diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index 8c394e30e5fe..f3f7b41116f7 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -713,10 +713,9 @@ static void __init xen_reserve_xen_mfnlist(void)
 		size = PFN_PHYS(xen_start_info->nr_p2m_frames);
 	}
 
-	if (!xen_is_e820_reserved(start, size)) {
-		memblock_reserve(start, size);
+	memblock_reserve(start, size);
+	if (!xen_is_e820_reserved(start, size))
 		return;
-	}
 
 #ifdef CONFIG_X86_32
 	/*
@@ -727,6 +726,7 @@ static void __init xen_reserve_xen_mfnlist(void)
 	BUG();
 #else
 	xen_relocate_p2m();
+	memblock_free(start, size);
 #endif
 }
 
diff --git a/drivers/xen/arm-device.c b/drivers/xen/arm-device.c
index 778acf80aacb..85dd20e05726 100644
--- a/drivers/xen/arm-device.c
+++ b/drivers/xen/arm-device.c
@@ -58,9 +58,13 @@ static int xen_map_device_mmio(const struct resource *resources,
 	xen_pfn_t *gpfns;
 	xen_ulong_t *idxs;
 	int *errs;
-	struct xen_add_to_physmap_range xatp;
 
 	for (i = 0; i < count; i++) {
+		struct xen_add_to_physmap_range xatp = {
+			.domid = DOMID_SELF,
+			.space = XENMAPSPACE_dev_mmio
+		};
+
 		r = &resources[i];
 		nr = DIV_ROUND_UP(resource_size(r), XEN_PAGE_SIZE);
 		if ((resource_type(r) != IORESOURCE_MEM) || (nr == 0))
@@ -87,9 +91,7 @@ static int xen_map_device_mmio(const struct resource *resources,
 			idxs[j] = XEN_PFN_DOWN(r->start) + j;
 		}
 
-		xatp.domid = DOMID_SELF;
 		xatp.size = nr;
-		xatp.space = XENMAPSPACE_dev_mmio;
 
 		set_xen_guest_handle(xatp.gpfns, gpfns);
 		set_xen_guest_handle(xatp.idxs, idxs);
diff --git a/drivers/xen/events/events_fifo.c b/drivers/xen/events/events_fifo.c
index c03f9c86c7e3..3c41470c7fc4 100644
--- a/drivers/xen/events/events_fifo.c
+++ b/drivers/xen/events/events_fifo.c
@@ -369,8 +369,7 @@ static void evtchn_fifo_resume(void)
 		}
 
 		ret = init_control_block(cpu, control_block);
-		if (ret < 0)
-			BUG();
+		BUG_ON(ret < 0);
 	}
 
 	/*
diff --git a/drivers/xen/evtchn.c b/drivers/xen/evtchn.c
index e8c7f09d01be..6890897a6f30 100644
--- a/drivers/xen/evtchn.c
+++ b/drivers/xen/evtchn.c
@@ -125,7 +125,7 @@ static int add_evtchn(struct per_user_data *u, struct user_evtchn *evtchn)
 	while (*new) {
 		struct user_evtchn *this;
 
-		this = container_of(*new, struct user_evtchn, node);
+		this = rb_entry(*new, struct user_evtchn, node);
 
 		parent = *new;
 		if (this->port < evtchn->port)
@@ -157,7 +157,7 @@ static struct user_evtchn *find_evtchn(struct per_user_data *u, unsigned port)
 	while (node) {
 		struct user_evtchn *evtchn;
 
