4 files changed, 192 insertions, 51 deletions

diff --git a/drivers/xen/xenbus/xenbus_comms.c b/drivers/xen/xenbus/xenbus_comms.c
index 090c61ee8fd..2eff7a6aaa2 100644
--- a/drivers/xen/xenbus/xenbus_comms.c
+++ b/drivers/xen/xenbus/xenbus_comms.c
@@ -212,7 +212,9 @@ int xb_init_comms(void)
 		printk(KERN_WARNING "XENBUS response ring is not quiescent "
 		       "(%08x:%08x): fixing up\n",
 		       intf->rsp_cons, intf->rsp_prod);
-		intf->rsp_cons = intf->rsp_prod;
+		/* breaks kdump */
+		if (!reset_devices)
+			intf->rsp_cons = intf->rsp_prod;
 	}
 
 	if (xenbus_irq) {
diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index bd2f90c9ac8..cef9b0bf63d 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -684,64 +684,74 @@ static int __init xenbus_probe_initcall(void)
 
 device_initcall(xenbus_probe_initcall);
 
-static int __init xenbus_init(void)
+/* Set up event channel for xenstored which is run as a local process
+ * (this is normally used only in dom0)
+ */
+static int __init xenstored_local_init(void)
 {
 	int err = 0;
 	unsigned long page = 0;
+	struct evtchn_alloc_unbound alloc_unbound;
 
-	DPRINTK("");
+	/* Allocate Xenstore page */
+	page = get_zeroed_page(GFP_KERNEL);
+	if (!page)
+		goto out_err;
 
-	err = -ENODEV;
-	if (!xen_domain())
-		return err;
+	xen_store_mfn = xen_start_info->store_mfn =
+		pfn_to_mfn(virt_to_phys((void *)page) >>
+			   PAGE_SHIFT);
 
-	/*
-	 * Domain0 doesn't have a store_evtchn or store_mfn yet.
-	 */
-	if (xen_initial_domain()) {
-		struct evtchn_alloc_unbound alloc_unbound;
+	/* Next allocate a local port which xenstored can bind to */
+	alloc_unbound.dom        = DOMID_SELF;
+	alloc_unbound.remote_dom = DOMID_SELF;
 
-		/* Allocate Xenstore page */
-		page = get_zeroed_page(GFP_KERNEL);
-		if (!page)
-			goto out_error;
+	err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
+					  &alloc_unbound);
+	if (err == -ENOSYS)
+		goto out_err;
 
-		xen_store_mfn = xen_start_info->store_mfn =
-			pfn_to_mfn(virt_to_phys((void *)page) >>
-				   PAGE_SHIFT);
+	BUG_ON(err);
+	xen_store_evtchn = xen_start_info->store_evtchn =
+		alloc_unbound.port;
 
-		/* Next allocate a local port which xenstored can bind to */
-		alloc_unbound.dom        = DOMID_SELF;
-		alloc_unbound.remote_dom = 0;
+	return 0;
 
-		err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
-						  &alloc_unbound);
-		if (err == -ENOSYS)
-			goto out_error;
+ out_err:
+	if (page != 0)
+		free_page(page);
+	return err;
+}
 
-		BUG_ON(err);
-		xen_store_evtchn = xen_start_info->store_evtchn =
-			alloc_unbound.port;
+static int __init xenbus_init(void)
+{
+	int err = 0;
 
