[PATCH 4.8 17/96] hv: acquire vmbus_connection.channel_mutex in vmbus_free_channels()

From: Greg Kroah-Hartman
Date: Fri Jan 06 2017 - 18:07:38 EST


4.8-stable review patch. If anyone has any objections, please let me know.

------------------

From: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>

commit abd1026da4a7700a8db370947f75cd17b6ae6f76 upstream.

"kernel BUG at drivers/hv/channel_mgmt.c:350!" is observed when hv_vmbus
module is unloaded. BUG_ON() was introduced in commit 85d9aa705184
("Drivers: hv: vmbus: add an API vmbus_hvsock_device_unregister()") as
vmbus_free_channels() codepath was apparently forgotten.

Fixes: 85d9aa705184 ("Drivers: hv: vmbus: add an API vmbus_hvsock_device_unregister()")

Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/hv/channel_mgmt.c | 2 ++
1 file changed, 2 insertions(+)

--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -348,6 +348,7 @@ void vmbus_free_channels(void)
{
struct vmbus_channel *channel, *tmp;

+ mutex_lock(&vmbus_connection.channel_mutex);
list_for_each_entry_safe(channel, tmp, &vmbus_connection.chn_list,
listentry) {
/* hv_process_channel_removal() needs this */
@@ -355,6 +356,7 @@ void vmbus_free_channels(void)

vmbus_device_unregister(channel->device_obj);
}
+ mutex_unlock(&vmbus_connection.channel_mutex);
}

/*