	netif = be->netif;
@@ -187,9 +194,14 @@ static int netback_uevent(struct xenbus_device *xdev, struct kobj_uevent_env *en
 		kfree(val);
 	}
 
-	if (add_uevent_var(env, "vif=%s", netif->dev->name))
-		return -ENOMEM;
-
+	down_read(&teardown_sem);
+	be = dev_get_drvdata(&xdev->dev);
+	if (be && be->netif)
+		if (add_uevent_var(env, "vif=%s", netif->dev->name)) {
+			up_read(&teardown_sem);
+			return -ENOMEM;
+		}
+	up_read(&teardown_sem);
 	return 0;
 }
 
@@ -199,6 +211,7 @@ static void backend_create_netif(struct backend_info *be)
 	int err;
 	long handle;
 	struct xenbus_device *dev = be->dev;
+	netif_t *netif;
 
 	if (be->netif != NULL)
 		return;
@@ -209,13 +222,13 @@ static void backend_create_netif(struct backend_info *be)
 		return;
 	}
 
-	be->netif = netif_alloc(&dev->dev, dev->otherend_id, handle);
-	if (IS_ERR(be->netif)) {
-		err = PTR_ERR(be->netif);
-		be->netif = NULL;
+	netif = netif_alloc(&dev->dev, dev->otherend_id, handle);
+	if (IS_ERR(netif)) {
+		err = PTR_ERR(netif);
 		xenbus_dev_fatal(dev, err, "creating interface");
 		return;
 	}
+	be->netif = netif;
 
 	kobject_uevent(&dev->dev.kobj, KOBJ_ONLINE);
 }

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