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>

1 files changed, 30 insertions, 0 deletions

diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 466374dbc98f..08eb71a22c14 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -1513,6 +1513,36 @@ init_cached_read_index(struct vmbus_channel *channel)
 }
 
 /*
+ * 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.
  */
 #define VMBUS_PKT_TRAILER       8