[PATCH 08/28] Drivers: hv: Update the ring buffer structure to match win8 functionality

K. Y. Srinivasan
2012-12-01T14:27:38Z

Update the ringbuffer structure to support win8 functionality.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
---
include/linux/hyperv.h | 28 +++++++++++++++++++++-------
1 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index b097bf9..2b54801 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -325,14 +325,28 @@ struct hv_ring_buffer {

u32 interrupt_mask;

- /* Pad it to PAGE_SIZE so that data starts on page boundary */
- u8 reserved[4084];
-
- /* NOTE:
- * The interrupt_mask field is used only for channels but since our
- * vmbus connection also uses this data structure and its data starts
- * here, we commented out this field.
+ /*
+ * Win8 uses some of the reserved bits to implement
+ * interrupt driven flow management. On the send side
+ * we can request that the receiver interrupt the sender
+ * when the ring transitions from being full to being able
+ * to handle a message of size "pending_send_sz".
+ *
+ * Add necessary state for this enhancement.
*/
+ u32 pending_send_sz;
+
+ u32 reserved1[12];
+
+ union {
+ struct {
+ u32 feat_pending_send_sz:1;
+ };
+ u32 value;
+ } feature_bits;
+
+ /* Pad it to PAGE_SIZE so that data starts on page boundary */
+ u8 reserved2[4028];

/*
* Ring data starts here + RingDataStartOffset
--
1.7.4.1