-		xen_store_interface = mfn_to_virt(xen_store_mfn);
+	if (!xen_domain())
+		return -ENODEV;
+
+	if (xen_hvm_domain()) {
+		uint64_t v = 0;
+		err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
+		if (err)
+			goto out_error;
+		xen_store_evtchn = (int)v;
+		err = hvm_get_parameter(HVM_PARAM_STORE_PFN, &v);
+		if (err)
+			goto out_error;
+		xen_store_mfn = (unsigned long)v;
+		xen_store_interface = ioremap(xen_store_mfn << PAGE_SHIFT, PAGE_SIZE);
 	} else {
-		if (xen_hvm_domain()) {
-			uint64_t v = 0;
-			err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
-			if (err)
-				goto out_error;
-			xen_store_evtchn = (int)v;
-			err = hvm_get_parameter(HVM_PARAM_STORE_PFN, &v);
+		xen_store_evtchn = xen_start_info->store_evtchn;
+		xen_store_mfn = xen_start_info->store_mfn;
+		if (xen_store_evtchn)
+			xenstored_ready = 1;
+		else {
+			err = xenstored_local_init();
 			if (err)
 				goto out_error;
-			xen_store_mfn = (unsigned long)v;
-			xen_store_interface = ioremap(xen_store_mfn << PAGE_SHIFT, PAGE_SIZE);
-		} else {
-			xen_store_evtchn = xen_start_info->store_evtchn;
-			xen_store_mfn = xen_start_info->store_mfn;
-			xen_store_interface = mfn_to_virt(xen_store_mfn);
-			xenstored_ready = 1;
 		}
+		xen_store_interface = mfn_to_virt(xen_store_mfn);
 	}
 
 	/* Initialize the interface to xenstore. */
@@ -760,12 +770,7 @@ static int __init xenbus_init(void)
 	proc_mkdir("xen", NULL);
 #endif
 
-	return 0;
-
-  out_error:
-	if (page != 0)
-		free_page(page);
-
+ out_error:
 	return err;
 }
 
diff --git a/drivers/xen/xenbus/xenbus_probe_frontend.c b/drivers/xen/xenbus/xenbus_probe_frontend.c
index ed2ba474a56..540587e18a9 100644
--- a/drivers/xen/xenbus/xenbus_probe_frontend.c
+++ b/drivers/xen/xenbus/xenbus_probe_frontend.c
@@ -248,10 +248,131 @@ int __xenbus_register_frontend(struct xenbus_driver *drv,
 }
 EXPORT_SYMBOL_GPL(__xenbus_register_frontend);
 