-		evtchn = container_of(node, struct user_evtchn, node);
+		evtchn = rb_entry(node, struct user_evtchn, node);
 
 		if (evtchn->port < port)
 			node = node->rb_left;
diff --git a/drivers/xen/xenbus/xenbus_comms.h b/drivers/xen/xenbus/xenbus_comms.h
index e74f9c1fbd80..867a2e425208 100644
--- a/drivers/xen/xenbus/xenbus_comms.h
+++ b/drivers/xen/xenbus/xenbus_comms.h
@@ -42,7 +42,6 @@ int xb_write(const void *data, unsigned len);
 int xb_read(void *data, unsigned len);
 int xb_data_to_read(void);
 int xb_wait_for_data_to_read(void);
-int xs_input_avail(void);
 extern struct xenstore_domain_interface *xen_store_interface;
 extern int xen_store_evtchn;
 extern enum xenstore_init xen_store_domain_type;
diff --git a/drivers/xen/xenbus/xenbus_dev_frontend.c b/drivers/xen/xenbus/xenbus_dev_frontend.c
index 6c0ead4be784..79130b310247 100644
--- a/drivers/xen/xenbus/xenbus_dev_frontend.c
+++ b/drivers/xen/xenbus/xenbus_dev_frontend.c
@@ -302,6 +302,29 @@ static void watch_fired(struct xenbus_watch *watch,
 	mutex_unlock(&adap->dev_data->reply_mutex);
 }
 
+static int xenbus_command_reply(struct xenbus_file_priv *u,
+				unsigned int msg_type, const char *reply)
+{
+	struct {
+		struct xsd_sockmsg hdr;
+		const char body[16];
+	} msg;
+	int rc;
+
+	msg.hdr = u->u.msg;
+	msg.hdr.type = msg_type;
+	msg.hdr.len = strlen(reply) + 1;
+	if (msg.hdr.len > sizeof(msg.body))
+		return -E2BIG;
+
+	mutex_lock(&u->reply_mutex);
+	rc = queue_reply(&u->read_buffers, &msg, sizeof(msg.hdr) + msg.hdr.len);
+	wake_up(&u->read_waitq);
+	mutex_unlock(&u->reply_mutex);
+
+	return rc;
+}
+
 static int xenbus_write_transaction(unsigned msg_type,
 				    struct xenbus_file_priv *u)
 {
@@ -316,12 +339,12 @@ static int xenbus_write_transaction(unsigned msg_type,
 			rc = -ENOMEM;
 			goto out;
 		}
-	} else if (msg_type == XS_TRANSACTION_END) {
+	} else if (u->u.msg.tx_id != 0) {
 		list_for_each_entry(trans, &u->transactions, list)
 			if (trans->handle.id == u->u.msg.tx_id)
 				break;
 		if (&trans->list == &u->transactions)
-			return -ESRCH;
+			return xenbus_command_reply(u, XS_ERROR, "ENOENT");
 	}
 
 	reply = xenbus_dev_request_and_reply(&u->u.msg);
@@ -372,12 +395,12 @@ static int xenbus_write_watch(unsigned msg_type, struct xenbus_file_priv *u)
 	path = u->u.buffer + sizeof(u->u.msg);
 	token = memchr(path, 0, u->u.msg.len);
 	if (token == NULL) {
-		rc = -EILSEQ;
+		rc = xenbus_command_reply(u, XS_ERROR, "EINVAL");
 		goto out;
 	}
 	token++;
 	if (memchr(token, 0, u->u.msg.len - (token - path)) == NULL) {
-		rc = -EILSEQ;
+		rc = xenbus_command_reply(u, XS_ERROR, "EINVAL");
 		goto out;
 	}
 
@@ -411,23 +434,7 @@ static int xenbus_write_watch(unsigned msg_type, struct xenbus_file_priv *u)
 	}
 
 	/* Success.  Synthesize a reply to say all is OK. */
-	{
-		struct {
-			struct xsd_sockmsg hdr;
-			char body[3];
-		} __packed reply = {
-			{
-				.type = msg_type,
-				.len = sizeof(reply.body)
-			},
-			"OK"
-		};
-
-		mutex_lock(&u->reply_mutex);
-		rc = queue_reply(&u->read_buffers, &reply, sizeof(reply));
-		wake_up(&u->read_waitq);
-		mutex_unlock(&u->reply_mutex);
-	}
+	rc = xenbus_command_reply(u, msg_type, "OK");
 
 out:
 	return rc;