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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: Dexuan Cui <decui@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Dexuan Cui 2015-12-14 16:01:49 -08:00 committed by Greg Kroah-Hartman
parent 64b7faf903
commit 34c6801e33
3 changed files with 6 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/hv/channel.c
View File

@ -575,12 +575,6 @@ static int vmbus_close_internal(struct vmbus_channel *channel)
free_pages((unsigned long)channel->ringbuffer_pages,
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* If the channel has been rescinded; process device removal.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:
tasklet_enable(tasklet);

6
drivers/hv/channel_mgmt.c
View File

@ -191,6 +191,8 @@ void hv_process_channel_removal(struct vmbus_channel *channel, u32 relid)
if (channel == NULL)
return;
BUG_ON(!channel->rescind);
if (channel->target_cpu != get_cpu()) {
put_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,
listentry) {
/* if we don't set rescind to true, vmbus_close_internal()
* won't invoke hv_process_channel_removal().
*/
/* hv_process_channel_removal() needs this */
channel->rescind = true;
vmbus_device_unregister(channel->device_obj);

15
drivers/hv/vmbus_drv.c
View File

@ -601,23 +601,11 @@ static int vmbus_remove(struct device *child_device)
{
struct hv_driver *drv;
struct hv_device *dev = device_to_hv_device(child_device);
u32 relid = dev->channel->offermsg.child_relid;
if (child_device->driver) {
drv = drv_to_hv_drv(child_device->driver);
if (drv->remove)
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;
@ -652,7 +640,10 @@ static void vmbus_shutdown(struct device *child_device)
static void vmbus_device_release(struct 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);
}