+static DECLARE_WAIT_QUEUE_HEAD(backend_state_wq);
+static int backend_state;
+
+static void xenbus_reset_backend_state_changed(struct xenbus_watch *w,
+					const char **v, unsigned int l)
+{
+	xenbus_scanf(XBT_NIL, v[XS_WATCH_PATH], "", "%i", &backend_state);
+	printk(KERN_DEBUG "XENBUS: backend %s %s\n",
+			v[XS_WATCH_PATH], xenbus_strstate(backend_state));
+	wake_up(&backend_state_wq);
+}
+
+static void xenbus_reset_wait_for_backend(char *be, int expected)
+{
+	long timeout;
+	timeout = wait_event_interruptible_timeout(backend_state_wq,
+			backend_state == expected, 5 * HZ);
+	if (timeout <= 0)
+		printk(KERN_INFO "XENBUS: backend %s timed out.\n", be);
+}
+
+/*
+ * Reset frontend if it is in Connected or Closed state.
+ * Wait for backend to catch up.
+ * State Connected happens during kdump, Closed after kexec.
+ */
+static void xenbus_reset_frontend(char *fe, char *be, int be_state)
+{
+	struct xenbus_watch be_watch;
+
+	printk(KERN_DEBUG "XENBUS: backend %s %s\n",
+			be, xenbus_strstate(be_state));
+
+	memset(&be_watch, 0, sizeof(be_watch));
+	be_watch.node = kasprintf(GFP_NOIO | __GFP_HIGH, "%s/state", be);
+	if (!be_watch.node)
+		return;
+
+	be_watch.callback = xenbus_reset_backend_state_changed;
+	backend_state = XenbusStateUnknown;
+
+	printk(KERN_INFO "XENBUS: triggering reconnect on %s\n", be);
+	register_xenbus_watch(&be_watch);
+
+	/* fall through to forward backend to state XenbusStateInitialising */
+	switch (be_state) {
+	case XenbusStateConnected:
+		xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateClosing);
+		xenbus_reset_wait_for_backend(be, XenbusStateClosing);
+
+	case XenbusStateClosing:
+		xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateClosed);
+		xenbus_reset_wait_for_backend(be, XenbusStateClosed);
+
+	case XenbusStateClosed:
+		xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateInitialising);
+		xenbus_reset_wait_for_backend(be, XenbusStateInitWait);
+	}
+
+	unregister_xenbus_watch(&be_watch);
+	printk(KERN_INFO "XENBUS: reconnect done on %s\n", be);
+	kfree(be_watch.node);
+}
+
+static void xenbus_check_frontend(char *class, char *dev)
+{
+	int be_state, fe_state, err;
+	char *backend, *frontend;
+
+	frontend = kasprintf(GFP_NOIO | __GFP_HIGH, "device/%s/%s", class, dev);
+	if (!frontend)
+		return;
+
+	err = xenbus_scanf(XBT_NIL, frontend, "state", "%i", &fe_state);
+	if (err != 1)
+		goto out;
+
+	switch (fe_state) {
+	case XenbusStateConnected:
+	case XenbusStateClosed:
+		printk(KERN_DEBUG "XENBUS: frontend %s %s\n",
+				frontend, xenbus_strstate(fe_state));
+		backend = xenbus_read(XBT_NIL, frontend, "backend", NULL);
+		if (!backend || IS_ERR(backend))
+			goto out;
+		err = xenbus_scanf(XBT_NIL, backend, "state", "%i", &be_state);
+		if (err == 1)
+			xenbus_reset_frontend(frontend, backend, be_state);
+		kfree(backend);
+		break;
+	default:
+		break;
+	}
+out:
+	kfree(frontend);
+}
+
+static void xenbus_reset_state(void)
+{
+	char **devclass, **dev;
+	int devclass_n, dev_n;
+	int i, j;
+
+	devclass = xenbus_directory(XBT_NIL, "device", "", &devclass_n);
+	if (IS_ERR(devclass))
+		return;
+
+	for (i = 0; i < devclass_n; i++) {
+		dev = xenbus_directory(XBT_NIL, "device", devclass[i], &dev_n);
+		if (IS_ERR(dev))
+			continue;
+		for (j = 0; j < dev_n; j++)
+			xenbus_check_frontend(devclass[i], dev[j]);
+		kfree(dev);
+	}
+	kfree(devclass);
+}
+
 static int frontend_probe_and_watch(struct notifier_block *notifier,
 				   unsigned long event,
 				   void *data)
 {
+	/* reset devices in Connected or Closed state */
+	if (xen_hvm_domain())
+		xenbus_reset_state();
 	/* Enumerate devices in xenstore and watch for changes. */
 	xenbus_probe_devices(&xenbus_frontend);
 	register_xenbus_watch(&fe_watch);
diff --git a/drivers/xen/xenbus/xenbus_xs.c b/drivers/xen/xenbus/xenbus_xs.c
index 5534690075a..b3b8f2f3ad1 100644
--- a/drivers/xen/xenbus/xenbus_xs.c
+++ b/drivers/xen/xenbus/xenbus_xs.c
@@ -45,6 +45,7 @@
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <xen/xenbus.h>
+#include <xen/xen.h>
 #include "xenbus_comms.h"
 
 struct xs_stored_msg {
@@ -620,6 +621,15 @@ static struct xenbus_watch *find_watch(const char *token)
 	return NULL;
 }
 
+static void xs_reset_watches(void)
+{
+	int err;
+
+	err = xs_error(xs_single(XBT_NIL, XS_RESET_WATCHES, "", NULL));
+	if (err && err != -EEXIST)
+		printk(KERN_WARNING "xs_reset_watches failed: %d\n", err);
+}
+
 /* Register callback to watch this node. */
 int register_xenbus_watch(struct xenbus_watch *watch)
 {
@@ -638,8 +648,7 @@ int register_xenbus_watch(struct xenbus_watch *watch)
 
 	err = xs_watch(watch->node, token);
 
-	/* Ignore errors due to multiple registration. */
-	if ((err != 0) && (err != -EEXIST)) {
+	if (err) {
 		spin_lock(&watches_lock);
 		list_del(&watch->list);
 		spin_unlock(&watches_lock);
@@ -897,5 +906,9 @@ int xs_init(void)
 	if (IS_ERR(task))
 		return PTR_ERR(task);
 
+	/* shutdown watches for kexec boot */
+	if (xen_hvm_domain())
+		xs_reset_watches();
+
 	return 0;
 }