1 files changed, 63 insertions, 5 deletions

diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
index 9cbbb831778a..8e30415b0eb7 100644
--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -533,6 +533,9 @@ struct hv_dynmem_device {
 	 */
 	struct task_struct *thread;
 
+	struct mutex ha_region_mutex;
+	struct completion waiter_event;
+
 	/*
 	 * A list of hot-add regions.
 	 */
@@ -549,7 +552,59 @@ struct hv_dynmem_device {
 static struct hv_dynmem_device dm_device;
 
 static void post_status(struct hv_dynmem_device *dm);
+
 #ifdef CONFIG_MEMORY_HOTPLUG
+static void acquire_region_mutex(bool trylock)
+{
+	if (trylock) {
+		reinit_completion(&dm_device.waiter_event);
+		while (!mutex_trylock(&dm_device.ha_region_mutex))
+			wait_for_completion(&dm_device.waiter_event);
+	} else {
+		mutex_lock(&dm_device.ha_region_mutex);
+	}
+}
+
+static void release_region_mutex(bool trylock)
+{
+	if (trylock) {
+		mutex_unlock(&dm_device.ha_region_mutex);
+	} else {
+		mutex_unlock(&dm_device.ha_region_mutex);
+		complete(&dm_device.waiter_event);
+	}
+}
+
+static int hv_memory_notifier(struct notifier_block *nb, unsigned long val,
+			      void *v)
+{
+	switch (val) {
+	case MEM_GOING_ONLINE:
+		acquire_region_mutex(true);
+		break;
+
+	case MEM_ONLINE:
+	case MEM_CANCEL_ONLINE:
+		release_region_mutex(true);
+		if (dm_device.ha_waiting) {
+			dm_device.ha_waiting = false;
+			complete(&dm_device.ol_waitevent);
+		}
+		break;
+
+	case MEM_GOING_OFFLINE:
+	case MEM_OFFLINE:
+	case MEM_CANCEL_OFFLINE:
+		break;
+	}
+	return NOTIFY_OK;
+}
+
+static struct notifier_block hv_memory_nb = {
+	.notifier_call = hv_memory_notifier,
+	.priority = 0
+};
+
 
 static void hv_bring_pgs_online(unsigned long start_pfn, unsigned long size)
 {
@@ -591,6 +646,7 @@ static void hv_mem_hot_add(unsigned long start, unsigned long size,
 		init_completion(&dm_device.ol_waitevent);
 		dm_device.ha_waiting = true;
 
+		release_region_mutex(false);
 		nid = memory_add_physaddr_to_nid(PFN_PHYS(start_pfn));
 		ret = add_memory(nid, PFN_PHYS((start_pfn)),
 				(HA_CHUNK << PAGE_SHIFT));
@@ -619,6 +675,7 @@ static void hv_mem_hot_add(unsigned long start, unsigned long size,
 		 * have not been "onlined" within the allowed time.
 		 */
 		wait_for_completion_timeout(&dm_device.ol_waitevent, 5*HZ);
+		acquire_region_mutex(false);
 		post_status(&dm_device);
 	}
 
@@ -632,11 +689,6 @@ static void hv_online_page(struct page *pg)
 	unsigned long cur_start_pgp;
 	unsigned long cur_end_pgp;
 
-	if (dm_device.ha_waiting) {
-		dm_device.ha_waiting = false;
-		complete(&dm_device.ol_waitevent);
-	}
-
 	list_for_each(cur, &dm_device.ha_region_list) {
 		has = list_entry(cur, struct hv_hotadd_state, list);
 		cur_start_pgp = (unsigned long)
@@ -834,6 +886,7 @@ static void hot_add_req(struct work_struct *dummy)
 	resp.hdr.size = sizeof(struct dm_hot_add_response);
 
 #ifdef CONFIG_MEMORY_HOTPLUG
+	acquire_region_mutex(false);
 	pg_start = dm->ha_wrk.ha_page_range.finfo.start_page;
 	pfn_cnt = dm->ha_wrk.ha_page_range.finfo.page_cnt;
 
@@ -865,6 +918,7 @@ static void hot_add_req(struct work_struct *dummy)
 	if (do_hot_add)
 		resp.page_count = process_hot_add(pg_start, pfn_cnt,
 						rg_start, rg_sz);
+	release_region_mutex(false);
 #endif
 	/*
 	 * The result field of the response structure has the
@@ -1388,7 +1442,9 @@ static int balloon_probe(struct hv_device *dev,
 	dm_device.next_version = DYNMEM_PROTOCOL_VERSION_WIN7;
 	init_completion(&dm_device.host_event);
 	init_completion(&dm_device.config_event);
+	init_completion(&dm_device.waiter_event);
 	INIT_LIST_HEAD(&dm_device.ha_region_list);
+	mutex_init(&dm_device.ha_region_mutex);
 	INIT_WORK(&dm_device.balloon_wrk.wrk, balloon_up);
 	INIT_WORK(&dm_device.ha_wrk.wrk, hot_add_req);
 	dm_device.host_specified_ha_region = false;
@@ -1402,6 +1458,7 @@ static int balloon_probe(struct hv_device *dev,
 
 #ifdef CONFIG_MEMORY_HOTPLUG
 	set_online_page_callback(&hv_online_page);
+	register_memory_notifier(&hv_memory_nb);
 #endif
 
 	hv_set_drvdata(dev, &dm_device);
@@ -1520,6 +1577,7 @@ static int balloon_remove(struct hv_device *dev)
 	kfree(send_buffer);
 #ifdef CONFIG_MEMORY_HOTPLUG
 	restore_online_page_callback(&hv_online_page);
+	unregister_memory_notifier(&hv_memory_nb);
 #endif
 	list_for_each_safe(cur, tmp, &dm->ha_region_list) {
 		has = list_entry(cur, struct hv_hotadd_state, list);