[PATCH 3/5] Drivers: hv: vmbus: Fix a bug in hv_need_to_signal_on_read()

[K. Y. Srinivasan]

We need to issue a full memory barrier prior making a signalling decision.

Signed-off-by: K. Y. Srinivasan <kys at microsoft.com>
Cc: stable at vger.kernel.org
---
 drivers/hv/ring_buffer.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index 2919395..67dc245 100644
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -104,6 +104,7 @@ static bool hv_need_to_signal_on_read(struct hv_ring_buffer_info *rbi)
 	u32 cur_write_sz;
 	u32 pending_sz;
 
+	mb();
 	pending_sz = READ_ONCE(rbi->ring_buffer->pending_send_sz);
 	/* If the other end is not blocked on write don't bother. */
 	if (pending_sz == 0)
-- 
1.7.4.1