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>

diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index 00e1be7..77d2579 100644 (file)
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -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-        * If the channel has been rescinded; process device removal.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);
 

diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index dc4fb0b..7903acc 100644 (file)
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -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);

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index ab888a1..f123bca 100644 (file)
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -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);
 
 }