Drivers: hv: vmbus: add an API vmbus_hvsock_device_unregister()

BugLink: http://bugs.launchpad.net/bugs/1541585

The hvsock driver needs this API to release all the resources related
to the channel.
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 85d9aa70)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

drivers/hv/channel_mgmt.c

@@ -310,6 +310,7 @@ void hv_process_channel_removal(struct vmbus_channel *channel, u32 relid)
 	vmbus_release_relid(relid);
 
 	BUG_ON(!channel->rescind);
+	BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));
 
 	if (channel->target_cpu != get_cpu()) {
 		put_cpu();
@@ -321,9 +322,7 @@ void hv_process_channel_removal(struct vmbus_channel *channel, u32 relid)
 	}
 
 	if (channel->primary_channel == NULL) {
-		mutex_lock(&vmbus_connection.channel_mutex);
 		list_del(&channel->listentry);
-		mutex_unlock(&vmbus_connection.channel_mutex);
 
 		primary_channel = channel;
 	} else {
@@ -367,6 +366,7 @@ static void vmbus_process_offer(struct vmbus_channel *newchannel)
 	bool fnew = true;
 	unsigned long flags;
 	u16 dev_type;
+	int ret;
 
 	/* Make sure this is a new offer */
 	mutex_lock(&vmbus_connection.channel_mutex);
@@ -449,7 +449,11 @@ static void vmbus_process_offer(struct vmbus_channel *newchannel)
 	 * binding which eventually invokes the device driver's AddDevice()
 	 * method.
 	 */
-	if (vmbus_device_register(newchannel->device_obj) != 0) {
+	mutex_lock(&vmbus_connection.channel_mutex);
+	ret = vmbus_device_register(newchannel->device_obj);
+	mutex_unlock(&vmbus_connection.channel_mutex);
+
+	if (ret != 0) {
 		pr_err("unable to add child device object (relid %d)\n",
 			newchannel->offermsg.child_relid);
 		kfree(newchannel->device_obj);
@@ -725,6 +729,8 @@ static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr)
 	struct device *dev;
 
 	rescind = (struct vmbus_channel_rescind_offer *)hdr;
+
+	mutex_lock(&vmbus_connection.channel_mutex);
 	channel = relid2channel(rescind->child_relid);
 
 	if (channel == NULL) {
@@ -733,7 +739,7 @@ static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr)
 		 * vmbus_process_offer(), we have already invoked
 		 * vmbus_release_relid() on error.
 		 */
-		return;
+		goto out;
 	}
 
 	spin_lock_irqsave(&channel->lock, flags);
@@ -743,7 +749,7 @@ static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr)
 	if (channel->device_obj) {
 		if (channel->chn_rescind_callback) {
 			channel->chn_rescind_callback(channel);
-			return;
+			goto out;
 		}
 		/*
 		 * We will have to unregister this device from the
@@ -758,8 +764,25 @@ static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr)
 		hv_process_channel_removal(channel,
 			channel->offermsg.child_relid);
 	}
+
+out:
+	mutex_unlock(&vmbus_connection.channel_mutex);
 }
 
+void vmbus_hvsock_device_unregister(struct vmbus_channel *channel)
+{
+	mutex_lock(&vmbus_connection.channel_mutex);
+
+	BUG_ON(!is_hvsock_channel(channel));
+
+	channel->rescind = true;
+	vmbus_device_unregister(channel->device_obj);
+
+	mutex_unlock(&vmbus_connection.channel_mutex);
+}
+EXPORT_SYMBOL_GPL(vmbus_hvsock_device_unregister);
+
+
 /*
  * vmbus_onoffers_delivered -
  * This is invoked when all offers have been delivered.

drivers/hv/connection.c

@@ -296,7 +296,8 @@ struct vmbus_channel *relid2channel(u32 relid)
 	struct list_head *cur, *tmp;
 	struct vmbus_channel *cur_sc;
 
-	mutex_lock(&vmbus_connection.channel_mutex);
+	BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));
+
 	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 		if (channel->offermsg.child_relid == relid) {
 			found_channel = channel;
@@ -315,7 +316,6 @@ struct vmbus_channel *relid2channel(u32 relid)
 			}
 		}
 	}
-	mutex_unlock(&vmbus_connection.channel_mutex);
 
 	return found_channel;
 }

include/linux/hyperv.h

@@ -1069,6 +1069,8 @@ int __must_check __vmbus_driver_register(struct hv_driver *hv_driver,
 					 const char *mod_name);
 void vmbus_driver_unregister(struct hv_driver *hv_driver);
 
+void vmbus_hvsock_device_unregister(struct vmbus_channel *channel);
+
 int vmbus_allocate_mmio(struct resource **new, struct hv_device *device_obj,
 			resource_size_t min, resource_size_t max,
 			resource_size_t size, resource_size_t align,