From 34c6801e3310ad286c7bb42bc88d42926b8f99bf Mon Sep 17 00:00:00 2001 From: Dexuan Cui Date: Mon, 14 Dec 2015 16:01:49 -0800 Subject: 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 Signed-off-by: K. Y. Srinivasan Signed-off-by: Greg Kroah-Hartman --- drivers/hv/channel_mgmt.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'drivers/hv/channel_mgmt.c') diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c index dc4fb0bccb8d..7903acc3403e 100644 --- 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); -- cgit v1.2.3