Drivers: hv: vmbus: Fix a rescind handling bug

The host can rescind a channel that has been offered to the
guest and once the channel is rescinded, the host does not
respond to any requests on that channel. Deal with the case where
the guest may be blocked waiting for a response from the host.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 25 insertions, 0 deletions

diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index b1e85d24bb4e..0af7e39006c8 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -147,6 +147,29 @@ static const struct {
 	{ HV_RDV_GUID	},
 };
 
+/*
+ * The rescinded channel may be blocked waiting for a response from the host;
+ * take care of that.
+ */
+static void vmbus_rescind_cleanup(struct vmbus_channel *channel)
+{
+	struct vmbus_channel_msginfo *msginfo;
+	unsigned long flags;
+
+
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+
+	list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
+				msglistentry) {
+
+		if (msginfo->waiting_channel == channel) {
+			complete(&msginfo->waitevent);
+			break;
+		}
+	}
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+}
+
 static bool is_unsupported_vmbus_devs(const uuid_le *guid)
 {
 	int i;
@@ -825,6 +848,8 @@ static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr)
 	channel->rescind = true;
 	spin_unlock_irqrestore(&channel->lock, flags);
 
+	vmbus_rescind_cleanup(channel);
+
 	if (channel->device_obj) {
 		if (channel->chn_rescind_callback) {
 			channel->chn_rescind_callback(channel);