vmbus: expose hv_begin/end_read

In order to implement NAPI in netvsc, the driver needs access to
control host interrupt mask.
Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hv/hyperv_vmbus.h

@@ -292,10 +292,6 @@ int hv_ringbuffer_read(struct vmbus_channel *channel,
 void hv_ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info,
 			    struct hv_ring_buffer_debug_info *debug_info);
 
-void hv_begin_read(struct hv_ring_buffer_info *rbi);
-
-u32 hv_end_read(struct hv_ring_buffer_info *rbi);
-
 /*
  * Maximum channels is determined by the size of the interrupt page
  * which is PAGE_SIZE. 1/2 of PAGE_SIZE is for send endpoint interrupt

drivers/hv/ring_buffer.c

@@ -32,26 +32,6 @@
 
 #include "hyperv_vmbus.h"
 
-void hv_begin_read(struct hv_ring_buffer_info *rbi)
-{
-	rbi->ring_buffer->interrupt_mask = 1;
-	virt_mb();
-}
-
-u32 hv_end_read(struct hv_ring_buffer_info *rbi)
-{
-
-	rbi->ring_buffer->interrupt_mask = 0;
-	virt_mb();
-
-	/*
-	 * Now check to see if the ring buffer is still empty.
-	 * If it is not, we raced and we need to process new
-	 * incoming messages.
-	 */
-	return hv_get_bytes_to_read(rbi);
-}
-
 /*
  * When we write to the ring buffer, check if the host needs to
  * be signaled. Here is the details of this protocol:

include/linux/hyperv.h

@@ -1512,6 +1512,36 @@ init_cached_read_index(struct vmbus_channel *channel)
 	rbi->cached_read_index = rbi->ring_buffer->read_index;
 }
 
+/*
+ * Mask off host interrupt callback notifications
+ */
+static inline void hv_begin_read(struct hv_ring_buffer_info *rbi)
+{
+	rbi->ring_buffer->interrupt_mask = 1;
+
+	/* make sure mask update is not reordered */
+	virt_mb();
+}
+
+/*
+ * Re-enable host callback and return number of outstanding bytes
+ */
+static inline u32 hv_end_read(struct hv_ring_buffer_info *rbi)
+{
+
+	rbi->ring_buffer->interrupt_mask = 0;
+
+	/* make sure mask update is not reordered */
+	virt_mb();
+
+	/*
+	 * Now check to see if the ring buffer is still empty.
+	 * If it is not, we raced and we need to process new
+	 * incoming messages.
+	 */
+	return hv_get_bytes_to_read(rbi);
+}
+
 /*
  * An API to support in-place processing of incoming VMBUS packets.
  */