From 7095a53d320f8b409bc8f6a844d97bebfe0f7ca3 Mon Sep 17 00:00:00 2001
From: "K. Y. Srinivasan" <kys@microsoft.com>
Date: Sat, 1 Dec 2012 06:46:32 -0800
Subject: [PATCH] --- yaml --- r: 354975 b: refs/heads/master c:
 6fdf3b21433e901dcba0ac186f00d604ce944f56 h: refs/heads/master i:   354973:
 dc8867f68486ab963c4ea3a8eccfff44106e0000   354971:
 9c6ed27c391862801d5cb045ec3364ca27d16d22   354967:
 7ba0716d804c6a7a3c2ce0312d56cdb444fb5cca   354959:
 a3ed94f9073f7658d5101b5c53e54df52701e36d   354943:
 c6895ebc13914748f5340350994c4020ba3cc58b v: v3

---
 [refs]                          |  2 +-
 trunk/drivers/hv/hyperv_vmbus.h |  4 ++++
 trunk/drivers/hv/ring_buffer.c  | 24 ++++++++++++++++++++++++
 3 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index ab0d486b4d52..e3ef283c86b3 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 0bffd25ce919f88ea6473150b66d26e7fa5712af
+refs/heads/master: 6fdf3b21433e901dcba0ac186f00d604ce944f56
diff --git a/trunk/drivers/hv/hyperv_vmbus.h b/trunk/drivers/hv/hyperv_vmbus.h
index d8d1fadb398a..3184f6ff4e74 100644
--- a/trunk/drivers/hv/hyperv_vmbus.h
+++ b/trunk/drivers/hv/hyperv_vmbus.h
@@ -570,6 +570,10 @@ u32 hv_get_ringbuffer_interrupt_mask(struct hv_ring_buffer_info *ring_info);
 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
diff --git a/trunk/drivers/hv/ring_buffer.c b/trunk/drivers/hv/ring_buffer.c
index 7233c88f01b8..001079287709 100644
--- a/trunk/drivers/hv/ring_buffer.c
+++ b/trunk/drivers/hv/ring_buffer.c
@@ -29,6 +29,30 @@
 
 #include "hyperv_vmbus.h"
 
+void hv_begin_read(struct hv_ring_buffer_info *rbi)
+{
+	rbi->ring_buffer->interrupt_mask = 1;
+	smp_mb();
+}
+
+u32 hv_end_read(struct hv_ring_buffer_info *rbi)
+{
+	u32 read;
+	u32 write;
+
+	rbi->ring_buffer->interrupt_mask = 0;
+	smp_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.
+	 */
+	hv_get_ringbuffer_availbytes(rbi, &read, &write);
+
+	return read;
+}
+
 
 /*
  * hv_get_next_write_location()