Drivers: hv: vmbus: Give control over how the ring access is serialized

On the channel send side, many of the VMBUS
device drivers explicity serialize access to the
outgoing ring buffer. Give more control to the
VMBUS device drivers in terms how to serialize
accesss to the outgoing ring buffer.
The default behavior will be to aquire the
ring lock to preserve the current behavior.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index c056f05..d23dab0 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -811,8 +811,24 @@
 	 * signaling control.
 	 */
 	enum hv_signal_policy  signal_policy;
+	/*
+	 * On the channel send side, many of the VMBUS
+	 * device drivers explicity serialize access to the
+	 * outgoing ring buffer. Give more control to the
+	 * VMBUS device drivers in terms how to serialize
+	 * accesss to the outgoing ring buffer.
+	 * The default behavior will be to aquire the
+	 * ring lock to preserve the current behavior.
+	 */
+	bool acquire_ring_lock;
+
 };
 
+static inline void set_channel_lock_state(struct vmbus_channel *c, bool state)
+{
+	c->acquire_ring_lock = state;
+}
+
 static inline bool is_hvsock_channel(const struct vmbus_channel *c)
 {
 	return !!(c->offermsg.offer.chn_flags &