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Commit 34c6801e authored by Dexuan Cui's avatar Dexuan Cui Committed by Greg Kroah-Hartman
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Drivers: hv: vmbus: fix rescind-offer handling for device without a driver 



In the path vmbus_onoffer_rescind() -> vmbus_device_unregister()  ->
device_unregister() -> ... -> __device_release_driver(), we can see for a
device without a driver loaded: dev->driver is NULL, so
dev->bus->remove(dev), namely vmbus_remove(), isn't invoked.

As a result, vmbus_remove() -> hv_process_channel_removal() isn't invoked
and some cleanups(like sending a CHANNELMSG_RELID_RELEASED message to the
host) aren't done.

We can demo the issue this way:
1. rmmod hv_utils;
2. disable the Heartbeat Integration Service in Hyper-V Manager and lsvmbus
shows the device disappears.
3. re-enable the Heartbeat in Hyper-V Manager and modprobe hv_utils, but
lsvmbus shows the device can't appear again.
This is because, the host thinks the VM hasn't released the relid, so can't
re-offer the device to the VM.

We can fix the issue by moving hv_process_channel_removal()
from vmbus_close_internal() to vmbus_device_release(), since the latter is
always invoked on device_unregister(), whether or not the dev has a driver
loaded.

Signed-off-by: default avatarDexuan Cui <decui@microsoft.com>
Signed-off-by: default avatarK. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 64b7faf9

drivers/hv/channel.c

+0 −6
Original line number Original line Diff line number Diff line
@@ -575,12 +575,6 @@ static int vmbus_close_internal(struct vmbus_channel *channel) 
	free_pages((unsigned long)channel->ringbuffer_pages,

	free_pages((unsigned long)channel->ringbuffer_pages,

		get_order(channel->ringbuffer_pagecount * PAGE_SIZE));

		get_order(channel->ringbuffer_pagecount * PAGE_SIZE));





	/*

	 * If the channel has been rescinded; process device removal.

	 */

	if (channel->rescind)

		hv_process_channel_removal(channel,

					   channel->offermsg.child_relid);

out:

out:

	tasklet_enable(tasklet);

	tasklet_enable(tasklet);

drivers/hv/channel_mgmt.c

+3 −3
Original line number Original line Diff line number Diff line
@@ -191,6 +191,8 @@ void hv_process_channel_removal(struct vmbus_channel *channel, u32 relid) 
	if (channel == NULL)

	if (channel == NULL)

		return;

		return;





	BUG_ON(!channel->rescind);



	if (channel->target_cpu != get_cpu()) {

	if (channel->target_cpu != get_cpu()) {

		put_cpu();

		put_cpu();

		smp_call_function_single(channel->target_cpu,

		smp_call_function_single(channel->target_cpu,
@@ -230,9 +232,7 @@ void vmbus_free_channels(void) 




	list_for_each_entry_safe(channel, tmp, &vmbus_connection.chn_list,

	list_for_each_entry_safe(channel, tmp, &vmbus_connection.chn_list,

		listentry) {

		listentry) {

		/* if we don't set rescind to true, vmbus_close_internal()

		/* hv_process_channel_removal() needs this */

		 * won't invoke hv_process_channel_removal().

		 */

		channel->rescind = true;

		channel->rescind = true;





		vmbus_device_unregister(channel->device_obj);

		vmbus_device_unregister(channel->device_obj);

drivers/hv/vmbus_drv.c

+3 −12
Original line number Original line Diff line number Diff line
@@ -601,23 +601,11 @@ static int vmbus_remove(struct device *child_device) 
{

{

	struct hv_driver *drv;

	struct hv_driver *drv;

	struct hv_device *dev = device_to_hv_device(child_device);

	struct hv_device *dev = device_to_hv_device(child_device);

	u32 relid = dev->channel->offermsg.child_relid;





	if (child_device->driver) {

	if (child_device->driver) {

		drv = drv_to_hv_drv(child_device->driver);

		drv = drv_to_hv_drv(child_device->driver);

		if (drv->remove)

		if (drv->remove)

			drv->remove(dev);

			drv->remove(dev);

		else {

			hv_process_channel_removal(dev->channel, relid);

			pr_err("remove not set for driver %s\n",

				dev_name(child_device));

		}

	} else {

		/*

		 * We don't have a driver for this device; deal with the

		 * rescind message by removing the channel.

		 */

		hv_process_channel_removal(dev->channel, relid);

	}

	}





	return 0;

	return 0;
@@ -652,7 +640,10 @@ static void vmbus_shutdown(struct device *child_device) 
static void vmbus_device_release(struct device *device)

static void vmbus_device_release(struct device *device)

{

{

	struct hv_device *hv_dev = device_to_hv_device(device);

	struct hv_device *hv_dev = device_to_hv_device(device);

	struct vmbus_channel *channel = hv_dev->channel;





	hv_process_channel_removal(channel,

				   channel->offermsg.child_relid);

	kfree(hv_dev);

	kfree(hv_dev);





}

}